1
|
Britan-Rosich Y, Ma J, Kotler E, Hassan F, Botvinnik A, Smith Y, Moshel O, Nasereddin A, Sharma G, Pikarsky E, Ross S, Kotler M. APOBEC3G protects the genome of human cultured cells and mice from radiation-induced damage. FEBS J 2023; 290:1822-1839. [PMID: 36325681 PMCID: PMC10079569 DOI: 10.1111/febs.16673] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2022] [Revised: 09/14/2022] [Accepted: 11/02/2022] [Indexed: 11/06/2022]
Abstract
Cytosine deaminases AID/APOBEC proteins act as potent nucleic acid editors, playing important roles in innate and adaptive immunity. However, the mutagenic effects of some of these proteins compromise genomic integrity and may promote tumorigenesis. Here, we demonstrate that human APOBEC3G (A3G), in addition to its role in innate immunity, promotes repair of double-strand breaks (DSBs) in vitro and in vivo. Transgenic mice expressing A3G successfully survived lethal irradiation, whereas wild-type controls quickly succumbed to radiation syndrome. Mass spectrometric analyses identified the differential upregulation of a plethora of proteins involved in DSB repair pathways in A3G-expressing cells early following irradiation to facilitate repair. Importantly, we find that A3G not only accelerates DSB repair but also promotes deamination-dependent error-free rejoining. These findings have two implications: (a) strategies aimed at inhibiting A3G may improve the efficacy of genotoxic therapies used to cure malignant tumours; and (b) enhancing A3G activity may reduce acute radiation syndrome in individuals exposed to ionizing radiation.
Collapse
Affiliation(s)
- Yelena Britan-Rosich
- Department of Pathology and Immunology, The Lautenberg Center for Immunology and Cancer Research, The Hebrew University Hadassah Medical School, Jerusalem, Israel
| | - Jing Ma
- Department of Microbiology and Immunology, College of Medicine, University of Illinois at Chicago, USA
| | - Eran Kotler
- Department of Genetics, Stanford University School of Medicine, Ca, USA
| | - Faizan Hassan
- Department of Pathology and Immunology, The Lautenberg Center for Immunology and Cancer Research, The Hebrew University Hadassah Medical School, Jerusalem, Israel
| | - Alexander Botvinnik
- Department of Pathology and Immunology, The Lautenberg Center for Immunology and Cancer Research, The Hebrew University Hadassah Medical School, Jerusalem, Israel
| | - Yoav Smith
- Genomic Data Analysis, Hadassah Medical School, Hebrew University, Jerusalem, Israel
| | - Ofra Moshel
- Core Research Facility, Institute for Drug Research, School of Pharmacy, Faculty of Medicine, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Abed Nasereddin
- Core Research Facility of the Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Gunjan Sharma
- Department of Pathology and Immunology, The Lautenberg Center for Immunology and Cancer Research, The Hebrew University Hadassah Medical School, Jerusalem, Israel
| | - Eli Pikarsky
- Department of Pathology and Immunology, The Lautenberg Center for Immunology and Cancer Research, The Hebrew University Hadassah Medical School, Jerusalem, Israel
| | - Susan Ross
- Department of Microbiology and Immunology, College of Medicine, University of Illinois at Chicago, USA
| | - Moshe Kotler
- Department of Pathology and Immunology, The Lautenberg Center for Immunology and Cancer Research, The Hebrew University Hadassah Medical School, Jerusalem, Israel
| |
Collapse
|
2
|
Pan Y, Shlyakhtenko LS, Lyubchenko YL. Insight into dynamics of APOBEC3G protein in complexes with DNA assessed by high speed AFM. Nanoscale Adv 2019; 1:4016-4024. [PMID: 33313478 PMCID: PMC7731963 DOI: 10.1039/c9na00457b] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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.
Collapse
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
| |
Collapse
|
3
|
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: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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.
Collapse
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.
| |
Collapse
|
4
|
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: 3.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 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.
Collapse
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
| |
Collapse
|
5
|
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: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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.
