The discovery of the antiviral APOBEC3 enzymes is regarded as one of the most therapeutically promising breakthroughs in HIV/AIDS molecular virology. Several APOBEC3s have the potential to restrict HIV replication by incorporating into assembling viral particles, physically interfering with the progression of reverse transcription, and deaminating viral cDNA cytosines to uracils. The latter antiviral activity is the defining hallmark of APOBEC3-mediated restriction, explaining the genomic strand G-to-A mutations that are frequently observed in patient-derived viral sequences. However, these potent antiviral activities are counteracted by the HIV virion infectivity factor (Vif), which heterodimerizes with CBF-beta in order to form an E3 ubiquitin ligase complex that degrades APOBEC3 enzymes. Here, we will address two persisting problems in this field. First, we will determine x-ray structures of APOBEC3-bound Vif/CBF-beta ubiquitin ligase complexes. These structures will provide insights into the APOBEC3-Vif binding mechanism, conformational changes, and the overall organization of these host-pathogen complexes. Second, we will elucidate X-ray structures of APOBEC3/single-stranded DNA complexes. These structures will provide insights into the mechanisms of enzymatic catalysis, DNA substrate recognition, and coupling between DNA-binding and the release of catalytic activity. We anticipate that structural information from both APOBEC3/Vif/CBF-beta and APOBEC3/single-stranded DNA macromolecular complexes will be important in the longer-term as the field continues to move toward drugging these interactions and enabling potent HIV-1 restriction through natural innate immunity.

Public Health Relevance

HIV infection can be controlled but not cured by current antiretroviral regimens. Understanding more about essential human/viral macromolecular interactions will provide new biological insights and could provide important information for future exploitation towards novel and potentially curative antiretroviral therapies.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM118000-03
Application #
9427995
Study Section
AIDS Molecular and Cellular Biology Study Section (AMCB)
Program Officer
Sakalian, Michael
Project Start
2016-04-15
Project End
2020-02-29
Budget Start
2018-03-01
Budget End
2019-02-28
Support Year
3
Fiscal Year
2018
Total Cost
Indirect Cost
Name
University of Minnesota Twin Cities
Department
Biochemistry
Type
Schools of Medicine
DUNS #
555917996
City
Minneapolis
State
MN
Country
United States
Zip Code
55455
Shi, Ke; Demir, Özlem; Carpenter, Michael A et al. (2017) Conformational Switch Regulates the DNA Cytosine Deaminase Activity of Human APOBEC3B. Sci Rep 7:17415
Richards, Christopher M; Li, Ming; Perkins, Angela L et al. (2017) Reassessing APOBEC3G Inhibition by HIV-1 Vif-Derived Peptides. J Mol Biol 429:88-96
Shi, Ke; Carpenter, Michael A; Banerjee, Surajit et al. (2017) Structural basis for targeted DNA cytosine deamination and mutagenesis by APOBEC3A and APOBEC3B. Nat Struct Mol Biol 24:131-139
Shaban, Nadine M; Shi, Ke; Li, Ming et al. (2016) 1.92 Angstrom Zinc-Free APOBEC3F Catalytic Domain Crystal Structure. J Mol Biol 428:2307-16