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Orndorff PB, van der Vaart A. Systematic assessment of the flexibility of uracil damaged DNA. J Biomol Struct Dyn 2024; 42:3958-3968. [PMID: 37261803 DOI: 10.1080/07391102.2023.2217683] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2023] [Accepted: 05/17/2023] [Indexed: 06/02/2023]
Abstract
Uracil is a common DNA lesion which is recognized and removed by uracil DNA-glycosylase (UDG) as a part of the base excision repair pathway. Excision proceeds by base flipping, and UDG efficiency is thought to depend on the ease of deformability of the bases neighboring the lesion. We used molecular dynamics simulations to assess the flexibility of a large library of dsDNA strands, containing all tetranucleotide motifs with U:A, U:G, T:A or C:G base pairs. Our study demonstrates that uracil damaged DNA largely follows trends in flexibility of undamaged DNA. Measured bending persistence lengths, groove widths, step parameters and base flipping propensities demonstrate that uracil increases the flexibility of DNA, and that U:G base paired strands are more flexible than U:A strands. Certain sequence contexts are more deformable than others, with a key role for the 3' base next to uracil. Flexibilities are large when this base is an A or G, and repressed for a C or T. A 5' T adjacent to the uracil strongly promotes flexibility, but other 5' bases are less influential. DNA bending is correlated to step deformations and base flipping, and bending aids flipping. Our study implies that the link between substrate flexibility and UDG efficiency is widely valid, helps explain why UDG prefers to bind U:G base paired strands, and suggests that the DNA bending angle of the UDG-substrate complex is optimal for base flipping.Communicated by Ramaswamy H. Sarma.
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Affiliation(s)
- Paul B Orndorff
- Department of Chemistry, University of South Florida, Tampa, Florida, USA
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2
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He Y, Zhou X, Chang C, Chen G, Liu W, Li G, Fan X, Sun M, Miao C, Huang Q, Ma Y, Yuan F, Chang X. Protein language models-assisted optimization of a uracil-N-glycosylase variant enables programmable T-to-G and T-to-C base editing. Mol Cell 2024; 84:1257-1270.e6. [PMID: 38377993 DOI: 10.1016/j.molcel.2024.01.021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2023] [Revised: 12/20/2023] [Accepted: 01/24/2024] [Indexed: 02/22/2024]
Abstract
Current base editors (BEs) use DNA deaminases, including cytidine deaminase in cytidine BE (CBE) or adenine deaminase in adenine BE (ABE), to facilitate transition nucleotide substitutions. Combining CBE or ABE with glycosylase enzymes can induce limited transversion mutations. Nonetheless, a critical demand remains for BEs capable of generating alternative mutation types, such as T>G corrections. In this study, we leveraged pre-trained protein language models to optimize a uracil-N-glycosylase (UNG) variant with altered specificity for thymines (eTDG). Notably, after two rounds of testing fewer than 50 top-ranking variants, more than 50% exhibited over 1.5-fold enhancement in enzymatic activities. When eTDG was fused with nCas9, it induced programmable T-to-S (G/C) substitutions and corrected db/db diabetic mutation in mice (up to 55%). Our findings not only establish orthogonal strategies for developing novel BEs but also demonstrate the capacities of protein language models for optimizing enzymes without extensive task-specific training data.
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Affiliation(s)
- Yan He
- Fudan University, 220 Handan Road, Shanghai 200433, China; School of Medicine, Westlake University, Hangzhou, Zhejiang 310014, China; School of Life Sciences, Westlake University, Hangzhou, Zhejiang 310014, China; Research Center for Industries of the Future (RCIF), Westlake University, Hangzhou, Zhejiang 310014, China; Institute of Basic Medical Sciences, Westlake Institute for Advanced Study, Hangzhou, Zhejiang 310014, China; Westlake Center for Genome Editing, Westlake Laboratory of Life Sciences and Biomedicine, Westlake University, 18 Shilongshan Road, Hangzhou, Zhejiang 310024, China
| | - Xibin Zhou
- School of Engineering, Westlake University, Hangzhou, Zhejiang 310014, China
| | - Chong Chang
- School of Medicine, Westlake University, Hangzhou, Zhejiang 310014, China; School of Life Sciences, Westlake University, Hangzhou, Zhejiang 310014, China; Research Center for Industries of the Future (RCIF), Westlake University, Hangzhou, Zhejiang 310014, China; Institute of Basic Medical Sciences, Westlake Institute for Advanced Study, Hangzhou, Zhejiang 310014, China; Westlake Center for Genome Editing, Westlake Laboratory of Life Sciences and Biomedicine, Westlake University, 18 Shilongshan Road, Hangzhou, Zhejiang 310024, China
| | - Ge Chen
- School of Medicine, Westlake University, Hangzhou, Zhejiang 310014, China; School of Life Sciences, Westlake University, Hangzhou, Zhejiang 310014, China; Research Center for Industries of the Future (RCIF), Westlake University, Hangzhou, Zhejiang 310014, China; Institute of Basic Medical Sciences, Westlake Institute for Advanced Study, Hangzhou, Zhejiang 310014, China; Westlake Center for Genome Editing, Westlake Laboratory of Life Sciences and Biomedicine, Westlake University, 18 Shilongshan Road, Hangzhou, Zhejiang 310024, China
| | - Weikuan Liu
- Fudan University, 220 Handan Road, Shanghai 200433, China; School of Medicine, Westlake University, Hangzhou, Zhejiang 310014, China; School of Life Sciences, Westlake University, Hangzhou, Zhejiang 310014, China; Research Center for Industries of the Future (RCIF), Westlake University, Hangzhou, Zhejiang 310014, China; Institute of Basic Medical Sciences, Westlake Institute for Advanced Study, Hangzhou, Zhejiang 310014, China; Westlake Center for Genome Editing, Westlake Laboratory of Life Sciences and Biomedicine, Westlake University, 18 Shilongshan Road, Hangzhou, Zhejiang 310024, China
| | - Geng Li
- School of Medicine, Westlake University, Hangzhou, Zhejiang 310014, China; School of Life Sciences, Westlake University, Hangzhou, Zhejiang 310014, China; Research Center for Industries of the Future (RCIF), Westlake University, Hangzhou, Zhejiang 310014, China; Institute of Basic Medical Sciences, Westlake Institute for Advanced Study, Hangzhou, Zhejiang 310014, China; Westlake Center for Genome Editing, Westlake Laboratory of Life Sciences and Biomedicine, Westlake University, 18 Shilongshan Road, Hangzhou, Zhejiang 310024, China
| | - Xiaoqi Fan
- School of Medicine, Westlake University, Hangzhou, Zhejiang 310014, China; School of Life Sciences, Westlake University, Hangzhou, Zhejiang 310014, China; Research Center for Industries of the Future (RCIF), Westlake University, Hangzhou, Zhejiang 310014, China; Institute of Basic Medical Sciences, Westlake Institute for Advanced Study, Hangzhou, Zhejiang 310014, China; Westlake Center for Genome Editing, Westlake Laboratory of Life Sciences and Biomedicine, Westlake University, 18 Shilongshan Road, Hangzhou, Zhejiang 310024, China
| | - Mingsun Sun
- School of Medicine, Westlake University, Hangzhou, Zhejiang 310014, China; School of Life Sciences, Westlake University, Hangzhou, Zhejiang 310014, China; Research Center for Industries of the Future (RCIF), Westlake University, Hangzhou, Zhejiang 310014, China; Institute of Basic Medical Sciences, Westlake Institute for Advanced Study, Hangzhou, Zhejiang 310014, China; Westlake Center for Genome Editing, Westlake Laboratory of Life Sciences and Biomedicine, Westlake University, 18 Shilongshan Road, Hangzhou, Zhejiang 310024, China
| | - Chensi Miao
- School of Medicine, Westlake University, Hangzhou, Zhejiang 310014, China; School of Life Sciences, Westlake University, Hangzhou, Zhejiang 310014, China; Research Center for Industries of the Future (RCIF), Westlake University, Hangzhou, Zhejiang 310014, China; Institute of Basic Medical Sciences, Westlake Institute for Advanced Study, Hangzhou, Zhejiang 310014, China; Westlake Center for Genome Editing, Westlake Laboratory of Life Sciences and Biomedicine, Westlake University, 18 Shilongshan Road, Hangzhou, Zhejiang 310024, China
| | - Qianyue Huang
- School of Medicine, Westlake University, Hangzhou, Zhejiang 310014, China; School of Life Sciences, Westlake University, Hangzhou, Zhejiang 310014, China; Research Center for Industries of the Future (RCIF), Westlake University, Hangzhou, Zhejiang 310014, China; Institute of Basic Medical Sciences, Westlake Institute for Advanced Study, Hangzhou, Zhejiang 310014, China; Westlake Center for Genome Editing, Westlake Laboratory of Life Sciences and Biomedicine, Westlake University, 18 Shilongshan Road, Hangzhou, Zhejiang 310024, China
| | - Yunqing Ma
- School of Medicine, Westlake University, Hangzhou, Zhejiang 310014, China; School of Life Sciences, Westlake University, Hangzhou, Zhejiang 310014, China; Research Center for Industries of the Future (RCIF), Westlake University, Hangzhou, Zhejiang 310014, China; Institute of Basic Medical Sciences, Westlake Institute for Advanced Study, Hangzhou, Zhejiang 310014, China; Westlake Center for Genome Editing, Westlake Laboratory of Life Sciences and Biomedicine, Westlake University, 18 Shilongshan Road, Hangzhou, Zhejiang 310024, China
| | - Fajie Yuan
- School of Engineering, Westlake University, Hangzhou, Zhejiang 310014, China.
| | - Xing Chang
- School of Medicine, Westlake University, Hangzhou, Zhejiang 310014, China; School of Life Sciences, Westlake University, Hangzhou, Zhejiang 310014, China; Research Center for Industries of the Future (RCIF), Westlake University, Hangzhou, Zhejiang 310014, China; Institute of Basic Medical Sciences, Westlake Institute for Advanced Study, Hangzhou, Zhejiang 310014, China; Westlake Center for Genome Editing, Westlake Laboratory of Life Sciences and Biomedicine, Westlake University, 18 Shilongshan Road, Hangzhou, Zhejiang 310024, China.
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Guo B, Hu C, Yang Z, Tang C, Zhang C, Wang F. Test strip coupled Cas12a-assisted signal amplification strategy for sensitive detection of uracil-DNA glycosylase. Lab Chip 2024; 24:1987-1995. [PMID: 38372397 DOI: 10.1039/d4lc00096j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/20/2024]
Abstract
Uracil-DNA glycosylase (UDG) is a base excision repair (BER) enzyme, which catalyzes the hydrolysis of uracil bases in DNA chains that contain uracil and N-glycosidic bonds of the sugar phosphate backbone. The expression of UDG enzyme is associated with a variety of genetic diseases including cancers. Hence, the identification of UDG activity in cellular processes holds immense importance for clinical investigation and diagnosis. In this study, we employed Cas12a protein and enzyme-assisted cycle amplification technology with a test strip to establish a precise platform for the detection of UDG enzyme. The designed platform enabled amplifying and releasing the target probe by reacting with the UDG enzyme. The amplified target probe can subsequently fuse with crRNA and Cas12a protein, stimulating the activation of the Cas12a protein to cleave the signal probe, ultimately generating a fluorescent signal. This technique showed the ability for evaluating UDG enzyme activity in different cell lysates. In addition, we have designed a detection probe to convert the fluorescence signal into test strip bands that can then be observed with the naked eye. Hence, our tool presented potential in both biomedical research and clinical diagnosis related to DNA repair enzymes.
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Affiliation(s)
- Bin Guo
- Engineering Research Center of Molecular and Neuro Imaging, Ministry of Education, School of Life Science and Technology, Xidian University, Xi'an 710071, China
| | - Chong Hu
- Engineering Research Center of Molecular and Neuro Imaging, Ministry of Education, School of Life Science and Technology, Xidian University, Xi'an 710071, China
| | - Zeping Yang
- Engineering Research Center of Molecular and Neuro Imaging, Ministry of Education, School of Life Science and Technology, Xidian University, Xi'an 710071, China
| | - Chu Tang
- Engineering Research Center of Molecular and Neuro Imaging, Ministry of Education, School of Life Science and Technology, Xidian University, Xi'an 710071, China
| | - Chuanxian Zhang
- Institute of Medical Engineering, School of Basic Medical Sciences, Xi'an Jiaotong University, Xi'an 710061, China.
| | - Fu Wang
- Engineering Research Center of Molecular and Neuro Imaging, Ministry of Education, School of Life Science and Technology, Xidian University, Xi'an 710071, China
- Institute of Medical Engineering, School of Basic Medical Sciences, Xi'an Jiaotong University, Xi'an 710061, China.
- Xianyang Key Laboratory of Molecular Imaging and Drug Synthesis, School of Pharmacy, Shaanxi Institute of International Trade & Commerce, Xianyang 712046, China
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Liang C, Yang Y, Ning P, Chang C, Cao W. Structural and functional coupling in cross-linking uracil-DNA glycosylase UDGX. Biosci Rep 2024; 44:BSR20231551. [PMID: 38059429 PMCID: PMC10776899 DOI: 10.1042/bsr20231551] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2023] [Revised: 11/14/2023] [Accepted: 12/05/2023] [Indexed: 12/08/2023] Open
Abstract
Enzymes in uracil-DNA glycosylase (UDG) superfamily are involved in removal of deaminated nucleobases such as uracil, methylcytosine derivatives such as formylcytosine and carboxylcytosine, and other base damage in DNA repair. UDGX is the latest addition of a new class to the UDG superfamily with a sporadic distribution in bacteria. UDGX type enzymes have a distinct biochemical property of cross-linking itself to the resulting AP site after uracil removal. Built on previous biochemical and structural analyses, this work comprehensively investigated the kinetic and enzymatic properties of Mycobacterium smegmatis UDGX. Kinetics and mutational analyses, coupled with structural information, defined the roles of E52, D56, D59, F65 of motif 1, H178 of motif 2 and N91, K94, R107 and H109 of motif 3 play in uracil excision and cross-linking. More importantly, a series of quantitative analyses underscored the structural coupling through inter-motif and intra-motif interactions and subsequent functional coupling of the uracil excision and cross-linking reactions. A catalytic model is proposed, which underlies this catalytic feature unique to UDGX type enzymes. This study offers new insight on the catalytic mechanism of UDGX and provides a unique example of enzyme evolution.
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Affiliation(s)
- Chuan Liang
- Department of Genetics and Biochemistry, Clemson University, Room 049 Life Sciences Facility, 190 Collings Street, Clemson, SC 29634, U.S.A
| | - Ye Yang
- Department of Genetics and Biochemistry, Clemson University, Room 049 Life Sciences Facility, 190 Collings Street, Clemson, SC 29634, U.S.A
| | - Ping Ning
- Department of Genetics and Biochemistry, Clemson University, Room 049 Life Sciences Facility, 190 Collings Street, Clemson, SC 29634, U.S.A
| | - Chenyan Chang
- Department of Genetics and Biochemistry, Clemson University, Room 049 Life Sciences Facility, 190 Collings Street, Clemson, SC 29634, U.S.A
| | - Weiguo Cao
- Department of Genetics and Biochemistry, Clemson University, Room 049 Life Sciences Facility, 190 Collings Street, Clemson, SC 29634, U.S.A
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Hayran AB, Liabakk NB, Aas PA, Kusnierczyk A, Vågbø CB, Sarno A, Iveland TS, Chawla K, Zahn A, Di Noia JM, Slupphaug G, Kavli B. RPA guides UNG to uracil in ssDNA to facilitate antibody class switching and repair of mutagenic uracil at the replication fork. Nucleic Acids Res 2024; 52:784-800. [PMID: 38000394 PMCID: PMC10810282 DOI: 10.1093/nar/gkad1115] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 10/27/2023] [Accepted: 11/06/2023] [Indexed: 11/26/2023] Open
Abstract
Activation-induced cytidine deaminase (AID) interacts with replication protein A (RPA), the major ssDNA-binding protein, to promote deamination of cytosine to uracil in transcribed immunoglobulin (Ig) genes. Uracil-DNA glycosylase (UNG) acts in concert with AID during Ig diversification. In addition, UNG preserves genome integrity by base-excision repair (BER) in the overall genome. How UNG is regulated to support both mutagenic processing and error-free repair remains unknown. UNG is expressed as two isoforms, UNG1 and UNG2, which both contain an RPA-binding helix that facilitates uracil excision from RPA-coated ssDNA. However, the impact of this interaction in antibody diversification and genome maintenance has not been investigated. Here, we generated B-cell clones with targeted mutations in the UNG RPA-binding motif, and analysed class switch recombination (CSR), mutation frequency (5' Ig Sμ), and genomic uracil in clones representing seven Ung genotypes. We show that the UNG:RPA interaction plays a crucial role in both CSR and repair of AID-induced uracil at the Ig loci. By contrast, the interaction had no significant impact on total genomic uracil levels. Thus, RPA coordinates UNG during CSR and pre-replicative repair of mutagenic uracil in ssDNA but is not essential in post-replicative and canonical BER of uracil in dsDNA.