Collapse
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
| |
Collapse
|
6
|
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.
Collapse
|
7
|
Richards CM, Li M, Perkins AL, Rathore A, Harki DA, Harris RS. Reassessing APOBEC3G Inhibition by HIV-1 Vif-Derived Peptides. J Mol Biol 2016; 429:88-96. [PMID: 27887868 DOI: 10.1016/j.jmb.2016.11.012] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Revised: 11/14/2016] [Accepted: 11/15/2016] [Indexed: 11/13/2022]
Abstract
The human APOBEC3G (A3G) enzyme restricts HIV-1 in the absence of the viral accessory protein viral infectivity factor (Vif) by deaminating viral cDNA cytosines to uracils. These uracil lesions base-pair with adenines during the completion of reverse transcription and result in A3G signature G-to-A mutations in the viral genome. Vif protects HIV-1 from A3G-mediated restriction by forming an E3-ubiquitin ligase complex to polyubiquitinate A3G and trigger its degradation. Prior studies indicated that Vif may also directly block the enzymatic activity of A3G and, provocatively, that Vif-derived peptides, Vif 25-39 and Vif 105-119, are similarly inhibitory. Here, we show that Vif 25-39 does not inhibit A3G enzymatic activity and that the inhibitory effect of Vif 105-119 and that of a shorter derivative Vif 107-115, although recapitulated, are non-specific. We also elaborate a simple method for assaying DNA cytosine deaminase activity that eliminates potential polymerase chain reaction-induced biases. Our results show that these Vif-derived peptides are unlikely to be useful as tools to study A3G function or as leads for the development of future therapeutics.
Collapse
Affiliation(s)
- Christopher M Richards
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, 321 Church Street S.E., Minneapolis, MN 55455, USA; Institute for Molecular Virology, University of Minnesota, 515 Delaware Street S.E., Minneapolis, MN 55455, USA
| | - Ming Li
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, 321 Church Street S.E., Minneapolis, MN 55455, USA; Institute for Molecular Virology, University of Minnesota, 515 Delaware Street S.E., Minneapolis, MN 55455, USA
| | - Angela L Perkins
- Department of Medicinal Chemistry, University of Minnesota, 2231 6th St. S.E., Minneapolis, MN 55455, USA
| | - Anurag Rathore
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, 321 Church Street S.E., Minneapolis, MN 55455, USA
| | - Daniel A Harki
- Department of Medicinal Chemistry, University of Minnesota, 2231 6th St. S.E., Minneapolis, MN 55455, USA
| | - Reuben S Harris
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, 321 Church Street S.E., Minneapolis, MN 55455, USA; Institute for Molecular Virology, University of Minnesota, 515 Delaware Street S.E., Minneapolis, MN 55455, USA; Howard Hughes Medical Institute, University of Minnesota, 2231 6th St. S.E., Minneapolis, MN 55455, USA.
| |
Collapse
|
8
|
Polevoda B, McDougall WM, Bennett RP, Salter JD, Smith HC. Structural and functional assessment of APOBEC3G macromolecular complexes. Methods 2016; 107:10-22. [PMID: 26988126 DOI: 10.1016/j.ymeth.2016.03.006] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Revised: 03/10/2016] [Accepted: 03/11/2016] [Indexed: 12/20/2022] Open
Abstract
There are eleven members in the human APOBEC family of proteins that are evolutionarily related through their zinc-dependent cytidine deaminase domains. The human APOBEC gene clusters arose on chromosome 6 and 22 through gene duplication and divergence to where current day APOBEC proteins are functionally diverse and broadly expressed in tissues. APOBEC serve enzymatic and non enzymatic functions in cells. In both cases, formation of higher-order structures driven by APOBEC protein-protein interactions and binding to RNA and/or single stranded DNA are integral to their function. In some circumstances, these interactions are regulatory and modulate APOBEC activities. We are just beginning to understand how macromolecular interactions drive processes such as APOBEC subcellular compartmentalization, formation of holoenzyme complexes, gene targeting, foreign DNA restriction, anti-retroviral activity, formation of ribonucleoprotein particles and APOBEC degradation. Protein-protein and protein-nucleic acid cross-linking methods coupled with mass spectrometry, electrophoretic mobility shift assays, glycerol gradient sedimentation, fluorescence anisotropy and APOBEC deaminase assays are enabling mapping of interacting surfaces that are essential for these functions. The goal of this methods review is through example of our research on APOBEC3G, describe the application of cross-linking methods to characterize and quantify macromolecular interactions and their functional implications. Given the homology in structure and function, it is proposed that these methods will be generally applicable to the discovery process for other APOBEC and RNA and DNA editing and modifying proteins.
