1
|
Sanchez A, Ortega P, Sakhtemani R, Manjunath L, Oh S, Bournique E, Becker A, Kim K, Durfee C, Temiz NA, Chen XS, Harris RS, Lawrence MS, Buisson R. Mesoscale DNA features impact APOBEC3A and APOBEC3B deaminase activity and shape tumor mutational landscapes. Nat Commun 2024; 15:2370. [PMID: 38499542 PMCID: PMC10948877 DOI: 10.1038/s41467-024-45909-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Accepted: 01/09/2024] [Indexed: 03/20/2024] Open
Abstract
Antiviral DNA cytosine deaminases APOBEC3A and APOBEC3B are major sources of mutations in cancer by catalyzing cytosine-to-uracil deamination. APOBEC3A preferentially targets single-stranded DNAs, with a noted affinity for DNA regions that adopt stem-loop secondary structures. However, the detailed substrate preferences of APOBEC3A and APOBEC3B have not been fully established, and the specific influence of the DNA sequence on APOBEC3A and APOBEC3B deaminase activity remains to be investigated. Here, we find that APOBEC3B also selectively targets DNA stem-loop structures, and they are distinct from those subjected to deamination by APOBEC3A. We develop Oligo-seq, an in vitro sequencing-based method to identify specific sequence contexts promoting APOBEC3A and APOBEC3B activity. Through this approach, we demonstrate that APOBEC3A and APOBEC3B deaminase activity is strongly regulated by specific sequences surrounding the targeted cytosine. Moreover, we identify the structural features of APOBEC3B and APOBEC3A responsible for their substrate preferences. Importantly, we determine that APOBEC3B-induced mutations in hairpin-forming sequences within tumor genomes differ from the DNA stem-loop sequences mutated by APOBEC3A. Together, our study provides evidence that APOBEC3A and APOBEC3B can generate distinct mutation landscapes in cancer genomes, driven by their unique substrate selectivity.
Collapse
Affiliation(s)
- Ambrocio Sanchez
- Department of Biological Chemistry, School of Medicine, University of California Irvine, Irvine, CA, USA
- Center for Epigenetics and Metabolism, Chao Family Comprehensive Cancer Center, University of California Irvine, Irvine, CA, USA
| | - Pedro Ortega
- Department of Biological Chemistry, School of Medicine, University of California Irvine, Irvine, CA, USA
- Center for Epigenetics and Metabolism, Chao Family Comprehensive Cancer Center, University of California Irvine, Irvine, CA, USA
| | - Ramin Sakhtemani
- Massachusetts General Hospital Cancer Center, Harvard Medical School, Boston, MA, USA
- Broad Institute of Harvard and MIT, Cambridge, MA, USA
| | - Lavanya Manjunath
- Department of Biological Chemistry, School of Medicine, University of California Irvine, Irvine, CA, USA
- Center for Epigenetics and Metabolism, Chao Family Comprehensive Cancer Center, University of California Irvine, Irvine, CA, USA
| | - Sunwoo Oh
- Department of Biological Chemistry, School of Medicine, University of California Irvine, Irvine, CA, USA
- Center for Epigenetics and Metabolism, Chao Family Comprehensive Cancer Center, University of California Irvine, Irvine, CA, USA
| | - Elodie Bournique
- Department of Biological Chemistry, School of Medicine, University of California Irvine, Irvine, CA, USA
- Center for Epigenetics and Metabolism, Chao Family Comprehensive Cancer Center, University of California Irvine, Irvine, CA, USA
| | - Alexandrea Becker
- Department of Biological Chemistry, School of Medicine, University of California Irvine, Irvine, CA, USA
- Center for Epigenetics and Metabolism, Chao Family Comprehensive Cancer Center, University of California Irvine, Irvine, CA, USA
| | - Kyumin Kim
- Molecular and Computational Biology, Departments of Biological Sciences and Chemistry, University of Southern California, Los Angeles, CA, USA
| | - Cameron Durfee
- Department of Biochemistry and Structural Biology, University of Texas Health San Antonio, San Antonio, TX, USA
| | - Nuri Alpay Temiz
- Institute for Health Informatics, University of Minnesota, Minneapolis, MN, USA
- Masonic Cancer Center, University of Minnesota, Minneapolis, MN, USA
| | - Xiaojiang S Chen
- Molecular and Computational Biology, Departments of Biological Sciences and Chemistry, University of Southern California, Los Angeles, CA, USA
| | - Reuben S Harris
- Department of Biochemistry and Structural Biology, University of Texas Health San Antonio, San Antonio, TX, USA
- Howard Hughes Medical Institute, University of Texas Health San Antonio, San Antonio, TX, USA
| | - Michael S Lawrence
- Massachusetts General Hospital Cancer Center, Harvard Medical School, Boston, MA, USA
- Broad Institute of Harvard and MIT, Cambridge, MA, USA
- Department of Pathology, Massachusetts General Hospital, Harvard Medical School, Boston, MA, USA
| | - Rémi Buisson
- Department of Biological Chemistry, School of Medicine, University of California Irvine, Irvine, CA, USA.
- Center for Epigenetics and Metabolism, Chao Family Comprehensive Cancer Center, University of California Irvine, Irvine, CA, USA.
- Department of Pharmaceutical Sciences, School of Pharmacy & Pharmaceutical Sciences, University of California Irvine, Irvine, CA, USA.
| |
Collapse
|
2
|
Sanchez A, Ortega P, Sakhtemani R, Manjunath L, Oh S, Bournique E, Becker A, Kim K, Durfee C, Temiz NA, Chen XS, Harris RS, Lawrence MS, Buisson R. Mesoscale DNA Features Impact APOBEC3A and APOBEC3B Deaminase Activity and Shape Tumor Mutational Landscapes. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.02.551499. [PMID: 37577509 PMCID: PMC10418229 DOI: 10.1101/2023.08.02.551499] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/15/2023]
Abstract
Antiviral DNA cytosine deaminases APOBEC3A and APOBEC3B are major sources of mutations in cancer by catalyzing cytosine-to-uracil deamination. APOBEC3A preferentially targets singlestranded DNAs, with a noted affinity for DNA regions that adopt stem-loop secondary structures. However, the detailed substrate preferences of APOBEC3A and APOBEC3B have been fully established, and the specific influence of the DNA sequence on APOBEC3A APOBEC3B deaminase activity remains to be investigated. Here, we find that APOBEC3B selectively targets DNA stem-loop structures, and they are distinct from those subjected deamination by APOBEC3A. We develop Oligo-seq, a novel in vitro sequencing-based to identify specific sequence contexts promoting APOBEC3A and APOBEC3B activity. Through this approach, we demonstrate that APOBEC3A an APOBEC3B deaminase activity is strongly regulated by specific sequences surrounding the targeted cytosine. Moreover, we identify structural features of APOBEC3B and APOBEC3A responsible for their substrate preferences. Importantly, we determine that APOBEC3B-induced mutations in hairpin-forming sequences within tumor genomes differ from the DNA stem-loop sequences mutated by APOBEC3A. Together, our study provides evidence that APOBEC3A and APOBEC3B can generate mutation landscapes in cancer genomes, driven by their unique substrate selectivity.