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Affiliation(s)
- Abdul B Hayran
- Department of Clinical and Molecular Medicine, NTNU Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
| | - Nina B Liabakk
- Department of Clinical and Molecular Medicine, NTNU Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
| | - Per A Aas
- Department of Clinical and Molecular Medicine, NTNU Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
| | - Anna Kusnierczyk
- Department of Clinical and Molecular Medicine, NTNU Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
- PROMEC - Proteomics and Modomics Experimental Core Facility at NTNU and the Central Norway Regional Health Authority, NO-7491 Trondheim, Norway
| | - Cathrine B Vågbø
- Department of Clinical and Molecular Medicine, NTNU Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
- PROMEC - Proteomics and Modomics Experimental Core Facility at NTNU and the Central Norway Regional Health Authority, NO-7491 Trondheim, Norway
| | - Antonio Sarno
- Department of Clinical and Molecular Medicine, NTNU Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
| | - Tobias S Iveland
- Department of Clinical and Molecular Medicine, NTNU Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
- Cancer Clinic, St. Olav's Hospital, Trondheim University Hospital, NO-7006 Trondheim, Norway
| | - Konika Chawla
- Department of Clinical and Molecular Medicine, NTNU Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
- BioCore - Bioinformatics Core Facility at NTNU and the Central Norway Regional Health Authority, NO-7491 Trondheim, Norway
| | - Astrid Zahn
- Institut de Recherches Cliniques de Montréal, 110 Av des Pins Ouest, Montréal, QC H2W 1R7, Canada
| | - Javier M Di Noia
- Institut de Recherches Cliniques de Montréal, 110 Av des Pins Ouest, Montréal, QC H2W 1R7, Canada
- Département of Médicine, Université de Montréal H3C 3J7 Montréal, Québec, Canada
| | - Geir Slupphaug
- Department of Clinical and Molecular Medicine, NTNU Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
- PROMEC - Proteomics and Modomics Experimental Core Facility at NTNU and the Central Norway Regional Health Authority, NO-7491 Trondheim, Norway
- Clinic of Laboratory Medicine, St. Olav's Hospital, Trondheim University Hospital, NO-7006 Trondheim, Norway
| | - Bodil Kavli
- Department of Clinical and Molecular Medicine, NTNU Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
- Clinic of Laboratory Medicine, St. Olav's Hospital, Trondheim University Hospital, NO-7006 Trondheim, Norway
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Smith KR, Paul S, Dong Q, Anannya O, Oldenburg DG, Forrest JC, McBride KM, Krug LT. Uracil-DNA glycosylase of murine gammaherpesvirus 68 binds cognate viral replication factors independently of its catalytic residues. mSphere 2023; 8:e0027823. [PMID: 37747202 PMCID: PMC10597349 DOI: 10.1128/msphere.00278-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2023] [Accepted: 08/03/2023] [Indexed: 09/26/2023] Open
Abstract
Herpesviruses are large double-stranded DNA viruses that encode core replication proteins and accessory factors involved in nucleotide metabolism and DNA repair. Mammalian uracil-DNA glycosylases (UNG) excise deleterious uracil residues from their genomic DNA. Each herpesvirus UNG studied to date has demonstrated conservation of the enzymatic function to excise uracil residues from DNA. We previously reported that a murine gammaherpesvirus (MHV68) with a stop codon in ORF46 (ORF46.stop) that encodes for vUNG was defective in lytic replication and latency in vivo. However, a mutant virus that expressed a catalytically inactive vUNG (ORF46.CM) had no replication defect unless coupled with additional mutations in the catalytic motif of the viral dUTPase (ORF54.CM). The disparate phenotypes observed in the vUNG mutants led us to explore the non-enzymatic properties of vUNG. Immunoprecipitation of vUNG followed by mass spectrometry in MHV68-infected fibroblasts identified a complex comprising the cognate viral DNA polymerase, vPOL, encoded by ORF9, and the viral DNA polymerase processivity factor, vPPF, encoded by ORF59. MHV68 vUNG co-localized with vPOL and vPPF in subnuclear structures consistent with viral replication compartments. In reciprocal co-immunoprecipitations, the vUNG formed a complex with the vPOL and vPPF upon transfection with either factor alone or in combination. Lastly, we determined that key catalytic residues of vUNG are not required for interactions with vPOL and vPPF upon transfection or in the context of infection. We conclude that the vUNG of MHV68 associates with vPOL and vPPF independently of its catalytic activity. IMPORTANCE Gammaherpesviruses encode a uracil-DNA glycosylase (vUNG) that is presumed to excise uracil residues from viral genomes. We previously identified the vUNG enzymatic activity, but not the protein itself, as dispensable for gammaherpesvirus replication in vivo. In this study, we report a non-enzymatic role for the viral UNG of a murine gammaherpesvirus in forming a complex with two key components of the viral DNA replication machinery. Understanding the role of the vUNG in this viral DNA replication complex may inform the development of antiviral drugs that combat gammaherpesvirus-associated cancers.
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Affiliation(s)
- Kyle R. Smith
- HIV and AIDS Malignancy Branch, National Cancer Institute, Bethesda, Maryland, USA
- Department of Microbiology and Immunology, Stony Brook University, Stony Brook, New York, USA
| | - Somnath Paul
- Department of Epigenetics and Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Qiwen Dong
- Molecular and Cellular Biology Program, Stony Brook University, Stony Brook, New York, USA
| | - Orchi Anannya
- Department of Physiology and Biophysics, Molecular and Cellular Biology Program, Stony Brook University, Stony Brook, New York, USA
| | - Darby G. Oldenburg
- Gundersen Medical Foundation, Gunderson Health System, La Crosse, Wisconsin, USA
| | - J. Craig Forrest
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, Arkansas, USA
| | - Kevin M. McBride
- Department of Epigenetics and Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, Houston, Texas, USA
| | - Laurie T. Krug
- HIV and AIDS Malignancy Branch, National Cancer Institute, Bethesda, Maryland, USA
- Department of Microbiology and Immunology, Stony Brook University, Stony Brook, New York, USA
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Torres JR, Lescano López I, Ayala AM, Alvarez ME. The Arabidopsis DNA glycosylase MBD4L repairs the nuclear genome in vivo. Plant J 2023; 115:1633-1646. [PMID: 37278489 DOI: 10.1111/tpj.16344] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Accepted: 06/02/2023] [Indexed: 06/07/2023]
Abstract
DNA glycosylases remove mispaired or modified bases from DNA initiating the base excision repair (BER) pathway. The DNA glycosylase MBD4 (methyl-CpG-binding domain protein 4) has been functionally characterized in mammals, but not yet in plants, where it is called MBD4-like (MBD4L). Mammalian MBD4 and Arabidopsis recombinant MBD4L excise U and T mispaired with G, as well as 5-fluorouracil (5-FU) and 5-bromouracil (5-BrU) in vitro. Here, we investigate the ability of Arabidopsis MBD4L to remove some of these substrates from the nuclear genome in vivo in coordination with uracil DNA glycosylase (AtUNG). We found that mbd4l mutants are hypersensitive to 5-FU and 5-BrU, as they displayed smaller size, less root growth, and higher cell death than control plants in both media. Using comet assays, we determined BER-associated DNA fragmentation in isolated nuclei and observed reduced DNA breaks in mbd4l plants under both conditions, but particularly with 5-BrU. The use of ung and ung x mbd4l mutants in these assays indicated that both MBD4L and AtUNG trigger nuclear DNA fragmentation in response to 5-FU. Consistently, we here report the nuclear localization of AtUNG based on the expression of AtUNG-GFP/RFP constructs in transgenic plants. Interestingly, MBD4L and AtUNG are transcriptionally coordinated but display not completely overlapping functions. MBD4L-deficient plants showed reduced expression of BER genes and enhanced expression of DNA damage response (DDR) gene markers. Overall, our findings indicate that Arabidopsis MBD4L is critical for maintaining nuclear genome integrity and preventing cell death under genotoxic stress conditions.
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Affiliation(s)
- José Roberto Torres
- Centro de Investigaciones en Química Biológica de Córdoba, CIQUIBIC, CONICET, Departamento de Química Biológica Ranwel Caputto, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Haya de la Torre y Medina Allende, Ciudad Universitaria, Córdoba, X5000HUA, Argentina
| | - Ignacio Lescano López
- Centro de Investigaciones en Química Biológica de Córdoba, CIQUIBIC, CONICET, Departamento de Química Biológica Ranwel Caputto, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Haya de la Torre y Medina Allende, Ciudad Universitaria, Córdoba, X5000HUA, Argentina
| | - Ana María Ayala
- Centro de Investigaciones en Química Biológica de Córdoba, CIQUIBIC, CONICET, Departamento de Química Biológica Ranwel Caputto, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Haya de la Torre y Medina Allende, Ciudad Universitaria, Córdoba, X5000HUA, Argentina
| | - María Elena Alvarez
- Centro de Investigaciones en Química Biológica de Córdoba, CIQUIBIC, CONICET, Departamento de Química Biológica Ranwel Caputto, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Haya de la Torre y Medina Allende, Ciudad Universitaria, Córdoba, X5000HUA, Argentina
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8
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Buckley RJ, Lou‐Hing A, Hanson KM, Ahmed NR, Cooper CDO, Bolt EL. Escherichia coli DNA repair helicase Lhr is also a uracil-DNA glycosylase. Mol Microbiol 2023; 120:298-306. [PMID: 37452011 PMCID: PMC10953399 DOI: 10.1111/mmi.15123] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2023] [Revised: 06/24/2023] [Accepted: 06/27/2023] [Indexed: 07/18/2023]
Abstract
DNA glycosylases protect genetic fidelity during DNA replication by removing potentially mutagenic chemically damaged DNA bases. Bacterial Lhr proteins are well-characterized DNA repair helicases that are fused to additional 600-700 amino acids of unknown function, but with structural homology to SecB chaperones and AlkZ DNA glycosylases. Here, we identify that Escherichia coli Lhr is a uracil-DNA glycosylase (UDG) that depends on an active site aspartic acid residue. We show that the Lhr DNA helicase activity is functionally independent of the UDG activity, but that the helicase domains are required for fully active UDG activity. Consistent with UDG activity, deletion of lhr from the E. coli chromosome sensitized cells to oxidative stress that triggers cytosine deamination to uracil. The ability of Lhr to translocate single-stranded DNA and remove uracil bases suggests a surveillance role to seek and remove potentially mutagenic base changes during replication stress.
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Affiliation(s)
| | - Anna Lou‐Hing
- School of Life SciencesUniversity of NottinghamNottinghamUK
| | - Karl M. Hanson
- School of Biological and Geographical Sciences, School of Applied SciencesUniversity of HuddersfieldHuddersfieldUK
| | - Nadia R. Ahmed
- School of Biological and Geographical Sciences, School of Applied SciencesUniversity of HuddersfieldHuddersfieldUK
| | - Christopher D. O. Cooper
- School of Biological and Geographical Sciences, School of Applied SciencesUniversity of HuddersfieldHuddersfieldUK
- CHARM Therapeutics LtdB900 Babraham Research CampusCambridgeUK
| | - Edward L. Bolt
- School of Life SciencesUniversity of NottinghamNottinghamUK
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9
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Mu Y, Zelazowska MA, Chen Z, Plummer JB, Dong Q, Krug LT, McBride KM. Divergent structures of Mammalian and gammaherpesvirus uracil DNA glycosylases confer distinct DNA binding and substrate activity. DNA Repair (Amst) 2023; 128:103515. [PMID: 37315375 PMCID: PMC10441670 DOI: 10.1016/j.dnarep.2023.103515] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Revised: 05/21/2023] [Accepted: 05/30/2023] [Indexed: 06/16/2023]
Abstract
Uracil DNA glycosylase (UNG) removes mutagenic uracil base from DNA to initiate base excision repair (BER). The result is an abasic site (AP site) that is further processed by the high-fidelity BER pathway to complete repair and maintain genome integrity. The gammaherpesviruses (GHVs), human Kaposi sarcoma herpesvirus (KSHV), Epstein-Barr virus (EBV), and murine gammaherpesvirus 68 (MHV68) encode functional UNGs that have a role in viral genome replication. Mammalian and GHVs UNG share overall structure and sequence similarity except for a divergent amino-terminal domain and a leucine loop motif in the DNA binding domain that varies in sequence and length. To determine if divergent domains contribute to functional differences between GHV and mammalian UNGs, we analyzed their roles in DNA interaction and catalysis. By utilizing chimeric UNGs with swapped domains we found that the leucine loop in GHV, but not mammalian UNGs facilitates interaction with AP sites and that the amino-terminal domain modulates this interaction. We also found that the leucine loop structure contributes to differential UDGase activity on uracil in single- versus double-stranded DNA. Taken together we demonstrate that the GHV UNGs evolved divergent domains from their mammalian counterparts that contribute to differential biochemical properties from their mammalian counterparts.
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Affiliation(s)
- Yunxiang Mu
- Department of Epigenetics and Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, Houston, TX 77054, USA
| | - Monika A Zelazowska
- Department of Epigenetics and Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, Houston, TX 77054, USA
| | - Zaowen Chen
- Department of Epigenetics and Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, Houston, TX 77054, USA
| | - Joshua B Plummer
- Department of Epigenetics and Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, Houston, TX 77054, USA
| | - Qiwen Dong
- Department of Microbiology and Immunology, Stony Brook University, Stony Brook, NY 11794, USA; Molecular and Cellular Biology Program, Stony Brook University, Stony Brook, NY 11794, USA
| | - Laurie T Krug
- Department of Microbiology and Immunology, Stony Brook University, Stony Brook, NY 11794, USA; HIV and AIDS Malignancy Branch, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, MD 20892, USA
| | - Kevin M McBride
- Department of Epigenetics and Molecular Carcinogenesis, The University of Texas MD Anderson Cancer Center, Houston, TX 77054, USA.
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10
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Rioux KL, Delaney S. Ionic strength modulates excision of uracil by SMUG1 from nucleosome core particles. DNA Repair (Amst) 2023; 125:103482. [PMID: 36931160 PMCID: PMC10073303 DOI: 10.1016/j.dnarep.2023.103482] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Revised: 03/04/2023] [Accepted: 03/07/2023] [Indexed: 03/14/2023]
Abstract
Ionic strength affects many cellular processes including the packaging of genetic material in eukaryotes. For example, chromatin fibers are compacted in high ionic strength environments as are the minimal unit of packaging in chromatin, nucleosome core particles (NCPs). Furthermore, ionic strength is known to modulate several aspects of NCP dynamics including transient unwrapping of DNA from the histone protein core, nucleosome gaping, and intra- and internucleosomal interactions of the N-terminal histone tails. Changes in NCP structure may also impact interactions of transcriptional, repair, and other cellular machinery with nucleosomal DNA. One repair process, base excision repair (BER), is impacted by NCP structure and may be further influenced by changes in ionic strength. Here we examine the effects of ionic strength on the initiation of BER using biochemical assays. Using a population of NCPs containing uracil (U) at dozens of geometric locations, excision of U by single-strand selective monofunctional uracil DNA glycosylase (SMUG1) is assessed at higher and lower ionic strengths. SMUG1 has increased excision activity in the lower ionic strength conditions. On duplex DNA, however, SMUG1 activity is largely unaffected by ionic strength except at short incubation times, suggesting that changes in SMUG1 activity are likely due to alterations in NCP structure and dynamics. These results allow us to further understand the cellular role of SMUG1 in a changing ionic environment and broadly contribute to the understanding of BER on chromatin and genomic stability.
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Affiliation(s)
- Katelyn L Rioux
- Department of Chemistry, Brown University, Providence, RI, USA
| | - Sarah Delaney
- Department of Chemistry, Brown University, Providence, RI, USA.