Collapse
Affiliation(s)
- Bogdan Polevoda
- Department of Biochemistry and Biophysics, University of Rochester, School of Medicine and Dentistry, 601 Elmwood Avenue, Rochester, NY 14642, USA
| | - William M McDougall
- Department of Biochemistry and Biophysics, University of Rochester, School of Medicine and Dentistry, 601 Elmwood Avenue, Rochester, NY 14642, USA
| | - Ryan P Bennett
- OyaGen, Inc, Rochester BioVenture Center, 77 Ridgeland Road, Rochester, NY 14623, USA
| | - Jason D Salter
- OyaGen, Inc, Rochester BioVenture Center, 77 Ridgeland Road, Rochester, NY 14623, USA
| | - Harold C Smith
- Department of Biochemistry and Biophysics, University of Rochester, School of Medicine and Dentistry, 601 Elmwood Avenue, Rochester, NY 14642, USA; Wilmot Cancer Institute, 601 Elmwood Avenue, Rochester, NY 14642, USA; Center for RNA Biology, 601 Elmwood Avenue, Rochester, NY 14642, USA; OyaGen, Inc, Rochester BioVenture Center, 77 Ridgeland Road, Rochester, NY 14623, USA; Center for AIDS Research, 601 Elmwood Avenue, Rochester, NY 14642, USA.
| |
Collapse
|
9
|
Polevoda B, McDougall WM, Tun BN, Cheung M, Salter JD, Friedman AE, Smith HC. RNA binding to APOBEC3G induces the disassembly of functional deaminase complexes by displacing single-stranded DNA substrates. Nucleic Acids Res 2015; 43:9434-45. [PMID: 26424853 PMCID: PMC4627094 DOI: 10.1093/nar/gkv970] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Revised: 09/14/2015] [Accepted: 09/15/2015] [Indexed: 11/14/2022] Open
Abstract
APOBEC3G (A3G) DNA deaminase activity requires a holoenzyme complex whose assembly on nascent viral reverse transcripts initiates with A3G dimers binding to ssDNA followed by formation of higher-order A3G homo oligomers. Catalytic activity is inhibited when A3G binds to RNA. Our prior studies suggested that RNA inhibited A3G binding to ssDNA. In this report, near equilibrium binding and gel shift analyses showed that A3G assembly and disassembly on ssDNA was an ordered process involving A3G dimers and multimers thereof. Although, fluorescence anisotropy showed that A3G had similar nanomolar affinity for RNA and ssDNA, RNA stochastically dissociated A3G dimers and higher-order oligomers from ssDNA, suggesting a different modality for RNA binding. Mass spectrometry mapping of A3G peptides cross-linked to nucleic acid suggested ssDNA only bound to three peptides, amino acids (aa) 181-194 in the N-terminus and aa 314-320 and 345-374 in the C-terminus that were part of a continuous exposed surface. RNA bound to these peptides and uniquely associated with three additional peptides in the N- terminus, aa 15-29, 41-52 and 83-99, that formed a continuous surface area adjacent to the ssDNA binding surface. The data predict a mechanistic model of RNA inhibition of ssDNA binding to A3G in which competitive and allosteric interactions determine RNA-bound versus ssDNA-bound conformational states.
