Abstract
Human APOBEC3G (hA3G) is a cytidine deaminase active on HIV single-stranded DNA. Small angle x-ray scattering and molecular envelope restorations predicted a C-terminal dimeric model for RNA-depleted hA3G in solution. Each subunit was elongated, suggesting that individual domains of hA3G are solvent-exposed and therefore may interact with other macromolecules even as isolated substructures. In this study, co-immunoprecipitation and in-cell quenched fluorescence resonance energy transfer assays reveal that hA3G forms RNA-independent oligomers through interactions within its C terminus. Residues 209-336 were necessary and sufficient for homoligomerization. N-terminal domains of hA3G were unable to multimerize but remained functional for Gag and viral infectivity factor (Vif) interactions when expressed apart from the C terminus. These findings corroborate the small angle x-ray scattering structural model and are instructive for development of high throughput screens that target specific domains and their functions to identify HIV/AIDS therapeutics.
Publication types
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Research Support, N.I.H., Extramural
MeSH terms
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APOBEC-3G Deaminase
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Cell Line
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Cytidine Deaminase / chemistry
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Cytidine Deaminase / genetics
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Cytidine Deaminase / metabolism*
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DNA, Single-Stranded / chemistry
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DNA, Single-Stranded / genetics
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DNA, Single-Stranded / metabolism
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DNA, Viral / chemistry
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DNA, Viral / genetics
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DNA, Viral / metabolism
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Dimerization
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HIV Core Protein p24 / chemistry
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HIV Core Protein p24 / genetics
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HIV Core Protein p24 / metabolism*
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HIV-1 / chemistry
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HIV-1 / genetics
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HIV-1 / metabolism*
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Humans
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Models, Molecular*
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Protein Structure, Quaternary
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Protein Structure, Tertiary / physiology
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vif Gene Products, Human Immunodeficiency Virus / chemistry
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vif Gene Products, Human Immunodeficiency Virus / genetics
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vif Gene Products, Human Immunodeficiency Virus / metabolism*
Substances
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DNA, Single-Stranded
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DNA, Viral
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HIV Core Protein p24
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p24 protein, Human Immunodeficiency Virus Type 1
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vif Gene Products, Human Immunodeficiency Virus
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vif protein, Human immunodeficiency virus 1
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APOBEC-3G Deaminase
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APOBEC3G protein, human
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Cytidine Deaminase