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11
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Lee M, Heo YB, Woo HM. Cytosine base editing in cyanobacteria by repressing archaic Type IV uracil-DNA glycosylase. Plant J 2023; 113:610-625. [PMID: 36565011 DOI: 10.1111/tpj.16074] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/19/2022] [Accepted: 12/19/2022] [Indexed: 06/17/2023]
Abstract
Base editing enables precise gene editing without requiring donor DNA or double-stranded breaks. To facilitate base editing tools, a uracil DNA glycosylase inhibitor (UGI) was fused to cytidine deaminase-Cas nickase to inhibit uracil DNA glycosylase (UDG). Herein, we revealed that the bacteriophage PBS2-derived UGI of the cytosine base editor (CBE) could not inhibit archaic Type IV UDG in oligoploid cyanobacteria. To overcome the limitation of the CBE, dCas12a-assisted gene repression of the udg allowed base editing at the desired targets with up to 100% mutation frequencies, and yielded correct phenotypes of desired mutants in cyanobacteria. Compared with the original CBE (BE3), base editing was analyzed within a broader C4-C16 window with a strong TC-motif preference. Using multiplexed CyanoCBE, while udg was repressed, simultaneous base editing at two different sites was achieved with lower mutation frequencies than single CBE. Our discovery of a Type IV UDG that is not inhibited by the UGI of the CBE in cyanobacteria and the development of dCas12a-mediated base editing should facilitate the application of base editing not only in cyanobacteria, but also in archaea and green algae that possess Type IV UDGs. We revealed the bacteriophage-derived UGI of the base editor did not repress Type IV UDG in cyanobacteria. To overcome the limitation, orthogonal dCas12a interference was successfully applied to repress the UDG gene expression in cyanobacteria during base editing occurred, yielding a premature translational termination at desired targets. This study will open a new opportunity to perform base editing with Type IV UDGs in archaea and green algae.
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Affiliation(s)
- Mieun Lee
- Department of Food Science and Biotechnology, Sungkyunkwan University (SKKU), 2066 Seobu-ro, Jangan-gu, Suwon, 16419, Republic of Korea
- BioFoundry Research Center, Institute of Biotechnology and Bioengineering, Sungkyunkwan University (SKKU), 2066 Seobu-ro, Jangan-gu, Suwon, 16419, Republic of Korea
| | - Yu Been Heo
- Department of Food Science and Biotechnology, Sungkyunkwan University (SKKU), 2066 Seobu-ro, Jangan-gu, Suwon, 16419, Republic of Korea
- BioFoundry Research Center, Institute of Biotechnology and Bioengineering, Sungkyunkwan University (SKKU), 2066 Seobu-ro, Jangan-gu, Suwon, 16419, Republic of Korea
| | - Han Min Woo
- Department of Food Science and Biotechnology, Sungkyunkwan University (SKKU), 2066 Seobu-ro, Jangan-gu, Suwon, 16419, Republic of Korea
- BioFoundry Research Center, Institute of Biotechnology and Bioengineering, Sungkyunkwan University (SKKU), 2066 Seobu-ro, Jangan-gu, Suwon, 16419, Republic of Korea
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12
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Stewart JA, Bhagwat AS. A redox-sensitive iron-sulfur cluster in murine FAM72A controls its ability to degrade the nuclear form of uracil-DNA glycosylase. DNA Repair (Amst) 2022; 118:103381. [PMID: 35908367 PMCID: PMC10996437 DOI: 10.1016/j.dnarep.2022.103381] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2022] [Revised: 07/19/2022] [Accepted: 07/25/2022] [Indexed: 11/20/2022]
Abstract
Murine FAM72A, mFAM72A, binds the nuclear form of uracil-DNA glycosylase, mUNG2, inhibits its activity and causes its degradation. In immunoprecipitation assays the human paralog, hFAM72A, binds hUNG2 and is a potential anti-cancer drug target because of its high expression in many cancers. Using purified mFAM72A, and mUNG2 proteins we show that mFAM72A binds mUNG2, and the N-terminal 25 amino acids of mUNG2 bind mFAM72A at a nanomolar dissociation constant. We also show that mFAM72A is present throughout the cells, and mUNG2 helps localize it to nuclei. Based on in silico models of mFAM72A-mUNG2 interactions, we constructed several mutants of mFAM72A and found that while they have reduced ability to deplete mUNG2, the mutations also destabilized the former protein. We confirmed that Withaferin A, a predicted lead molecule for the design of FAM72A inhibitors, binds mFAM72A with micromolar affinity but has little affinity to mUNG2. We identified two potential metal-binding sites in mFAM72A and show that one of the sites contains an Fe-S cluster. This redox-sensitive cluster is involved in the mFAM72A-mUNG2 interaction and modulates mFAM72A activity. Hydrogen peroxide treatment of cells increases mUNG2 depletion in a FAM72A-dependent fashion suggesting that mFAM72A activity is redox-sensitive.
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Affiliation(s)
- Jessica A Stewart
- Department of Chemistry, Wayne State University, Detroit, MI 48202, USA
| | - Ashok S Bhagwat
- Department of Chemistry, Wayne State University, Detroit, MI 48202, USA; Department of Biochemistry, Microbiology and Immunology, Wayne State University School of Medicine, Detroit, MI 48201, USA.
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13
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Raj P, Selvam K, Roy K, Mani Tripathi S, Kesharwani S, Gopal B, Varshney U, Sundriyal S. Identification of a new and diverse set of Mycobacterium tuberculosstais uracil-DNA glycosylase (MtUng) inhibitors using structure-based virtual screening: experimental validation and molecular dynamics studies. Bioorg Med Chem Lett 2022; 76:129008. [PMID: 36174837 DOI: 10.1016/j.bmcl.2022.129008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2022] [Revised: 09/18/2022] [Accepted: 09/23/2022] [Indexed: 11/19/2022]
Abstract
Mycobacterium tuberculosis uracil-DNA glycosylase (MtUng), a key DNA repair enzyme, represents an attractive target for the design of new antimycobacterial agents. However, only a limited number of weak MtUng inhibitors are reported, primarily based on the uracil ring, and hence, lack diversity. We report the first structure-based virtual screening (SBVS) using three separate libraries consisting of uracil and non-uracil small molecules, together with the FDA-approved drugs. Twenty diverse virtual hits with the highest predicted binding were procured and screened using a fluorescence-based assay to evaluate their potential to inhibit MtUng. Several of these molecules were found to inhibit MtUng activity at low mM and µM levels, comparable to or better than several other reported Ung inhibitors. Thus, these molecules represent a diverse set of scaffolds for developing next-generation MtUng inhibitors. The most active uracil-based compound 5 (IC50 = 0.14 mM) was found to be ∼15-fold more potent than the positive control, uracil. The binding stability and conformation of compound 5 in complex with the enzyme were further confirmed using molecular dynamics simulation.
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Affiliation(s)
- Prateek Raj
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560012, India
| | - Karthik Selvam
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore 560012, India
| | - Koyel Roy
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore 560012, India
| | - Shailesh Mani Tripathi
- Department of Pharmacy, Birla Institute of Technology and Science Pilani, Pilani Campus, Rajasthan 333031, India
| | - Sharyu Kesharwani
- Department of Pharmacy, Birla Institute of Technology and Science Pilani, Pilani Campus, Rajasthan 333031, India
| | | | - Umesh Varshney
- Department of Microbiology and Cell Biology, Indian Institute of Science, Bangalore 560012, India; Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore 560064, India
| | - Sandeep Sundriyal
- Department of Pharmacy, Birla Institute of Technology and Science Pilani, Pilani Campus, Rajasthan 333031, India.
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14
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Kulkarni RS, Greenwood SN, Weiser BP. Assay design for analysis of human uracil DNA glycosylase. Methods Enzymol 2022; 679:343-362. [PMID: 36682870 DOI: 10.1016/bs.mie.2022.07.033] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Human uracil DNA glycosylase (UNG2) is an enzyme whose primary function is to remove uracil bases from genomic DNA. UNG2 activity is critical when uracil bases are elevated in DNA during class switch recombination and somatic hypermutation, and additionally, UNG2 affects the efficacy of thymidylate synthase inhibitors that increase genomic uracil levels. Here, we summarize the enzymatic properties of UNG2 and its mitochondrial analog UNG1. To facilitate studies on the activity of these highly conserved proteins, we discuss three fluorescence-based enzyme assays that have informed much of our understanding on UNG2 function. The assays use synthetic DNA oligonucleotide substrates with uracil bases incorporated in the DNA, and the substrates can be single-stranded, double-stranded, or form other structures such as DNA hairpins or junctions. The fluorescence signal reporting uracil base excision by UNG2 is detected in different ways: (1) Excision of uracil from end-labeled oligonucleotides is measured by visualizing UNG2 reaction products with denaturing PAGE; (2) Uracil excision from dsDNA substrates is detected in solution by base pairing uracil with 2-aminopurine, whose intrinsic fluorescence is enhanced upon uracil excision; or (3) UNG2 excision of uracil from a hairpin molecular beacon substrate changes the structure of the substrate and turns on fluorescence by relieving a fluorescence quench. In addition to their utility in characterizing UNG2 properties, these assays are being adapted to discover inhibitors of the enzyme and to determine how protein-protein interactions affect UNG2 function.
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Affiliation(s)
- Rashmi S Kulkarni
- Department of Molecular Biology, Rowan University School of Osteopathic Medicine, Stratford, NJ, United States
| | - Sharon N Greenwood
- Department of Molecular Biology, Rowan University School of Osteopathic Medicine, Stratford, NJ, United States
| | - Brian P Weiser
- Department of Molecular Biology, Rowan University School of Osteopathic Medicine, Stratford, NJ, United States.
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15
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Lai MY, Bukhari FDM, Zulkefli NZ, Ismail I, Mustapa NI, Soh TST, Hassan AH, Peariasamy KM, Lee YL, Suppiah J, Thayan R, Lau YL. Colorimetric detection of SARS-CoV-2 by uracil-DNA glycosylase (UDG) reverse transcription loop-mediated isothermal amplification (RT-LAMP). Int J Infect Dis 2022; 120:132-134. [PMID: 35472524 PMCID: PMC9035611 DOI: 10.1016/j.ijid.2022.04.036] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2022] [Revised: 04/01/2022] [Accepted: 04/20/2022] [Indexed: 12/14/2022] Open
Abstract
OBJECTIVES Preventing reverse transcription loop-mediated isothermal amplification (RT-LAMP) carryover contamination could be solved by adding deoxyuridine triphosphate (dUTP) and uracil-DNA glycosylase (UDG) into the reaction master mix. METHODS RNA was extracted from nasopharyngeal swab samples by a simple RNA extraction method. RESULTS Testing of 77 samples demonstrated 91.2% sensitivity (95% confidence interval [CI]: 78-98.2%) and 100% specificity (95% confidence interval: 92-100%) using UDG RT-LAMP. CONCLUSION This colorimetric UDG RT-LAMP is a simple-to-use, fast, and easy-to-interpret method, which could serve as an alternative for diagnosis of SARS-CoV-2 infection, especially in remote hospitals and laboratories with under-equipped medical facilities.
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Affiliation(s)
- Meng Yee Lai
- Department of Parasitology, Faculty of Medicine, Universiti Malaya, 50603 Kuala Lumpur, Malaysia
| | | | - Nur Zulaikha Zulkefli
- Department of Parasitology, Faculty of Medicine, Universiti Malaya, 50603 Kuala Lumpur, Malaysia
| | - Ilyiana Ismail
- Department of Pathology, Hospital Sungai Buloh, Ministry of Health, Malaysia
| | - Nur Izati Mustapa
- Department of Pathology, Hospital Sungai Buloh, Ministry of Health, Malaysia
| | | | - Afifah Haji Hassan
- Department of Pathology, Hospital Sungai Buloh, Ministry of Health, Malaysia
| | - Kalaiarasu M Peariasamy
- Institute for Clinical Research, National Institutes of Health, Ministry of Health, Malaysia
| | - Yee Leng Lee
- Clinical Research Centre, Hospital Sungai Buloh, Ministry of Health, Malaysia
| | - Jeyanthi Suppiah
- Virology Unit, Infectious Disease Research Centre, Institute for Medical Research, National Institutes of Health, Ministry of Health, Malaysia
| | - Ravindran Thayan
- Virology Unit, Infectious Disease Research Centre, Institute for Medical Research, National Institutes of Health, Ministry of Health, Malaysia
| | - Yee Ling Lau
- Department of Parasitology, Faculty of Medicine, Universiti Malaya, 50603 Kuala Lumpur, Malaysia.
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16
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Kitamura K, Fukano K, Que L, Li Y, Wakae K, Muramatsu M. Activities of endogenous APOBEC3s and uracil-DNA-glycosylase affect the hypermutation frequency of hepatitis B virus cccDNA. J Gen Virol 2022; 103. [PMID: 35438620 DOI: 10.1099/jgv.0.001732] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The covalently closed circular DNA (cccDNA) of hepatitis B virus (HBV) plays a key role in the persistence of viral infection. We have previously shown that overexpression of an antiviral factor APOBEC3G (A3G) induces hypermutation in duck HBV (DHBV) cccDNA, whereas uracil-DNA-glycosylase (UNG) reduces these mutations. In this study, using cell-culture systems, we examined whether endogenous A3s and UNG affect HBV cccDNA mutation frequency. IFNγ stimulation induced a significant increase in endogenous A3G expression and cccDNA hypermutation. UNG inhibition enhanced the IFNγ-mediated hypermutation frequency. Transfection of reconstructed cccDNA revealed that this enhanced hypermutation caused a reduction in viral replication. These results suggest that the balance of endogenous A3s and UNG activities affects HBV cccDNA mutation and replication competency.
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Affiliation(s)
- Kouichi Kitamura
- Department of Virology II, National Institute of Infectious Diseases, Murayama branch, 4-7-1 Gakuen, Musashi-murayama, Tokyo 208-0011, Japan
| | - Kento Fukano
- Department of Virology II, National Institute of Infectious Diseases, Murayama branch, 4-7-1 Gakuen, Musashi-murayama, Tokyo 208-0011, Japan
| | - Lusheng Que
- Department of Virology II, National Institute of Infectious Diseases, Murayama branch, 4-7-1 Gakuen, Musashi-murayama, Tokyo 208-0011, Japan
| | - Yingfang Li
- Department of Virology II, National Institute of Infectious Diseases, Murayama branch, 4-7-1 Gakuen, Musashi-murayama, Tokyo 208-0011, Japan
| | - Kousho Wakae
- Department of Virology II, National Institute of Infectious Diseases, Murayama branch, 4-7-1 Gakuen, Musashi-murayama, Tokyo 208-0011, Japan
| | - Masamichi Muramatsu
- Department of Virology II, National Institute of Infectious Diseases, Murayama branch, 4-7-1 Gakuen, Musashi-murayama, Tokyo 208-0011, Japan
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17
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Wang Y, Sun W, Wang J, Wang X, Xu Y, Guo Y, Wang Y, Zhang M, Jiang L, Liu S, Huang J. Ultrasensitive Uracil-DNA Glycosylase Activity Assay and Its Inhibitor Screening Based on Primer Remodeling Jointly via Repair Enzyme and Polymerase. Langmuir 2022; 38:3868-3875. [PMID: 35298179 DOI: 10.1021/acs.langmuir.2c00115] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
The development of isothermal nucleic acid amplification techniques has great significance for highly sensitive biosensing in modern biology and biomedicine. A facile and robust exponential rolling circle amplification (RCA) strategy is proposed based on primer-remodeling amplification jointly via a repair enzyme and polymerase, and uracil-DNA glycosylase (UDG) is selected as a model analyte. Two kinds of complexes, complex I and complex II, are preprepared by hybridizing a circular template (CT) with a uracil-containing hairpin probe and tetrahydrofuran abasic site mimic (AP site)-embedded fluorescence-quenched probe (AFP), respectively. The target UDG specifically binds to complex I, resulting in the generation of an AP site, followed by cleavage via endonuclease IV (Endo IV) and the successive trimming of unmatched 3' terminus via phi29 DNA polymerase, thus producing a useable primer-CT complex that actuates the primary RCA. Then, numerous complex II anneal with the first-generation RCA product (RP), generating a complex II-RP assembly containing AP sites within the DNA duplex. With the aid of Endo IV and phi29, AFP, as a pre-primer in complex II, is converted into a mature primer to initiate additional rounds of RCA. So, countless AFPs are cleaved, releasing remarkably strong fluorescent signals. The biosensor is demonstrated to enable rapid and accurate detection of the UDG activity with an improved detection limit as low as 4.7 × 10-5 U·mL-1. Moreover, this biosensor is successfully applied for UDG inhibitor screening and complicated biological samples analysis. Compared to the previous exponential RCA methods, our proposed strategy offers additional advantages, including excellent stability, optional design of CT, and simplified operating steps. Therefore, this proposed strategy may create a useful and practical platform for ultrasensitive detection of low levels of analytes in clinical diagnosis and fundamental biomedicine research.