Collapse
Affiliation(s)
- Bogdan Polevoda
- Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry, 601 Elmwood Avenue, Rochester, NY 14642, USA Center for RNA Biology, University of Rochester School of Medicine and Dentistry, 601 Elmwood Avenue, Rochester, NY 14642, USA
| | - William M McDougall
- Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry, 601 Elmwood Avenue, Rochester, NY 14642, USA Center for RNA Biology, University of Rochester School of Medicine and Dentistry, 601 Elmwood Avenue, Rochester, NY 14642, USA
| | - Bradley N Tun
- Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry, 601 Elmwood Avenue, Rochester, NY 14642, USA
| | - Michael Cheung
- Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry, 601 Elmwood Avenue, Rochester, NY 14642, USA
| | - Jason D Salter
- OyaGen, Inc, Rochester BioVenture Center, 77 Ridgeland Road, Rochester, NY 14623, USA
| | - Alan E Friedman
- Environmental Health Sciences Center, University of Rochester School of Medicine and Dentistry, 601 Elmwood Avenue, Rochester, NY 14642, USA
| | - Harold C Smith
- Department of Biochemistry and Biophysics, University of Rochester School of Medicine and Dentistry, 601 Elmwood Avenue, Rochester, NY 14642, USA Center for RNA Biology, University of Rochester School of Medicine and Dentistry, 601 Elmwood Avenue, Rochester, NY 14642, USA OyaGen, Inc, Rochester BioVenture Center, 77 Ridgeland Road, Rochester, NY 14623, USA Environmental Health Sciences Center, University of Rochester School of Medicine and Dentistry, 601 Elmwood Avenue, Rochester, NY 14642, USA Center for AIDS Research, University of Rochester School of Medicine and Dentistry, 601 Elmwood Avenue, Rochester, NY 14642, USA
| |
Collapse
|
10
|
Shi K, Carpenter MA, Kurahashi K, Harris RS, Aihara H. Crystal Structure of the DNA Deaminase APOBEC3B Catalytic Domain. J Biol Chem 2015; 290:28120-28130. [PMID: 26416889 DOI: 10.1074/jbc.m115.679951] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Indexed: 11/06/2022] Open
Abstract
Functional and deep sequencing studies have combined to demonstrate the involvement of APOBEC3B in cancer mutagenesis. APOBEC3B is a single-stranded DNA cytosine deaminase that functions normally as a nuclear-localized restriction factor of DNA-based pathogens. However, it is overexpressed in cancer cells and elicits an intrinsic preference for 5'-TC motifs in single-stranded DNA, which is the most frequently mutated dinucleotide in breast, head/neck, lung, bladder, cervical, and several other tumor types. In many cases, APOBEC3B mutagenesis accounts for the majority of both dispersed and clustered (kataegis) cytosine mutations. Here, we report the first structures of the APOBEC3B catalytic domain in multiple crystal forms. These structures reveal a tightly closed active site conformation and suggest that substrate accessibility is regulated by adjacent flexible loops. Residues important for catalysis are identified by mutation analyses, and the results provide insights into the mechanism of target site selection. We also report a nucleotide (dCMP)-bound crystal structure that informs a multistep model for binding single-stranded DNA. Overall, these high resolution crystal structures provide a framework for further mechanistic studies and the development of novel anti-cancer drugs to inhibit this enzyme, dampen tumor evolution, and minimize adverse outcomes such as drug resistance and metastasis.
Collapse
Affiliation(s)
- Ke Shi
- Department of Biochemistry, Molecular Biology, and Biophysics; Institute for Molecular Virology; Masonic Cancer Center.
| | - Michael A Carpenter
- Department of Biochemistry, Molecular Biology, and Biophysics; Institute for Molecular Virology; Masonic Cancer Center
| | - Kayo Kurahashi
- Department of Biochemistry, Molecular Biology, and Biophysics; Institute for Molecular Virology; Masonic Cancer Center
| | - Reuben S Harris
- Department of Biochemistry, Molecular Biology, and Biophysics; Institute for Molecular Virology; Masonic Cancer Center; Howard Hughes Medical Institute, University of Minnesota, Minneapolis, Minnesota 55455
| | - Hideki Aihara
- Department of Biochemistry, Molecular Biology, and Biophysics; Institute for Molecular Virology; Masonic Cancer Center
| |
Collapse
|
11
|
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: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [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.