Collapse
|
3
|
Roelofs PA, Martens JW, Harris RS, Span PN. Clinical Implications of APOBEC3-Mediated Mutagenesis in Breast Cancer. Clin Cancer Res 2023; 29:1658-1669. [PMID: 36478188 PMCID: PMC10159886 DOI: 10.1158/1078-0432.ccr-22-2861] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2022] [Revised: 10/30/2022] [Accepted: 11/28/2022] [Indexed: 12/13/2022]
Abstract
Over recent years, members of the APOBEC3 family of cytosine deaminases have been implicated in increased cancer genome mutagenesis, thereby contributing to intratumor and intertumor genomic heterogeneity and therapy resistance in, among others, breast cancer. Understanding the available methods for clinical detection of these enzymes, the conditions required for their (dysregulated) expression, the clinical impact they have, and the clinical implications they may offer is crucial in understanding the current impact of APOBEC3-mediated mutagenesis in breast cancer. Here, we provide a comprehensive review of recent developments in the detection of APOBEC3-mediated mutagenesis and responsible APOBEC3 enzymes, summarize the pathways that control their expression, and explore the clinical ramifications and opportunities they pose. We propose that APOBEC3-mediated mutagenesis can function as a helpful predictive biomarker in several standard-of-care breast cancer treatment plans and may be a novel target for treatment.
Collapse
Affiliation(s)
- Pieter A. Roelofs
- Department of Radiation Oncology, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands
- Department of Biochemistry, Molecular Biology and Biophysics, Masonic Cancer Center, University of Minnesota, Minneapolis, MN 55455, USA
| | - John W.M. Martens
- Erasmus MC Cancer Institute, Erasmus University Medical Center, 3000 CA Rotterdam, The Netherlands
| | - Reuben S. Harris
- Department of Biochemistry, Molecular Biology and Biophysics, Masonic Cancer Center, University of Minnesota, Minneapolis, MN 55455, USA
- Department of Biochemistry and Structural Biology, University of Texas Health San Antonio, San Antonio, TX 78229, USA
- Howard Hughes Medical Institute, University of Texas Health San Antonio, San Antonio, TX 78229, USA
| | - Paul N. Span
- Department of Radiation Oncology, Radboud University Medical Center, 6525 GA Nijmegen, The Netherlands
| |
Collapse
|
4
|
Jones KM, Shehata M, Carpenter MA, Amaro RE, Harki DA. APOBEC3A Catalytic Inactivity Mutation Induces Tertiary Structure Destabilization. ACS Med Chem Lett 2023; 14:338-343. [PMID: 36923917 PMCID: PMC10009786 DOI: 10.1021/acsmedchemlett.2c00517] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Accepted: 02/03/2023] [Indexed: 02/16/2023] Open
Abstract
APOBEC3A (A3A)-catalyzed DNA cytosine deamination is implicated in virus and cancer mutagenesis, and A3A is a target for small molecule drug discovery. The catalytic glutamic acid (E72) is frequently mutated in biochemical studies to characterize deamination-dependent versus deamination-independent A3A functions. Additionally, catalytically active A3A is toxic in bacterial expression systems, which adversely affects yield during recombinant A3A expression. Here, we demonstrate that mutating the catalytic glutamic acid to an isosteric glutamine (E72Q) significantly decreases the thermal stability of the protein, compared to the alanine-inactivating mutation (E72A). Differential scanning fluorimetry and mass spectrometry reveal that A3A E72Q is less thermally stable than A3A E72A or wild-type A3A. Strikingly, A3A E72Q is partially denatured at 37 °C and binds single-stranded DNA with significantly poorer affinity compared to A3A E72A. This study constitutes an important cautionary note on A3A protein design and informs that A3A E72A is the preferred catalytic inactivation mutation for most applications.
Collapse
Affiliation(s)
- Katherine
F. M. Jones
- Department
of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Mohamed Shehata
- Department
of Chemistry and Biochemistry, University
of California − San Diego, La Jolla, California 92093, United States
| | - Michael A. Carpenter
- Department
of Biochemistry & Structural Biology, University of Texas Health Science Center San Antonio, San Antonio, Texas 78229, United States
| | - Rommie E. Amaro
- Department
of Chemistry and Biochemistry, University
of California − San Diego, La Jolla, California 92093, United States
| | - Daniel A. Harki
- Department
of Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
- Department
of Medicinal Chemistry, University of Minnesota, Minneapolis, Minnesota 55455, United States
| |
Collapse
|
5
|
Papini C, Wang Z, Kudalkar SN, Schrank TP, Tang S, Sasaki T, Wu C, Tejada B, Ziegler SJ, Xiong Y, Issaeva N, Yarbrough WG, Anderson KS. Exploring ABOBEC3A and APOBEC3B substrate specificity and their role in HPV positive head and neck cancer. iScience 2022; 25:105077. [PMID: 36164654 PMCID: PMC9508485 DOI: 10.1016/j.isci.2022.105077] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2022] [Revised: 08/05/2022] [Accepted: 08/31/2022] [Indexed: 12/03/2022] Open
Abstract
APOBEC3 family members are cytidine deaminases catalyzing conversion of cytidine to uracil. Many studies have established a link between APOBEC3 expression and cancer development and progression, especially APOBEC3A (A3A) and APOBEC3B (A3B). Preclinical studies with human papillomavirus positive (HPV+) head and neck squamous cell carcinoma (HNSCC) and clinical trial specimens revealed induction of A3B, but not A3A expression after demethylation. We examined the kinetic features of the cytidine deaminase activity for full length A3B and found that longer substrates and a purine at −2 position favored by A3B, whereas A3A prefers shorter substrates and an adenine or thymine at −2 position. The importance and biological significance of A3B catalytic activity rather than A3A and a preference for purine at the −2 position was also established in HPV+ HNSCCs. Our study explored factors influencing formation of A3A and A3B-related cancer mutations that are essential for understanding APOBEC3-related carcinogenesis and facilitating drug discovery. A3B is upregulated after 5-AzaC treatment and related to 5-AzaC sensitivity in HPV+ HNSCC Full-length A3B prefers longer substrates and a purine at −2 site biochemically A3B also prefers a purine at −2 site in both HPV+ and HPV− HNSCC cells A3B signature at -2 site linked to poor patient survival in HPV+ HNSCC low smokers
Collapse
Affiliation(s)
- Christina Papini
- Department of Pharmacology, Yale University School of Medicine, 333 Cedar St., New Haven, CT 06520, USA
| | - Zechen Wang
- Department of Pharmacology, Yale University School of Medicine, 333 Cedar St., New Haven, CT 06520, USA
| | - Shalley N Kudalkar
- Department of Pharmacology, Yale University School of Medicine, 333 Cedar St., New Haven, CT 06520, USA
| | - Travis Parke Schrank
- Department of Otolaryngology/Head and Neck Surgery, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Su Tang
- Department of Pharmacology, Yale University School of Medicine, 333 Cedar St., New Haven, CT 06520, USA
| | - Tomoaki Sasaki
- Department of Pharmacology, Yale University School of Medicine, 333 Cedar St., New Haven, CT 06520, USA
| | - Cory Wu
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520, USA
| | - Brandon Tejada
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520, USA
| | - Samantha J Ziegler
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520, USA
| | - Yong Xiong
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520, USA
| | - Natalia Issaeva
- Department of Otolaryngology/Head and Neck Surgery, University of North Carolina, Chapel Hill, NC 27599, USA.,Department of Pathology and Lab Medicine, Lineberger Cancer Center, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Wendell G Yarbrough
- Department of Otolaryngology/Head and Neck Surgery, University of North Carolina, Chapel Hill, NC 27599, USA.,Department of Pathology and Lab Medicine, Lineberger Cancer Center, University of North Carolina, Chapel Hill, NC 27599, USA
| | - Karen S Anderson
- Department of Pharmacology, Yale University School of Medicine, 333 Cedar St., New Haven, CT 06520, USA.,Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT 06520, USA
| |
Collapse
|
6
|
The optimal pH of AID is skewed from that of its catalytic pocket by DNA-binding residues and surface charge. Biochem J 2021; 479:39-55. [PMID: 34870314 DOI: 10.1042/bcj20210529] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Revised: 12/02/2021] [Accepted: 12/06/2021] [Indexed: 11/17/2022]
Abstract
Activation-induced cytidine deaminase (AID) is a member of the apolipoprotein B mRNA editing enzyme, catalytic polypeptide-like (APOBEC) family of cytidine deaminases. AID mutates immunoglobulin loci to initiate secondary antibody diversification. The APOBEC3 (A3) sub-branch mutates viral pathogens in the cytosol and acidic endosomal compartments. Accordingly, AID functions optimally near neutral pH, while most A3s are acid-adapted (optimal pH 5.5-6.5). To gain a structural understanding for this pH disparity, we constructed high-resolution maps of AID catalytic activity vs pH. We found AID's optimal pH was 7.3 but it retained most (>70%) of the activity at pH 8. Probing of ssDNA-binding residues near the catalytic pocket, key for bending ssDNA into the pocket (e.g R25) yielded mutants with altered pH preference, corroborating previous findings that the equivalent residue in APOBEC3G (H216) underlies its acidic pH preference. AID from bony fish exhibited more basic optimal pH (pH 7.5-8.1) and several R25-equivalent mutants altered pH preference. Comparison of pH optima across the AID/APOBEC3 family revealed an inverse correlation between positive surface charge and overall catalysis. The paralogue with the most robust catalytic activity (APOBEC3A) has the lowest surface charge, most acidic pH preference, while the paralogue with the most lethargic catalytic rate (AID) has the most positive surface charge and highest optimal pH. We suggest one possible mechanism is through surface charge dictating an overall optimal pH that is different from the optimal pH of the catalytic pocket microenvironment. These findings illuminate an additional structural mechanism that regulates AID/APOBEC3 mutagenesis.
Collapse
|
7
|
Gaba A, Hix MA, Suhail S, Flath B, Boysan B, Williams DR, Pelletier T, Emerman M, Morcos F, Cisneros GA, Chelico L. Divergence in Dimerization and Activity of Primate APOBEC3C. J Mol Biol 2021; 433:167306. [PMID: 34666043 PMCID: PMC9202443 DOI: 10.1016/j.jmb.2021.167306] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2021] [Revised: 10/08/2021] [Accepted: 10/08/2021] [Indexed: 11/21/2022]
Abstract
The APOBEC3 (A3) family of single-stranded DNA cytidine deaminases are host restriction factors that inhibit lentiviruses, such as HIV-1, in the absence of the Vif protein that causes their degradation. Deamination of cytidine in HIV-1 (−)DNA forms uracil that causes inactivating mutations when uracil is used as a template for (+)DNA synthesis. For APOBEC3C (A3C), the chimpanzee and gorilla orthologues are more active than human A3C, and we determined that Old World Monkey A3C from rhesus macaque (rh) is not active against HIV-1. Biochemical, virological, and coevolutionary analyses combined with molecular dynamics simulations showed that the key amino acids needed to promote rhA3C antiviral activity, 44, 45, and 144, also promoted dimerization and changes to the dynamics of loop 1, near the enzyme active site. Although forced evolution of rhA3C resulted in a similar dimer interface with hominid A3C, the key amino acid contacts were different. Overall, our results determine the basis for why rhA3C is less active than human A3C and establish the amino acid network for dimerization and increased activity. Based on identification of the key amino acids determining Old World Monkey antiviral activity we predict that other Old World Monkey A3Cs did not impart anti-lentiviral activity, despite fixation of a key residue needed for hominid A3C activity. Overall, the coevolutionary analysis of the A3C dimerization interface presented also provides a basis from which to analyze dimerization interfaces of other A3 family members.
Collapse
Affiliation(s)
- Amit Gaba
- Department of Biochemistry, Microbiology, and Immunology, College of Medicine, University of Saskatchewan, Saskatoon, Canada. https://twitter.com/optimist1023
| | - Mark A Hix
- Department of Chemistry, University of North Texas, Denton, TX, USA. https://twitter.com/markahix
| | - Sana Suhail
- Department of Biological Sciences, Center for Systems Biology, University of Texas at Dallas, Richardson, TX, USA. https://twitter.com/sakuraa_329
| | - Ben Flath
- Department of Biochemistry, Microbiology, and Immunology, College of Medicine, University of Saskatchewan, Saskatoon, Canada
| | - Brock Boysan
- Department of Chemistry, University of North Texas, Denton, TX, USA
| | - Danielle R Williams
- Division of Human Biology, Fred Hutchinson Cancer Research Center, Seattle, WA, USA. https://twitter.com/dani_renee_
| | - Tomas Pelletier
- Department of Biochemistry, Microbiology, and Immunology, College of Medicine, University of Saskatchewan, Saskatoon, Canada
| | - 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. https://twitter.com/memerman
| | - Faruck Morcos
- Department of Biological Sciences, Center for Systems Biology, University of Texas at Dallas, Richardson, TX, USA; Department of Bioengineering, University of Texas at Dallas, Dallas, TX, USA. https://twitter.com/MorcosLab
| | - G Andrés Cisneros
- Department of Chemistry, University of North Texas, Denton, TX, USA. https://twitter.com/CisnerosRes
| | - Linda Chelico
- Department of Biochemistry, Microbiology, and Immunology, College of Medicine, University of Saskatchewan, Saskatoon, Canada.
| |
Collapse
|
8
|
King JJ, Borzooee F, Im J, Asgharpour M, Ghorbani A, Diamond CP, Fifield H, Berghuis L, Larijani M. Structure-Based Design of First-Generation Small Molecule Inhibitors Targeting the Catalytic Pockets of AID, APOBEC3A, and APOBEC3B. ACS Pharmacol Transl Sci 2021; 4:1390-1407. [PMID: 34423273 PMCID: PMC8369683 DOI: 10.1021/acsptsci.1c00091] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Indexed: 12/12/2022]
Abstract
![]()
Activation-induced
cytidine deaminase (AID) initiates antibody
diversification by mutating immunoglobulin loci in B lymphocytes.