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Affiliation(s)
- Yu Wang
- School of Biological Sciences and Technology, University of Jinan, Jinan 250022, P. R. China
| | - Wenyu Sun
- School of Biological Sciences and Technology, University of Jinan, Jinan 250022, P. R. China
| | - Jingfeng Wang
- College of Chemistry and Molecular Sciences, Wuhan University, Wuhan 430072, P. R. China
| | - Xu Wang
- Shandong Institute of Metrology and Science, Jinan 250014, P. R. China
| | - Yicheng Xu
- School of Biological Sciences and Technology, University of Jinan, Jinan 250022, P. R. China
| | - Yuanzhen Guo
- School of Biological Sciences and Technology, University of Jinan, Jinan 250022, P. R. China
| | - Yeru Wang
- School of Biological Sciences and Technology, University of Jinan, Jinan 250022, P. R. China
| | - Manru Zhang
- School of Water Conservancy and Environment, University of Jinan, Jinan 250022, P. R. China
| | - Long Jiang
- School of Water Conservancy and Environment, University of Jinan, Jinan 250022, P. R. China
| | - Su Liu
- School of Water Conservancy and Environment, University of Jinan, Jinan 250022, P. R. China
| | - Jiadong Huang
- School of Biological Sciences and Technology, University of Jinan, Jinan 250022, P. R. China
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18
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Alexeeva M, Moen MN, Xu XM, Rasmussen A, Leiros I, Kirpekar F, Klungland A, Alsøe L, Nilsen H, Bjelland S. Intrinsic Strand-Incision Activity of Human UNG: Implications for Nick Generation in Immunoglobulin Gene Diversification. Front Immunol 2021; 12:762032. [PMID: 35003074 PMCID: PMC8730318 DOI: 10.3389/fimmu.2021.762032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2021] [Accepted: 11/17/2021] [Indexed: 12/05/2022] Open
Abstract
Uracil arises in cellular DNA by cytosine (C) deamination and erroneous replicative incorporation of deoxyuridine monophosphate opposite adenine. The former generates C → thymine transition mutations if uracil is not removed by uracil-DNA glycosylase (UDG) and replaced by C by the base excision repair (BER) pathway. The primary human UDG is hUNG. During immunoglobulin gene diversification in activated B cells, targeted cytosine deamination by activation-induced cytidine deaminase followed by uracil excision by hUNG is important for class switch recombination (CSR) and somatic hypermutation by providing the substrate for DNA double-strand breaks and mutagenesis, respectively. However, considerable uncertainty remains regarding the mechanisms leading to DNA incision following uracil excision: based on the general BER scheme, apurinic/apyrimidinic (AP) endonuclease (APE1 and/or APE2) is believed to generate the strand break by incising the AP site generated by hUNG. We report here that hUNG may incise the DNA backbone subsequent to uracil excision resulting in a 3´-α,β-unsaturated aldehyde designated uracil-DNA incision product (UIP), and a 5´-phosphate. The formation of UIP accords with an elimination (E2) reaction where deprotonation of C2´ occurs via the formation of a C1´ enolate intermediate. UIP is removed from the 3´-end by hAPE1. This shows that the first two steps in uracil BER can be performed by hUNG, which might explain the significant residual CSR activity in cells deficient in APE1 and APE2.
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Affiliation(s)
- Marina Alexeeva
- Department of Chemistry, Bioscience and Environmental Technology, University of Stavanger, Stavanger, Norway
| | - Marivi Nabong Moen
- Department of Chemistry, Bioscience and Environmental Technology, University of Stavanger, Stavanger, Norway
- Department of Microbiology, Oslo University Hospital, Oslo, Norway
| | - Xiang Ming Xu
- Department of Chemistry, Bioscience and Environmental Technology, University of Stavanger, Stavanger, Norway
| | - Anette Rasmussen
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Ingar Leiros
- Department of Chemistry, University of Tromsø-The Arctic University of Norway, Tromsø, Norway
| | - Finn Kirpekar
- Department of Biochemistry and Molecular Biology, University of Southern Denmark, Odense, Denmark
| | - Arne Klungland
- Department of Microbiology, Oslo University Hospital, Oslo, Norway
| | - Lene Alsøe
- Department of Clinical Molecular Biology, University of Oslo, Oslo, Norway
- Section of Clinical Molecular Biology, Akershus University Hospital, Lørenskog, Norway
| | - Hilde Nilsen
- Department of Clinical Molecular Biology, University of Oslo, Oslo, Norway
- Section of Clinical Molecular Biology, Akershus University Hospital, Lørenskog, Norway
- *Correspondence: Svein Bjelland, ; Hilde Nilsen,
| | - Svein Bjelland
- Department of Chemistry, Bioscience and Environmental Technology, University of Stavanger, Stavanger, Norway
- Section of Clinical Molecular Biology, Akershus University Hospital, Lørenskog, Norway
- *Correspondence: Svein Bjelland, ; Hilde Nilsen,
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Taglialatela A, Leuzzi G, Sannino V, Cuella-Martin R, Huang JW, Wu-Baer F, Baer R, Costanzo V, Ciccia A. REV1-Polζ maintains the viability of homologous recombination-deficient cancer cells through mutagenic repair of PRIMPOL-dependent ssDNA gaps. Mol Cell 2021; 81:4008-4025.e7. [PMID: 34508659 PMCID: PMC8500949 DOI: 10.1016/j.molcel.2021.08.016] [Citation(s) in RCA: 71] [Impact Index Per Article: 23.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2020] [Revised: 05/29/2021] [Accepted: 08/11/2021] [Indexed: 12/11/2022]
Abstract
BRCA1/2 mutant tumor cells display an elevated mutation burden, the etiology of which remains unclear. Here, we report that these cells accumulate ssDNA gaps and spontaneous mutations during unperturbed DNA replication due to repriming by the DNA primase-polymerase PRIMPOL. Gap accumulation requires the DNA glycosylase SMUG1 and is exacerbated by depletion of the translesion synthesis (TLS) factor RAD18 or inhibition of the error-prone TLS polymerase complex REV1-Polζ by the small molecule JH-RE-06. JH-RE-06 treatment of BRCA1/2-deficient cells results in reduced mutation rates and PRIMPOL- and SMUG1-dependent loss of viability. Through cellular and animal studies, we demonstrate that JH-RE-06 is preferentially toxic toward HR-deficient cancer cells. Furthermore, JH-RE-06 remains effective toward PARP inhibitor (PARPi)-resistant BRCA1 mutant cells and displays additive toxicity with crosslinking agents or PARPi. Collectively, these studies identify a protective and mutagenic role for REV1-Polζ in BRCA1/2 mutant cells and provide the rationale for using REV1-Polζ inhibitors to treat BRCA1/2 mutant tumors.
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Affiliation(s)
- Angelo Taglialatela
- Department of Genetics and Development, Herbert Irving Comprehensive Cancer Center, Columbia University Irving Medical Center, New York, NY, USA
| | - Giuseppe Leuzzi
- Department of Genetics and Development, Herbert Irving Comprehensive Cancer Center, Columbia University Irving Medical Center, New York, NY, USA
| | - Vincenzo Sannino
- DNA Metabolism Laboratory, IFOM, FIRC Institute for Molecular Oncology, Milan, Italy; Department of Oncology and Hematology-Oncology, University of Milan, Milan, Italy
| | - Raquel Cuella-Martin
- Department of Genetics and Development, Herbert Irving Comprehensive Cancer Center, Columbia University Irving Medical Center, New York, NY, USA
| | - Jen-Wei Huang
- Department of Genetics and Development, Herbert Irving Comprehensive Cancer Center, Columbia University Irving Medical Center, New York, NY, USA
| | - Foon Wu-Baer
- Institute for Cancer Genetics, Department of Pathology & Cell Biology, Herbert Irving Comprehensive Cancer Center, Columbia University Irving Medical Center, New York, NY, USA
| | - Richard Baer
- Institute for Cancer Genetics, Department of Pathology & Cell Biology, Herbert Irving Comprehensive Cancer Center, Columbia University Irving Medical Center, New York, NY, USA
| | - Vincenzo Costanzo
- DNA Metabolism Laboratory, IFOM, FIRC Institute for Molecular Oncology, Milan, Italy; Department of Oncology and Hematology-Oncology, University of Milan, Milan, Italy
| | - Alberto Ciccia
- Department of Genetics and Development, Herbert Irving Comprehensive Cancer Center, Columbia University Irving Medical Center, New York, NY, USA.
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20
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Zhang L, Jiang D, Gan Q, Shi H, Miao L, Gong Y, Oger P. Identification of a novel bifunctional uracil DNA glycosylase from Thermococcus barophilus Ch5. Appl Microbiol Biotechnol 2021; 105:5449-5460. [PMID: 34223949 DOI: 10.1007/s00253-021-11422-8] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2021] [Revised: 05/22/2021] [Accepted: 06/10/2021] [Indexed: 11/25/2022]
Abstract
Genomes of hyperthermophiles are facing a severe challenge due to increased deamination rates of cytosine induced by high temperature, which could be counteracted by base excision repair mediated by uracil DNA glycosylase (UDG) or other repair pathways. Our previous work has shown that the two UDGs (Tba UDG247 and Tba UDG194) encoded by the genome of the hyperthermophilic euryarchaeon Thermococcus barophilus Ch5 can remove uracil from DNA at high temperature. Herein, we provide evidence that Tba UDG247 is a novel bifunctional glycosylase which can excise uracil from DNA and further cleave the phosphodiester bo nd of the generated apurinic/apyrimidinic (AP) site, which has never been described to date. In addition to cleaving uracil-containing DNA, Tba UDG247 can also cleave AP-containing ssDNA although at lower efficiency, thereby suggesting that the enzyme might be involved in repair of AP site in DNA. Kinetic analyses showed that Tba UDG247 displays a faster rate for uracil excision than for AP cleavage, thus suggesting that cleaving AP site by the enzyme is a rate-limiting step for its bifunctionality. Phylogenetic analysis showed that Tba UDG247 is clustered on a separate branch distant from all the reported UDGs. Overall, we designated Tba UDG247 as the prototype of a novel family of bifunctional UDGs. KEY POINTS: We first reported a novel DNA glycosylase with bifunctionality. Tba UDG247 possesses an AP lyase activity.
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Affiliation(s)
- Likui Zhang
- College of Environmental Science and Engineering, Yangzhou University, Yangzhou, China.
- Guangling College, Yangzhou University, Yangzhou, China.
| | - Donghao Jiang
- College of Environmental Science and Engineering, Yangzhou University, Yangzhou, China
| | - Qi Gan
- College of Environmental Science and Engineering, Yangzhou University, Yangzhou, China
| | - Haoqiang Shi
- College of Environmental Science and Engineering, Yangzhou University, Yangzhou, China
| | - Li Miao
- College of Environmental Science and Engineering, Yangzhou University, Yangzhou, China
| | - Yong Gong
- Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, Chinese Academy of Sciences, Guangzhou, China.
| | - Philippe Oger
- Univ Lyon, INSA de Lyon, CNRS UMR 5240, Villeurbanne, France.
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21
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Christenson ES, Gizzi A, Cui J, Egleston M, Seamon KJ, DePasquale M, Orris B, Park BH, Stivers JT. Inhibition of Human Uracil DNA Glycosylase Sensitizes a Large Fraction of Colorectal Cancer Cells to 5-Fluorodeoxyuridine and Raltitrexed but Not Fluorouracil. Mol Pharmacol 2021; 99:412-425. [PMID: 33795350 PMCID: PMC11033954 DOI: 10.1124/molpharm.120.000191] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Accepted: 03/09/2021] [Indexed: 01/22/2023] Open
Abstract
Previous short-hairpin RNA knockdown studies have established that depletion of human uracil DNA glycosylase (hUNG) sensitizes some cell lines to 5-fluorodeoxyuridine (FdU). Here, we selectively inhibit the catalytic activity of hUNG by lentiviral transduction of uracil DNA glycosylase inhibitor protein into a large panel of cancer cell lines under control of a doxycycline-inducible promoter. This induced inhibition strategy better assesses the therapeutic potential of small-molecule targeting of hUNG. In total, 6 of 11 colorectal lines showed 6- to 70-fold increases in FdU potency upon hUNG inhibition ("responsive"). This hUNG-dependent response was not observed with fluorouracil (FU), indicating that FU does not operate through the same DNA repair mechanism as FdU in vitro. Potency of the thymidylate synthase inhibitor raltitrexed (RTX), which elevates deoxyuridine triphosphate levels, was only incrementally enhanced upon hUNG inhibition (<40%), suggesting that responsiveness is associated with incorporation and persistence of FdU in DNA rather than deoxyuridine. The importance of FU/A and FU/G lesions in the toxicity of FdU is supported by the observation that dT supplementation completely rescued the toxic effects of U/A lesions resulting from RTX, but dT only increased the IC50 for FdU, which forms both FU/A and FU/G mismatches. Contrary to previous reports, cellular responsiveness to hUNG inhibition did not correlate with p53 status or thymine DNA glycosylase expression. A model is suggested in which the persistence of FU/A and FU/G base pairs in the absence of hUNG activity elicits an apoptotic DNA damage response in both responsive and nonresponsive colorectal lines. SIGNIFICANCE STATEMENT: The pyrimidine base 5-fluorouracil is a mainstay chemotherapeutic for treatment of advanced colorectal cancer. Here, this study shows that its deoxynucleoside form, 5-fluorodeoxyuridine (FdU), operates by a distinct DNA incorporation mechanism that is strongly potentiated by inhibition of the DNA repair enzyme human uracil DNA glycosylase. The hUNG-dependent mechanism was present in over 50% of colorectal cell lines tested, suggesting that a significant fraction of human cancers may be sensitized to FdU in the presence of a small-molecule hUNG inhibitor.
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Affiliation(s)
- Eric S Christenson
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland (E.S.C., A.G., J.C., M.E., K.J.S., B.O., J.T.S.); Lieber Institute for Brain Development, Baltimore, Maryland (M.D.); and Vanderbilt University Medical Center/Vanderbilt-Ingram Cancer Center, Nashville, Tennessee (B.H.P.)
| | - Anthony Gizzi
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland (E.S.C., A.G., J.C., M.E., K.J.S., B.O., J.T.S.); Lieber Institute for Brain Development, Baltimore, Maryland (M.D.); and Vanderbilt University Medical Center/Vanderbilt-Ingram Cancer Center, Nashville, Tennessee (B.H.P.)
| | - Junru Cui
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland (E.S.C., A.G., J.C., M.E., K.J.S., B.O., J.T.S.); Lieber Institute for Brain Development, Baltimore, Maryland (M.D.); and Vanderbilt University Medical Center/Vanderbilt-Ingram Cancer Center, Nashville, Tennessee (B.H.P.)
| | - Matthew Egleston
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland (E.S.C., A.G., J.C., M.E., K.J.S., B.O., J.T.S.); Lieber Institute for Brain Development, Baltimore, Maryland (M.D.); and Vanderbilt University Medical Center/Vanderbilt-Ingram Cancer Center, Nashville, Tennessee (B.H.P.)
| | - Kyle J Seamon
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland (E.S.C., A.G., J.C., M.E., K.J.S., B.O., J.T.S.); Lieber Institute for Brain Development, Baltimore, Maryland (M.D.); and Vanderbilt University Medical Center/Vanderbilt-Ingram Cancer Center, Nashville, Tennessee (B.H.P.)
| | - Michael DePasquale
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland (E.S.C., A.G., J.C., M.E., K.J.S., B.O., J.T.S.); Lieber Institute for Brain Development, Baltimore, Maryland (M.D.); and Vanderbilt University Medical Center/Vanderbilt-Ingram Cancer Center, Nashville, Tennessee (B.H.P.)
| | - Benjamin Orris
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland (E.S.C., A.G., J.C., M.E., K.J.S., B.O., J.T.S.); Lieber Institute for Brain Development, Baltimore, Maryland (M.D.); and Vanderbilt University Medical Center/Vanderbilt-Ingram Cancer Center, Nashville, Tennessee (B.H.P.)
| | - Ben H Park
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland (E.S.C., A.G., J.C., M.E., K.J.S., B.O., J.T.S.); Lieber Institute for Brain Development, Baltimore, Maryland (M.D.); and Vanderbilt University Medical Center/Vanderbilt-Ingram Cancer Center, Nashville, Tennessee (B.H.P.)
| | - James T Stivers
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, Maryland (E.S.C., A.G., J.C., M.E., K.J.S., B.O., J.T.S.); Lieber Institute for Brain Development, Baltimore, Maryland (M.D.); and Vanderbilt University Medical Center/Vanderbilt-Ingram Cancer Center, Nashville, Tennessee (B.H.P.)
