| Structural highlights
Function
[ABC3B_HUMAN] DNA deaminase (cytidine deaminase) which acts as an inhibitor of retrovirus replication and retrotransposon mobility via deaminase-dependent and -independent mechanisms. After the penetration of retroviral nucleocapsids into target cells of infection and the initiation of reverse transcription, it can induce the conversion of cytosine to uracil in the minus-sense single-strand viral DNA, leading to G-to-A hypermutations in the subsequent plus-strand viral DNA. The resultant detrimental levels of mutations in the proviral genome, along with a deamination-independent mechanism that works prior to the proviral integration, together exert efficient antiretroviral effects in infected target cells. Selectively targets single-stranded DNA and does not deaminate double-stranded DNA or single-or double-stranded RNA. Exhibits antiviral activity against simian immunodeficiency virus (SIV), hepatitis B virus (HBV) and human T-cell leukemia virus type 1 (HTLV-1) and may inhibit the mobility of LTR and non-LTR retrotransposons.[1] [2] [3] [4] [5] [6]
Publication Abstract from PubMed
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 multi-step 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.
Crystal Structure of the DNA Deaminase APOBEC3B Catalytic Domain.,Shi K, Carpenter MA, Kurahashi K, Harris RS, Aihara H J Biol Chem. 2015 Sep 28. pii: jbc.M115.679951. PMID:26416889[7]
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.
References
- ↑ Mariani R, Chen D, Schrofelbauer B, Navarro F, Konig R, Bollman B, Munk C, Nymark-McMahon H, Landau NR. Species-specific exclusion of APOBEC3G from HIV-1 virions by Vif. Cell. 2003 Jul 11;114(1):21-31. PMID:12859895
- ↑ Yu Q, Chen D, Konig R, Mariani R, Unutmaz D, Landau NR. APOBEC3B and APOBEC3C are potent inhibitors of simian immunodeficiency virus replication. J Biol Chem. 2004 Dec 17;279(51):53379-86. Epub 2004 Oct 4. PMID:15466872 doi:http://dx.doi.org/10.1074/jbc.M408802200
- ↑ Rose KM, Marin M, Kozak SL, Kabat D. Regulated production and anti-HIV type 1 activities of cytidine deaminases APOBEC3B, 3F, and 3G. AIDS Res Hum Retroviruses. 2005 Jul;21(7):611-9. PMID:16060832 doi:http://dx.doi.org/10.1089/aid.2005.21.611
- ↑ Chen H, Lilley CE, Yu Q, Lee DV, Chou J, Narvaiza I, Landau NR, Weitzman MD. APOBEC3A is a potent inhibitor of adeno-associated virus and retrotransposons. Curr Biol. 2006 Mar 7;16(5):480-5. PMID:16527742 doi:10.1016/j.cub.2006.01.031
- ↑ Stenglein MD, Burns MB, Li M, Lengyel J, Harris RS. APOBEC3 proteins mediate the clearance of foreign DNA from human cells. Nat Struct Mol Biol. 2010 Feb;17(2):222-9. doi: 10.1038/nsmb.1744. Epub 2010 Jan , 10. PMID:20062055 doi:10.1038/nsmb.1744
- ↑ Ooms M, Krikoni A, Kress AK, Simon V, Munk C. APOBEC3A, APOBEC3B, and APOBEC3H haplotype 2 restrict human T-lymphotropic virus type 1. J Virol. 2012 Jun;86(11):6097-108. doi: 10.1128/JVI.06570-11. Epub 2012 Mar 28. PMID:22457529 doi:10.1128/JVI.06570-11
- ↑ Shi K, Carpenter MA, Kurahashi K, Harris RS, Aihara H. Crystal Structure of the DNA Deaminase APOBEC3B Catalytic Domain. J Biol Chem. 2015 Sep 28. pii: jbc.M115.679951. PMID:26416889 doi:http://dx.doi.org/10.1074/jbc.M115.679951
|