AID and related APOBEC3 (A3) enzymes also induce genome-wide mutations
and lesions implicated in tumorigenesis and tumor progression. The
most prevalent mutation signatures across diverse tumor genomes are
attributable to the mistargeted mutagenic activities of AID/A3s. Thus,
inhibiting AID/A3s has been suggested to be of therapeutic benefit.
We previously used a computational-biochemical approach to gain insight
into the structure of AID’s catalytic pocket, which resulted
in the discovery of a novel type of regulatory catalytic pocket closure
that regulates AID/A3s that we termed the “Schrodinger’s
CATalytic pocket”. Our findings were subsequently confirmed
by direct structural studies. Here, we describe our search for small
molecules that target the catalytic pocket of AID. We identified small
molecules that inhibit purified AID, AID in cell extracts, and endogenous
AID of lymphoma cells. Analogue expansion yielded derivatives with
improved potencies. These were found to also inhibit A3A and A3B,
the two most tumorigenic siblings of AID. Two compounds exhibit low
micromolar IC50 inhibition of AID and A3A, exhibiting the
strongest potency for A3A. Docking suggests key interactions between
their warheads and residues lining the catalytic pockets of AID, A3A,
and A3B and between the tails and DNA-interacting residues on the
surface proximal to the catalytic pocket opening. Accordingly, mutants
of these residues decreased inhibition potency. The chemistry and
abundance of key stabilizing interactions between the small molecules
and residues within and immediately outside the catalytic pockets
are promising for therapeutic development.
Collapse
Affiliation(s)
- Justin J King
- Department of Molecular Biology and Biochemistry, Faculty of Science, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada.,Program in immunology and Infectious Diseases, Division of Biomedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John's, Newfoundland A1B 3 V6, Canada
| | - Faezeh Borzooee
- Department of Molecular Biology and Biochemistry, Faculty of Science, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada.,Program in immunology and Infectious Diseases, Division of Biomedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John's, Newfoundland A1B 3 V6, Canada
| | - Junbum Im
- Program in immunology and Infectious Diseases, Division of Biomedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John's, Newfoundland A1B 3 V6, Canada.,BC Cancer Research/Terry Fox Labs, University of British Columbia, Vancouver, British Columbia BC V5Z 1L3, Canada
| | - Mahdi Asgharpour
- Department of Molecular Biology and Biochemistry, Faculty of Science, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada.,Program in immunology and Infectious Diseases, Division of Biomedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John's, Newfoundland A1B 3 V6, Canada
| | - Atefeh Ghorbani
- Department of Molecular Biology and Biochemistry, Faculty of Science, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada.,Program in immunology and Infectious Diseases, Division of Biomedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John's, Newfoundland A1B 3 V6, Canada
| | - Cody P Diamond
- Program in immunology and Infectious Diseases, Division of Biomedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John's, Newfoundland A1B 3 V6, Canada
| | - Heather Fifield
- Program in immunology and Infectious Diseases, Division of Biomedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John's, Newfoundland A1B 3 V6, Canada
| | - Lesley Berghuis
- Program in immunology and Infectious Diseases, Division of Biomedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John's, Newfoundland A1B 3 V6, Canada
| | - Mani Larijani
- Department of Molecular Biology and Biochemistry, Faculty of Science, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada.,Program in immunology and Infectious Diseases, Division of Biomedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John's, Newfoundland A1B 3 V6, Canada
| |
Collapse
|
9
|
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: 14] [Impact Index Per Article: 4.7] [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.
Collapse
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.
| |
Collapse
|
10
|
Structural Characterization of a Minimal Antibody against Human APOBEC3B. Viruses 2021; 13:v13040663. [PMID: 33921405 PMCID: PMC8070380 DOI: 10.3390/v13040663] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 03/31/2021] [Accepted: 04/09/2021] [Indexed: 01/03/2023] Open
Abstract
APOBEC3B (A3B) is one of seven human APOBEC3 DNA cytosine deaminases that restrict viral infections as part of the overall innate immune response, but it also plays a major role in tumor evolution by mutating genomic DNA. Given the importance of A3B as a restriction factor of viral infections and as a driver of multiple human cancers, selective antibodies against A3B are highly desirable for its specific detection in various research and possibly diagnostic applications. Here, we describe a high-affinity minimal antibody, designated 5G7, obtained via a phage display screening against the C-terminal catalytic domain (ctd) of A3B. 5G7 also binds APOBEC3A that is highly homologous to A3Bctd but does not bind the catalytic domain of APOBEC3G, another Z1-type deaminase domain. The crystal structure of 5G7 shows a canonical arrangement of the heavy and light chain variable domains, with their complementarity-determining region (CDR) loops lining an antigen-binding cleft that accommodates a pair of α-helices. To understand the mechanism of A3Bctd recognition by 5G7, we used the crystal structures of A3Bctd and 5G7 as templates and computationally predicted the A3B-5G7 complex structure. Stable binding poses obtained by the simulation were further tested by site-directed mutagenesis and in vitro binding analyses. These studies mapped the epitope for 5G7 to a portion of C-terminal α6 helix of A3Bctd, with Arg374 playing an essential role. The same region of A3Bctd was used previously as a peptide antigen for generating a rabbit monoclonal antibody (mAb 5210-87-13), suggesting that this region is particularly immunogenic and that these antibodies from very different origins may share similar binding modes. Our studies provide a platform for the development of selective antibodies against A3B and other APOBEC3 family enzymes.
Collapse
|
11
|
Maiti A, Hou S, Schiffer CA, Matsuo H. Interactions of APOBEC3s with DNA and RNA. Curr Opin Struct Biol 2021; 67:195-204. [PMID: 33486429 DOI: 10.1016/j.sbi.2020.12.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2020] [Revised: 11/25/2020] [Accepted: 12/03/2020] [Indexed: 02/06/2023]
Abstract
APOBEC3 enzymes are key enzymes in our innate immune system regulating antiviral response in HIV and unfortunately adding diversity in cancer as they deaminate cytosine. Seven unique single and double domain APOBEC3s provide them with unique activity and specificity profiles for this deamination. Recent crystal and NMR structures of APOBEC3 complexes are unraveling the variety of epitopes involved in binding nucleic acids, including at the catalytic site, elsewhere on the catalytic domain and in the inactive N-terminal domain. The interplay between these diverse interactions is critical to uncovering the mechanisms by which APOBEC3s recognize and process their substrates.