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22
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Fugger K, Bajrami I, Silva Dos Santos M, Young SJ, Kunzelmann S, Kelly G, Hewitt G, Patel H, Goldstone R, Carell T, Boulton SJ, MacRae J, Taylor IA, West SC. Targeting the nucleotide salvage factor DNPH1 sensitizes BRCA-deficient cells to PARP inhibitors. Science 2021; 372:156-165. [PMID: 33833118 PMCID: PMC7610649 DOI: 10.1126/science.abb4542] [Citation(s) in RCA: 59] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2020] [Revised: 12/31/2020] [Accepted: 02/24/2021] [Indexed: 12/13/2022]
Abstract
Mutations in the BRCA1 or BRCA2 tumor suppressor genes predispose individuals to breast and ovarian cancer. In the clinic, these cancers are treated with inhibitors that target poly(ADP-ribose) polymerase (PARP). We show that inhibition of DNPH1, a protein that eliminates cytotoxic nucleotide 5-hydroxymethyl-deoxyuridine (hmdU) monophosphate, potentiates the sensitivity of BRCA-deficient cells to PARP inhibitors (PARPi). Synthetic lethality was mediated by the action of SMUG1 glycosylase on genomic hmdU, leading to PARP trapping, replication fork collapse, DNA break formation, and apoptosis. BRCA1-deficient cells that acquired resistance to PARPi were resensitized by treatment with hmdU and DNPH1 inhibition. Because genomic hmdU is a key determinant of PARPi sensitivity, targeting DNPH1 provides a promising strategy for the hypersensitization of BRCA-deficient cancers to PARPi therapy.
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Affiliation(s)
- Kasper Fugger
- The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK.
| | | | | | | | | | - Geoff Kelly
- MRC Biomedical NMR Centre, The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Graeme Hewitt
- The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Harshil Patel
- The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | | | - Thomas Carell
- Faculty of Chemistry and Pharmacy, Ludwig-Maximilians-Universität München, Butenandtstrasse 5-13, Building F, 81377 Munich, Germany
| | - Simon J Boulton
- The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - James MacRae
- The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Ian A Taylor
- The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK
| | - Stephen C West
- The Francis Crick Institute, 1 Midland Road, London NW1 1AT, UK.
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23
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Alekseeva IV, Bakman AS, Iakovlev DA, Kuznetsov NA, Fedorova OS. [Comparative Analysis of the Activity of the Polymorphic Variants of Human Uracil-DNA-Glycosylases SMUG1 and MBD4]. Mol Biol (Mosk) 2021; 55:277-288. [PMID: 33871441 DOI: 10.31857/s0026898421020026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2020] [Accepted: 10/26/2020] [Indexed: 06/12/2023]
Abstract
The human N-glycosylases SMUG1 and MBD4 catalyze the removal of uracil residues from DNA resulting from cytosine deamination or replication errors. For polymorphic variants of SMUG1 (G90C, P240H, N244S, N248Y) and the MBD4^(cat) catalytic domain (S470L, G507S, R512W, H557D), the structures of enzyme-substrate complexes were obtained by molecular dynamic simulation. It was experimentally found that the SNP variants of SMUG1, N244S and N248Y, had increased catalytic activity compared to the wild-type enzyme, probably due to the acceleration of the dissociation of the enzyme-product complex and an increase in the enzyme turnover rate. All other SNP variants of SMUG1 (G90C, P240H) and MBD4^(cat), in which amino acid substitutions disrupted the substrate binding region and/or active site, had significantly lower catalytic activity than the wild-type enzymes.
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Affiliation(s)
- I V Alekseeva
- Institute of Chemical Biology and Fundamental Medicine, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090 Russia
| | - A S Bakman
- Institute of Chemical Biology and Fundamental Medicine, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090 Russia
- Department of Natural Sciences, Novosibirsk State University, Novosibirsk, 630090 Russia
| | - D A Iakovlev
- Institute of Chemical Biology and Fundamental Medicine, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090 Russia
| | - N A Kuznetsov
- Institute of Chemical Biology and Fundamental Medicine, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090 Russia
| | - O S Fedorova
- Institute of Chemical Biology and Fundamental Medicine, Siberian Branch, Russian Academy of Sciences, Novosibirsk, 630090 Russia
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24
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Raja S, Van Houten B. The Multiple Cellular Roles of SMUG1 in Genome Maintenance and Cancer. Int J Mol Sci 2021; 22:ijms22041981. [PMID: 33671338 PMCID: PMC7922111 DOI: 10.3390/ijms22041981] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2021] [Revised: 02/12/2021] [Accepted: 02/13/2021] [Indexed: 12/20/2022] Open
Abstract
Single-strand selective monofunctional uracil DNA glycosylase 1 (SMUG1) works to remove uracil and certain oxidized bases from DNA during base excision repair (BER). This review provides a historical characterization of SMUG1 and 5-hydroxymethyl-2′-deoxyuridine (5-hmdU) one important substrate of this enzyme. Biochemical and structural analyses provide remarkable insight into the mechanism of this glycosylase: SMUG1 has a unique helical wedge that influences damage recognition during repair. Rodent studies suggest that, while SMUG1 shares substrate specificity with another uracil glycosylase UNG2, loss of SMUG1 can have unique cellular phenotypes. This review highlights the multiple roles SMUG1 may play in preserving genome stability, and how the loss of SMUG1 activity may promote cancer. Finally, we discuss recent studies indicating SMUG1 has moonlighting functions beyond BER, playing a critical role in RNA processing including the RNA component of telomerase.
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Affiliation(s)
- Sripriya Raja
- Molecular Pharmacology Graduate Program, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15213, USA;
- UPMC Hillman Cancer Center, University of Pittsburgh, Pittsburgh, PA 15213, USA
| | - Bennett Van Houten
- Molecular Pharmacology Graduate Program, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15213, USA;
- UPMC Hillman Cancer Center, University of Pittsburgh, Pittsburgh, PA 15213, USA
- Department of Pharmacology and Chemical Biology, School of Medicine, University of Pittsburgh, Pittsburgh, PA 15213, USA
- Correspondence: ; Tel.: +1412-623-7762; Fax: +1-412-623-7761
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25
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Delgado P, Álvarez-Prado ÁF, Marina-Zárate E, Sernandez IV, Mur SM, de la Barrera J, Sanchez-Cabo F, Cañamero M, de Molina A, Belver L, de Yébenes VG, Ramiro AR. Interplay between UNG and AID governs intratumoral heterogeneity in mature B cell lymphoma. PLoS Genet 2020; 16:e1008960. [PMID: 33362210 PMCID: PMC7790409 DOI: 10.1371/journal.pgen.1008960] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Revised: 01/07/2021] [Accepted: 11/08/2020] [Indexed: 12/11/2022] Open
Abstract
Most B cell lymphomas originate from B cells that have germinal center (GC) experience and bear chromosome translocations and numerous point mutations. GC B cells remodel their immunoglobulin (Ig) genes by somatic hypermutation (SHM) and class switch recombination (CSR) in their Ig genes. Activation Induced Deaminase (AID) initiates CSR and SHM by generating U:G mismatches on Ig DNA that can then be processed by Uracyl-N-glycosylase (UNG). AID promotes collateral damage in the form of chromosome translocations and off-target SHM, however, the exact contribution of AID activity to lymphoma generation and progression is not completely understood. Here we show using a conditional knock-in strategy that AID supra-activity alone is not sufficient to generate B cell transformation. In contrast, in the absence of UNG, AID supra-expression increases SHM and promotes lymphoma. Whole exome sequencing revealed that AID heavily contributes to lymphoma SHM, promoting subclonal variability and a wider range of oncogenic variants. Thus, our data provide direct evidence that UNG is a brake to AID-induced intratumoral heterogeneity and evolution of B cell lymphoma.
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Affiliation(s)
- Pilar Delgado
- B Lymphocyte Biology Lab. Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain
| | - Ángel F. Álvarez-Prado
- B Lymphocyte Biology Lab. Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain
| | - Ester Marina-Zárate
- B Lymphocyte Biology Lab. Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain
| | - Isora V. Sernandez
- B Lymphocyte Biology Lab. Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain
| | - Sonia M. Mur
- B Lymphocyte Biology Lab. Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain
| | - Jorge de la Barrera
- Bioinformatics Unit. Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain
| | - Fátima Sanchez-Cabo
- Bioinformatics Unit. Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain
| | | | - Antonio de Molina
- Comparative Medicine Unit, Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain
| | - Laura Belver
- B Lymphocyte Biology Lab. Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain
| | - Virginia G. de Yébenes
- B Lymphocyte Biology Lab. Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain
| | - Almudena R. Ramiro
- B Lymphocyte Biology Lab. Centro Nacional de Investigaciones Cardiovasculares (CNIC), Madrid, Spain
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26
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Meshesha M, Esadze A, Cui J, Churgulia N, Sahu SK, Stivers JT. Deficient uracil base excision repair leads to persistent dUMP in HIV proviruses during infection of monocytes and macrophages. PLoS One 2020; 15:e0235012. [PMID: 32663205 PMCID: PMC7360050 DOI: 10.1371/journal.pone.0235012] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Accepted: 06/05/2020] [Indexed: 11/19/2022] Open
Abstract
Non-dividing cells of the myeloid lineage such as monocytes and macrophages are target cells of HIV that have low dNTP pool concentrations and elevated levels of dUTP, which leads to frequent incorporation of dUMP opposite to A during reverse transcription ("uracilation"). One factor determining the fate of dUMP in proviral DNA is the host cell uracil base excision repair (UBER) system. Here we explore the relative UBER capacity of monocytes (MC) and monocyte-derived macrophages (MDM) and the fate of integrated uracilated viruses in both cell types to understand the implications of viral dUMP on HIV diversification and infectivity. We find that the kinetics for MC infection is compatible with their lifetime in vivo and their near absence of hUNG2 activity is consistent with the retention of viral dUMP at high levels at least until differentiation into macrophages, where UBER becomes possible. Overexpression of human uracil DNA glycosylase in MDM prior to infection resulted in rapid removal of dUMP from HIV cDNA and near complete depletion of dUMP-containing viral copies. This finding establishes that the low hUNG2 expression level in these cells limits UBER but that hUNG2 is restrictive against uracilated viruses. In contrast, overexpression of hUNG2 after viral integration did not accelerate the excision of uracils, suggesting that they may poorly accessible in the context of chromatin. We found that viral DNA molecules with incorporated dUMP contained unique (+) strand transversion mutations that were not observed when dUMP was absent (G→T, T→A, T→G, A→C). These observations and other considerations suggest that dUMP introduces errors predominantly during (-) strand synthesis when the template is RNA. Overall, the likelihood of producing a functional virus from in vitro infection of MC is about 50-fold and 300-fold reduced as compared to MDM and activated T cells. The results implicate viral dUMP incorporation in MC and MDM as a potential viral diversification and restriction pathway during human HIV infection.
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Affiliation(s)
- Mesfin Meshesha
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
| | - Alexandre Esadze
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
| | - Junru Cui
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
| | - Natela Churgulia
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
| | - Sushil Kumar Sahu
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
| | - James T. Stivers
- Department of Pharmacology and Molecular Sciences, Johns Hopkins University School of Medicine, Baltimore, MD, United States of America
- * E-mail:
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27
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Karwowski BT. The Influence of (5' R)- and (5' S)-5',8-Cyclo-2'-Deoxyadenosine on UDG and hAPE1 Activity. Tandem Lesions are the Base Excision Repair System's Nightmare. Cells 2019; 8:cells8111303. [PMID: 31652769 PMCID: PMC6912673 DOI: 10.3390/cells8111303] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2019] [Revised: 10/21/2019] [Accepted: 10/22/2019] [Indexed: 12/30/2022] Open
Abstract
DNA lesions are formed continuously in each living cell as a result of environmental factors, ionisation radiation, metabolic processes, etc. Most lesions are removed from the genome by the base excision repair system (BER). The activation of the BER protein cascade starts with DNA damage recognition by glycosylases. Uracil-DNA glycosylase (UDG) is one of the most evolutionary preserved glycosylases which remove the frequently occurring 2′-deoxyuridine from single (ss) and double-stranded (ds) oligonucleotides. Conversely, the unique tandem lesions (5′R)- and (5′S)-5′,8-cyclo-2′-deoxyadenosine (cdA) are not suitable substrates for BER machinery and are released from the genome by the nucleotide excision repair (NER) system. However, the cyclopurines appearing in a clustered DNA damage structure can influence the BER process of other lesions like dU. In this article, UDG inhibition by 5′S- and 5′R-cdA is shown and discussed in an experimental and theoretical manner. This phenomenon was observed when a tandem lesion appears in single or double-stranded oligonucleotides next to dU, on its 3′-end side. The cdA shift to the 5′-end side of dU in ss-DNA stops this effect in both cdA diastereomers. Surprisingly, in the case of ds-DNA, 5′S-cdA completely blocks uracil excision by UDG. Conversely, 5′R-cdA allows glycosylase for uracil removal, but the subsequently formed apurinic/apyrimidinic (AP) site is not suitable for human AP-site endonuclease 1 (hAPE1) activity. In conclusion, the appearance of the discussed tandem lesion in the structure of single or double-stranded DNA can stop the entire base repair process at its beginning, which due to UDG and hAPE1 inhibition can lead to mutagenesis. On the other hand, the presented results can cast some light on the UDG or hAPE1 inhibitors being used as a potential treatment.
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Affiliation(s)
- Bolesław T Karwowski
- DNA Damage Laboratory of the Food Science Department, Faculty of Pharmacy, Medical University of Lodz, ul. Muszynskiego 1, 90-151 Lodz, Poland.
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Iakovlev DA, Alekseeva IV, Vorobjev YN, Kuznetsov NA, Fedorova OS. The Role of Active-Site Residues Phe98, His239, and Arg243 in DNA Binding and in the Catalysis of Human Uracil-DNA Glycosylase SMUG1. Molecules 2019; 24:molecules24173133. [PMID: 31466351 PMCID: PMC6749576 DOI: 10.3390/molecules24173133] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Revised: 08/26/2019] [Accepted: 08/27/2019] [Indexed: 11/16/2022] Open
Abstract
Human SMUG1 (hSMUG1) hydrolyzes the N-glycosidic bond of uracil and some uracil lesions formed in the course of epigenetic regulation. Despite the functional importance of hSMUG1 in the DNA repair pathway, the damage recognition mechanism has been elusive to date. In the present study, our objective was to build a model structure of the enzyme-DNA complex of wild-type hSMUG1 and several hSMUG1 mutants containing substitution F98W, H239A, or R243A. Enzymatic activity of these mutant enzymes was examined by polyacrylamide gel electrophoresis analysis of the reaction product formation and pre-steady-state analysis of DNA conformational changes during enzyme-DNA complex formation. It was shown that substitutions F98W and H239A disrupt specific contacts generated by the respective wild-type residues, namely stacking with a flipped out Ura base in the damaged base-binding pocket or electrostatic interactions with DNA in cases of Phe98 and His239, respectively. A loss of the Arg side chain in the case of R243A reduced the rate of DNA bending and increased the enzyme turnover rate, indicating facilitation of the product release step.