Collapse
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.
| |
Collapse
|
12
|
Shandilya SMD, Bohn MF, Schiffer CA. A computational analysis of the structural determinants of APOBEC3's catalytic activity and vulnerability to HIV-1 Vif. Virology 2014; 471-473:105-16. [PMID: 25461536 PMCID: PMC4857191 DOI: 10.1016/j.virol.2014.09.023] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2014] [Revised: 09/29/2014] [Accepted: 09/30/2014] [Indexed: 11/23/2022]
Abstract
APOBEC3s (A3) are Zn(2+) dependent cytidine deaminases with diverse biological functions and implications for cancer and immunity. Four of the seven human A3s restrict HIV by 'hypermutating' the reverse-transcribed viral genomic DNA. HIV Virion Infectivity Factor (Vif) counters this restriction by targeting A3s to proteasomal degradation. However, there is no apparent correlation between catalytic activity, Vif binding, and sequence similarity between A3 domains. Our comparative structural analysis reveals features required for binding Vif and features influencing polynucleotide deaminase activity in A3 proteins. All Vif-binding A3s share a negatively charged surface region that includes residues previously implicated in binding the highly-positively charged Vif. Additionally, catalytically active A3s share a positively charged groove near the Zn(2+) coordinating active site, which may accommodate the negatively charged polynucleotide substrate. Our findings suggest surface electrostatics, as well as the spatial extent of substrate accommodating region, are critical determinants of substrate and Vif binding across A3 proteins with implications for anti-retroviral and anti-cancer therapeutic design.
Collapse
Affiliation(s)
- Shivender M D Shandilya
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Markus-Frederik Bohn
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Celia A Schiffer
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605, USA.
| |
Collapse
|
13
|
Bélanger K, Savoie M, Rosales Gerpe MC, Couture JF, Langlois MA. Binding of RNA by APOBEC3G controls deamination-independent restriction of retroviruses. Nucleic Acids Res 2013; 41:7438-52. [PMID: 23761443 PMCID: PMC3753645 DOI: 10.1093/nar/gkt527] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2013] [Revised: 05/19/2013] [Accepted: 05/21/2013] [Indexed: 11/19/2022] Open
Abstract
APOBEC3G (A3G) is a host-encoded protein that potently restricts the infectivity of a broad range of retroviruses. This can occur by mechanisms dependent on catalytic activity, resulting in the mutagenic deamination of nascent viral cDNA, and/or by other means that are independent of its catalytic activity. It is not yet known to what extent deamination-independent processes contribute to the overall restriction, how they exactly work or how they are regulated. Here, we show that alanine substitution of either tryptophan 94 (W94A) or 127 (W127A) in the non-catalytic N-terminal domain of A3G severely impedes RNA binding and alleviates deamination-independent restriction while still maintaining DNA mutator activity. Substitution of both tryptophans (W94A/W127A) produces a more severe phenotype in which RNA binding and RNA-dependent protein oligomerization are completely abrogated. We further demonstrate that RNA binding is specifically required for crippling late reverse transcript accumulation, preventing proviral DNA integration and, consequently, restricting viral particle release. We did not find that deaminase activity made a significant contribution to the restriction of any of these processes. In summary, this work reveals that there is a direct correlation between A3G's capacity to bind RNA and its ability to inhibit retroviral infectivity in a deamination-independent manner.