Collapse
Affiliation(s)
- Atanu Maiti
- Basic Science Program, 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
| | - 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.
| |
Collapse
|
12
|
King JJ, Larijani M. Structural plasticity of substrate selection by activation-induced cytidine deaminase as a regulator of its genome-wide mutagenic activity. FEBS Lett 2020; 595:3-13. [PMID: 33089497 DOI: 10.1002/1873-3468.13962] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Revised: 09/28/2020] [Accepted: 10/08/2020] [Indexed: 01/25/2023]
Abstract
Activation-induced cytidine deaminase (AID) mediates somatic hypermutation and class-switch recombination of antibodies. Computational-biochemical and crystallography analyses of AID have identified three surface grooves for binding single-stranded DNA (ssDNA). Functional studies have also found evidence for RNA-binding motifs on AID. Although AID and the related apolipoprotein B mRNA-editing enzyme catalytic polypeptide-like (APOBEC) enzymes share a conserved core, AID uniquely features multiple substrate-binding motifs on its surface. Here we suggest that combinatorial deployment of AID's multiple ssDNA- or RNA-binding motifs yields many substrate-binding modes that can accommodate ssDNA, RNA, or DNA/RNA substrates of diverse structures. We also suggest that AID oligomerization generates yet additional novel substrate-binding modes. We propose that this plasticity in substrate choice is an evolved aspect of AID's structure that contributes to the regulation of its differential mutagenic activity at various loci.
Collapse
Affiliation(s)
- Justin J King
- Program in Immunology and Infectious Diseases, Department of Biomedical Sciences, Faculty of Medicine, Memorial University of Newfoundland, St. John's, Canada
| | - Mani Larijani
- Department of Molecular Biology and Biochemistry, Faculty of Science, Simon Fraser University, Burnaby, Canada
| |
Collapse
|
13
|
Ng JF, Fraternali F. Understanding the structural details of APOBEC3-DNA interactions using graph-based representations. Curr Res Struct Biol 2020; 2:130-143. [PMID: 34235473 PMCID: PMC8244423 DOI: 10.1016/j.crstbi.2020.07.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2020] [Revised: 07/17/2020] [Accepted: 07/21/2020] [Indexed: 12/22/2022] Open
Abstract
Human APOBEC3 (A3; apolipoprotein B mRNA editing catalytic polypeptide-like 3) is a family of seven enzymes involved in generating mutations in nascent reverse transcripts of many retroviruses, as well as the human genome in a range of cancer types. The structural details of the interaction between A3 proteins and DNA molecules are only available for a few family members. Here we use homology modelling techniques to address the difference in structural coverage of human A3 enzymes interacting with different DNA substrates. A3-DNA interfaces are represented as residue networks ("graphs"), based on which features at these interfaces are compared and quantified. We demonstrate that graph-based representations are effective in highlighting structural features of A3-DNA interfaces. By large-scale in silico mutagenesis of the bound DNA chain, we predicted the preference of substrate DNA sequence for multiple A3 domains. These data suggested that computational modelling approaches could contribute in the exploration of the structural basis for sequence specificity in A3 substrate selection, and demonstrated the utility of graph-based approaches in evaluating a large number of structural models generated in silico. APOBEC3(A3)-DNA structures have been resolved with modified deaminase domains. Structural modelling of interaction between wild-type A3 domains and DNA substrates. Graph-based representations reveal structural differences across A3-DNA interfaces. Using in silico mutagenesis we compared substrate preference of multiple A3 domains. Graph-based approaches can efficiently compare a large number of structural models.
Collapse
|
14
|
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: 4.5] [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.
Collapse
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.)
| |
Collapse
|
15
|
Rallapalli KL, Komor AC, Paesani F. Computer simulations explain mutation-induced effects on the DNA editing by adenine base editors. SCIENCE ADVANCES 2020; 6:eaaz2309. [PMID: 32181363 PMCID: PMC7056309 DOI: 10.1126/sciadv.aaz2309] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/22/2019] [Accepted: 12/11/2019] [Indexed: 06/10/2023]
Abstract
Adenine base editors, which were developed by engineering a transfer RNA adenosine deaminase enzyme (TadA) into a DNA editing enzyme (TadA*), enable precise modification of A:T to G⋮C base pairs. Here, we use molecular dynamics simulations to uncover the structural and functional roles played by the initial mutations in the onset of the DNA editing activity by TadA*. Atomistic insights reveal that early mutations lead to intricate conformational changes in the structure of TadA*. In particular, the first mutation, Asp108Asn, induces an enhancement in the binding affinity of TadA to DNA. In silico and in vivo reversion analyses verify the importance of this single mutation in imparting functional promiscuity to TadA* and demonstrate that TadA* performs DNA base editing as a monomer rather than a dimer.
Collapse
Affiliation(s)
- Kartik L. Rallapalli
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093, USA
| | - Alexis C. Komor
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093, USA
| | - Francesco Paesani
- Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093, USA
- Materials Science and Engineering, University of California, San Diego, La Jolla, CA 92093, USA
- San Diego Supercomputer Center, University of California, San Diego, La Jolla, CA 92093, USA
| |
Collapse
|
16
|
McCann JL, Salamango DJ, Law EK, Brown WL, Harris RS. MagnEdit-interacting factors that recruit DNA-editing enzymes to single base targets. Life Sci Alliance 2020; 3:3/4/e201900606. [PMID: 32094150 PMCID: PMC7043409 DOI: 10.26508/lsa.201900606] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2019] [Revised: 02/14/2020] [Accepted: 02/17/2020] [Indexed: 12/17/2022] Open
Abstract
This study reports a new, non-covalent strategy—called MagnEdit—that attracts the DNA cytosine deaminase APOBEC3B to a Cas9-directed site for C-to-T editing. Although CRISPR/Cas9 technology has created a renaissance in genome engineering, particularly for gene knockout generation, methods to introduce precise single base changes are also highly desirable. The covalent fusion of a DNA-editing enzyme such as APOBEC to a Cas9 nickase complex has heightened hopes for such precision genome engineering. However, current cytosine base editors are prone to undesirable off-target mutations, including, most frequently, target-adjacent mutations. Here, we report a method to “attract” the DNA deaminase, APOBEC3B, to a target cytosine base for specific editing with minimal damage to adjacent cytosine bases. The key to this system is fusing an APOBEC-interacting protein (not APOBEC itself) to Cas9n, which attracts nuclear APOBEC3B transiently to the target site for editing. Several APOBEC3B interactors were tested and one, hnRNPUL1, demonstrated proof-of-concept with successful C-to-T editing of episomal and chromosomal substrates and lower frequencies of target-adjacent events.
Collapse
Affiliation(s)
- Jennifer L McCann
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN, USA.,Institute for Molecular Virology, University of Minnesota, Minneapolis, MN, USA.,Masonic Cancer Center, University of Minnesota, Minneapolis, MN, USA.,Center for Genome Engineering, University of Minnesota, Minneapolis, MN, USA.,Howard Hughes Medical Institute, University of Minnesota, Minneapolis, MN, USA
| | - Daniel J Salamango
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN, USA.,Institute for Molecular Virology, University of Minnesota, Minneapolis, MN, USA.,Masonic Cancer Center, University of Minnesota, Minneapolis, MN, USA.,Center for Genome Engineering, University of Minnesota, Minneapolis, MN, USA
| | - Emily K Law
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN, USA.,Institute for Molecular Virology, University of Minnesota, Minneapolis, MN, USA.,Masonic Cancer Center, University of Minnesota, Minneapolis, MN, USA.,Center for Genome Engineering, University of Minnesota, Minneapolis, MN, USA.,Howard Hughes Medical Institute, University of Minnesota, Minneapolis, MN, USA
| | - William L Brown
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN, USA.,Institute for Molecular Virology, University of Minnesota, Minneapolis, MN, USA.,Masonic Cancer Center, University of Minnesota, Minneapolis, MN, USA.,Center for Genome Engineering, University of Minnesota, Minneapolis, MN, USA
| | - Reuben S Harris
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN, USA .,Institute for Molecular Virology, University of Minnesota, Minneapolis, MN, USA.,Masonic Cancer Center, University of Minnesota, Minneapolis, MN, USA.,Center for Genome Engineering, University of Minnesota, Minneapolis, MN, USA.,Howard Hughes Medical Institute, University of Minnesota, Minneapolis, MN, USA
| |
Collapse
|
17
|
Shi K, Demir Ö, Carpenter MA, Banerjee S, Harki DA, Amaro RE, Harris RS, Aihara H. Active site plasticity and possible modes of chemical inhibition of the human DNA deaminase APOBEC3B. FASEB Bioadv 2020; 2:49-58. [PMID: 32123856 PMCID: PMC6996314 DOI: 10.1096/fba.2019-00068] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Revised: 08/19/2019] [Accepted: 11/30/2019] [Indexed: 01/24/2023] Open
Abstract
The single-stranded DNA cytosine deaminase APOBEC3B (A3B) functions in innate immunity against viruses, but it is also strongly implicated in eliciting mutations in cancer genomes. Because of the critical role of A3B in promoting virus and tumor evolution, small molecule inhibitors are desirable. However, there is no reported structure for any of the APOBEC3-family enzymes in complex with a small molecule bound in the active site, which hampers the development of small molecules targeting A3B. Here we report high-resolution structures of an active A3B catalytic domain chimera with loop 7 residues exchanged with those from the corresponding region of APOBEC3G (A3G). The structures reveal novel open conformations lacking the catalytically essential zinc ion, with the highly conserved active site residues extensively rearranged. These inactive conformations are stabilized by 2-pyrimidone or an iodide ion bound in the active site. Molecular dynamics simulations corroborate the remarkable plasticity of the engineered active site and identify key interactions that stabilize the native A3B active site. These data provide insights into A3B active site dynamics and suggest possible modes of its inhibition by small molecules, which would aid in rational design of selective A3B inhibitors for constraining virus and tumor evolution.
Collapse
Affiliation(s)
- Ke Shi
- Department of Biochemistry, Molecular Biology and BiophysicsUniversity of MinnesotaMinneapolisMNUSA
- Masonic Cancer CenterUniversity of MinnesotaMinneapolisMNUSA
- Institute for Molecular VirologyUniversity of MinnesotaMinneapolisMNUSA
| | - Özlem Demir
- Department of Chemistry and BiochemistryUniversity of California, San DiegoLa JollaCAUSA
| | - Michael A. Carpenter
- Department of Biochemistry, Molecular Biology and BiophysicsUniversity of MinnesotaMinneapolisMNUSA
- Masonic Cancer CenterUniversity of MinnesotaMinneapolisMNUSA
- Institute for Molecular VirologyUniversity of MinnesotaMinneapolisMNUSA
- Center for Genome EngineeringUniversity of MinnesotaMinneapolisMNUSA
- Howard Hughes Medical InstituteUniversity of MinnesotaMinneapolisMNUSA
| | - Surajit Banerjee
- Northeastern Collaborative Access TeamCornell UniversityLemontILUSA
| | - Daniel A. Harki
- Masonic Cancer CenterUniversity of MinnesotaMinneapolisMNUSA
- Institute for Molecular VirologyUniversity of MinnesotaMinneapolisMNUSA
- Department of Medicinal ChemistryUniversity of MinnesotaMinneapolisMNUSA
| | - Rommie E. Amaro
- Department of Chemistry and BiochemistryUniversity of California, San DiegoLa JollaCAUSA
| | - Reuben S. Harris
- Department of Biochemistry, Molecular Biology and BiophysicsUniversity of MinnesotaMinneapolisMNUSA
- Masonic Cancer CenterUniversity of MinnesotaMinneapolisMNUSA
- Institute for Molecular VirologyUniversity of MinnesotaMinneapolisMNUSA
- Center for Genome EngineeringUniversity of MinnesotaMinneapolisMNUSA
- Howard Hughes Medical InstituteUniversity of MinnesotaMinneapolisMNUSA
| | - Hideki Aihara
- Department of Biochemistry, Molecular Biology and BiophysicsUniversity of MinnesotaMinneapolisMNUSA
- Masonic Cancer CenterUniversity of MinnesotaMinneapolisMNUSA
- Institute for Molecular VirologyUniversity of MinnesotaMinneapolisMNUSA
| |
Collapse
|
18
|
Wang J, Becker JT, Shi K, Lauer KV, Salamango DJ, Aihara H, Shaban NM, Harris RS. The Role of RNA in HIV-1 Vif-Mediated Degradation of APOBEC3H. J Mol Biol 2019; 431:5019-5031. [PMID: 31628948 DOI: 10.1016/j.jmb.2019.09.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2019] [Revised: 09/04/2019] [Accepted: 09/16/2019] [Indexed: 11/17/2022]
Abstract
As many as five members of the APOBEC3 family of DNA cytosine deaminases are capable of inhibiting HIV-1 replication by deaminating viral cDNA cytosines and interfering with reverse transcription. HIV-1 counteracts restriction with the virally encoded Vif protein, which forms a hybrid ubiquitin ligase complex that directly binds APOBEC3 enzymes and targets them for proteasomal degradation. APOBEC3H (A3H) is unique among family members by dimerization through cellular and viral duplex RNA species. RNA binding is required for localization of A3H to the cytoplasmic compartment, for efficient packaging into nascent HIV-1 particles and ultimately for effective virus restriction activity. Here we compared wild-type human A3H and RNA binding-defective mutants to ask whether RNA may be a factor in the functional interaction with HIV-1 Vif. We used structural modeling, immunoblotting, live cell imaging, and split green fluorescence protein (GFP) reconstitution approaches to assess the capability of HIV-1 Vif to promote the degradation of wild-type A3H in comparison to RNA binding-defective mutants. The results combined to show that RNA is not strictly required for Vif-mediated degradation of A3H, and that RNA and Vif are likely to bind this single-domain DNA cytosine deaminase on physically distinct surfaces. However, a subset of the results also indicated that the A3H degradation process may be affected by A3H protein structure, subcellular localization, and differences in the constellation of A3H interaction partners, suggesting additional factors may also influence the fate and functionality of this host-pathogen interaction.
Collapse
Affiliation(s)
- Jiayi Wang
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA; Masonic Cancer Center, University of Minnesota, Minneapolis, MN 55455, USA; Institute for Molecular Virology, University of Minnesota, Minneapolis, MN 55455, USA; Center for Genome Engineering, University of Minnesota, Minneapolis, MN 55455, USA
| | - Jordan T Becker
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA; Masonic Cancer Center, University of Minnesota, Minneapolis, MN 55455, USA; Institute for Molecular Virology, University of Minnesota, Minneapolis, MN 55455, USA; Center for Genome Engineering, University of Minnesota, Minneapolis, MN 55455, USA
| | - Ke Shi
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA; Masonic Cancer Center, University of Minnesota, Minneapolis, MN 55455, USA; Institute for Molecular Virology, University of Minnesota, Minneapolis, MN 55455, USA
| | - Kate V Lauer
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA; Masonic Cancer Center, University of Minnesota, Minneapolis, MN 55455, USA; Institute for Molecular Virology, University of Minnesota, Minneapolis, MN 55455, USA; Center for Genome Engineering, University of Minnesota, Minneapolis, MN 55455, USA
| | - Daniel J Salamango
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA; Masonic Cancer Center, University of Minnesota, Minneapolis, MN 55455, USA; Institute for Molecular Virology, University of Minnesota, Minneapolis, MN 55455, USA; Center for Genome Engineering, University of Minnesota, Minneapolis, MN 55455, USA
| | - Hideki Aihara
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA; Masonic Cancer Center, University of Minnesota, Minneapolis, MN 55455, USA; Institute for Molecular Virology, University of Minnesota, Minneapolis, MN 55455, USA
| | - Nadine M Shaban
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA; Masonic Cancer Center, University of Minnesota, Minneapolis, MN 55455, USA; Institute for Molecular Virology, University of Minnesota, Minneapolis, MN 55455, USA; Center for Genome Engineering, University of Minnesota, Minneapolis, MN 55455, USA.
| | - Reuben S Harris
- Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA; Masonic Cancer Center, University of Minnesota, Minneapolis, MN 55455, USA; Institute for Molecular Virology, University of Minnesota, Minneapolis, MN 55455, USA; Center for Genome Engineering, University of Minnesota, Minneapolis, MN 55455, USA; Howard Hughes Medical Institute, University of Minnesota, Minneapolis, MN 55455, USA.
| |
Collapse
|
19
|
Ziegler SJ, Hu Y, Devarkar SC, Xiong Y. APOBEC3A Loop 1 Is a Determinant for Single-Stranded DNA Binding and Deamination. Biochemistry 2019; 58:3838-3847. [PMID: 31448897 DOI: 10.1021/acs.biochem.9b00394] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The apolipoprotein B mRNA editing enzyme catalytic polypeptide-like 3 (APOBEC3 or A3) family of proteins functions in the innate immune system. The A3 proteins are interferon inducible and hypermutate deoxycytidine to deoxyuridine in foreign single-stranded DNA (ssDNA). However, this deaminase activity cannot discriminate between foreign and host ssDNA at the biochemical level, which presents a significant danger when A3 proteins gain access to the nucleus. Interestingly, this A3 capability can be harnessed when coupled with novel CRISPR-Cas9 proteins to create a targeted base editor. Specifically, A3A has been used in vitro to revert mutations associated with disease states. Recent structural studies have shown the importance of loop regions of A3A and A3G in ssDNA recognition and positioning for deamination. In this work, we further examined loop 1 of A3A to determine how it affects substrate selection, as well as the efficiency of deamination, in the hopes of advancing the potential of A3A in base editing technology. We found that mutating residue H29 enhanced deamination activity without changing substrate specificity. Also interestingly, we found that increasing the length of loop 1 decreases substrate specificity. Overall, these results lead to a better understanding of substrate recognition and deamination by A3A and the A3 family of proteins.
Collapse
Affiliation(s)
- Samantha J Ziegler
- Department of Molecular Biophysics and Biochemistry , Yale University , New Haven , Connecticut 06511 , United States
| | - Yingxia Hu
- Department of Molecular Biophysics and Biochemistry , Yale University , New Haven , Connecticut 06511 , United States
| | - Swapnil C Devarkar
- Department of Molecular Biophysics and Biochemistry , Yale University , New Haven , Connecticut 06511 , United States
| | - Yong Xiong
- Department of Molecular Biophysics and Biochemistry , Yale University , New Haven , Connecticut 06511 , United States
| |
Collapse
|
20
|
AID, APOBEC3A and APOBEC3B efficiently deaminate deoxycytidines neighboring DNA damage induced by oxidation or alkylation. Biochim Biophys Acta Gen Subj 2019; 1863:129415. [PMID: 31404619 DOI: 10.1016/j.bbagen.2019.129415] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Revised: 07/26/2019] [Accepted: 08/07/2019] [Indexed: 12/29/2022]
Abstract
BACKGROUND AID/APOBEC3 (A3) enzymes instigate genomic mutations that are involved in immunity and cancer. Although they can deaminate any deoxycytidine (dC) to deoxyuridine (dU), each family member has a signature preference determined by nucleotides surrounding the target dC. This WRC (W = A/T, R = A/G) and YC (Y = T/C) hotspot preference is established for AID and A3A/A3B, respectively. Base alkylation and oxidation are two of the most common types of DNA damage induced environmentally or by chemotherapy. Here we examined the activity of AID, A3A and A3B on dCs neighboring such damaged bases. METHODS Substrates were designed to contain target dCs either in normal WRC/YC hotspots, or in oxidized/alkylated DNA motifs. AID, A3A and A3B were purified and deamination kinetics of each were compared between substrates containing damaged vs. normal motifs. RESULTS All three enzymes efficiently deaminated dC when common damaged bases were present in the -2 or -1 positions. Strikingly, some damaged motifs supported comparable or higher catalytic efficiencies by AID, A3A and A3B than the WRC/YC motifs which are their most favored normal sequences. Based on the resolved interactions of AID, A3A and A3B with DNA, we modeled interactions with alkylated or oxidized bases. Corroborating the enzyme assay data, the surface regions that recognize normal bases are predicted to also interact robustly with oxidized and alkylated bases. CONCLUSIONS AID, A3A and A3B can efficiently recognize and deaminate dC whose neighbouring nucleotides are damaged. GENERAL SIGNIFICANCE Beyond AID/A3s initiating DNA damage, some forms of pre-existing damaged DNA can constitute favored targets of AID/A3s if encountered.
