title: Reassessing APOBEC3G Inhibition by HIV-1 Vif-Derived Peptides.
abstract: The human APOBEC3G (A3G) enzyme restricts HIV-1 in the absence of the viral accessory protein viral infectivity factor (Vif) by deaminating viral cDNA cytosines to uracils. These uracil lesions base-pair with adenines during the completion of reverse transcription and result in A3G signature G-to-A mutations in the viral genome. Vif protects HIV-1 from A3G-mediated restriction by forming an E3-ubiquitin ligase complex to polyubiquitinate A3G and trigger its degradation. Prior studies indicated that Vif may also directly block the enzymatic activity of A3G and, provocatively, that Vif-derived peptides, Vif 25-39 and Vif 105-119, are similarly inhibitory. Here, we show that Vif 25-39 does not inhibit A3G enzymatic activity and that the inhibitory effect of Vif 105-119 and that of a shorter derivative Vif 107-115, although recapitulated, are non-specific. We also elaborate a simple method for assaying DNA cytosine deaminase activity that eliminates potential polymerase chain reaction-induced biases. Our results show that these Vif-derived peptides are unlikely to be useful as tools to study A3G function or as leads for the development of future therapeutics.
authors.affiliation: Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, 321 Church Street S.E., Minneapolis, MN 55455, USA; Institute for Molecular Virology, University of Minnesota, 515 Delaware Street S.E., Minneapolis, MN 55455, USA.
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Richards
authors.affiliation: Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, 321 Church Street S.E., Minneapolis, MN 55455, USA; Institute for Molecular Virology, University of Minnesota, 515 Delaware Street S.E., Minneapolis, MN 55455, USA.
authors.forename: Ming
authors.initials: M
authors.lastname: Li
authors.affiliation: Department of Medicinal Chemistry, University of Minnesota, 2231 6th St. S.E., Minneapolis, MN 55455, USA.
authors.forename: Angela L
authors.initials: AL
authors.lastname: Perkins
authors.affiliation: Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, 321 Church Street S.E., Minneapolis, MN 55455, USA.
authors.forename: Anurag
authors.initials: A
authors.lastname: Rathore
authors.affiliation: Department of Medicinal Chemistry, University of Minnesota, 2231 6th St. S.E., Minneapolis, MN 55455, USA.
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Harki
authors.affiliation: Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, 321 Church Street S.E., Minneapolis, MN 55455, USA; Institute for Molecular Virology, University of Minnesota, 515 Delaware Street S.E., Minneapolis, MN 55455, USA; Howard Hughes Medical Institute, University of Minnesota, 2231 6th St. S.E., Minneapolis, MN 55455, USA. