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Huebert DNG, Ghorbani A, Lam SYB, Larijani M. Coevolution of Lentiviral Vif with Host A3F and A3G: Insights from Computational Modelling and Ancestral Sequence Reconstruction. Viruses 2025; 17:393. [PMID: 40143321 PMCID: PMC11946711 DOI: 10.3390/v17030393] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2024] [Revised: 03/03/2025] [Accepted: 03/05/2025] [Indexed: 03/28/2025] Open
Abstract
The evolutionary arms race between host restriction factors and viral antagonists provides crucial insights into immune system evolution and viral adaptation. This study investigates the structural and evolutionary dynamics of the double-domain restriction factors A3F and A3G and their viral inhibitor, Vif, across diverse primate species. By constructing 3D structural homology models and integrating ancestral sequence reconstruction (ASR), we identified patterns of sequence diversity, structural conservation, and functional adaptation. Inactive CD1 (Catalytic Domain 1) domains displayed greater sequence diversity and more positive surface charges than active CD2 domains, aiding nucleotide chain binding and intersegmental transfer. Despite variability, the CD2 DNA-binding grooves remained structurally consistent with conserved residues maintaining critical functions. A3F and A3G diverged in loop 7' interaction strategies, utilising distinct molecular interactions to facilitate their roles. Vif exhibited charge variation linked to host species, reflecting its coevolution with A3 proteins. These findings illuminate how structural adaptations and charge dynamics enable both restriction factors and their viral antagonists to adapt to selective pressures. Our results emphasize the importance of studying structural evolution in host-virus interactions, with implications for understanding immune defense mechanisms, zoonotic risks, and viral evolution. This work establishes a foundation for further exploration of restriction factor diversity and coevolution across species.
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Affiliation(s)
- David Nicolas Giuseppe Huebert
- Immunology and Infectious Diseases Program, Division of Biomedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John’s, NL A1C 5S7, Canada; (D.N.G.H.); (A.G.)
- Structural Biology and Immunology Program, Department of Molecular Biology and Biochemistry, Faculty of Science, Simon Fraser University, Burnaby, BC V5A 1S6, Canada;
| | - Atefeh Ghorbani
- Immunology and Infectious Diseases Program, Division of Biomedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John’s, NL A1C 5S7, Canada; (D.N.G.H.); (A.G.)
| | - Shaw Yick Brian Lam
- Structural Biology and Immunology Program, Department of Molecular Biology and Biochemistry, Faculty of Science, Simon Fraser University, Burnaby, BC V5A 1S6, Canada;
| | - Mani Larijani
- Immunology and Infectious Diseases Program, Division of Biomedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John’s, NL A1C 5S7, Canada; (D.N.G.H.); (A.G.)
- Structural Biology and Immunology Program, Department of Molecular Biology and Biochemistry, Faculty of Science, Simon Fraser University, Burnaby, BC V5A 1S6, Canada;
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2
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Kamba K, Wan L, Unzai S, Morishita R, Takaori-Kondo A, Nagata T, Katahira M. Direct inhibition of human APOBEC3 deaminases by HIV-1 Vif independent of the proteolysis pathway. Biophys J 2024; 123:294-306. [PMID: 38115583 PMCID: PMC10870137 DOI: 10.1016/j.bpj.2023.12.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Revised: 12/01/2023] [Accepted: 12/14/2023] [Indexed: 12/21/2023] Open
Abstract
HIV-1 Vif is known to counteract the antiviral activity of human apolipoprotein B mRNA-editing catalytic polypeptide-like (A3), a cytidine deaminase, in various ways. However, the precise mechanism behind this interaction has remained elusive. Within infected cells, Vif forms a complex called VβBCC, comprising CBFβ and the components of E3 ubiquitin ligase, Elongin B, Elongin C, and Cullin5. Together with the ubiquitin-conjugating enzyme, VβBCC induces ubiquitination-mediated proteasomal degradation of A3. However, Vif exhibits additional counteractive effects. In this study, we elucidate that VβBCC inhibits deamination by A3G, A3F, and A3B independently of proteasomal degradation. Surprisingly, we discovered that this inhibition for A3G is directly attributed to the interaction between VβBCC and the C-terminal domain of A3G. Previously, it was believed that Vif did not interact with the C-terminal domain. Our findings suggest that inhibiting the interaction between VβBCC and the C-terminal domain, as well as the N-terminal domain known to be targeted for ubiquitination, of A3G may be needed to prevent counteraction by Vif.
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Affiliation(s)
- Keisuke Kamba
- Institute of Advanced Energy, Kyoto University, Uji, Kyoto, Japan
| | - Li Wan
- Institute of Advanced Energy, Kyoto University, Uji, Kyoto, Japan; Graduate School of Energy Science, Kyoto University, Uji, Kyoto, Japan
| | - Satoru Unzai
- Department of Frontier Bioscience, Hosei University, Koganei, Tokyo, Japan
| | - Ryo Morishita
- CellFree Sciences Co., Ltd., Matsuyama, Ehime, Japan
| | - Akifumi Takaori-Kondo
- Department of Hematology and Oncology Graduate School of Medicine, Kyoto University, Sakyo-ku, Kyoto, Japan
| | - Takashi Nagata
- Institute of Advanced Energy, Kyoto University, Uji, Kyoto, Japan; Graduate School of Energy Science, Kyoto University, Uji, Kyoto, Japan.
| | - Masato Katahira
- Institute of Advanced Energy, Kyoto University, Uji, Kyoto, Japan; Graduate School of Energy Science, Kyoto University, Uji, Kyoto, Japan.
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3
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Liu Y, Lan W, Wang C, Cao C. Two different kinds of interaction modes of deaminase APOBEC3A with single-stranded DNA in solution detected by nuclear magnetic resonance. Protein Sci 2022; 31:443-453. [PMID: 34792260 PMCID: PMC8819843 DOI: 10.1002/pro.4242] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2021] [Revised: 11/09/2021] [Accepted: 11/09/2021] [Indexed: 02/03/2023]
Abstract
APOBEC3A (A3A) deaminates deoxycytidine in target motif TC in a single-stranded DNA (we termed it as TC DNA), which mortally mutates viral pathogens and immunoglobulins, and leads to the diversification and lethality of cancers. The crystal structure of A3A-DNA revealed a unique U-shaped recognition mode of target base dC0 . However, when TC DNA was titrated into 15 N-labeled A3A solution, we observed two sets of 1 H-15 N cross-peaks of A3A in HSQC spectra, and two sets of 1 H-1 H cross-peaks of DNA in two-dimensional 13 C,15 N-filtered TOCSY spectra, indicating two different kinds of conformers of either A3A or TC DNA existing in solution. Here, mainly by NMR, we demonstrated that one DNA conformer interacted with one A3A conformer, forming a specific complex A3AS -DNAS in a way almost similar to that observed in the reported crystal A3A-DNA structure, where dC0 inserted into zinc ion binding center. While the other DNA conformer bound with another A3A conformer, but dC0 did not extend into the zinc-binding pocket, forming a nonspecific A3ANS -DNANS complex. The NMR solution structure implied three sites Asn61 , His182 and Arg189 were necessary to DNA recognition. These observations indicate a distinctive way from that reported in X-ray crystal structure, suggesting an unexpected mode of deaminase APOBEC3A to identify target motif TC in DNA in solution.
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Affiliation(s)
- Yaping Liu
- State Key Laboratory of Bioorganic and Natural Product ChemistryCenter for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of SciencesShanghaiChina,University of Chinese Academy of ScienceBeijingChina
| | - Wenxian Lan
- State Key Laboratory of Bioorganic and Natural Product ChemistryCenter for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of SciencesShanghaiChina
| | - Chunxi Wang
- State Key Laboratory of Bioorganic and Natural Product ChemistryCenter for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of SciencesShanghaiChina
| | - Chunyang Cao
- State Key Laboratory of Bioorganic and Natural Product ChemistryCenter for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of SciencesShanghaiChina,University of Chinese Academy of ScienceBeijingChina
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4
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Kaake RM, Echeverria I, Kim SJ, Von Dollen J, Chesarino NM, Feng Y, Yu C, Ta H, Chelico L, Huang L, Gross J, Sali A, Krogan NJ. Characterization of an A3G-Vif HIV-1-CRL5-CBFβ Structure Using a Cross-linking Mass Spectrometry Pipeline for Integrative Modeling of Host-Pathogen Complexes. Mol Cell Proteomics 2021; 20:100132. [PMID: 34389466 PMCID: PMC8459920 DOI: 10.1016/j.mcpro.2021.100132] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2021] [Revised: 07/15/2021] [Accepted: 08/04/2021] [Indexed: 10/24/2022] Open
Abstract
Structural analysis of host-pathogen protein complexes remains challenging, largely due to their structural heterogeneity. Here, we describe a pipeline for the structural characterization of these complexes using integrative structure modeling based on chemical cross-links and residue-protein contacts inferred from mutagenesis studies. We used this approach on the HIV-1 Vif protein bound to restriction factor APOBEC3G (A3G), the Cullin-5 E3 ring ligase (CRL5), and the cellular transcription factor Core Binding Factor Beta (CBFβ) to determine the structure of the (A3G-Vif-CRL5-CBFβ) complex. Using the MS-cleavable DSSO cross-linker to obtain a set of 132 cross-links within this reconstituted complex along with the atomic structures of the subunits and mutagenesis data, we computed an integrative structure model of the heptameric A3G-Vif-CRL5-CBFβ complex. The structure, which was validated using a series of tests, reveals that A3G is bound to Vif mostly through its N-terminal domain. Moreover, the model ensemble quantifies the dynamic heterogeneity of the A3G C-terminal domain and Cul5 positions. Finally, the model was used to rationalize previous structural, mutagenesis and functional data not used for modeling, including information related to the A3G-bound and unbound structures as well as mapping functional mutations to the A3G-Vif interface. The experimental and computational approach described here is generally applicable to other challenging host-pathogen protein complexes.
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Affiliation(s)
- Robyn M Kaake
- Department of Cellular and Molecular Pharmacology, California Institute for Quantitative Biosciences, University of California, San Francisco, San Francisco, California, USA; Quantitative Biosciences Institute, University of California, San Francisco, San Francisco, California, USA; Gladstone Institute of Data Science and Biotechnology, J. David Gladstone Institutes, San Francisco, California, USA
| | - Ignacia Echeverria
- Department of Cellular and Molecular Pharmacology, California Institute for Quantitative Biosciences, University of California, San Francisco, San Francisco, California, USA; Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, California, USA
| | - Seung Joong Kim
- Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, California, USA
| | - John Von Dollen
- Department of Cellular and Molecular Pharmacology, California Institute for Quantitative Biosciences, University of California, San Francisco, San Francisco, California, USA; Quantitative Biosciences Institute, University of California, San Francisco, San Francisco, California, USA
| | - Nicholas M Chesarino
- Divisions of Human Biology and Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, Washington, USA
| | - Yuqing Feng
- Department of Biochemistry, Microbiology, Immunology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Clinton Yu
- Department of Physiology & Biophysics, University of California, Irvine, California, USA
| | - Hai Ta
- Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, California, USA
| | - Linda Chelico
- Department of Biochemistry, Microbiology, Immunology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Lan Huang
- Department of Physiology & Biophysics, University of California, Irvine, California, USA
| | - John Gross
- Quantitative Biosciences Institute, University of California, San Francisco, San Francisco, California, USA; Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, California, USA
| | - Andrej Sali
- Quantitative Biosciences Institute, University of California, San Francisco, San Francisco, California, USA; Department of Bioengineering and Therapeutic Sciences, University of California, San Francisco, San Francisco, California, USA; Department of Pharmaceutical Chemistry, University of California, San Francisco, San Francisco, California, USA.
| | - Nevan J Krogan
- Department of Cellular and Molecular Pharmacology, California Institute for Quantitative Biosciences, University of California, San Francisco, San Francisco, California, USA; Quantitative Biosciences Institute, University of California, San Francisco, San Francisco, California, USA; Gladstone Institute of Data Science and Biotechnology, J. David Gladstone Institutes, San Francisco, California, USA.
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5
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Hou S, Lee JM, Myint W, Matsuo H, Kurt Yilmaz N, Schiffer CA. Structural basis of substrate specificity in human cytidine deaminase family APOBEC3s. J Biol Chem 2021; 297:100909. [PMID: 34171358 PMCID: PMC8313598 DOI: 10.1016/j.jbc.2021.100909] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2021] [Revised: 06/21/2021] [Accepted: 06/21/2021] [Indexed: 01/22/2023] Open
Abstract
The human cytidine deaminase family of APOBEC3s (A3s) plays critical roles in both innate immunity and the development of cancers. A3s comprise seven functionally overlapping but distinct members that can be exploited as nucleotide base editors for treating genetic diseases. Although overall structurally similar, A3s have vastly varying deamination activity and substrate preferences. Recent crystal structures of ssDNA-bound A3s together with experimental studies have provided some insights into distinct substrate specificities among the family members. However, the molecular interactions responsible for their distinct biological functions and how structure regulates substrate specificity are not clear. In this study, we identified the structural basis of substrate specificities in three catalytically active A3 domains whose crystal structures have been previously characterized: A3A, A3B- CTD, and A3G-CTD. Through molecular modeling and dynamic simulations, we found an interdependency between ssDNA substrate binding conformation and nucleotide sequence specificity. In addition to the U-shaped conformation seen in the crystal structure with the CTC0 motif, A3A can accommodate the CCC0 motif when ssDNA is in a more linear (L) conformation. A3B can also bind both U- and L-shaped ssDNA, unlike A3G, which can stably recognize only linear ssDNA. These varied conformations are stabilized by sequence-specific interactions with active site loops 1 and 7, which are highly variable among A3s. Our results explain the molecular basis of previously observed substrate specificities in A3s and have implications for designing A3-specific inhibitors for cancer therapy as well as engineering base-editing systems for gene therapy.
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Affiliation(s)
- Shurong Hou
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts, USA
| | - Jeong Min Lee
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts, USA
| | - Wazo Myint
- Basic Research Laboratory, Frederick National Laboratory for Cancer Research, Frederick, Maryland, USA
| | - Hiroshi Matsuo
- Basic Research Laboratory, Frederick National Laboratory for Cancer Research, Frederick, Maryland, USA
| | - Nese Kurt Yilmaz
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts, USA.
| | - Celia A Schiffer
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, Massachusetts, USA.
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6
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Bahmani L, Baghi M, Peymani M, Javeri A, Ghaedi K. MiR-141-3p and miR-200a-3p are involved in Th17 cell differentiation by negatively regulating RARB expression. Hum Cell 2021; 34:1375-1387. [PMID: 34086186 DOI: 10.1007/s13577-021-00558-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Accepted: 05/24/2021] [Indexed: 01/09/2023]
Abstract
Among T helper (Th) lineages differentiated from naïve CD4+ T cells, interleukin (IL)-17-producing Th17 cells are highly correlated with the pathogenesis of autoimmune disorders. This study aimed to clarify the involvement of miR-141-3p and miR-200a-3p in Th17 cell differentiation as well as explore their potential target genes involved. For this purpose, human naïve CD4+ T cells were cultured under Th17 cell polarizing condition. The differentiation process was confirmed through measurement of IL-17 secretion using the ELISA method and assessment of Th17 cell-defining genes expression during the differentiation period. MiR-141-3p and miR-200a-3p downstream genes were identified via consensus and integration in silico approach and their expression pattern and alterations were evaluated by quantitative real-time PCR. Finally, direct interaction between both microRNAs (miRNAs) and their common predicted target sequences was approved by dual-luciferase reporter assay. Highly increased IL-17 secretion and Th17 lineage-specific genes expression confirmed Th17 cell differentiation. Our results have demonstrated that miR-141-3p and miR-200a-3p are Th17 cell-associated miRNAs and their expression level is upregulated significantly during Th17 cell induction. We have also found that retinoic acid receptor beta (RARB) gene, whose product has been reported as a negative regulator of Th17 cell generation, is a direct target of both miRNAs and its downregulation can affect the transcriptional level of JAK/STAT pathway genes. Overall, our results have identified two novel Th17 lineage-associated miRNAs and have provided evidence for the RARB-dependent mechanism of miR-141-3p and miR-200a-3p-induced Th17 cell differentiation and hence Th17-mediated autoimmunity.
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Affiliation(s)
- Leila Bahmani
- Department of Stem Cells and Regenerative Medicine, Institute for Medical Biotechnology, National Institute of Genetic Engineering and Biotechnology (NIGEB), Pajoohesh Blvd., P.O. Code 14965-161, Tehran, Iran
| | - Masoud Baghi
- Department of Cell and Molecular Biology and Microbiology, Faculty of Biological Science and Technology, University of Isfahan, Hezar Jerib Ave., Azadi Sq., P.O. Code 81746-73441, Isfahan, Iran.,Department of Animal Biotechnology, Cell Science Research Center, Royan Institute for Biotechnology, ACECR, Isfahan, Iran
| | - Maryam Peymani
- Department of Biology, Faculty of Basic Sciences, Shahrekord Branch, Islamic Azad University, Shahrekord, Iran
| | - Arash Javeri
- Department of Stem Cells and Regenerative Medicine, Institute for Medical Biotechnology, National Institute of Genetic Engineering and Biotechnology (NIGEB), Pajoohesh Blvd., P.O. Code 14965-161, Tehran, Iran.
| | - Kamran Ghaedi
- Department of Cell and Molecular Biology and Microbiology, Faculty of Biological Science and Technology, University of Isfahan, Hezar Jerib Ave., Azadi Sq., P.O. Code 81746-73441, Isfahan, Iran.
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7
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Insights into the Structures and Multimeric Status of APOBEC Proteins Involved in Viral Restriction and Other Cellular Functions. Viruses 2021; 13:v13030497. [PMID: 33802945 PMCID: PMC8002816 DOI: 10.3390/v13030497] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Revised: 03/15/2021] [Accepted: 03/15/2021] [Indexed: 12/16/2022] Open
Abstract
Apolipoprotein B mRNA editing catalytic polypeptide-like (APOBEC) proteins belong to a family of deaminase proteins that can catalyze the deamination of cytosine to uracil on single-stranded DNA or/and RNA. APOBEC proteins are involved in diverse biological functions, including adaptive and innate immunity, which are critical for restricting viral infection and endogenous retroelements. Dysregulation of their functions can cause undesired genomic mutations and RNA modification, leading to various associated diseases, such as hyper-IgM syndrome and cancer. This review focuses on the structural and biochemical data on the multimerization status of individual APOBECs and the associated functional implications. Many APOBECs form various multimeric complexes, and multimerization is an important way to regulate functions for some of these proteins at several levels, such as deaminase activity, protein stability, subcellular localization, protein storage and activation, virion packaging, and antiviral activity. The multimerization of some APOBECs is more complicated than others, due to the associated complex RNA binding modes.
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8
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The Role of APOBECs in Viral Replication. Microorganisms 2020; 8:microorganisms8121899. [PMID: 33266042 PMCID: PMC7760323 DOI: 10.3390/microorganisms8121899] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 11/25/2020] [Accepted: 11/26/2020] [Indexed: 12/14/2022] Open
Abstract
Apolipoprotein B mRNA-editing enzyme catalytic polypeptide-like (APOBEC) proteins are a diverse and evolutionarily conserved family of cytidine deaminases that provide a variety of functions from tissue-specific gene expression and immunoglobulin diversity to control of viruses and retrotransposons. APOBEC family expansion has been documented among mammalian species, suggesting a powerful selection for their activity. Enzymes with a duplicated zinc-binding domain often have catalytically active and inactive domains, yet both have antiviral function. Although APOBEC antiviral function was discovered through hypermutation of HIV-1 genomes lacking an active Vif protein, much evidence indicates that APOBECs also inhibit virus replication through mechanisms other than mutagenesis. Multiple steps of the viral replication cycle may be affected, although nucleic acid replication is a primary target. Packaging of APOBECs into virions was first noted with HIV-1, yet is not a prerequisite for viral inhibition. APOBEC antagonism may occur in viral producer and recipient cells. Signatures of APOBEC activity include G-to-A and C-to-T mutations in a particular sequence context. The importance of APOBEC activity for viral inhibition is reflected in the identification of numerous viral factors, including HIV-1 Vif, which are dedicated to antagonism of these deaminases. Such viral antagonists often are only partially successful, leading to APOBEC selection for viral variants that enhance replication or avoid immune elimination.
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9
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Maiti A, Myint W, Delviks-Frankenberry KA, Hou S, Kanai T, Balachandran V, Sierra Rodriguez C, Tripathi R, Kurt Yilmaz N, Pathak VK, Schiffer CA, Matsuo H. Crystal Structure of a Soluble APOBEC3G Variant Suggests ssDNA to Bind in a Channel that Extends between the Two Domains. J Mol Biol 2020; 432:6042-6060. [PMID: 33098858 DOI: 10.1016/j.jmb.2020.10.020] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Revised: 10/09/2020] [Accepted: 10/16/2020] [Indexed: 11/16/2022]
Abstract
APOBEC3G (A3G) is a single-stranded DNA (ssDNA) cytosine deaminase that can restrict HIV-1 infection by mutating the viral genome. A3G consists of a non-catalytic N-terminal domain (NTD) and a catalytic C-terminal domain (CTD) connected by a short linker. While the CTD catalyzes cytosine deamination, the NTD is believed to provide additional affinity for ssDNA. Structures of both A3G domains have been solved individually; however, a full-length A3G structure has been challenging. Recently, crystal structures of full-length rhesus macaque A3G variants were solved which suggested dimerization mechanisms and RNA binding surfaces, whereas the dimerization appeared to compromise catalytic activity. We determined the crystal structure of a soluble variant of human A3G (sA3G) at 2.5 Å and from these data generated a model structure of wild-type A3G. This model demonstrated that the NTD was rotated 90° relative to the CTD along the major axis of the molecule, an orientation that forms a positively charged channel connected to the CTD catalytic site, consisting of NTD loop-1 and CTD loop-3. Structure-based mutations, in vitro deamination and DNA binding assays, and HIV-1 restriction assays identify R24, located in the NTD loop-1, as essential to a critical interaction with ssDNA. Furthermore, sA3G was shown to bind a deoxy-cytidine dinucleotide near the catalytic Zn2+, yet not in the catalytic position, where the interactions between deoxy-cytidines and CTD loop-1 and loop-7 residues were different from those formed with substrate. These new interactions suggest a mechanism explaining why A3G exhibits a 3' to 5' directional preference in processive deamination.
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Affiliation(s)
- Atanu Maiti
- Basic Science Program, Frederick National Laboratory for Cancer Research, Frederick, MD 21702, USA
| | - Wazo Myint
- Basic Science Program, Frederick National Laboratory for Cancer Research, Frederick, MD 21702, USA
| | - Krista A Delviks-Frankenberry
- Viral Mutation Section, HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute at Frederick, Frederick, MD 21702, USA
| | - Shurong Hou
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01655, USA
| | - Tapan Kanai
- Basic Science Program, Frederick National Laboratory for Cancer Research, Frederick, MD 21702, USA; Department of Chemistry, Banasthali University, Banasthali 304022, Rajasthan, India
| | | | | | - Rashmi Tripathi
- Department of Bioscience and Biotechnology, Banasthali University, Banasthali 304022, Rajasthan, India
| | - Nese Kurt Yilmaz
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01655, USA
| | - Vinay K Pathak
- Viral Mutation Section, HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute at Frederick, Frederick, MD 21702, USA
| | - Celia A Schiffer
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01655, USA
| | - Hiroshi Matsuo
- Basic Science Program, Frederick National Laboratory for Cancer Research, Frederick, MD 21702, USA.
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10
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Delviks-Frankenberry KA, Desimmie BA, Pathak VK. Structural Insights into APOBEC3-Mediated Lentiviral Restriction. Viruses 2020; 12:E587. [PMID: 32471198 PMCID: PMC7354603 DOI: 10.3390/v12060587] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 05/22/2020] [Accepted: 05/24/2020] [Indexed: 01/18/2023] Open
Abstract
Mammals have developed clever adaptive and innate immune defense mechanisms to protect against invading bacterial and viral pathogens. Human innate immunity is continuously evolving to expand the repertoire of restriction factors and one such family of intrinsic restriction factors is the APOBEC3 (A3) family of cytidine deaminases. The coordinated expression of seven members of the A3 family of cytidine deaminases provides intrinsic immunity against numerous foreign infectious agents and protects the host from exogenous retroviruses and endogenous retroelements. Four members of the A3 proteins-A3G, A3F, A3H, and A3D-restrict HIV-1 in the absence of virion infectivity factor (Vif); their incorporation into progeny virions is a prerequisite for cytidine deaminase-dependent and -independent activities that inhibit viral replication in the host target cell. HIV-1 encodes Vif, an accessory protein that antagonizes A3 proteins by targeting them for polyubiquitination and subsequent proteasomal degradation in the virus producing cells. In this review, we summarize our current understanding of the role of human A3 proteins as barriers against HIV-1 infection, how Vif overcomes their antiviral activity, and highlight recent structural and functional insights into A3-mediated restriction of lentiviruses.