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Affiliation(s)
- Danila A Iakovlev
- Institute of Chemical Biology and Fundamental Medicine (ICBFM), Siberian Branch of Russian Academy of Sciences, 8 Lavrentyev Ave., Novosibirsk 630090, Russia
| | - Irina V Alekseeva
- Institute of Chemical Biology and Fundamental Medicine (ICBFM), Siberian Branch of Russian Academy of Sciences, 8 Lavrentyev Ave., Novosibirsk 630090, Russia
| | - Yury N Vorobjev
- Institute of Chemical Biology and Fundamental Medicine (ICBFM), Siberian Branch of Russian Academy of Sciences, 8 Lavrentyev Ave., Novosibirsk 630090, Russia
| | - Nikita A Kuznetsov
- Institute of Chemical Biology and Fundamental Medicine (ICBFM), Siberian Branch of Russian Academy of Sciences, 8 Lavrentyev Ave., Novosibirsk 630090, Russia.
- Department of Natural Sciences, Novosibirsk State University (NSU), 2 Pirogova St., Novosibirsk 630090, Russia.
| | - Olga S Fedorova
- Institute of Chemical Biology and Fundamental Medicine (ICBFM), Siberian Branch of Russian Academy of Sciences, 8 Lavrentyev Ave., Novosibirsk 630090, Russia.
- Department of Natural Sciences, Novosibirsk State University (NSU), 2 Pirogova St., Novosibirsk 630090, Russia.
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Ertuzun T, Semerci A, Cakir ME, Ekmekcioglu A, Gok MO, Soltys DT, de Souza-Pinto NC, Sezerman U, Muftuoglu M. Investigation of base excision repair gene variants in late-onset Alzheimer's disease. PLoS One 2019; 14:e0221362. [PMID: 31415677 PMCID: PMC6695184 DOI: 10.1371/journal.pone.0221362] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Accepted: 08/05/2019] [Indexed: 12/03/2022] Open
Abstract
Base excision repair (BER) defects and concomitant oxidative DNA damage accumulation play a role in the etiology and progression of late-onset Alzheimer’s disease (LOAD). However, it is not known whether genetic variant(s) of specific BER genes contribute to reduced BER activity in LOAD patients and whether they are associated with risk, development and/or progression of LOAD. Therefore, we performed targeted next generation sequencing for three BER genes, uracil glycosylase (UNG), endonuclease VIII-like DNA glycosylase 1 (NEIL1) and polymerase β (POLβ) including promoter, exonic and intronic regions in peripheral blood samples and postmortem brain tissues (temporal cortex, TC and cerebellum, CE) from LOAD patients, high-pathology control and cognitively normal age-matched controls. In addition, the known LOAD risk factor, APOE was included in this study to test whether any BER gene variants associate with APOE variants, particularly APOE ε4. We show that UNG carry five significant variants (rs1610925, rs2268406, rs80001089, rs1018782 and rs1018783) in blood samples of Turkish LOAD patients compared to age-matched controls and one of them (UNG rs80001089) is also significant in TC from Brazilian LOAD patients (p<0.05). The significant variants present only in CE and TC from LOAD are UNG rs2569987 and POLβ rs1012381950, respectively. There is also significant epistatic relationship (p = 0.0410) between UNG rs80001089 and NEIL1 rs7182283 in TC from LOAD subjects. Our results suggest that significant BER gene variants may be associated with the risk of LOAD in non-APOE ε4 carriers. On the other hand, there are no significant UNG, NEIL1 and POLβ variants that could affect their protein level and function, suggesting that there may be other factors such as post-transcriptional or–translational modifications responsible for the reduced activities and protein levels of these genes in LOAD pathogenesis. Further studies with increased sample size are needed to confirm the relationship between BER variants and LOAD risk.
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Affiliation(s)
- Tugce Ertuzun
- Department of Molecular Biology and Genetics
- Department of Medical Biotechnology, Acibadem Mehmet Ali Aydinlar University, Istanbul, Turkey
| | - Asli Semerci
- Department of Medical Biotechnology, Acibadem Mehmet Ali Aydinlar University, Istanbul, Turkey
| | - Mehmet Emin Cakir
- Department of Neurology, Medeniyet University, Goztepe Training and Research Hospital, Istanbul, Turkey
| | - Aysegul Ekmekcioglu
- Department of Medical Biotechnology, Acibadem Mehmet Ali Aydinlar University, Istanbul, Turkey
| | - Mehmet Oguz Gok
- Department of Medical Biotechnology, Acibadem Mehmet Ali Aydinlar University, Istanbul, Turkey
| | - Daniela T. Soltys
- Departmento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil
| | - Nadja C. de Souza-Pinto
- Departmento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil
| | - Ugur Sezerman
- Department of Biostatistics and Medical Informatics, Acibadem Mehmet Ali Aydinlar University, Istanbul, Turkey
| | - Meltem Muftuoglu
- Department of Molecular Biology and Genetics
- Department of Medical Biotechnology, Acibadem Mehmet Ali Aydinlar University, Istanbul, Turkey
- * E-mail:
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Zmasek CM, Knipe DM, Pellett PE, Scheuermann RH. Classification of human Herpesviridae proteins using Domain-architecture Aware Inference of Orthologs (DAIO). Virology 2019; 529:29-42. [PMID: 30660046 PMCID: PMC6502252 DOI: 10.1016/j.virol.2019.01.005] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/16/2018] [Revised: 01/04/2019] [Accepted: 01/04/2019] [Indexed: 12/13/2022]
Abstract
We developed a computational approach called Domain-architecture Aware Inference of Orthologs (DAIO) for the analysis of protein orthology by combining phylogenetic and protein domain-architecture information. Using DAIO, we performed a systematic study of the proteomes of all human Herpesviridae species to define Strict Ortholog Groups (SOGs). In addition to assessing the taxonomic distribution for each protein based on sequence similarity, we performed a protein domain-architecture analysis for every protein family and computationally inferred gene duplication events. While many herpesvirus proteins have evolved without any detectable gene duplications or domain rearrangements, numerous herpesvirus protein families do exhibit complex evolutionary histories. Some proteins acquired additional domains (e.g., DNA polymerase), whereas others show a combination of domain acquisition and gene duplication (e.g., betaherpesvirus US22 family), with possible functional implications. This novel classification system of SOGs for human Herpesviridae proteins is available through the Virus Pathogen Resource (ViPR, www.viprbrc.org).
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Affiliation(s)
| | - David M Knipe
- Department of Microbiology and Immunobiology, Harvard Medical School, Boston, MA 02115, USA
| | - Philip E Pellett
- Department of Biochemistry, Microbiology & Immunology, Wayne State University School of Medicine, Detroit, MI 48201, USA
| | - Richard H Scheuermann
- J. Craig Venter Institute, La Jolla, CA 92037, USA; Department of Pathology, University of California, San Diego, CA 92093, USA; Division of Vaccine Discovery, La Jolla Institute for Allergy and Immunology, La Jolla, CA 92037, USA.
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Shinmura K, Kato H, Kawanishi Y, Goto M, Tao H, Yoshimura K, Nakamura S, Misawa K, Sugimura H. Defective repair capacity of variant proteins of the DNA glycosylase NTHL1 for 5-hydroxyuracil, an oxidation product of cytosine. Free Radic Biol Med 2019; 131:264-273. [PMID: 30552997 DOI: 10.1016/j.freeradbiomed.2018.12.010] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/28/2018] [Revised: 12/09/2018] [Accepted: 12/11/2018] [Indexed: 12/20/2022]
Abstract
The NTHL1 gene encodes DNA glycosylase, which is involved in base excision repair, and biallelic mutations of this gene result in NTHL1-associated polyposis (NAP), a hereditary disease characterized by colorectal polyposis and multiple types of carcinomas. However, no proper functional characterization of variant NTHL1 proteins has been done so far. Herein, we report functional evaluation of variant NTHL1 proteins to aid in the accurate diagnosis of NAP. First, we investigated whether it would be appropriate to use 5-hydroxyuracil (5OHU), an oxidation product of cytosine, for the evaluation. In the supF forward mutation assay, 5OHU caused an increase of the mutation frequency in human cells, and the C→T mutation was predominant among the 5OHU-induced mutations. In addition, in DNA cleavage activity assay, 5OHU was excised by NTHL1 as well as four other DNA glycosylases (SMUG1, NEIL1, TDG, and UNG2). When human cells overexpressing the five DNA glycosylases were established, it was found that each of the five DNA glycosylases, including NTHL1, had the ability to suppress 5OHU-induced mutations. Based on the above results, we performed functional evaluation of eight NTHL1 variants using 5OHU-containing DNA substrate or shuttle plasmid. The DNA cleavage activity assay showed that the variants of NTHL1, Q90X, Y130X, R153X, and Q287X, but not R19Q, V179I, V217F, or G286S, showed defective repair activity for 5OHU and two other oxidatively damaged bases. Moreover, the supF forward mutation assay showed that the four truncated-type NTHL1 variants showed a reduced ability to suppress 5OHU-induced mutations in human cells. These results suggest that the NTHL1 variants Q90X, Y130X, R153X, and Q287X, but not R19Q, V179I, V217F, or G286S, were defective in 5OHU repair and the alleles encoding them were considered to be pathogenic for NAP.
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Affiliation(s)
- Kazuya Shinmura
- Department of Tumor Pathology, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi Ward, Hamamatsu, Japan.
| | - Hisami Kato
- Department of Tumor Pathology, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi Ward, Hamamatsu, Japan
| | - Yuichi Kawanishi
- Advanced Research Facilities and Services, Preeminent Medical Photonics Education and Research Center, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Masanori Goto
- Division of Tumor Pathology, Department of Pathology, Asahikawa Medical University, Asahikawa, Japan
| | - Hong Tao
- Department of Tumor Pathology, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi Ward, Hamamatsu, Japan
| | - Katsuhiro Yoshimura
- Department of Tumor Pathology, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi Ward, Hamamatsu, Japan
| | - Satoki Nakamura
- Department of Tumor Pathology, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi Ward, Hamamatsu, Japan
| | - Kiyoshi Misawa
- Department of Otolaryngology/Head and Neck Surgery, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Haruhiko Sugimura
- Department of Tumor Pathology, Hamamatsu University School of Medicine, 1-20-1 Handayama, Higashi Ward, Hamamatsu, Japan
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Yang Y, Park SH, Alford-Zappala M, Lee HW, Li J, Cunningham RP, Cao W. Role of endonuclease III enzymes in uracil repair. Mutat Res 2019; 813:20-30. [PMID: 30590231 PMCID: PMC6378108 DOI: 10.1016/j.mrfmmm.2018.12.001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Revised: 12/07/2018] [Accepted: 12/10/2018] [Indexed: 06/09/2023]
Abstract
Endonuclease III is a DNA glycosylase previously known for its repair activity on oxidative pyrimidine damage. Uracil is a deamination product derived from cytosine. Uracil DNA N-glycosylase (UNG) and mismatch-specific uracil DNA glycosylase (MUG) are two known repair enzymes with enzymatic activity on uracil in E. coli. Here we report a G/U specific uracil DNA glycosylase activity in E. coli endonuclease III (endo III, Nth), which is comparable to MUG but significantly lower than its thymine glycol DNA glycosylase activity. The possibility that the novel activity is due to contamination is ruled out by expressing the wild type nth gene and an active site mutant in a uracil-repair-deficient genetic background. Consistent with the biochemical analysis, analyses of lac+ reversion and mutation frequencies in the presence of human AID induced cytosine deamination indicate the endo III can play a role in repair of cytosine deamination. In addition to E. coli, UDG activity is found in endo III homologs from other organisms. E. coli nucleoside diphosphate kinase (Ndk) was also tested for UDG activity because it was previously reported as an uracil repair enzyme. Under the assay conditions, very limited UDG activity was detected in single-stranded uracil-containing DNA from E. coli Ndk and no UDG activity was detected in human Ndk homologs. This study provides definitive clarification on uracil repair by endo III and reveals that endonuclease III is a G/U-specific UDG that can be viewed as a prototype for the human MBD4 uracil DNA glycosylase.
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Affiliation(s)
- Ye Yang
- Department of Genetics and Biochemistry, Clemson University, Room 049 Life Sciences Facility, 190 Collings Street, Clemson, SC 29634, USA
| | - Sung-Hyun Park
- Department of Genetics and Biochemistry, Clemson University, Room 049 Life Sciences Facility, 190 Collings Street, Clemson, SC 29634, USA
| | - Maria Alford-Zappala
- Department of Biological Sciences, The University at Albany, SUNY, 1400 Washington Avenue, Albany, NY 12222, USA
| | - Hyun-Wook Lee
- Department of Genetics and Biochemistry, Clemson University, Room 049 Life Sciences Facility, 190 Collings Street, Clemson, SC 29634, USA
| | - Jing Li
- Department of Genetics and Biochemistry, Clemson University, Room 049 Life Sciences Facility, 190 Collings Street, Clemson, SC 29634, USA
| | - Richard P Cunningham
- Department of Biological Sciences, The University at Albany, SUNY, 1400 Washington Avenue, Albany, NY 12222, USA
| | - Weiguo Cao
- Department of Genetics and Biochemistry, Clemson University, Room 049 Life Sciences Facility, 190 Collings Street, Clemson, SC 29634, USA.
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Rodriguez Y, Duan M, Wyrick JJ, Smerdon MJ. A cassette of basic amino acids in histone H2B regulates nucleosome dynamics and access to DNA damage. J Biol Chem 2018; 293:7376-7386. [PMID: 29588367 PMCID: PMC5949990 DOI: 10.1074/jbc.ra117.000358] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2017] [Revised: 03/12/2018] [Indexed: 12/25/2022] Open
Abstract
Nucleosome dynamics, such as spontaneous DNA unwrapping, are postulated to have a critical role in regulating the access of DNA repair machinery to DNA lesions within nucleosomes. However, the specific histone domains that regulate nucleosome dynamics and the impact of such changes in intrinsic nucleosome dynamics on DNA repair are not well understood. Previous studies identified a highly conserved region in the N-terminal tail of histone H2B known as the histone H2Brepression (or HBR) domain, which has a significant influence on gene expression, chromatin assembly, and DNA damage formation and repair. However, the molecular mechanism(s) that may account for these observations are limited. In this study, we characterized the stability and dynamics of ΔHBR mutant nucleosome core particles (NCPs) in vitro by restriction enzyme accessibility (REA), FRET, and temperature-induced sliding of histone octamers. Our results indicate that ΔHBR-NCPs are more dynamic, with a larger steady-state fraction of the NCP population occupying the unwrapped state than for WT-NCPs. Additionally, ΔHBR-histone octamers are more susceptible to temperature-induced sliding on DNA than WT histone octamers. Furthermore, we show that the activity of base excision repair enzymes at uracil lesions and single nucleotide gaps is enhanced in a site-specific manner in ΔHBR-NCPs. This enhanced activity correlates well with regions exhibiting increased DNA unwrapping. Finally, removal of the HBR domain is not sufficient to completely alleviate the structural constraints imposed by histone octamers on the activity of base excision repair enzymes.
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Affiliation(s)
- Yesenia Rodriguez
- From Biochemistry and Biophysics, School of Molecular Biosciences, Pullman, Washington 99164-7520
| | - Mingrui Duan
- From Biochemistry and Biophysics, School of Molecular Biosciences, Pullman, Washington 99164-7520
| | - John J Wyrick
- From Biochemistry and Biophysics, School of Molecular Biosciences, Pullman, Washington 99164-7520; Center for Reproductive Biology, Washington State University, Pullman, Washington 99164-7520
| | - Michael J Smerdon
- From Biochemistry and Biophysics, School of Molecular Biosciences, Pullman, Washington 99164-7520.
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Fallahi S, Moosavi SF, Karimi A, Chegeni AS, Saki M, Namdari P, Rashno MM, Varzi AM, Tarrahi MJ, Almasian M. An advanced uracil DNA glycosylase-supplemented loop-mediated isothermal amplification (UDG-LAMP) technique used in the sensitive and specific detection of Cryptosporidium parvum, Cryptosporidium hominis, and Cryptosporidium meleagridis in AIDS patients. Diagn Microbiol Infect Dis 2017; 91:6-12. [PMID: 29366630 DOI: 10.1016/j.diagmicrobio.2017.12.017] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2017] [Revised: 12/15/2017] [Accepted: 12/16/2017] [Indexed: 11/18/2022]
Abstract
The rapid and accurate detection of Cryptosporidium spp. is critically important for the prevention and timely treatment of cryptosporidiosis in AIDS patients (APs). This study was conducted to examine a UDG-LAMP technique for the first time to diagnose cryptosporidiosis in APs. After collecting demographic and clinical data, three stool samples were collected from the participants (120 volunteering APs). The microscopic examination of stained smears using the acid-fast method and the UDG-LAMP assay were performed for each sample. 10% of APs were infected with Cryptosporidium spp. The number of detected cryptosporidiosis cases using the acid-fast staining and UDG-LAMP methods were significantly different (P < 0.001). Diarrhea and weight loss were found to be significantly associated with cryptosporidiosis in patients (P < 0.05). The pretreatment of LAMP reagents with UDG successfully eliminated the likelihood of product re-amplification remaining from previous reactions. The UDG-LAMP technique could detect cryptosporidiosis in APs with high sensitivity and rapidity without carryover contamination.