Collapse
|
21
|
Wagner JR, Demir Ö, Carpenter MA, Aihara H, Harki DA, Harris RS, Amaro RE. Determinants of Oligonucleotide Selectivity of APOBEC3B. J Chem Inf Model 2019; 59:2264-2273. [PMID: 30130104 PMCID: PMC6644697 DOI: 10.1021/acs.jcim.8b00427] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
APOBEC3B (A3B) is a prominent source of mutation in many cancers. To date, it has been difficult to capture the native protein-DNA interactions that confer A3B's substrate specificity by crystallography due to the highly dynamic nature of wild-type A3B active site. We use computational tools to restore a recent crystal structure of a DNA-bound A3B C-terminal domain mutant construct to its wild type sequence, and run molecular dynamics simulations to study its substrate recognition mechanisms. Analysis of these simulations reveal dynamics of the native A3Bctd-oligonucleotide interactions, including the experimentally inaccessible loop 1-oligonucleotide interactions. A second series of simulations in which the target cytosine nucleotide was computationally mutated from a deoxyribose to a ribose show a change in sugar ring pucker, leading to a rearrangement of the binding site and revealing a potential intermediate in the binding pathway. Finally, apo simulations of A3B, starting from the DNA-bound open state, experience a rapid and consistent closure of the binding site, reaching conformations incompatible with substrate binding. This study reveals a more realistic and dynamic view of the wild type A3B binding site and provides novel insights for structure-guided design efforts for A3B.
Collapse
Affiliation(s)
- Jeffrey R Wagner
- Department of Chemistry and Biochemistry , University of California, San Diego , La Jolla , California 92093-0340 , United States
| | - Özlem Demir
- Department of Chemistry and Biochemistry , University of California, San Diego , La Jolla , California 92093-0340 , United States
| | - Michael A Carpenter
- Department of Biochemistry, Molecular Biology and Biophysics , University of Minnesota , Minneapolis , Minnesota 55455 , United States
- Masonic Cancer Center , University of Minnesota , Minneapolis , Minnesota 55455 , United States
- Institute for Molecular Virology , University of Minnesota , Minneapolis , Minnesota 55455 , United States
| | - Hideki Aihara
- Department of Biochemistry, Molecular Biology and Biophysics , University of Minnesota , Minneapolis , Minnesota 55455 , United States
- Masonic Cancer Center , University of Minnesota , Minneapolis , Minnesota 55455 , United States
- Institute for Molecular Virology , University of Minnesota , Minneapolis , Minnesota 55455 , United States
| | - Daniel A Harki
- Department of Medicinal Chemistry , University of Minnesota , Minneapolis , Minnesota 55455 , United States
| | - Reuben S Harris
- Department of Biochemistry, Molecular Biology and Biophysics , University of Minnesota , Minneapolis , Minnesota 55455 , United States
- Masonic Cancer Center , University of Minnesota , Minneapolis , Minnesota 55455 , United States
- Institute for Molecular Virology , University of Minnesota , Minneapolis , Minnesota 55455 , United States
- Howard Hughes Medical Institute , University of Minnesota , Minneapolis , Minnesota 55455 , United States
| | - Rommie E Amaro
- Department of Chemistry and Biochemistry , University of California, San Diego , La Jolla , California 92093-0340 , United States
| |
Collapse
|
22
|
Salter JD, Polevoda B, Bennett RP, Smith HC. Regulation of Antiviral Innate Immunity Through APOBEC Ribonucleoprotein Complexes. Subcell Biochem 2019; 93:193-219. [PMID: 31939152 DOI: 10.1007/978-3-030-28151-9_6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The DNA mutagenic enzyme known as APOBEC3G (A3G) plays a critical role in innate immunity to Human Immunodeficiency Virus-1 (HIV-1 ). A3G is a zinc-dependent enzyme that mutates select deoxycytidines (dC) to deoxyuridine (dU) through deamination within nascent single stranded DNA (ssDNA) during HIV reverse transcription. This activity requires that the enzyme be delivered to viral replication complexes by redistributing from the cytoplasm of infected cells to budding virions through what appears to be an RNA-dependent process. Once inside infected cells, A3G must bind to nascent ssDNA reverse transcripts for dC to dU base modification gene editing. In this chapter we will discuss data indicating that ssDNA deaminase activity of A3G is regulated by RNA binding to A3G and ribonucleoprotein complex formation along with evidence suggesting that RNA-selective interactions with A3G are temporally and mechanistically important in this process.
Collapse
Affiliation(s)
- Jason D Salter
- OyaGen, Inc, 77 Ridgeland Road, Rochester, NY, 14623, USA
| | - Bogdan Polevoda
- Department of Biochemistry and Biophysics, School of Medicine and Dentistry, University of Rochester, 601 Elmwood Ave, Rochester, NY, 14642, USA
| | - Ryan P Bennett
- OyaGen, Inc, 77 Ridgeland Road, Rochester, NY, 14623, USA
| | - Harold C Smith
- OyaGen, Inc, 77 Ridgeland Road, Rochester, NY, 14623, USA. .,Department of Biochemistry and Biophysics, School of Medicine and Dentistry, University of Rochester, 601 Elmwood Ave, Rochester, NY, 14642, USA.
| |
Collapse
|
23
|
Coelho MA, Li S, Pane LS, Firth M, Ciotta G, Wrigley JD, Cuomo ME, Maresca M, Taylor BJM. BE-FLARE: a fluorescent reporter of base editing activity reveals editing characteristics of APOBEC3A and APOBEC3B. BMC Biol 2018; 16:150. [PMID: 30593278 PMCID: PMC6309101 DOI: 10.1186/s12915-018-0617-1] [Citation(s) in RCA: 36] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2018] [Accepted: 12/03/2018] [Indexed: 02/07/2023] Open
Abstract
BACKGROUND Base Editing is a precise genome editing method that uses a deaminase-Cas9 fusion protein to mutate cytidine to thymidine in target DNA in situ without the generation of a double-strand break. However, the efficient enrichment of genetically modified cells using this technique is limited by the ability to detect such events. RESULTS We have developed a Base Editing FLuorescent Activity REporter (BE-FLARE), which allows for the enrichment of cells that have undergone editing of target loci based on a fluorescence shift from BFP to GFP. We used BE-FLARE to evaluate the editing efficiency of APOBEC3A and APOBEC3B family members as alternatives deaminase domains to the rat APOBEC1 domain used in base editor 3 (BE3). We identified human APOBEC3A and APOBEC3B as highly efficient cytidine deaminases for base editing applications with unique properties. CONCLUSIONS Using BE-FLARE to report on the efficiency and precision of editing events, we outline workflows for the accelerated generation of genetically engineered cell models and the discovery of alternative base editors.
Collapse
Affiliation(s)
| | - Songyuan Li
- Discovery Sciences, IMED Biotech Unit, AstraZeneca, Gothenburg, Sweden
| | - Luna Simona Pane
- Discovery Sciences, IMED Biotech Unit, AstraZeneca, Gothenburg, Sweden
| | - Mike Firth
- Discovery Sciences, IMED Biotech Unit, AstraZeneca, Cambridge, UK
| | - Giovanni Ciotta
- Discovery Sciences, IMED Biotech Unit, AstraZeneca, Cambridge, UK
| | | | | | - Marcello Maresca
- Discovery Sciences, IMED Biotech Unit, AstraZeneca, Gothenburg, Sweden
| | | |
Collapse
|
24
|
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: 2.5] [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.
Collapse
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
| |
Collapse
|
25
|
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: 43] [Impact Index Per Article: 7.2] [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.
Collapse
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.
| |
Collapse
|