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Affiliation(s)
| | | | - Vinay K. Pathak
- Viral Mutation Section, HIV Dynamics and Replication Program, National Cancer Institute at Frederick, Frederick, MD 21702, USA; (K.A.D.-F.); (B.A.D.)
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11
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Hix MA, Cisneros GA. Computational Investigation of APOBEC3H Substrate Orientation and Selectivity. J Phys Chem B 2020; 124:3903-3908. [PMID: 32321250 PMCID: PMC7313631 DOI: 10.1021/acs.jpcb.0c01857] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
APOBEC3H is a cytidine deaminase protein most well-known for its involvement in antiretroviral activity in humans. It acts upon a single stranded DNA (ssDNA) substrate with preferential targeting of a 5'-TCA-3' motif. Currently available crystal structures do not include the ssDNA substrate in the A3H system, nor is the mechanism of recognition for the preferred sequence known. To determine the position and orientation of the substrate in the active site, we used high-performance computing to perform molecular dynamics simulations on several systems of APOBEC3H. We examined different DNA sequences in the active site to determine the structural and chemical mechanism by which the preferred sequence is recognized. We found residues N49, K50, K51, and K52 to be relevant to the recognition of 3'-adenine and residues S86 and S87 to be relevant to the recognition of 5'-thymine, with both recognitions primarily driven by electrostatic nonbonded interactions.
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Affiliation(s)
- Mark A Hix
- Department of Chemistry, University of North Texas, Denton, Texas 76203, United States
| | - G Andrés Cisneros
- Department of Chemistry, University of North Texas, Denton, Texas 76203, United States
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12
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Solomon WC, Myint W, Hou S, Kanai T, Tripathi R, Kurt Yilmaz N, Schiffer CA, Matsuo H. Mechanism for APOBEC3G catalytic exclusion of RNA and non-substrate DNA. Nucleic Acids Res 2019; 47:7676-7689. [PMID: 31424549 PMCID: PMC6698744 DOI: 10.1093/nar/gkz550] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Revised: 06/06/2019] [Accepted: 06/11/2019] [Indexed: 12/17/2022] Open
Abstract
The potent antiretroviral protein APOBEC3G (A3G) specifically targets and deaminates deoxycytidine nucleotides, generating deoxyuridine, in single stranded DNA (ssDNA) intermediates produced during HIV replication. A non-catalytic domain in A3G binds strongly to RNA, an interaction crucial for recruitment of A3G to the virion; yet, A3G displays no deamination activity for cytidines in viral RNA. Here, we report NMR and molecular dynamics (MD) simulation analysis for interactions between A3Gctd and multiple substrate or non-substrate DNA and RNA, in combination with deamination assays. NMR ssDNA-binding experiments revealed that the interaction with residues in helix1 and loop1 (T201-L220) distinguishes the binding mode of substrate ssDNA from non-substrate. Using 2′-deoxy-2′-fluorine substituted cytidines, we show that a 2′-endo sugar conformation of the target deoxycytidine is favored for substrate binding and deamination. Trajectories of the MD simulation indicate that a ribose 2′-hydroxyl group destabilizes the π-π stacking of the target cytosine and H257, resulting in dislocation of the target cytosine base from the catalytic position. Interestingly, APOBEC3A, which can deaminate ribocytidines, retains the ribocytidine in the catalytic position throughout the MD simulation. Our results indicate that A3Gctd catalytic selectivity against RNA is dictated by both the sugar conformation and 2′-hydroxyl group.
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Affiliation(s)
- William C Solomon
- Department of Biochemistry, Molecular Biology and Biophysics, Institute for Molecular Virology, University of Minnesota, Minneapolis, MN 55455, USA
| | - Wazo Myint
- Basic Research Laboratory, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, Frederick, MD 21702, USA
| | - Shurong Hou
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01655, USA
| | - Tapan Kanai
- Basic Research Laboratory, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, Frederick, MD 21702, USA.,Department of Chemistry, Banasthali University, Banasthali-304022, Rajasthan, India
| | - Rashmi Tripathi
- Department of Bioscience and Biotechnology, Banasthali University, Banasthali-304022, Rajasthan, India
| | - Nese Kurt Yilmaz
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01655, USA
| | - Celia A Schiffer
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01655, USA
| | - Hiroshi Matsuo
- Basic Research Laboratory, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, Frederick, MD 21702, USA
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13
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Pan Y, Shlyakhtenko LS, Lyubchenko YL. Insight into dynamics of APOBEC3G protein in complexes with DNA assessed by high speed AFM. NANOSCALE ADVANCES 2019; 1:4016-4024. [PMID: 33313478 PMCID: PMC7731963 DOI: 10.1039/c9na00457b] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/24/2019] [Accepted: 09/03/2019] [Indexed: 06/12/2023]
Abstract
APOBEC3G (A3G) is a single-stranded DNA (ssDNA) binding protein that restricts the HIV virus by deamination of dC to dU during reverse transcription of the viral genome. A3G has two zing-binding domains: the N-terminal domain (NTD), which efficiently binds ssDNA, and the C-terminal catalytic domain (CTD), which supports deaminase activity of A3G. Until now, structural information on A3G has lacked, preventing elucidation of the molecular mechanisms underlying its interaction with ssDNA and deaminase activity. We have recently built a computational model for the full-length A3G monomer and validated its structure by data obtained from time-lapse High-Speed Atomic Force Microscopy (HS AFM). Here time-lapse HS AFM was applied to directly visualize the structure and dynamics of A3G in complexes with ssDNA. Our results demonstrate a highly dynamic structure of A3G, where two domains of the protein fluctuate between compact globular and extended dumbbell structures. Quantitative analysis of our data revealed a substantial increase in the number of A3G dumbbell structures in the presence of the DNA substrate, suggesting the interaction of A3G with the ssDNA substrate stabilizes this dumbbell structure. Based on these data, we proposed a model explaining the interaction of globular and dumbbell structures of A3G with ssDNA and suggested a possible role of the dumbbell structure in A3G function.
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Affiliation(s)
- Yangang Pan
- Department of Pharmaceutical Sciences, College of Pharmacy, WSH, University of Nebraska Medical CenterOmahaNebraska 68198-6025USA
| | - Luda S. Shlyakhtenko
- Department of Pharmaceutical Sciences, College of Pharmacy, WSH, University of Nebraska Medical CenterOmahaNebraska 68198-6025USA
| | - Yuri L. Lyubchenko
- Department of Pharmaceutical Sciences, College of Pharmacy, WSH, University of Nebraska Medical CenterOmahaNebraska 68198-6025USA
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14
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Yan X, Lan W, Wang C, Cao C. Structural Investigations on the Interactions between Cytidine Deaminase Human APOBEC3G and DNA. Chem Asian J 2019; 14:2235-2241. [PMID: 31116511 DOI: 10.1002/asia.201900480] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2019] [Revised: 05/20/2019] [Indexed: 02/05/2023]
Abstract
Human APOBEC3G (A3G) inhibits the replication of human immunodeficiency virus-1 by deaminating cytidine at the 3'-end in the target motif 5'-CCC-3' in viral cDNA during reverse transcription. It in vitro deaminates two consecutive cytidines in a 3'->5' order. Although a crystal structure of the A3G catalytic domain (A3G-CD2) with DNA was reported, it is unknown why residues involved in enzymatic reaction are distributed widely. Here, we introduced an iodine atom into the C-5 position of cytidine (dC6 I ) in DNA 5'-ATTC4 C5 C6 I A7 ATT-3' (TCCC6 I ). It switches the deamination sequence preference from CCC to TCC, although small dC6 I deamination was observed. Solution structures of A3G-CD2 in complexes with products DNA TCUC6 I and TCUU6 I indicate that the substrate DNA binds A3G-CD2 in TCC and CCC modes. The dC6 deamination correlates with the 4th base type. The CCC mode favours dC6 deamination, while the TCC mode results in dC5 deamination. These studies present an extensive basis to design inhibitors to impede viral evolvability.
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Affiliation(s)
- Xiaoxuan Yan
- State Key Laboratory of Bioorganic and Natural Products Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of Science, 345 Lingling Road, Shanghai, 200032, China.,University of Chinese Academy of Sciences, No. 19(A) Yuquan Road, Shijingshan District, Beijing, 100049, China
| | - Wenxian Lan
- State Key Laboratory of Bioorganic and Natural Products Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of Science, 345 Lingling Road, Shanghai, 200032, China
| | - Chunxi Wang
- State Key Laboratory of Bioorganic and Natural Products Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of Science, 345 Lingling Road, Shanghai, 200032, China
| | - Chunyang Cao
- State Key Laboratory of Bioorganic and Natural Products Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, Chinese Academy of Science, 345 Lingling Road, Shanghai, 200032, China.,University of Chinese Academy of Sciences, No. 19(A) Yuquan Road, Shijingshan District, Beijing, 100049, China
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15
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Hou S, Silvas TV, Leidner F, Nalivaika EA, Matsuo H, Kurt Yilmaz N, Schiffer CA. Structural Analysis of the Active Site and DNA Binding of Human Cytidine Deaminase APOBEC3B. J Chem Theory Comput 2018; 15:637-647. [PMID: 30457868 DOI: 10.1021/acs.jctc.8b00545] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
APOBEC3 (A3) proteins, a family of human cytidine deaminases, protect the host from endogenous retro-elements and exogenous viral infections by introducing hypermutations. However, overexpressed A3s can modify genomic DNA to promote tumorigenesis, especially A3B. Despite their overall similarity, A3 proteins have distinct deamination activity. Recently determined A3 structures have revealed the molecular determinants of nucleotide specificity and DNA binding. However, for A3B, the structural basis for regulation of deamination activity and the role of active site loops in coordinating DNA had remained unknown. Using advanced molecular modeling followed by experimental mutational analysis and dynamics simulations, we investigated the molecular mechanism of DNA binding by A3B-CTD. We modeled fully native A3B-DNA structure, and we identified Arg211 in loop 1 as the gatekeeper coordinating DNA and critical residue for nucleotide specificity. We also identified a unique autoinhibited conformation in A3B-CTD that restricts access and binding of DNA to the active site. Our results reveal the structural basis for DNA binding and relatively lower catalytic activity of A3B and provide opportunities for rational design of specific inhibitors to benefit cancer therapeutics.
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Affiliation(s)
- Shurong Hou
- Department of Biochemistry and Molecular Pharmacology , University of Massachusetts Medical School , Worcester , Massachusetts 01655 , United States
| | - Tania V Silvas
- Department of Biochemistry and Molecular Pharmacology , University of Massachusetts Medical School , Worcester , Massachusetts 01655 , United States
| | - Florian Leidner
- Department of Biochemistry and Molecular Pharmacology , University of Massachusetts Medical School , Worcester , Massachusetts 01655 , United States
| | - Ellen A Nalivaika
- Department of Biochemistry and Molecular Pharmacology , University of Massachusetts Medical School , Worcester , Massachusetts 01655 , United States
| | - Hiroshi Matsuo
- Basic Research Laboratory, Leidos Biomedical Research, Inc. , Frederick National Laboratory for Cancer Research , Frederick , Maryland 21702 , United States
| | - Nese Kurt Yilmaz
- Department of Biochemistry and Molecular Pharmacology , University of Massachusetts Medical School , Worcester , Massachusetts 01655 , United States
| | - Celia A Schiffer
- Department of Biochemistry and Molecular Pharmacology , University of Massachusetts Medical School , Worcester , Massachusetts 01655 , United States
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16
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Crystal Structure of Cytidine Deaminase Human APOBEC3F Chimeric Catalytic Domain in Complex with DNA. CHINESE J CHEM 2018. [DOI: 10.1002/cjoc.201800508] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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17
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Maiti A, Myint W, Kanai T, Delviks-Frankenberry K, Sierra Rodriguez C, Pathak VK, Schiffer CA, Matsuo H. Crystal structure of the catalytic domain of HIV-1 restriction factor APOBEC3G in complex with ssDNA. Nat Commun 2018; 9:2460. [PMID: 29941968 PMCID: PMC6018426 DOI: 10.1038/s41467-018-04872-8] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Accepted: 05/29/2018] [Indexed: 12/03/2022] Open
Abstract
The human APOBEC3G protein is a cytidine deaminase that generates cytidine to deoxy-uridine mutations in single-stranded DNA (ssDNA), and capable of restricting replication of HIV-1 by generating mutations in viral genome. The mechanism by which APOBEC3G specifically deaminates 5′-CC motifs has remained elusive since structural studies have been hampered due to apparently weak ssDNA binding of the catalytic domain of APOBEC3G. We overcame the problem by generating a highly active variant with higher ssDNA affinity. Here, we present the crystal structure of this variant complexed with a ssDNA substrate at 1.86 Å resolution. This structure reveals atomic-level interactions by which APOBEC3G recognizes a functionally-relevant 5′-TCCCA sequence. This complex also reveals a key role of W211 in substrate recognition, implicating a similar recognition in activation-induced cytidine deaminase (AID) with a conserved tryptophan. APOBEC3G (A3G) is a single-stranded DNA (ssDNA) cytidine deaminase that restricts HIV-1. Here the authors provide molecular insights into A3G substrate recognition by determining the 1.86 Å resolution crystal structure of its catalytic domain bound to ssDNA.
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Affiliation(s)
- Atanu Maiti
- Basic Science Program, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, Frederick, MD, 21702, USA
| | - Wazo Myint
- Basic Science Program, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, Frederick, MD, 21702, USA
| | - Tapan Kanai
- Basic Science Program, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, Frederick, MD, 21702, USA
| | - Krista Delviks-Frankenberry
- Viral Mutation Section, HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute at Frederick, Frederick, MD, 21702, USA
| | - Christina Sierra Rodriguez
- Basic Science Program, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, Frederick, MD, 21702, USA
| | - Vinay K Pathak
- Viral Mutation Section, HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute at Frederick, Frederick, MD, 21702, USA
| | - Celia A Schiffer
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA, 01655, USA
| | - Hiroshi Matsuo
- Basic Science Program, Leidos Biomedical Research, Inc., Frederick National Laboratory for Cancer Research, Frederick, MD, 21702, USA.
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18
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Salter JD, Smith HC. Modeling the Embrace of a Mutator: APOBEC Selection of Nucleic Acid Ligands. Trends Biochem Sci 2018; 43:606-622. [PMID: 29803538 PMCID: PMC6073885 DOI: 10.1016/j.tibs.2018.04.013] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2018] [Revised: 04/25/2018] [Accepted: 04/30/2018] [Indexed: 12/17/2022]
Abstract
The 11-member APOBEC (apolipoprotein B mRNA editing catalytic polypeptide-like) family of zinc-dependent cytidine deaminases bind to RNA and single-stranded DNA (ssDNA) and, in specific contexts, modify select (deoxy)cytidines to (deoxy)uridines. In this review, we describe advances made through high-resolution co-crystal structures of APOBECs bound to mono- or oligonucleotides that reveal potential substrate-specific binding sites at the active site and non-sequence-specific nucleic acid binding sites distal to the active site. We also discuss the effect of APOBEC oligomerization on functionality. Future structural studies will need to address how ssDNA binding away from the active site may enhance catalysis and the mechanism by which RNA binding may modulate catalytic activity on ssDNA. APOBEC proteins catalyze deamination of cytidine or deoxycytidine in either a sequence-specific or semi-specific manner on either DNA or RNA. APOBECs each possess the cytidine deaminase core fold, but sequence and structural differences among loops surrounding the zinc-dependent active site impart differences in sequence-dependent target preferences, binding affinity, catalytic rate, and regulation of substrate access to the active site among the 11 family members. APOBECs also regulate the deamination reaction through additional nucleic acid substrate binding sites located within surface grooves or patches of positive electrostatic potential that are distal to the active site but may do so nonspecifically. Binding of nonsubstrate RNA and RNA-mediated oligomerization by APOBECs that deaminate ssDNA downregulates catalytic activity but also controls APOBEC subcellular or virion localization. The presence of a second, though noncatalytic, cytidine deaminase domain for some APOBECs and the ability of some APOBECs to oligomerize add additional molecular surfaces for positive or negative regulation of catalysis through nucleic acid binding.
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Affiliation(s)
- Jason D Salter
- OyaGen, Inc., 77 Ridgeland Road, Rochester, NY 14623, USA.
| | - Harold C Smith
- OyaGen, Inc., 77 Ridgeland Road, Rochester, NY 14623, USA; University of Rochester, School of Medicine and Dentistry, Department of Biochemistry and Biophysics, 601 Elmwood Avenue, Rochester, NY 14642, USA.
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19
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Zhang Q, Zhang J, Gavathiotis E. ICBS 2017 in Shanghai-Illuminating Life with Chemical Innovation. ACS Chem Biol 2018; 13:1111-1122. [PMID: 29677443 PMCID: PMC6855916 DOI: 10.1021/acschembio.8b00220] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Affiliation(s)
- Qi Zhang
- Department of Chemistry, Fudan University, Shanghai 200433, China
| | - Jingyu Zhang
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai 200237, China
| | - Evripidis Gavathiotis
- Department of Biochemistry, Department of Medicine, Albert Einstein College of Medicine, New York 10461, United States
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20
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Ziegler SJ, Liu C, Landau M, Buzovetsky O, Desimmie BA, Zhao Q, Sasaki T, Burdick RC, Pathak VK, Anderson KS, Xiong Y. Insights into DNA substrate selection by APOBEC3G from structural, biochemical, and functional studies. PLoS One 2018; 13:e0195048. [PMID: 29596531 PMCID: PMC5875850 DOI: 10.1371/journal.pone.0195048] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2017] [Accepted: 03/15/2018] [Indexed: 01/27/2023] Open
Abstract
Human apolipoprotein B mRNA-editing enzyme-catalytic polypeptide-like 3 (A3) proteins are a family of cytidine deaminases that catalyze the conversion of deoxycytidine (dC) to deoxyuridine (dU) in single-stranded DNA (ssDNA). A3 proteins act in the innate immune response to viral infection by mutating the viral ssDNA. One of the most well-studied human A3 family members is A3G, which is a potent inhibitor of HIV-1. Each A3 protein prefers a specific substrate sequence for catalysis-for example, A3G deaminates the third dC in the CCCA sequence motif. However, the interaction between A3G and ssDNA is difficult to characterize due to poor solution behavior of the full-length protein and loss of DNA affinity of the truncated protein. Here, we present a novel DNA-anchoring fusion strategy using the protection of telomeres protein 1 (Pot1) which has nanomolar affinity for ssDNA, with which we captured an A3G-ssDNA interaction. We crystallized a non-preferred adenine in the -1 nucleotide-binding pocket of A3G. The structure reveals a unique conformation of the catalytic site loops that sheds light onto how the enzyme scans substrate in the -1 pocket. Furthermore, our biochemistry and virology studies provide evidence that the nucleotide-binding pockets on A3G influence each other in selecting the preferred DNA substrate. Together, the results provide insights into the mechanism by which A3G selects and deaminates its preferred substrates and help define how A3 proteins are tailored to recognize specific DNA sequences. This knowledge contributes to a better understanding of the mechanism of DNA substrate selection by A3G, as well as A3G antiviral activity against HIV-1.
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Affiliation(s)
- Samantha J. Ziegler
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, United States of America
| | - Chang Liu
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, United States of America
| | - Mark Landau
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, United States of America
- Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Olga Buzovetsky
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, United States of America
| | - Belete A. Desimmie
- Viral Mutation Section, HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute at Frederick, Frederick, Maryland, United States of America
| | - Qi Zhao
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, United States of America
| | - Tomoaki Sasaki
- Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Ryan C. Burdick
- Viral Mutation Section, HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute at Frederick, Frederick, Maryland, United States of America
| | - Vinay K. Pathak
- Viral Mutation Section, HIV Dynamics and Replication Program, Center for Cancer Research, National Cancer Institute at Frederick, Frederick, Maryland, United States of America
| | - Karen S. Anderson
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, United States of America
- Department of Pharmacology, Yale University School of Medicine, New Haven, Connecticut, United States of America
| | - Yong Xiong
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, United States of America
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21
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Fang Y, Xiao X, Li SX, Wolfe A, Chen XS. Molecular Interactions of a DNA Modifying Enzyme APOBEC3F Catalytic Domain with a Single-Stranded DNA. J Mol Biol 2018; 430:87-101. [PMID: 29191651 PMCID: PMC5738261 DOI: 10.1016/j.jmb.2017.11.007] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2017] [Revised: 11/14/2017] [Accepted: 11/14/2017] [Indexed: 12/11/2022]
Abstract
The single-stranded DNA (ssDNA) cytidine deaminase APOBEC3F (A3F) deaminates cytosine (C) to uracil (U) and is a known restriction factor of HIV-1. Its C-terminal catalytic domain (CD2) alone is capable of binding single-stranded nucleic acids and is important for deamination. However, little is known about how the CD2 interacts with ssDNA. Here we report a crystal structure of A3F-CD2 in complex with a 10-nucleotide ssDNA composed of poly-thymine, which reveals a novel positively charged nucleic acid binding site distal to the active center that plays a key role in substrate DNA binding and catalytic activity. Lysine and tyrosine residues within this binding site interact with the ssDNA, and mutating these residues dramatically impairs both ssDNA binding and catalytic activity. This binding site is not conserved in APOBEC3G (A3G), which may explain differences in ssDNA-binding characteristics between A3F-CD2 and A3G-CD2. In addition, we observed an alternative Zn-coordination conformation around the active center. These findings reveal the structural relationships between nucleic acid interactions and catalytic activity of A3F.
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Affiliation(s)
- Yao Fang
- Molecular and Computational Biology, Departments of Biological Sciences and Chemistry, University of Southern California, Los Angeles, CA 90089, USA; 161 Hospital of PLA, Wuhan, 430012, China; Department of Clinical Microbiology and Immunology of Southwest Hospital, Third Military Medical University, Chongqing 400038, China
| | - Xiao Xiao
- Molecular and Computational Biology, Departments of Biological Sciences and Chemistry, University of Southern California, Los Angeles, CA 90089, USA; Genetic Molecular and Cellular Biology Program, Keck School of Medicine, University of Southern California, Los Angeles, CA 90089, USA
| | - Shu-Xing Li
- Center of Excellence in NanoBiophysics, Los Angeles, CA 90089, USA
| | - Aaron Wolfe
- Molecular and Computational Biology, Departments of Biological Sciences and Chemistry, University of Southern California, Los Angeles, CA 90089, USA; Genetic Molecular and Cellular Biology Program, Keck School of Medicine, University of Southern California, Los Angeles, CA 90089, USA
| | - Xiaojiang S Chen
- Molecular and Computational Biology, Departments of Biological Sciences and Chemistry, University of Southern California, Los Angeles, CA 90089, USA; Genetic Molecular and Cellular Biology Program, Keck School of Medicine, University of Southern California, Los Angeles, CA 90089, USA; Center of Excellence in NanoBiophysics, Los Angeles, CA 90089, USA; Norris Comprehensive Cancer Center, University of Southern California, Los Angeles, CA 90089, USA.
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22
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Chen C, Ma X, Hu Q, Li X, Huang F, Zhang J, Pan T, Xia J, Liu C, Zhang H. Moloney leukemia virus 10 (MOV10) inhibits the degradation of APOBEC3G through interference with the Vif-mediated ubiquitin-proteasome pathway. Retrovirology 2017; 14:56. [PMID: 29258557 PMCID: PMC5735797 DOI: 10.1186/s12977-017-0382-1] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2017] [Accepted: 12/11/2017] [Indexed: 12/13/2022] Open
Abstract
Background MOV10 protein has ATP-dependent 5′–3′ RNA helicase activity and belongs to the UPF1p superfamily. It can inhibit human immunodeficiency virus type 1 (HIV-1) replication at multiple stages and interact with apolipoprotein-B-mRNA-editing enzyme catalytic polypeptide-like 3G (APOBEC3G or A3G), a member of the cytidine deaminase family that exerts potent inhibitory effects against HIV-1 infection. However, HIV-1-encoded virion infectivity factor (Vif) protein specifically mediates the degradation of A3G via the ubiquitin–proteasome system (UPS). Results We demonstrate that MOV10 counteracts Vif-mediated degradation of A3G by inhibiting the assembly of the Vif-CBF-β-Cullin 5-ElonginB-ElonginC complex. Through interference with UPS, MOV10 enhances the level of A3G in HIV-1-infected cells and virions, and synergistically inhibits the replication and infectivity of HIV-1. In addition, the DEAG-box of MOV10 is required for inhibition of Vif-mediated A3G degradation as the DEAG-box mutant significantly loses this ability. Conclusions Our results demonstrate a novel mechanism involved in the anti-HIV-1 function of MOV10. Given that both MOV10 and A3G belong to the interferon antiviral system, their synergistic inhibition of HIV-1 suggests that these proteins may play complicated roles in antiviral functions.
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Affiliation(s)
- Cancan Chen
- Institute of Human Virology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China.,Key Laboratory of Tropical Disease Control of Ministry of Education, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China.,Department of Pathology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, 510080, China
| | - Xiaocao Ma
- Institute of Human Virology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China.,Key Laboratory of Tropical Disease Control of Ministry of Education, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China
| | - Qifei Hu
- Institute of Human Virology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China.,Key Laboratory of Tropical Disease Control of Ministry of Education, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China
| | - Xinghua Li
- Department of Infectious Diseases, The Fifth Affiliated Hospital, Sun Yat-sen University, Zhuhai, 519000, China
| | - Feng Huang
- Institute of Human Virology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China.,Key Laboratory of Tropical Disease Control of Ministry of Education, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China
| | - Junsong Zhang
- Institute of Human Virology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China.,Key Laboratory of Tropical Disease Control of Ministry of Education, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China
| | - Ting Pan
- Institute of Human Virology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China.,Key Laboratory of Tropical Disease Control of Ministry of Education, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China
| | - Jinyu Xia
- Department of Infectious Diseases, The Fifth Affiliated Hospital, Sun Yat-sen University, Zhuhai, 519000, China
| | - Chao Liu
- Institute of Human Virology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China. .,Key Laboratory of Tropical Disease Control of Ministry of Education, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China.
| | - Hui Zhang
- Institute of Human Virology, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China.,Key Laboratory of Tropical Disease Control of Ministry of Education, Zhongshan School of Medicine, Sun Yat-sen University, Guangzhou, 510080, China
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23
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Lee S, Wang C, Liu H, Xiong J, Jiji R, Hong X, Yan X, Chen Z, Hammel M, Wang Y, Dai S, Wang J, Jiang C, Zhang G. Hydrogen bonds are a primary driving force for de novo protein folding. Acta Crystallogr D Struct Biol 2017; 73:955-969. [PMID: 29199976 PMCID: PMC5713874 DOI: 10.1107/s2059798317015303] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2017] [Accepted: 10/20/2017] [Indexed: 01/09/2023] Open
Abstract
The protein-folding mechanism remains a major puzzle in life science. Purified soluble activation-induced cytidine deaminase (AID) is one of the most difficult proteins to obtain. Starting from inclusion bodies containing a C-terminally truncated version of AID (residues 1-153; AID153), an optimized in vitro folding procedure was derived to obtain large amounts of AID153, which led to crystals with good quality and to final structural determination. Interestingly, it was found that the final refolding yield of the protein is proline residue-dependent. The difference in the distribution of cis and trans configurations of proline residues in the protein after complete denaturation is a major determining factor of the final yield. A point mutation of one of four proline residues to an asparagine led to a near-doubling of the yield of refolded protein after complete denaturation. It was concluded that the driving force behind protein folding could not overcome the cis-to-trans proline isomerization, or vice versa, during the protein-folding process. Furthermore, it was found that successful refolding of proteins optimally occurs at high pH values, which may mimic protein folding in vivo. It was found that high pH values could induce the polarization of peptide bonds, which may trigger the formation of protein secondary structures through hydrogen bonds. It is proposed that a hydrophobic environment coupled with negative charges is essential for protein folding. Combined with our earlier discoveries on protein-unfolding mechanisms, it is proposed that hydrogen bonds are a primary driving force for de novo protein folding.
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Affiliation(s)
- Schuyler Lee
- Department of Biomedical Research, National Jewish Health, Denver, CO 80206, USA
- Department of Immunology and Microbiology, School of Medicine, University of Colorado Denver, Aurora, CO 80206, USA
| | - Chao Wang
- Department of Biomedical Research, National Jewish Health, Denver, CO 80206, USA
| | - Haolin Liu
- Department of Biomedical Research, National Jewish Health, Denver, CO 80206, USA
- Department of Immunology and Microbiology, School of Medicine, University of Colorado Denver, Aurora, CO 80206, USA
| | - Jian Xiong
- Department of Chemistry, University of Missouri, Columbus, Mississippi, USA
| | - Renee Jiji
- Department of Chemistry, University of Missouri, Columbus, Mississippi, USA
| | - Xia Hong
- Department of Biomedical Research, National Jewish Health, Denver, CO 80206, USA
| | - Xiaoxue Yan
- Department of Biomedical Research, National Jewish Health, Denver, CO 80206, USA
| | - Zhangguo Chen
- Department of Immunology and Microbiology, School of Medicine, University of Colorado Denver, Aurora, CO 80206, USA
| | - Michal Hammel
- Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA
| | - Yang Wang
- Department of Biomedical Research, National Jewish Health, Denver, CO 80206, USA
- Department of Immunology and Microbiology, School of Medicine, University of Colorado Denver, Aurora, CO 80206, USA
| | - Shaodong Dai
- Department of Biomedical Research, National Jewish Health, Denver, CO 80206, USA
- Department of Immunology and Microbiology, School of Medicine, University of Colorado Denver, Aurora, CO 80206, USA
| | - Jing Wang
- Department of Immunology and Microbiology, School of Medicine, University of Colorado Denver, Aurora, CO 80206, USA
| | - Chengyu Jiang
- Department of Biochemistry and Molecular Biology, Peking Union Medical College, Beijing 100005, People’s Republic of China
| | - Gongyi Zhang
- Department of Biomedical Research, National Jewish Health, Denver, CO 80206, USA
- Department of Immunology and Microbiology, School of Medicine, University of Colorado Denver, Aurora, CO 80206, USA
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24
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Gorle S, Pan Y, Sun Z, Shlyakhtenko LS, Harris RS, Lyubchenko YL, Vuković L. Computational Model and Dynamics of Monomeric Full-Length APOBEC3G. ACS CENTRAL SCIENCE 2017; 3:1180-1188. [PMID: 29202020 PMCID: PMC5704289 DOI: 10.1021/acscentsci.7b00346] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2017] [Indexed: 05/29/2023]
Abstract
APOBEC3G (A3G) is a restriction factor that provides innate immunity against HIV-1 in the absence of viral infectivity factor (Vif) protein. However, structural information about A3G, which can aid in unraveling the mechanisms that govern its interactions and define its antiviral activity, remains unknown. Here, we built a computer model of a full-length A3G using docking approaches and molecular dynamics simulations, based on the available X-ray and NMR structural data for the two protein domains. The model revealed a large-scale dynamics of the A3G monomer, as the two A3G domains can assume compact forms or extended dumbbell type forms with domains visibly separated from each other. To validate the A3G model, we performed time-lapse high-speed atomic force microscopy (HS-AFM) experiments enabling us to get images of a fully hydrated A3G and to directly visualize its dynamics. HS-AFM confirmed that A3G exists in two forms, a globular form (∼84% of the time) and a dumbbell form (∼16% of the time), and can dynamically switch from one form to the other. The obtained HS-AFM results are in line with the computer modeling, which demonstrates a similar distribution between two forms. Furthermore, our simulations capture the complete process of A3G switching from the DNA-bound state to the closed state. The revealed dynamic nature of monomeric A3G could aid in target recognition including scanning for cytosine locations along the DNA strand and in interactions with viral RNA during packaging into HIV-1 particles.
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Affiliation(s)
- Suresh Gorle
- Department
of Chemistry, University of Texas at El
Paso, El Paso, Texas 79968, United States
| | - Yangang Pan
- Department
of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, Omaha, Nebraska 68198-6025, United States
| | - Zhiqiang Sun
- Department
of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, Omaha, Nebraska 68198-6025, United States
| | - Luda S. Shlyakhtenko
- Department
of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, Omaha, Nebraska 68198-6025, United States
| | - Reuben S. Harris
- Department
of Biochemistry, Molecular Biology and Biophysics, Institute for Molecular
Virology, Center for Genome Engineering, Masonic Cancer Center, University of Minnesota, Minneapolis, Minnesota 55455, United States
- Howard
Hughes Medical Institute, University of
Minnesota, Minneapolis, Minnesota 55455, United States
| | - Yuri L. Lyubchenko
- Department
of Pharmaceutical Sciences, College of Pharmacy, University of Nebraska Medical Center, Omaha, Nebraska 68198-6025, United States
| | - Lela Vuković
- Department
of Chemistry, University of Texas at El
Paso, El Paso, Texas 79968, United States
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25
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Bohn JA, Thummar K, York A, Raymond A, Brown WC, Bieniasz PD, Hatziioannou T, Smith JL. APOBEC3H structure reveals an unusual mechanism of interaction with duplex RNA. Nat Commun 2017; 8:1021. [PMID: 29044109 PMCID: PMC5647330 DOI: 10.1038/s41467-017-01309-6] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Accepted: 09/06/2017] [Indexed: 11/08/2022] Open
Abstract
The APOBEC3 family of cytidine deaminases cause lethal hypermutation of retroviruses via deamination of newly reverse-transcribed viral DNA. Their ability to bind RNA is essential for virion infiltration and antiviral activity, yet the mechanisms of viral RNA recognition are unknown. By screening naturally occurring, polymorphic, non-human primate APOBEC3H variants for biological and crystallization properties, we obtained a 2.24-Å crystal structure of pig-tailed macaque APOBEC3H with bound RNA. Here, we report that APOBEC3H forms a dimer around a short RNA duplex and, despite the bound RNA, has potent cytidine deaminase activity. The structure reveals an unusual RNA-binding mode in which two APOBEC3H molecules at opposite ends of a seven-base-pair duplex interact extensively with both RNA strands, but form no protein-protein contacts. CLIP-seq analysis revealed that APOBEC3H preferentially binds to sequences in the viral genome predicted to contain duplexes, a property that may facilitate both virion incorporation and catalytic activity.
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Affiliation(s)
- Jennifer A Bohn
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, 48109, USA
- Department of Biological Chemistry, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Keyur Thummar
- Laboratory of Retrovirology, The Rockefeller University, New York, NY, 10065, USA
- Howard Hughes Medical Institute, The Rockefeller University, New York, NY, 10065, USA
| | - Ashley York
- Laboratory of Retrovirology, The Rockefeller University, New York, NY, 10065, USA
- Howard Hughes Medical Institute, The Rockefeller University, New York, NY, 10065, USA
| | - Alice Raymond
- Laboratory of Retrovirology, The Rockefeller University, New York, NY, 10065, USA
- Howard Hughes Medical Institute, The Rockefeller University, New York, NY, 10065, USA
| | - W Clay Brown
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Paul D Bieniasz
- Laboratory of Retrovirology, The Rockefeller University, New York, NY, 10065, USA
- Howard Hughes Medical Institute, The Rockefeller University, New York, NY, 10065, USA
| | | | - Janet L Smith
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, 48109, USA.
- Department of Biological Chemistry, University of Michigan, Ann Arbor, MI, 48109, USA.
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26
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Dimerization regulates both deaminase-dependent and deaminase-independent HIV-1 restriction by APOBEC3G. Nat Commun 2017; 8:597. [PMID: 28928403 PMCID: PMC5605669 DOI: 10.1038/s41467-017-00501-y] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Accepted: 07/04/2017] [Indexed: 01/09/2023] Open
Abstract
APOBEC3G (A3G) is a human enzyme that inhibits human immunodeficiency virus type 1 (HIV-1) infectivity, in the absence of the viral infectivity factor Vif, through deoxycytidine deamination and a deamination-independent mechanism. A3G converts from a fast to a slow binding state through oligomerization, which suggests that large A3G oligomers could block HIV-1 reverse transcriptase-mediated DNA synthesis, thereby inhibiting HIV-1 replication. However, it is unclear how the small number of A3G molecules found in the virus could form large oligomers. Here we measure the single-stranded DNA binding and oligomerization kinetics of wild-type and oligomerization-deficient A3G, and find that A3G first transiently binds DNA as a monomer. Subsequently, A3G forms N-terminal domain-mediated dimers, whose dissociation from DNA is reduced and their deaminase activity inhibited. Overall, our results suggest that the A3G molecules packaged in the virion first deaminate viral DNA as monomers before dimerizing to form multiple enzymatically deficient roadblocks that may inhibit reverse transcription. APOBEC3G inhibits HIV-1 viral replication via catalytic and non-catalytic processes. Here the authors show that APOBEC3G binds single-stranded DNA as an active deaminase monomer, subsequently forming catalytic-inactive dimers that block reverse transcriptase-mediated DNA synthesis.
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27
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Adolph MB, Ara A, Feng Y, Wittkopp CJ, Emerman M, Fraser JS, Chelico L. Cytidine deaminase efficiency of the lentiviral viral restriction factor APOBEC3C correlates with dimerization. Nucleic Acids Res 2017; 45:3378-3394. [PMID: 28158858 PMCID: PMC5389708 DOI: 10.1093/nar/gkx066] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2016] [Accepted: 01/24/2017] [Indexed: 01/28/2023] Open
Abstract
The seven APOBEC3 (A3) enzymes in primates restrict HIV/SIV replication to differing degrees by deaminating cytosine in viral (−)DNA, which forms promutagenic uracils that inactivate the virus. A polymorphism in human APOBEC3C (A3C) that encodes an S188I mutation increases the enzymatic activity of the protein and its ability to restrict HIV-1, and correlates with increased propensity to form dimers. However, other hominid A3C proteins only have an S188, suggesting they should be less active like the common form of human A3C. Nonetheless, here we demonstrate that chimpanzee and gorilla A3C have approximately equivalent activity to human A3C I188 and that chimpanzee and gorilla A3C form dimers at the same interface as human A3C S188I, but through different amino acids. For each of these hominid A3C enzymes, dimerization enables processivity on single-stranded DNA and results in higher levels of mutagenesis during reverse transcription in vitro and in cells. For increased mutagenic activity, formation of a dimer was more important than specific amino acids and the dimer interface is unique from other A3 enzymes. We propose that dimerization is a predictor of A3C enzyme activity.
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Affiliation(s)
- Madison B Adolph
- Department of Microbiology and Immunology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Anjuman Ara
- Department of Microbiology and Immunology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Yuqing Feng
- Department of Microbiology and Immunology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
| | - Cristina J Wittkopp
- Department of Microbiology, University of Washington, Fred Hutchinson Cancer Research Center, Seattle, WA, USA.,Division of Human Biology, Fred Hutchinson Cancer Research Center, Seattle, WA, USA.,Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - Michael Emerman
- Division of Human Biology, Fred Hutchinson Cancer Research Center, Seattle, WA, USA.,Division of Basic Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA, USA
| | - James S Fraser
- Department of Bioengineering and Therapeutic Science and California Institute for Quantitative Biology, University of California, San Francisco, San Francisco, CA, USA
| | - Linda Chelico
- Department of Microbiology and Immunology, University of Saskatchewan, Saskatoon, Saskatchewan, Canada
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28
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Yang B, Li X, Lei L, Chen J. APOBEC: From mutator to editor. J Genet Genomics 2017; 44:423-437. [PMID: 28964683 DOI: 10.1016/j.jgg.2017.04.009] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2017] [Revised: 04/04/2017] [Accepted: 04/10/2017] [Indexed: 12/21/2022]
Abstract
APOBECs (apolipoprotein B mRNA editing enzyme, catalytic polypeptide-like) are a family of cytidine deaminases that prefer single-stranded nucleic acids as substrates. Besides their physiological functions, APOBEC family members have been found to cause hypermutations of cancer genomes, which could be correlated with cancer development and poor prognosis. Recently, APOBEC family members have been combined with the versatile CRISPR/Cas9 system to perform targeted base editing or induce hypermutagenesis. This combination improved the CRISPR/Cas9-mediated gene editing at single-base precision, greatly enhancing its usefulness. Here, we review the physiological functions and structural characteristics of APOBEC family members and their roles as endogenous mutators that contribute to hypermutations during carcinogenesis. We also review the various iterations of the APOBEC-CRISPR/Cas9 gene-editing tools, pointing out their features and limitations as well as the possibilities for future developments.
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Affiliation(s)
- Bei Yang
- Shanghai Institute for Advanced Immunochemical Studies, ShanghaiTech University, Shanghai 201210, China.
| | - Xiaosa Li
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Liqun Lei
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China
| | - Jia Chen
- School of Life Science and Technology, ShanghaiTech University, Shanghai 201210, China.
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29
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Harjes S, Jameson GB, Filichev VV, Edwards P, Harjes E. NMR-based method of small changes reveals how DNA mutator APOBEC3A interacts with its single-stranded DNA substrate. Nucleic Acids Res 2017; 45:5602-5613. [PMID: 28369637 PMCID: PMC5435981 DOI: 10.1093/nar/gkx196] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Revised: 02/21/2017] [Accepted: 03/14/2017] [Indexed: 12/14/2022] Open
Abstract
APOBEC3 proteins are double-edged swords. They deaminate cytosine to uracil in single-stranded DNA and provide protection, as part of our innate immune system, against viruses and retrotransposons, but they are also involved in cancer evolution and development of drug resistance. We report a solution-state model of APOBEC3A interaction with its single-stranded DNA substrate obtained with the 'method of small changes'. This method compares pairwise the 2D 15N-1H NMR spectra of APOBEC3A bearing a deactivating mutation E72A in the presence of 36 slightly different DNA substrates. From changes in chemical shifts of peptide N-H moieties, the positions of each nucleotide relative to the protein can be identified. This provided distance restraints for molecular-dynamic simulations to derive a 3-D molecular model of the APOBEC3A-ssDNA complex. The model reveals that loops 1 and 7 of APOBEC3A move to accommodate substrate binding, indicating an important role for protein-DNA dynamics. Overall, our method may prove useful to study other DNA-protein complexes where crystallographic techniques or full NMR structure calculations are hindered by weak binding or other problems. Subsequent to submission, an APOBEC3A structure with a bound DNA oligomer was published and coordinates released, which has provided an unbiased validation of the 'method of small changes'.
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Affiliation(s)
- Stefan Harjes
- Institute of Fundamental Sciences, Massey University, Palmerston North 4442, New Zealand
| | - Geoffrey B. Jameson
- Institute of Fundamental Sciences, Massey University, Palmerston North 4442, New Zealand
| | - Vyacheslav V. Filichev
- Institute of Fundamental Sciences, Massey University, Palmerston North 4442, New Zealand
| | - Patrick J. B. Edwards
- Institute of Fundamental Sciences, Massey University, Palmerston North 4442, New Zealand
| | - Elena Harjes
- Institute of Fundamental Sciences, Massey University, Palmerston North 4442, New Zealand
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30
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Crystal structure of APOBEC3A bound to single-stranded DNA reveals structural basis for cytidine deamination and specificity. Nat Commun 2017; 8:15024. [PMID: 28452355 PMCID: PMC5414352 DOI: 10.1038/ncomms15024] [Citation(s) in RCA: 126] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2016] [Accepted: 02/20/2017] [Indexed: 12/21/2022] Open
Abstract
Nucleic acid editing enzymes are essential components of the immune system that lethally mutate viral pathogens and somatically mutate immunoglobulins, and contribute to the diversification and lethality of cancers. Among these enzymes are the seven human APOBEC3 deoxycytidine deaminases, each with unique target sequence specificity and subcellular localization. While the enzymology and biological consequences have been extensively studied, the mechanism by which APOBEC3s recognize and edit DNA remains elusive. Here we present the crystal structure of a complex of a cytidine deaminase with ssDNA bound in the active site at 2.2 Å. This structure not only visualizes the active site poised for catalysis of APOBEC3A, but pinpoints the residues that confer specificity towards CC/TC motifs. The APOBEC3A-ssDNA complex defines the 5'-3' directionality and subtle conformational changes that clench the ssDNA within the binding groove, revealing the architecture and mechanism of ssDNA recognition that is likely conserved among all polynucleotide deaminases, thereby opening the door for the design of mechanistic-based therapeutics.
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31
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King JJ, Larijani M. A Novel Regulator of Activation-Induced Cytidine Deaminase/APOBECs in Immunity and Cancer: Schrödinger's CATalytic Pocket. Front Immunol 2017; 8:351. [PMID: 28439266 PMCID: PMC5382155 DOI: 10.3389/fimmu.2017.00351] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Accepted: 03/10/2017] [Indexed: 12/20/2022] Open
Abstract
Activation-induced cytidine deaminase (AID) and its relative APOBEC3 cytidine deaminases boost immune response by mutating immune or viral genes. Because of their genome-mutating activities, AID/APOBECs are also drivers of tumorigenesis. Due to highly charged surfaces, extensive non-specific protein-protein/nucleic acid interactions, formation of polydisperse oligomers, and general insolubility, structure elucidation of these proteins by X-ray crystallography and NMR has been challenging. Hence, almost all available AID/APOBEC structures are of mutated and/or truncated versions. In 2015, we reported a functional structure for AID using a combined computational-biochemical approach. In so doing, we described a new regulatory mechanism that is a first for human DNA/RNA-editing enzymes. This mechanism involves dynamic closure of the catalytic pocket. Subsequent X-ray and NMR studies confirmed our discovery by showing that other APOBEC3s also close their catalytic pockets. Here, we highlight catalytic pocket closure as an emerging and important regulatory mechanism of AID/APOBEC3s. We focus on three sub-topics: first, we propose that variable pocket closure rates across AID/APOBEC3s underlie differential activity in immunity and cancer and review supporting evidence. Second, we discuss dynamic pocket closure as an ever-present internal regulator, in contrast to other proposed regulatory mechanisms that involve extrinsic binding partners. Third, we compare the merits of classical approaches of X-ray and NMR, with that of emerging computational-biochemical approaches, for structural elucidation specifically for AID/APOBEC3s.
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Affiliation(s)
- Justin J. King
- Immunology and Infectious Diseases Program, Division of Biomedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John’s, NL, Canada
| | - Mani Larijani
- Immunology and Infectious Diseases Program, Division of Biomedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John’s, NL, Canada
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32
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Polevoda B, Joseph R, Friedman AE, Bennett RP, Greiner R, De Zoysa T, Stewart RA, Smith HC. DNA mutagenic activity and capacity for HIV-1 restriction of the cytidine deaminase APOBEC3G depend on whether DNA or RNA binds to tyrosine 315. J Biol Chem 2017; 292:8642-8656. [PMID: 28381554 DOI: 10.1074/jbc.m116.767889] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2016] [Revised: 04/04/2017] [Indexed: 12/23/2022] Open
Abstract
APOBEC3G (A3G) belongs to the AID/APOBEC protein family of cytidine deaminases (CDA) that bind to nucleic acids. A3G mutates the HIV genome by deamination of dC to dU, leading to accumulation of virus-inactivating mutations. Binding to cellular RNAs inhibits A3G binding to substrate single-stranded (ss) DNA and CDA activity. Bulk RNA and substrate ssDNA bind to the same three A3G tryptic peptides (amino acids 181-194, 314-320, and 345-374) that form parts of a continuously exposed protein surface extending from the catalytic domain in the C terminus of A3G to its N terminus. We show here that the A3G tyrosines 181 and 315 directly cross-linked ssDNA. Binding experiments showed that a Y315A mutation alone significantly reduced A3G binding to both ssDNA and RNA, whereas Y181A and Y182A mutations only moderately affected A3G nucleic acid binding. Consistent with these findings, the Y315A mutant exhibited little to no deaminase activity in an Escherichia coli DNA mutator reporter, whereas Y181A and Y182A mutants retained ∼50% of wild-type A3G activity. The Y315A mutant also showed a markedly reduced ability to assemble into viral particles and had reduced antiviral activity. In uninfected cells, the impaired RNA-binding capacity of Y315A was evident by a shift of A3G from high-molecular-mass ribonucleoprotein complexes to low-molecular-mass complexes. We conclude that Tyr-315 is essential for coordinating ssDNA interaction with or entry to the deaminase domain and hypothesize that RNA bound to Tyr-315 may be sufficient to competitively inhibit ssDNA deaminase-dependent antiviral activity.
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Affiliation(s)
- Bogdan Polevoda
- From the Departments of Biochemistry and Biophysics and.,Center for RNA Biology, and
| | | | | | | | | | | | | | - Harold C Smith
- From the Departments of Biochemistry and Biophysics and .,Center for RNA Biology, and.,OyaGen, Inc., Rochester, New York 14623.,Center for AIDS Research, University of Rochester Medical Center, Rochester, New York 14642 and
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33
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Pan Y, Sun Z, Maiti A, Kanai T, Matsuo H, Li M, Harris RS, Shlyakhtenko LS, Lyubchenko YL. Nanoscale Characterization of Interaction of APOBEC3G with RNA. Biochemistry 2017; 56:1473-1481. [PMID: 28029777 DOI: 10.1021/acs.biochem.6b01189] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The human cytidine deaminase APOBEC3G (A3G) is a potent inhibitor of the HIV-1 virus in the absence of viral infectivity factor (Vif). The molecular mechanism of A3G antiviral activity is primarily attributed to deamination of single-stranded DNA (ssDNA); however, the nondeamination mechanism also contributes to HIV-1 restriction. The interaction of A3G with ssDNA and RNA is required for its antiviral activity. Here we used atomic force microscopy to directly visualize A3G-RNA and A3G-ssDNA complexes and compare them to each other. Our results showed that A3G in A3G-RNA complexes exists primarily in monomeric-dimeric states, similar to its stoichiometry in complexes with ssDNA. New A3G-RNA complexes in which A3G binds to two RNA molecules were identified. These data suggest the existence of two separate RNA binding sites on A3G. Such complexes were not observed with ssDNA substrates. Time-lapse high-speed atomic force microscopy was applied to characterize the dynamics of the complexes. The data revealed that the two RNA binding sites have different affinities for A3G. On the basis of the obtained results, a model for the interaction of A3G with RNA is proposed.