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Affiliation(s)
- Shirzad Fallahi
- Razi Herbal Medicine Research Center, Lorestan University of Medical Sciences, Khorramabad, Iran; Department of Medical Parasitology and Mycology, Faculty of Medicine, Lorestan University of Medical Sciences, Khorramabad, Iran.
| | - Seyedeh Fatemeh Moosavi
- Department of Medical Parasitology and Mycology, Faculty of Medicine, Lorestan University of Medical Sciences, Khorramabad, Iran
| | - Azadeh Karimi
- Department of Medical Parasitology and Mycology, Faculty of Medicine, Lorestan University of Medical Sciences, Khorramabad, Iran
| | - Ali Sharafi Chegeni
- Department of Communicable Disease Control and Prevention, Deputy of Health, Lorestan University of Medical Sciences, Khorramabad, Iran
| | - Mohammad Saki
- Department of Communicable Disease Control and Prevention, Deputy of Health, Lorestan University of Medical Sciences, Khorramabad, Iran
| | - Parsa Namdari
- Medical Student, Faculty of Medicine, University of Debrecen, Hungary
| | | | - Ali Mohamad Varzi
- Department of Immunology, Faculty of Medicine, Lorestan University of Medical Sciences, Khorramabad, Iran
| | - Mohammad Javad Tarrahi
- Department of Epidemiology and Statistics, Behavioral Sciences Research Center, Isfahan University of Medical Science, Isfahan, Iran
| | - Mohammad Almasian
- School of Medicine, Lorestan University of Medical Sciences, Khorramabad, Iran
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Cai M, Huang Z, Liao Z, Chen T, Wang P, Jiang S, Chen D, Peng T, Bian Y, Hong G, Yang H, Zeng Z, Li X, Li M. Characterization of the subcellular localization and nuclear import molecular mechanisms of herpes simplex virus 1 UL2. Biol Chem 2017; 398:509-517. [PMID: 27865090 DOI: 10.1515/hsz-2016-0268] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2016] [Accepted: 11/16/2016] [Indexed: 11/15/2022]
Abstract
As a crucial protein, the herpes simplex virus 1 (HSV-1) UL2 protein has been shown to take part in various stages of viral infection, nonetheless, its exact subcellular localization and transport molecular determinants are not well known thus far. In the present study, by using live cells fluorescent microscopy assay, UL2 tagged with enhanced yellow fluorescent protein was transiently expressed in live cells and showed a completely nuclear accumulation without the presence of other HSV-1 proteins. Moreover, the nuclear transport of UL2 was characterized to be assisted by multiple transport pathways through Ran-, importin α1-, α5-, α7-, β1- and transportin-1 cellular transport receptors. Consequently, these results will improve understanding of UL2-mediated biological functions in HSV-1 infection cycles.
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Du W, Li J, Xiao F, Yu R, Jiang J. A label-free and highly sensitive strategy for uracil-DNA glycosylase activity detection based on stem-loop primer-mediated exponential amplification (SPEA). Anal Chim Acta 2017; 991:127-132. [PMID: 29031294 DOI: 10.1016/j.aca.2017.08.042] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2017] [Revised: 08/23/2017] [Accepted: 08/28/2017] [Indexed: 11/19/2022]
Abstract
Uracil-DNA glycosylase (UDG) plays essential roles in base excision repair (BER) pathway by eliminating uracil from DNA to sustain the genome integrity. Sensitive detection of UDG activity is of great significance in the study of many fundamental biochemical processes and clinical applications. We develop a label-free method for UDG activity detection using stem-loop primer-mediated exponential amplification (SPEA). In the presence of active UDG, the uracil base in helper hairpin probe (HP) can be excised to generate an abasic site (AP site), which can be cleaved by endonuclease IV (Endo IV) with a blocked primer released. This primer then triggers the strand displacement reaction to produce a dumb-bell structure DNA, which can initiate a loop-mediated isothermal amplification (LAMP) reaction. This reaction generates a large number of long double-strand DNA replicates, which can be stained by SYBR Green (SG) I to deliver enhanced fluorescence for quantitative detection of UDG activity. A linear range from 0.001 U/mL to 1 U/mL and a detection limit down to 0.00068 U/mL are achieved. This strategy has also been demonstrated for UDG assay in complex cell lysates, implying its great potential for UDG based clinical diagnostics and therapeutics.
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Affiliation(s)
- Wenfang Du
- State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, PR China
| | - Junjie Li
- State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, PR China
| | - Fubing Xiao
- State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, PR China
| | - Ruqin Yu
- State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, PR China.
| | - Jianhui Jiang
- State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, PR China.
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Li J, Yang Y, Guevara J, Wang L, Cao W. Identification of a prototypical single-stranded uracil DNA glycosylase from Listeria innocua. DNA Repair (Amst) 2017; 57:107-115. [PMID: 28719838 PMCID: PMC5568478 DOI: 10.1016/j.dnarep.2017.07.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Revised: 07/04/2017] [Accepted: 07/05/2017] [Indexed: 12/23/2022]
Abstract
A recent phylogenetic study on UDG superfamily estimated a new clade of family 3 enzymes (SMUG1-like), which shares a lower homology with canonic SMUG1 enzymes. The enzymatic properties of the newly found putative DNA glycosylase are unknown. To test the potential UDG activity and evaluate phylogenetic classification, we isolated one SMUG1-like glycosylase representative from Listeria innocua (Lin). A biochemical screening of DNA glycosylase activity in vitro indicates that Lin SMUG1-like glycosylase is a single-strand selective uracil DNA glycosylase. The UDG activity on DNA bubble structures provides clue to its physiological significance in vivo. Mutagenesis and molecular modeling analyses reveal that Lin SMUG1-like glycosylase has similar functional motifs with SMUG1 enzymes; however, it contains a distinct catalytic doublet S67-S68 in motif 1 that is not found in any families in the UDG superfamily. Experimental investigation shows that the S67M-S68N double mutant is catalytically more active than either S67M or S68N single mutant. Coupled with mutual information analysis, the results indicate a high degree of correlation in the evolution of SMUG1-like enzymes. This study underscores the functional and catalytic diversity in the evolution of enzymes in UDG superfamily.
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Affiliation(s)
- Jing Li
- Department of Genetics and Biochemistry, Clemson University, Room 060 Life Sciences Facility, 190 Collings Street, Clemson, SC 29634, USA
| | - Ye Yang
- Department of Genetics and Biochemistry, Clemson University, Room 060 Life Sciences Facility, 190 Collings Street, Clemson, SC 29634, USA
| | - Jose Guevara
- Department of Genetics and Biochemistry, Clemson University, Room 060 Life Sciences Facility, 190 Collings Street, Clemson, SC 29634, USA
| | - Liangjiang Wang
- Department of Genetics and Biochemistry, Clemson University, Room 060 Life Sciences Facility, 190 Collings Street, Clemson, SC 29634, USA
| | - Weiguo Cao
- Department of Genetics and Biochemistry, Clemson University, Room 060 Life Sciences Facility, 190 Collings Street, Clemson, SC 29634, USA.
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Komor AC, Zhao KT, Packer MS, Gaudelli NM, Waterbury AL, Koblan LW, Kim YB, Badran AH, Liu DR. Improved base excision repair inhibition and bacteriophage Mu Gam protein yields C:G-to-T:A base editors with higher efficiency and product purity. Sci Adv 2017; 3:eaao4774. [PMID: 28875174 PMCID: PMC5576876 DOI: 10.1126/sciadv.aao4774] [Citation(s) in RCA: 470] [Impact Index Per Article: 67.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2017] [Accepted: 08/04/2017] [Indexed: 05/17/2023]
Abstract
We recently developed base editing, the programmable conversion of target C:G base pairs to T:A without inducing double-stranded DNA breaks (DSBs) or requiring homology-directed repair using engineered fusions of Cas9 variants and cytidine deaminases. Over the past year, the third-generation base editor (BE3) and related technologies have been successfully used by many researchers in a wide range of organisms. The product distribution of base editing-the frequency with which the target C:G is converted to mixtures of undesired by-products, along with the desired T:A product-varies in a target site-dependent manner. We characterize determinants of base editing outcomes in human cells and establish that the formation of undesired products is dependent on uracil N-glycosylase (UNG) and is more likely to occur at target sites containing only a single C within the base editing activity window. We engineered CDA1-BE3 and AID-BE3, which use cytidine deaminase homologs that increase base editing efficiency for some sequences. On the basis of these observations, we engineered fourth-generation base editors (BE4 and SaBE4) that increase the efficiency of C:G to T:A base editing by approximately 50%, while halving the frequency of undesired by-products compared to BE3. Fusing BE3, BE4, SaBE3, or SaBE4 to Gam, a bacteriophage Mu protein that binds DSBs greatly reduces indel formation during base editing, in most cases to below 1.5%, and further improves product purity. BE4, SaBE4, BE4-Gam, and SaBE4-Gam represent the state of the art in C:G-to-T:A base editing, and we recommend their use in future efforts.
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Affiliation(s)
- Alexis C. Komor
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA 02138, USA
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Kevin T. Zhao
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA 02138, USA
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Michael S. Packer
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA 02138, USA
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Nicole M. Gaudelli
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA 02138, USA
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Amanda L. Waterbury
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA
| | - Luke W. Koblan
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA 02138, USA
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Y. Bill Kim
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA 02138, USA
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - Ahmed H. Badran
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA 02138, USA
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
| | - David R. Liu
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA
- Howard Hughes Medical Institute, Harvard University, Cambridge, MA 02138, USA
- Broad Institute of MIT and Harvard, Cambridge, MA 02142, USA
- Corresponding author.
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Abstract
Uracil-DNA glycosylases (UDG/UNG) are enzymes that remove uracil from DNA and initiate base-excision repair. These enzymes play a key role in maintaining genomic integrity by reducing the mutagenic events caused by G:C to A:T transition mutations. The recent finding that a family of RNA editing enzymes (AID/APOBECs) can deaminate cytosine in DNA has raised the interest in these base-excision repair enzymes. The methodology presented here focuses on determining the regulation of the nuclear isoform of uracil-DNA glycosylase (nUDG), a 36,000 Da protein. In synchronized HeLa cells, nUDG protein levels decrease to barely detectable levels during the S phase of the cell cycle. Immunoblot analysis of immunoprecipitated or affinity-isolated nUDG reveals ubiquitin-conjugated nUDG when proteolysis is inhibited by agents that block proteasomal-dependent protein degradation.
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Affiliation(s)
- Jennifer A Fischer
- Department of Molecular Biology, University of Medicine and Dentistry of New Jersey, Stratford, NJ, USA
| | - Salvatore J Caradonna
- Department of Molecular Biology, Rowan School of Osteopathic Medicine, University of Medicine and Dentistry of New Jersey, Two Medical Center Drive, Stratford, NJ, 08084, USA.
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Liu Z, Hu Y, Gong Y, Zhang W, Liu C, Wang Q, Deng H. Hydrogen peroxide mediated mitochondrial UNG1-PRDX3 interaction and UNG1 degradation. Free Radic Biol Med 2016; 99:54-62. [PMID: 27480846 DOI: 10.1016/j.freeradbiomed.2016.07.030] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Revised: 07/09/2016] [Accepted: 07/29/2016] [Indexed: 01/13/2023]
Abstract
Isoform 1 of uracil-DNA glycosylase (UNG1) is the major protein for initiating base-excision repair in mitochondria and is in close proximity to the respiratory chain that generates reactive oxygen species (ROS). Effects of ROS on the stability of UNG1 have not been well characterized. In the present study, we found that overexpression of UNG1 enhanced cells' resistance to oxidative stress and protected mitochondrial DNA (mtDNA) from oxidation. Proteomics analysis showed that UNG1 bound to eight proteins in the mitochondria, including PAPSS2, CD70 antigen, and AGR2 under normal growth conditions, whereas UNG1 mainly bound to Peroxiredoxin 3 (PRDX3) via a disulfide linkage under oxidative stress. We further demonstrated that the UNG1-PRDX3 interaction protected UNG1 from ROS-mediated degradation and prevented mtDNA oxidation. Moreover, our results show that ROS-mediated UNG1 degradation was Lon protease 1 (LonP1)-dependent and mitochondrial UNG1 degradation was aggravated by knockdown of PRDX3 expression. Taken together, these results reveal a novel function of UNG1 in the recruitment of PRDX3 to mtDNA under oxidative stress, enabling protection of UNG1 and UNG1-bound DNA from ROS damage and enhancing cell resistance to oxidative stress.
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Affiliation(s)
- Zhilei Liu
- MOE Key Laboratory of Bioinformatics and the Center of Biomedical Analsis, School of Life Sciences, Tsinghua University, Beijing, China
| | - Yadong Hu
- MOE Key Laboratory of Bioinformatics and the Center of Biomedical Analsis, School of Life Sciences, Tsinghua University, Beijing, China; Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu, China
| | - Yiyi Gong
- MOE Key Laboratory of Bioinformatics and the Center of Biomedical Analsis, School of Life Sciences, Tsinghua University, Beijing, China
| | - Wenhao Zhang
- MOE Key Laboratory of Bioinformatics and the Center of Biomedical Analsis, School of Life Sciences, Tsinghua University, Beijing, China
| | - Chongdong Liu
- Beijing Chaoyang Hospital Affiliated to Capital Medical University, Beijing, China
| | - Qingtao Wang
- Beijing Chaoyang Hospital Affiliated to Capital Medical University, Beijing, China
| | - Haiteng Deng
- MOE Key Laboratory of Bioinformatics and the Center of Biomedical Analsis, School of Life Sciences, Tsinghua University, Beijing, China.
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41
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Park KS, Lee CY, Kang KS, Park HG. Aptamer-mediated universal enzyme assay based on target-triggered DNA polymerase activity. Biosens Bioelectron 2016; 88:48-54. [PMID: 27499380 DOI: 10.1016/j.bios.2016.07.038] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2016] [Revised: 07/06/2016] [Accepted: 07/11/2016] [Indexed: 11/18/2022]
Abstract
We herein describe an innovative method for a universal fluorescence turn-on enzyme assay, which relies on the target enzyme-triggered DNA polymerase activity. In the first target recognition step, the target enzyme is designed to destabilize detection probe derived from an aptamer specific to DNA polymerase containing the overhang sequence and the complementary blocker DNA, which consequently leads to the recovery of DNA polymerase activity inhibited by the detection probe. This target-triggered polymerase activity is monitored in the second signal transduction step based on primer extension reaction coupled with TaqMan probe. Utilizing this design principle, we have successfully detected the activities of two model enzymes, exonuclease I and uracil DNA glycosylase with high sensitivity and selectivity. Since this strategy is composed of separated target recognition and signal transduction modules, it could be universally employed for the sensitive determination of numerous different target enzymes by simply redesigning the overhang sequence of detection probe, while keeping TaqMan probe-based signal transduction module as a universal signaling tool.
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Affiliation(s)
- Ki Soo Park
- Department of Chemical and Biomolecular Engineering (BK 21+ program), Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 305-338, Republic of Korea; Center for Systems Biology, Massachusetts General Hospital and Harvard Medical School, Boston, MA 02114, USA
| | - Chang Yeol Lee
- Department of Chemical and Biomolecular Engineering (BK 21+ program), Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 305-338, Republic of Korea
| | - Kyoung Suk Kang
- Department of Chemical and Biomolecular Engineering (BK 21+ program), Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 305-338, Republic of Korea
| | - Hyun Gyu Park
- Department of Chemical and Biomolecular Engineering (BK 21+ program), Korea Advanced Institute of Science and Technology (KAIST), 291 Daehak-ro, Yuseong-gu, Daejeon 305-338, Republic of Korea.
