The cellular APOBEC3F and -3G proteins restrict the ability of retroviruses, including HIV-1, to successfully infect human cells. This novel innate immune defense occurs by APOBEC-catalyzed deamination of nascent cytosine residues in the cDNA strand of a replicating retrovirus. At least four mechanistic steps are required for APOBEC-dependent retroviral restriction. First, these APOBEC proteins must avoid the HIV-1 counterdefense protein Vif, which can mediate their destruction. Second, the APOBECs must incorporate into viral particles. Third, upon retroviral reverse transcription the APOBECs deaminate nascent cDNA cytosines. This produces uracil residues within the retroviral DNA, which are regarded as lesions by cellular DNA repair pathways. Thus, the fourth step may involve both the replication and fixation of minus strand uracils as plus strand adenines (hypermutation) and also the recognition and processing of uracils by other unidentified cellular enzymes. The latter event is likely to block the retrovirus from integrating. This proposal will better define these steps by delineating the key APOBEC protein domains and amino acid residues required for the first three steps. A powerful combination of model microbial, biochemical and retroviral systems will be used and complemented with somatic cell genetic techniques. These systems will be further applied to identify cellular DNA repair enzymes, likely base excision repair proteins, responsible for the fourth step. Finally, the identity and relative contributions of the APOBEC proteins that inhibit HIV-1 infection in the primary human viral reservoirs will be defined. Together the proposed studies will result in a fundamental understanding of the mechanism of APOBEC-dependent retroviral restriction. This will assist the rational design of therapies that could potentially attenuate HIV-1 by modulating the cellular APOBEC defense and the retroviral Vif counterdefense. The consequences of failing to appreciate these fundamental steps could be catastrophic as mis-regulation/expression of APOBEC family members has been associated with carcinogenesis.
| Yoshikawa, Rokusuke; Izumi, Taisuke; Yamada, Eri et al. (2016) A Naturally Occurring Domestic Cat APOBEC3 Variant Confers Resistance to Feline Immunodeficiency Virus Infection. J Virol 90:474-85 |
| Shaban, Nadine M; Shi, Ke; Li, Ming et al. (2016) 1.92 Angstrom Zinc-Free APOBEC3F Catalytic Domain Crystal Structure. J Mol Biol 428:2307-2316 |
| Richards, Christopher; Albin, John S; Demir, Özlem et al. (2015) The Binding Interface between Human APOBEC3F and HIV-1 Vif Elucidated by Genetic and Computational Approaches. Cell Rep 13:1781-8 |
| Anderson, Brett D; Harris, Reuben S (2015) Transcriptional regulation of APOBEC3 antiviral immunity through the CBF-?/RUNX axis. Sci Adv 1:e1500296 |
| Leonard, Brandon; McCann, Jennifer L; Starrett, Gabriel J et al. (2015) The PKC/NF-?B signaling pathway induces APOBEC3B expression in multiple human cancers. Cancer Res 75:4538-47 |
| Harris, Reuben S; Dudley, Jaquelin P (2015) APOBECs and virus restriction. Virology 479-480:131-45 |
| Yoshikawa, Rokusuke; Takeuchi, Junko S; Yamada, Eri et al. (2015) Vif determines the requirement for CBF-? in APOBEC3 degradation. J Gen Virol 96:887-92 |
| Harris, Reuben S; Perrino, Fred W; Shaban, Nadine M (2015) The multidimensional nature of antiviral innate immunity. Cell Host Microbe 17:423-5 |
| Harris, Reuben S (2015) Molecular mechanism and clinical impact of APOBEC3B-catalyzed mutagenesis in breast cancer. Breast Cancer Res 17:8 |
| Shi, Ke; Carpenter, Michael A; Kurahashi, Kayo et al. (2015) Crystal Structure of the DNA Deaminase APOBEC3B Catalytic Domain. J Biol Chem 290:28120-30 |
Showing the most recent 10 out of 65 publications