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Affiliation(s)
- Yangang Pan
- Department of Pharmaceutical Sciences, College of Pharmacy, WSH, University of Nebraska Medical Center , 986025 Nebraska Medical Center, Omaha, Nebraska 68198-6025, United States
| | - Zhiqiang Sun
- Department of Pharmaceutical Sciences, College of Pharmacy, WSH, University of Nebraska Medical Center , 986025 Nebraska Medical Center, Omaha, Nebraska 68198-6025, United States
| | - Atanu Maiti
- Frederick National Laboratory for Cancer Research, Leidos Biomedical Research, Inc. , Advanced Technology Research Facility, 8560 Progress Drive, Frederick, Maryland 21702, United States
| | - Tapan Kanai
- Frederick National Laboratory for Cancer Research, Leidos Biomedical Research, Inc. , Advanced Technology Research Facility, 8560 Progress Drive, Frederick, Maryland 21702, United States
| | - Hiroshi Matsuo
- Frederick National Laboratory for Cancer Research, Leidos Biomedical Research, Inc. , Advanced Technology Research Facility, 8560 Progress Drive, Frederick, Maryland 21702, United States
| | - Ming Li
- Department of Biochemistry, Molecular Biology and Biophysics, Institute for Molecular Virology, Center for Genome Engineering, Masonic Cancer Center, University of Minnesota , Minneapolis, Minnesota 55455, United States
| | - Reuben S Harris
- Department of Biochemistry, Molecular Biology and Biophysics, Institute for Molecular Virology, Center for Genome Engineering, Masonic Cancer Center, University of Minnesota , Minneapolis, Minnesota 55455, United States.,Howard Hughes Medical Institute, University of Minnesota , Minneapolis, Minnesota 55455, United States
| | - Luda S Shlyakhtenko
- Department of Pharmaceutical Sciences, College of Pharmacy, WSH, University of Nebraska Medical Center , 986025 Nebraska Medical Center, Omaha, Nebraska 68198-6025, United States
| | - Yuri L Lyubchenko
- Department of Pharmaceutical Sciences, College of Pharmacy, WSH, University of Nebraska Medical Center , 986025 Nebraska Medical Center, Omaha, Nebraska 68198-6025, United States
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34
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Okada A, Iwatani Y. APOBEC3G-Mediated G-to-A Hypermutation of the HIV-1 Genome: The Missing Link in Antiviral Molecular Mechanisms. Front Microbiol 2016; 7:2027. [PMID: 28066353 PMCID: PMC5165236 DOI: 10.3389/fmicb.2016.02027] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2016] [Accepted: 12/02/2016] [Indexed: 12/20/2022] Open
Abstract
APOBEC3G (A3G) is a member of the cellular polynucleotide cytidine deaminases, which catalyze the deamination of cytosine (dC) to uracil (dU) in single-stranded DNA. These enzymes potently inhibit the replication of a variety of retroviruses and retrotransposons, including HIV-1. A3G is incorporated into vif-deficient HIV-1 virions and targets viral reverse transcripts, particularly minus-stranded DNA products, in newly infected cells. It is well established that the enzymatic activity of A3G is closely correlated with the potential to greatly inhibit HIV-1 replication in the absence of Vif. However, the details of the underlying molecular mechanisms are not fully understood. One potential mechanism of A3G antiviral activity is that the A3G-dependent deamination may trigger degradation of the dU-containing reverse transcripts by cellular uracil DNA glycosylases (UDGs). More recently, another mechanism has been suggested, in which the virion-incorporated A3G generates lethal levels of the G-to-A hypermutation in the viral DNA genome, thus potentially driving the viruses into “error catastrophe” mode. In this mini review article, we summarize the deaminase-dependent and deaminase-independent molecular mechanisms of A3G and discuss how A3G-mediated deamination is linked to antiviral mechanisms.
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Affiliation(s)
- Ayaka Okada
- Department of Microbiology and Immunology, Laboratory of Infectious Diseases, Clinical Research Center, National Hospital Organization Nagoya Medical Center Nagoya, Japan
| | - Yasumasa Iwatani
- Department of Microbiology and Immunology, Laboratory of Infectious Diseases, Clinical Research Center, National Hospital Organization Nagoya Medical CenterNagoya, Japan; Department of AIDS Research, Nagoya University Graduate School of MedicineNagoya, Japan
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35
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Sharma S, Patnaik SK, Taggart RT, Baysal BE. The double-domain cytidine deaminase APOBEC3G is a cellular site-specific RNA editing enzyme. Sci Rep 2016; 6:39100. [PMID: 27974822 PMCID: PMC5156925 DOI: 10.1038/srep39100] [Citation(s) in RCA: 63] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2016] [Accepted: 11/16/2016] [Indexed: 11/10/2022] Open
Abstract
APOBEC3G is a cytidine deaminase with two homologous domains and restricts retroelements and HIV-1. APOBEC3G deaminates single-stranded DNAs via its C-terminal domain, whereas the N-terminal domain is considered non-catalytic. Although APOBEC3G is known to bind RNAs, APOBEC3G-mediated RNA editing has not been observed. We recently discovered RNA editing by the single-domain enzyme APOBEC3A in innate immune cells. To determine if APOBEC3G is capable of RNA editing, we transiently expressed APOBEC3G in the HEK293T cell line and performed transcriptome-wide RNA sequencing. We show that APOBEC3G causes site-specific C-to-U editing of mRNAs from over 600 genes. The edited cytidines are often flanked by inverted repeats, but are largely distinct from those deaminated by APOBEC3A. We verified protein-recoding RNA editing of selected genes including several that are known to be involved in HIV-1 infectivity. APOBEC3G co-purifies with highly edited mRNA substrates. We find that conserved catalytic residues in both cytidine deaminase domains are required for RNA editing. Our findings demonstrate the novel RNA editing function of APOBEC3G and suggest a role for the N-terminal domain in RNA editing.
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Affiliation(s)
- Shraddha Sharma
- Departments of Pathology and Thoracic Surgery, Roswell Park Cancer Institute, Elm and Carlton Streets Buffalo, NY, 14263, USA
| | - Santosh K. Patnaik
- Departments of Pathology and Thoracic Surgery, Roswell Park Cancer Institute, Elm and Carlton Streets Buffalo, NY, 14263, USA
| | - Robert T. Taggart
- Departments of Pathology and Thoracic Surgery, Roswell Park Cancer Institute, Elm and Carlton Streets Buffalo, NY, 14263, USA
| | - Bora E. Baysal
- Departments of Pathology and Thoracic Surgery, Roswell Park Cancer Institute, Elm and Carlton Streets Buffalo, NY, 14263, USA
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36
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Xiao X, Li SX, Yang H, Chen XS. Crystal structures of APOBEC3G N-domain alone and its complex with DNA. Nat Commun 2016; 7:12193. [PMID: 27480941 PMCID: PMC4974639 DOI: 10.1038/ncomms12193] [Citation(s) in RCA: 69] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2015] [Accepted: 06/08/2016] [Indexed: 11/09/2022] Open
Abstract
APOBEC3G (A3G) is a potent restriction factor of HIV-1. The N-terminal domain of A3G (A3G-CD1) is responsible for oligomerization and nucleic acid binding, both of which are essential for anti-HIV activity. As a countermeasure, HIV-1 viral infectivity factor (Vif) binds A3G-CD1 to mediate A3G degradation. The structural basis for the functions of A3G-CD1 remains elusive. Here, we report the crystal structures of a primate A3G-CD1 (rA3G-CD1) alone and in complex with single-stranded DNA (ssDNA). rA3G-CD1 shares a conserved core structure with the previously determined catalytic APOBECs, but displays unique features for surface charge, dimerization and nucleic acid binding. Its co-crystal structure with ssDNA reveals how the conformations of loops and residues surrounding the Zn-coordinated centre (Zn-centre) change upon DNA binding. The dimerization interface of rA3G-CD1 is important for oligomerization, nucleic acid binding and Vif-mediated degradation. These findings elucidate the molecular basis of antiviral mechanism and HIV-Vif targeting of A3G.
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Affiliation(s)
- Xiao Xiao
- Genetic, Molecular and Cellular Biology Program, Keck School of Medicine, University of Southern California, Los Angeles, California 90089, USA.,Molecular and Computational Biology Program, Departments of Biological Sciences and Chemistry, University of Southern California, Los Angeles, California 90089, USA
| | - Shu-Xing Li
- Molecular and Computational Biology Program, Departments of Biological Sciences and Chemistry, University of Southern California, Los Angeles, California 90089, USA.,Center of Excellence in NanoBiophysics, University of Southern California, Los Angeles, California 90089, USA
| | - Hanjing Yang
- Molecular and Computational Biology Program, Departments of Biological Sciences and Chemistry, University of Southern California, Los Angeles, California 90089, USA
| | - Xiaojiang S Chen
- Genetic, Molecular and Cellular Biology Program, Keck School of Medicine, University of Southern California, Los Angeles, California 90089, USA.,Molecular and Computational Biology Program, Departments of Biological Sciences and Chemistry, University of Southern California, Los Angeles, California 90089, USA.,Center of Excellence in NanoBiophysics, University of Southern California, Los Angeles, California 90089, USA.,Norris Comprehensive Cancer Center, University of Southern California, Los Angeles, California 90089, USA
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37
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The APOBEC Protein Family: United by Structure, Divergent in Function. Trends Biochem Sci 2016; 41:578-594. [PMID: 27283515 DOI: 10.1016/j.tibs.2016.05.001] [Citation(s) in RCA: 274] [Impact Index Per Article: 30.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2016] [Revised: 04/28/2016] [Accepted: 05/03/2016] [Indexed: 12/13/2022]
Abstract
The APOBEC (apolipoprotein B mRNA editing catalytic polypeptide-like) family of proteins have diverse and important functions in human health and disease. These proteins have an intrinsic ability to bind to both RNA and single-stranded (ss) DNA. Both function and tissue-specific expression varies widely for each APOBEC protein. We are beginning to understand that the activity of APOBEC proteins is regulated through genetic alterations, changes in their transcription and mRNA processing, and through their interactions with other macromolecules in the cell. Loss of cellular control of APOBEC activities leads to DNA hypermutation and promiscuous RNA editing associated with the development of cancer or viral drug resistance, underscoring the importance of understanding how APOBEC proteins are regulated.
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38
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Shaban NM, Shi K, Li M, Aihara H, Harris RS. 1.92 Angstrom Zinc-Free APOBEC3F Catalytic Domain Crystal Structure. J Mol Biol 2016; 428:2307-2316. [PMID: 27139641 PMCID: PMC5142242 DOI: 10.1016/j.jmb.2016.04.026] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2016] [Revised: 04/13/2016] [Accepted: 04/19/2016] [Indexed: 01/07/2023]
Abstract
The APOBEC3 family of DNA cytosine deaminases is capable of restricting the replication of HIV-1 and other pathogens. Here, we report a 1.92 Å resolution crystal structure of the Vif-binding and catalytic domain of APOBEC3F (A3F). This structure is distinct from the previously published APOBEC and phylogenetically related deaminase structures, as it is the first without zinc in the active site. We determined an additional structure containing zinc in the same crystal form that allows direct comparison with the zinc-free structure. In the absence of zinc, the conserved active site residues that normally participate in zinc coordination show unique conformations, including a 90 degree rotation of His249 and disulfide bond formation between Cys280 and Cys283. We found that zinc coordination is influenced by pH, and treating the protein at low pH in crystallization buffer is sufficient to remove zinc. Zinc coordination and catalytic activity are reconstituted with the addition of zinc only in a reduced environment likely due to the two active site cysteines readily forming a disulfide bond when not coordinating zinc. We show that the enzyme is active in the presence of zinc and cobalt but not with other divalent metals. These results unexpectedly demonstrate that zinc is not required for the structural integrity of A3F and suggest that metal coordination may be a strategy for regulating the activity of A3F and related deaminases.