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42
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Wang J, Yi G, Ou J, Liu J, Liu X. [Cloning, expression, purification and characterization of two uracil-DNA glycosylases from Sulfolobus acidocaldarius]. Wei Sheng Wu Xue Bao 2015; 55:1036-1041. [PMID: 26665601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
OBJECTIVE To characterize uracil-DNA glycosylase from acidophilic and thermophilic Sulfolobus acidocaldarius. METHODS We cloned udgIV and udgV genes from S. acidocaldarius, expressed the two recombinant UDG proteins in E. coli species BL21 (DE3) Rosetta-pLysS, purified the recombinant UDGs and characterized the removal of dU by UDGs. RESULTS We successfully expressed two S. acidocaldarius UDGs and found both UDGs having the activity of dU removal. In comparison to UDGV, UDGIV was more efficient in dU removal, with a 750-foldactivity. CONCLUSION In comparison to UDGV, UDGIV from S. acidocaldarius was a more efficient enzyme responsible for the removal of dU from DNA in vitro.
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Abstract
DNA damage in chromatin comes in many forms, including single base lesions that induce base excision repair (BER). We and others have shown that the structural location of DNA lesions within nucleosomes greatly influences their accessibility to repair enzymes. Indeed, a difference in the location of uracil as small as one-half turn of the DNA backbone on the histone surface can result in a 10-fold difference in the time course of its removal in vitro. In addition, the cell has evolved several interdependent processes capable of enhancing the accessibility of excision repair enzymes to DNA lesions in nucleosomes, including post-translational modification of histones, ATP-dependent chromatin remodeling and interchange of histone variants in nucleosomes. In this review, we focus on different factors that affect accessibility of BER enzymes to nucleosomal DNA.
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Affiliation(s)
- Yesenia Rodriguez
- School of Molecular Biosciences, Washington State University, Pullman, WA 99164-7520, United States
| | - John M Hinz
- School of Molecular Biosciences, Washington State University, Pullman, WA 99164-7520, United States
| | - Michael J Smerdon
- School of Molecular Biosciences, Washington State University, Pullman, WA 99164-7520, United States.
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Kato Y, Moriwaki T, Funakoshi M, Zhang-Akiyama QM. Caenorhabditis elegans EXO-3 contributes to longevity and reproduction: differential roles in somatic cells and germ cells. Mutat Res 2015; 772:46-54. [PMID: 25772110 DOI: 10.1016/j.mrfmmm.2015.01.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Revised: 11/05/2014] [Accepted: 01/08/2015] [Indexed: 06/04/2023]
Abstract
Apurinic/apyrimidinic (AP) sites are the major DNA damage generated continuously even under normal conditions, and inhibit DNA replication/transcription. AP endonucleases are ubiquitous enzymes required for the repair of AP sites and 3' blocking ends, but their physiological roles in multicellular organisms are not fully understood. In this study, we investigated how an AP endonuclease functions in a multicellular organism (Caenorhabditis elegans (C. elegans)). EXO-3 is one of the AP endonucleases in C. elegans. Using an exo-3 mutant worm, we found that deletion of the exo-3 gene caused shortened lifespan in an ung-1-dependent manner. UNG-1 is a uracil DNA glycosylase in C. elegans, and the present finding suggested that UNG-1 is the major producer of AP sites that affects lifespan, and EXO-3 contributes to longevity by completing the repair of uracil. Next we found that the exo-3 gene was abundantly expressed in the gonads, and AP sites in the gonad were efficiently repaired, suggesting that EXO-3 functioned particularly in the gonad. Deletion of the exo-3 gene resulted in a significant decrease in self-brood size. This was rescued by deficiency of NTH-1, which is a bifunctional DNA glycosylase in C. elegans that recognizes oxidative base damage. This result suggested that the major substrate of EXO-3 in the gonad was 3' blocking end generated by NTH-1, and that EXO-3 played an important role in reproduction. A contribution of EXO-3 to reproduction was also suggested by our finding here that the decrease of self-brood size of the exo-3 mutant became more marked when worms were treated with methyl methanesulfonate (MMS) and sodium bisulfite (NaHSO3). This study demonstrated differential roles of EXO-3 in somatic cells and germ cells.
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Affiliation(s)
- Yuichi Kato
- Laboratory of Stress Response Biology, Graduate School of Science, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto 606-8502, Japan
| | - Takahito Moriwaki
- Laboratory of Stress Response Biology, Graduate School of Science, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto 606-8502, Japan
| | - Masafumi Funakoshi
- Laboratory of Stress Response Biology, Graduate School of Science, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto 606-8502, Japan
| | - Qiu-Mei Zhang-Akiyama
- Laboratory of Stress Response Biology, Graduate School of Science, Kyoto University, Kitashirakawa Oiwake-cho, Sakyo-ku, Kyoto 606-8502, Japan.
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45
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Lu X, Nguyen TA, Appella E, Donehower LA. Homeostatic Regulation of Base Excision Repair by a p53-Induced Phosphatase: Linking Stress Response Pathways with DNA Repair Proteins. Cell Cycle 2014; 3:1363-6. [PMID: 15539943 DOI: 10.4161/cc.3.11.1241] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
The p53 protein plays a central role in the integration of cellular stress responses. If the cell incurs DNA damage, p53-induced cell cycle arrest is accompanied by p53-facilitated DNA repair. In particular, p53 has been demonstrated to promote both nucleotide excision repair (NER) and base excision repair (BER). Once these repair processes are completed, p53 activity declines and the cell can reenter the cell cycle. A critical mediator of this p53 negative regulatory feedback loop is Mdm2, a p53 transcriptional target whose protein mediates p53 proteolytic degradation. Another such p53 transcriptional target that may function in a p53 negative regulation is the PPM1D phosphatase. PPM1D may inhibit p53 activity through inactivating dephosphorylation of the p38 MAP kinase. We have recently shown that PPM1D suppresses BER in part through dephosphorylation of a key BER effector, the nuclear isoform of uracil DNA glycosylase, or UNG2. This finding further links p53 signaling to DNA repair pathways and illustrates a mechanism by which activated DNA repair systems are returned to a deactivated, homeostatic state.
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Affiliation(s)
- Xiongbin Lu
- Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, Texas 77030, USA
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46
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Assefa NG, Niiranen L, Johnson KA, Leiros HKS, Smalås AO, Willassen NP, Moe E. Structural and biophysical analysis of interactions between cod and human uracil-DNA N-glycosylase (UNG) and UNG inhibitor (Ugi). Acta Crystallogr D Biol Crystallogr 2014; 70:2093-100. [PMID: 25084329 PMCID: PMC4118823 DOI: 10.1107/s1399004714011699] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/08/2013] [Accepted: 05/20/2014] [Indexed: 12/01/2022]
Abstract
Uracil-DNA N-glycosylase from Atlantic cod (cUNG) shows cold-adapted features such as high catalytic efficiency, a low temperature optimum for activity and reduced thermal stability compared with its mesophilic homologue human UNG (hUNG). In order to understand the role of the enzyme-substrate interaction related to the cold-adapted properties, the structure of cUNG in complex with a bacteriophage encoded natural UNG inhibitor (Ugi) has been determined. The interaction has also been analyzed by isothermal titration calorimetry (ITC). The crystal structure of cUNG-Ugi was determined to a resolution of 1.9 Å with eight complexes in the asymmetric unit related through noncrystallographic symmetry. A comparison of the cUNG-Ugi complex with previously determined structures of UNG-Ugi shows that they are very similar, and confirmed the nucleotide-mimicking properties of Ugi. Biophysically, the interaction between cUNG and Ugi is very strong and shows a binding constant (Kb) which is one order of magnitude larger than that for hUNG-Ugi. The binding of both cUNG and hUNG to Ugi was shown to be favoured by both enthalpic and entropic forces; however, the binding of cUNG to Ugi is mainly dominated by enthalpy, while the entropic term is dominant for hUNG. The observed differences in the binding properties may be explained by an overall greater positive electrostatic surface potential in the protein-Ugi interface of cUNG and the slightly more hydrophobic surface of hUNG.
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Affiliation(s)
- Netsanet Gizaw Assefa
- Department of Chemistry/Norstruct, UiT The Arctic University of Norway, 9037 Tromsø, Norway
| | - Laila Niiranen
- Department of Chemistry/Norstruct, UiT The Arctic University of Norway, 9037 Tromsø, Norway
- Department of Biochemistry, University of Turku, FIN-20014 Turku, Finland
| | - Kenneth A. Johnson
- Department of Chemistry/Norstruct, UiT The Arctic University of Norway, 9037 Tromsø, Norway
| | | | - Arne Oskar Smalås
- Department of Chemistry/Norstruct, UiT The Arctic University of Norway, 9037 Tromsø, Norway
| | - Nils Peder Willassen
- Department of Chemistry/Norstruct, UiT The Arctic University of Norway, 9037 Tromsø, Norway
| | - Elin Moe
- Department of Chemistry/Norstruct, UiT The Arctic University of Norway, 9037 Tromsø, Norway
- Instituto de Tecnologia Quimica e Biologica (ITQB), Universidade Nova de Lisboa, Avenida da Republica (EAN), 2780-157 Oeiras, Portugal
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Theruvathu JA, Darwanto A, Hsu CW, Sowers LC. The effect of Pot1 binding on the repair of thymine analogs in a telomeric DNA sequence. Nucleic Acids Res 2014; 42:9063-73. [PMID: 25053838 PMCID: PMC4132724 DOI: 10.1093/nar/gku602] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/21/2014] [Revised: 06/05/2014] [Accepted: 06/23/2014] [Indexed: 12/31/2022] Open
Abstract
Telomeric DNA can form duplex regions or single-stranded loops that bind multiple proteins, preventing it from being processed as a DNA repair intermediate. The bases within these regions are susceptible to damage; however, mechanisms for the repair of telomere damage are as yet poorly understood. We have examined the effect of three thymine (T) analogs including uracil (U), 5-fluorouracil (5FU) and 5-hydroxymethyluracil (5hmU) on DNA-protein interactions and DNA repair within the GGTTAC telomeric sequence. The replacement of T with U or 5FU interferes with Pot1 (Pot1pN protein of Schizosaccharomyces pombe) binding. Surprisingly, 5hmU substitution only modestly diminishes Pot1 binding suggesting that hydrophobicity of the T-methyl group likely plays a minor role in protein binding. In the GGTTAC sequence, all three analogs can be cleaved by DNA glycosylases; however, glycosylase activity is blocked if Pot1 binds. An abasic site at the G or T positions is cleaved by the endonuclease APE1 when in a duplex but not when single-stranded. Abasic site formation thermally destabilizes the duplex that could push a damaged DNA segment into a single-stranded loop. The inability to enzymatically cleave abasic sites in single-stranded telomere regions would block completion of the base excision repair cycle potentially causing telomere attrition.
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Affiliation(s)
- Jacob A Theruvathu
- Department of Pharmacology and Toxicology, The University of Texas Medical Branch, 3.330 Basic Science Building, 301 University Blvd, Galveston, TX 77555-0617, USA
| | - Agus Darwanto
- Department of Pharmacology and Toxicology, The University of Texas Medical Branch, 3.330 Basic Science Building, 301 University Blvd, Galveston, TX 77555-0617, USA
| | - Chia Wei Hsu
- Department of Pharmacology and Toxicology, The University of Texas Medical Branch, 3.330 Basic Science Building, 301 University Blvd, Galveston, TX 77555-0617, USA
| | - Lawrence C Sowers
- Department of Pharmacology and Toxicology, The University of Texas Medical Branch, 3.330 Basic Science Building, 301 University Blvd, Galveston, TX 77555-0617, USA
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48
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Dmitrochenko AE, Turiianskaia OM, Gilep AA, Usanov SA, Iantsevich AV. [An effective scheme to produce recombinant uracil-DNA glycosylase of Escherichia coli for PCR diagnostics]. Prikl Biokhim Mikrobiol 2014; 50:398-407. [PMID: 25707116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
An effective scheme has been developed to produce recombinant uracil-DNA glycosylase of Escherichia coli K12 intended to be used for PCR diagnostics, making it possible to achieve a high yield of the end product using a two-stage purification. The gene encoding this enzyme was cloned into the pCWori vector within the same reading frame with six residues of histidine in the C-erminal sequence. Using this vector and the E. coli DH5alpha, a host-vector expression system has been developed and conditions for protein synthesis have been optimized. To purify the protein, metal affinity chromatography with further dialysis was used to remove imidazole. The enzyme yield was no less than 60 mg of the end protein per 1 L of the culture medium. The concordance between amino acid sequences of the recombinant and native enzymes was proved by peptide mass fingerprinting and mass spectrometry. A rapid test to determine the activity of the enzyme preparation was suggested. It was found that the activity of 1.0 mg of the recombinant protein is no less than 3 x 10(3) units. The recombinant enzyme was most stable at pH 8.0 and an ionic strength of the solution equal to 200 mM; it lost its activity completely for 10 min at 60 degrees C. Storage during 1 h at 20 degrees C resulted in the loss of no more than 30% of activity. In the enzyme preparation, the activity of DNase was absent. The free energy of the unfolding of the protein globule of the recombinant uracil-DNA glycosylase is 23.1 +/- 0.2 kJ/mol. The data obtained indicate that the recombinant enzyme may be recommended for use in PCR diagnostics to prevent the appearance of false positive results caused by pollution of the reaction mixture by products of the preceding reactions.
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49
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Knævelsrud I, Kazazic S, Birkeland NK, Bjelland S. The pH optimum of native uracil-DNA glycosylase of Archaeoglobus fulgidus compared to recombinant enzyme indicates adaption to cytosolic pH. Acta Biochim Pol 2014; 61:393-395. [PMID: 24936520] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2014] [Revised: 04/24/2014] [Accepted: 05/02/2014] [Indexed: 06/03/2023]
Abstract
Uracil-DNA glycosylase of Archaeoglobus fulgidus (Afung) in cell extracts exhibited maximal activity around pH 6.2 as compared to pH 4.8 for the purified recombinant enzyme expressed in Escherichia coli. Native Afung thus seems to be adapted to the intracellular pH of A. fulgidus, determined to be 7.0±0.1. Both recombinant and native Afung exhibited a broad temperature optimum for activity around 80°C, reflecting the A. fulgidus optimal growth temperature of 83°C. Adaption to the neutral conditions in the A. fulgidus cytoplasm might be due to covalent modifications or accessory factors, or due to a different folding when expressed in the native host.
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Affiliation(s)
- Ingeborg Knævelsrud
- Faculty of Science and Technology, Department of Mathematics and Natural Sciences-Centre for Organelle Research, University of Stavanger, Stavanger, Norway and Department of Biology and Centre for Geobiology, University of Bergen, Bergen, Norway
| | - Sabina Kazazic
- Faculty of Science and Technology, Department of Mathematics and Natural Sciences-Centre for Organelle Research, University of Stavanger, Stavanger, Norway
| | - Nils-Kåre Birkeland
- Department of Biology and Centre for Geobiology, University of Bergen, Bergen, Norway
| | - Svein Bjelland
- Faculty of Science and Technology, Department of Mathematics and Natural Sciences-Centre for Organelle Research, University of Stavanger, Stavanger, Norway
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50
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Kimber ST, Brown T, Fox KR. A mutant of uracil DNA glycosylase that distinguishes between cytosine and 5-methylcytosine. PLoS One 2014; 9:e95394. [PMID: 24740413 PMCID: PMC3989344 DOI: 10.1371/journal.pone.0095394] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2014] [Accepted: 03/25/2014] [Indexed: 11/19/2022] Open
Abstract
We demonstrate that a mutant of uracil DNA glycosylase (N123D:L191A) distinguishes between cytosine and methylcytosine. Uracil DNA glycosylase (UDG) efficiently removes uracil from DNA in a reaction in which the base is flipped into the enzyme’s active site. Uracil is selected over cytosine by a pattern of specific hydrogen bonds, and thymine is excluded by steric clash of its 5-methyl group with Y66. The N123D mutation generates an enzyme that excises cytosine. This N123D:L191A mutant excises C when it is mispaired with A or opposite an abasic site, but not when it is paired with G. In contrast no cleavage is observed with any substrates that contain 5-methylcytosine. This enzyme may offer a new approach for discriminating between cytosine and 5-methylcytosine.
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Affiliation(s)
- Scott T. Kimber
- Centre for Biological Sciences, University of Southampton, Highfield, Southampton, United Kingdom
| | - Tom Brown
- Department of Chemistry, University of Oxford, Chemistry Research Laboratory, Oxford, United Kingdom
| | - Keith R. Fox
- Centre for Biological Sciences, University of Southampton, Highfield, Southampton, United Kingdom
- * E-mail:
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