Collapse
Affiliation(s)
- Kasandra Bélanger
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario, Canada K1H 8M5, Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, Ontario, Canada K1H 8M5, Emerging Pathogens Research Centre, University of Ottawa, Ottawa, Ontario, Canada K1H 8M5 and Department of Pathology and Laboratory Medicine, University of Ottawa, Ottawa, Ontario, Canada K1H 8M5
| | - Mathieu Savoie
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario, Canada K1H 8M5, Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, Ontario, Canada K1H 8M5, Emerging Pathogens Research Centre, University of Ottawa, Ottawa, Ontario, Canada K1H 8M5 and Department of Pathology and Laboratory Medicine, University of Ottawa, Ottawa, Ontario, Canada K1H 8M5
| | - María Carla Rosales Gerpe
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario, Canada K1H 8M5, Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, Ontario, Canada K1H 8M5, Emerging Pathogens Research Centre, University of Ottawa, Ottawa, Ontario, Canada K1H 8M5 and Department of Pathology and Laboratory Medicine, University of Ottawa, Ottawa, Ontario, Canada K1H 8M5
| | - Jean-François Couture
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario, Canada K1H 8M5, Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, Ontario, Canada K1H 8M5, Emerging Pathogens Research Centre, University of Ottawa, Ottawa, Ontario, Canada K1H 8M5 and Department of Pathology and Laboratory Medicine, University of Ottawa, Ottawa, Ontario, Canada K1H 8M5
| | - Marc-André Langlois
- Department of Biochemistry, Microbiology and Immunology, University of Ottawa, Ottawa, Ontario, Canada K1H 8M5, Ottawa Institute of Systems Biology, University of Ottawa, Ottawa, Ontario, Canada K1H 8M5, Emerging Pathogens Research Centre, University of Ottawa, Ottawa, Ontario, Canada K1H 8M5 and Department of Pathology and Laboratory Medicine, University of Ottawa, Ottawa, Ontario, Canada K1H 8M5
| |
Collapse
|
14
|
Harjes S, Solomon WC, Li M, Chen KM, Harjes E, Harris RS, Matsuo H. Impact of H216 on the DNA binding and catalytic activities of the HIV restriction factor APOBEC3G. J Virol 2013; 87:7008-14. [PMID: 23596292 DOI: 10.1128/JVI.03173-12] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
APOBEC3G has an important role in human defense against retroviral pathogens, including HIV-1. Its single-stranded DNA cytosine deaminase activity, located in its C-terminal domain (A3Gctd), can mutate viral cDNA and restrict infectivity. We used time-resolved nuclear magnetic resonance (NMR) spectroscopy to determine kinetic parameters of A3Gctd's deamination reactions within a 5'-CCC hot spot sequence. A3Gctd exhibited a 45-fold preference for 5'-CCC substrate over 5'-CCU substrate, which explains why A3G displays almost no processivity within a 5'-CCC motif. In addition, A3Gctd's shortest substrate sequence was found to be a pentanucleotide containing 5'-CCC flanked on both sides by a single nucleotide. A3Gctd as well as full-length A3G showed peak deamination velocities at pH 5.5. We found that H216 is responsible for this pH dependence, suggesting that protonation of H216 could play a key role in substrate binding. Protonation of H216 appeared important for HIV-1 restriction activity as well, since substitutions of H216 resulted in lower restriction in vivo.
Collapse
|
15
|
Abstract
The ability to regulate and even target mutagenesis is an extremely valuable cellular asset. Enzyme-catalyzed DNA cytosine deamination is a molecular strategy employed by vertebrates to promote antibody diversity and defend against foreign nucleic acids. Ten years ago, a family of cellular enzymes was first described with several proving capable of deaminating DNA and inhibiting HIV-1 replication. Ensuing studies on the apolipoprotein B mRNA-editing enzyme catalytic polypeptide-like 3 (APOBEC3) restriction factors have uncovered a broad-spectrum innate defense network that suppresses the replication of numerous endogenous and exogenous DNA-based parasites. Although many viruses possess equally elaborate counter-defense mechanisms, the APOBEC3 enzymes offer a tantalizing possibility of leveraging innate immunity to fend off viral infection. Here, we focus on mechanisms of retroelement restriction by the APOBEC3 family of restriction enzymes, and we consider the therapeutic benefits, as well as the possible pathological consequences, of arming cells with active DNA deaminases.
Collapse
Affiliation(s)
- Eric W Refsland
- Department of Biochemistry, University of Minnesota, Minneapolis, MN 55455, USA
| | | |
Collapse
|