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Affiliation(s)
- Nadine M. Shaban
- Department of Biochemistry, Molecular Biology, and Biophysics, Masonic Cancer Center, Institute for Molecular Virology, University of Minnesota, Minneapolis, MN 55455,Correspondence: ;
| | - Ke Shi
- Department of Biochemistry, Molecular Biology, and Biophysics, Masonic Cancer Center, Institute for Molecular Virology, University of Minnesota, Minneapolis, MN 55455
| | - Ming Li
- Department of Biochemistry, Molecular Biology, and Biophysics, Masonic Cancer Center, Institute for Molecular Virology, University of Minnesota, Minneapolis, MN 55455
| | - Hideki Aihara
- Department of Biochemistry, Molecular Biology, and Biophysics, Masonic Cancer Center, Institute for Molecular Virology, University of Minnesota, Minneapolis, MN 55455
| | - Reuben S. Harris
- Department of Biochemistry, Molecular Biology, and Biophysics, Masonic Cancer Center, Institute for Molecular Virology, University of Minnesota, Minneapolis, MN 55455,Howard Hughes Medical Institute, University of Minnesota, Minneapolis, MN 55455,Correspondence: ;
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39
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Pham P, Afif SA, Shimoda M, Maeda K, Sakaguchi N, Pedersen LC, Goodman MF. Structural analysis of the activation-induced deoxycytidine deaminase required in immunoglobulin diversification. DNA Repair (Amst) 2016; 43:48-56. [PMID: 27258794 DOI: 10.1016/j.dnarep.2016.05.029] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Accepted: 05/10/2016] [Indexed: 12/18/2022]
Abstract
Activation-induced deoxycytidine deaminase (AID) initiates somatic hypermutation (SHM) and class-switch recombination (CSR) by deaminating C→U during transcription of Ig-variable (V) and Ig-switch (S) region DNA, which is essential to produce high-affinity antibodies. Here we report the crystal structure of a soluble human AID variant at 2.8Å resolution that favors targeting WRC motifs (W=A/T, R=A/G) in vitro, and executes Ig V SHM in Ramos B-cells. A specificity loop extending away from the active site to accommodate two purine bases next to C, differs significantly in sequence, length, and conformation from APOBEC proteins Apo3A and Apo3G, which strongly favor pyrimidines at -1 and -2 positions. Individual amino acid contributions to specificity and processivity were measured in relation to a proposed ssDNA binding cleft. This study provides a structural basis for residue contributions to DNA scanning properties unique to AID, and for disease mutations in human HIGM-2 syndrome.
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Affiliation(s)
- Phuong Pham
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, 90089, United States
| | - Samir A Afif
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, 90089, United States
| | - Mayuko Shimoda
- Department of Immunology, Graduate School of Medical Sciences, Kumamoto University, 1-1-1 Honjo, Chuo-ku, Kumamoto, 860-8556, Japan; Laboratory of Host Defence, Research Institute for Microbial Diseases, Osaka University, 3-1 Yamada-oka, Suita, 565-0871, Japan; World Premier International Research Center Initiative, Immunology Frontier Research Center, Osaka University, 3-1 Yamada-oka, Suita, 565-0871, Japan
| | - Kazuhiko Maeda
- Laboratory of Host Defence, Research Institute for Microbial Diseases, Osaka University, 3-1 Yamada-oka, Suita, 565-0871, Japan; World Premier International Research Center Initiative, Immunology Frontier Research Center, Osaka University, 3-1 Yamada-oka, Suita, 565-0871, Japan
| | - Nobuo Sakaguchi
- World Premier International Research Center Initiative, Immunology Frontier Research Center, Osaka University, 3-1 Yamada-oka, Suita, 565-0871, Japan; Tokyo Metropolitan Institute of Medical Science, 2-1-6, Kamikitazawa, Setagaya-ku, Tokyo, 156-8506, Japan
| | - Lars C Pedersen
- Genome Integrity and Structural Biology Laboratory, National Institute of Environmental Health Sciences, Research Triangle Park, NC, 27709, United States
| | - Myron F Goodman
- Department of Biological Sciences, University of Southern California, Los Angeles, CA, 90089, United States; Department of Chemistry, University of Southern California, Los Angeles, CA 90089, United States.
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40
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Kamba K, Nagata T, Katahira M. Characterization of the Deamination Coupled with Sliding along DNA of Anti-HIV Factor APOBEC3G on the Basis of the pH-Dependence of Deamination Revealed by Real-Time NMR Monitoring. Front Microbiol 2016; 7:587. [PMID: 27199921 PMCID: PMC4848395 DOI: 10.3389/fmicb.2016.00587] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Accepted: 04/11/2016] [Indexed: 11/29/2022] Open
Abstract
Human APOBEC3G (A3G) is an antiviral factor that inactivates HIV. The C-terminal domain of A3G (A3G-CTD) deaminates cytosines into uracils within single-stranded DNA (ssDNA), which is reverse-transcribed from the viral RNA genome. The deaminase activity of A3G is highly sequence-specific; the third position (underlined) of a triplet cytosine (CCC) hotspot is converted into CCU. A3G deaminates a CCC that is located close to the 5′ end of ssDNA more effectively than ones that are less close to the 5′ end, so-called 3′ → 5′ polarity. We had developed an NMR method that can be used to analyze the deamination reaction in real-time. Using this method, we previously showed that 3′ → 5′ polarity can be explained rationally by A3G-CTD's nonspecific ssDNA-binding and sliding direction-dependent deamination activities. We then demonstrated that the phosphate backbone is important for A3G-CTD to slide on the ssDNA and to exert the 3′ → 5′ polarity, probably due to an electrostatic intermolecular interaction. In this study, we investigate the pH effects on the structure, deaminase activity, and 3′ → 5′ polarity of A3G-CTD. Firstly, A3G-CTD was shown to retain the native structure in the pH range of 4.0–10.5 by CD spectroscopy. Next, deamination assaying involving real-time NMR spectroscopy for 10-mer ssDNA containing a single CCC revealed that A3G-CTD's deaminase activity decreases as the pH increases in the range of pH 6.5–12.7. This is explained by destabilization of the complex between A3G-CTD and ssDNA due to the weakened electrostatic interaction with the increase in pH. Finally, deamination assaying for 38-mer ssDNA having two CCC hotspots connected by a long poly-adenine linker showed that A3G-CTD retains the same pH deaminase activity preference toward each CCC as that toward the CCC of the 10-mer DNA. Importantly, the 3′ → 5′ polarity turned out to increase as the pH decreases in the range of 6.5–8.0. This suggests that A3G-CTD tends to continue sliding without abortion at lower pH, while A3G-CTD tends to dissociate from ssDNA during sliding at higher pH due to the weakened electrostatic interaction.
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Affiliation(s)
- Keisuke Kamba
- Institute of Advanced Energy, Kyoto UniversityKyoto, Japan; Graduate School of Energy Science, Kyoto UniversityKyoto, Japan
| | - Takashi Nagata
- Institute of Advanced Energy, Kyoto UniversityKyoto, Japan; Graduate School of Energy Science, Kyoto UniversityKyoto, Japan
| | - Masato Katahira
- Institute of Advanced Energy, Kyoto UniversityKyoto, Japan; Graduate School of Energy Science, Kyoto UniversityKyoto, Japan
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Abstract
Although the replicative life cycle of HIV within CD4 T cells is understood in molecular detail, less is known about how this human retrovirus promotes the loss of CD4 T lymphocytes. It is this cell death process that drives clinical progression to acquired immune deficiency syndrome (AIDS). Recent studies have highlighted how abortive infection of resting and thus nonpermissive CD4 T cells in lymphoid tissues triggers a lethal innate immune response against the incomplete DNA products generated by inefficient viral reverse transcription in these cells. Sensing of these DNA fragments results in pyroptosis, a highly inflammatory form of programmed cell death, that potentially further perpetuates chronic inflammation and immune activation. As discussed here, these studies cast CD4 T cell death during HIV infection in a different light. Further, they identify drug targets that may be exploited to both block CD4 T cell demise and the chronic inflammatory response generated during pyroptosis.
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Affiliation(s)
- Gilad Doitsh
- Gladstone Institute of Virology and Immunology, 1650 Owens Street, San Francisco, CA 94158, USA.
| | - Warner C Greene
- Gladstone Institute of Virology and Immunology, 1650 Owens Street, San Francisco, CA 94158, USA; Department of Medicine, University of California, San Francisco, San Francisco, CA 94143, USA; Department of Microbiology and Immunology, University of California, San Francisco, San Francisco, CA 94143, USA.
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42
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Marx A, Galilee M, Alian A. Zinc enhancement of cytidine deaminase activity highlights a potential allosteric role of loop-3 in regulating APOBEC3 enzymes. Sci Rep 2015; 5:18191. [PMID: 26678087 PMCID: PMC4683357 DOI: 10.1038/srep18191] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Accepted: 11/16/2015] [Indexed: 12/25/2022] Open
Abstract
The strong association of APOBEC3 cytidine deaminases with somatic mutations leading to cancers accentuates the importance of their tight intracellular regulation to minimize cellular transformations. We reveal a novel allosteric regulatory mechanism of APOBEC3 enzymes showing that APOBEC3G and APOBEC3A coordination of a secondary zinc ion, reminiscent to ancestral deoxycytidylate deaminases, enhances deamination activity. Zinc binding is pinpointed to loop-3 which whilst highly variable harbors a catalytically essential and spatially conserved asparagine at its N-terminus. We suggest that loop-3 may play a general role in allosterically tuning the activity of zinc-dependent cytidine deaminase family members.
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Affiliation(s)
- Ailie Marx
- Faculty of Biology, Technion - Israel Institute of Technology, Haifa 320003, Israel
| | - Meytal Galilee
- Faculty of Biology, Technion - Israel Institute of Technology, Haifa 320003, Israel
| | - Akram Alian
- Faculty of Biology, Technion - Israel Institute of Technology, Haifa 320003, Israel
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43
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APOBEC3G Interacts with ssDNA by Two Modes: AFM Studies. Sci Rep 2015; 5:15648. [PMID: 26503602 PMCID: PMC4621513 DOI: 10.1038/srep15648] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2015] [Accepted: 10/01/2015] [Indexed: 11/17/2022] Open
Abstract
APOBEC3G (A3G) protein has antiviral activity against HIV and other pathogenic retroviruses. A3G has two domains: a catalytic C-terminal domain (CTD) that deaminates cytidine, and a N-terminal domain (NTD) that binds to ssDNA. Although abundant information exists about the biological activities of A3G protein, the interplay between sequence specific deaminase activity and A3G binding to ssDNA remains controversial. We used the topographic imaging and force spectroscopy modalities of Atomic Force Spectroscopy (AFM) to characterize the interaction of A3G protein with deaminase specific and nonspecific ssDNA substrates. AFM imaging demonstrated that A3G has elevated affinity for deaminase specific ssDNA than for nonspecific ssDNA. AFM force spectroscopy revealed two distinct binding modes by which A3G interacts with ssDNA. One mode requires sequence specificity, as demonstrated by stronger and more stable complexes with deaminase specific ssDNA than with nonspecific ssDNA. Overall these observations enforce prior studies suggesting that both domains of A3G contribute to the sequence specific binding of ssDNA.
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Bélanger K, Langlois MA. RNA-binding residues in the N-terminus of APOBEC3G influence its DNA sequence specificity and retrovirus restriction efficiency. Virology 2015; 483:141-8. [PMID: 25974865 DOI: 10.1016/j.virol.2015.04.019] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2015] [Revised: 04/01/2015] [Accepted: 04/15/2015] [Indexed: 10/23/2022]
Abstract
APOBEC3G (A3G) is a host-expressed protein that inactivates retroviruses through the mutagenic deamination of cytosines (C) to uracils (U) in single-stranded DNA (ssDNA) replication products. A3G prefers to deaminate cytosines preceded by a cytosine (5'CC), whereas all other A3 proteins target cytosines in a 5'TC motifs. Structural and mutational studies have mapped the dinucleotide deamination preference of A3G to residues in loop 7 of the catalytic C-terminal domain of the protein. Here we report that A3G with a double W94A/W127A substitution in its N-terminus, designed to abolish RNA binding and protein oligomerization, alters the DNA deamination specificity of the enzyme from 5'CC to 5'TC on proviral DNA. We also show that the double substitution severely impairs its deaminase and antiretroviral activities on Vif-deficient HIV-1. Our results highlight that the N-terminal domain of the full length A3G protein has an important influence on its DNA sequence specificity and mutator activity.
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Affiliation(s)
- Kasandra Bélanger
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada
| | - Marc-André Langlois
- Department of Biochemistry, Microbiology and Immunology, Faculty of Medicine, University of Ottawa, Ottawa, Ontario, Canada.
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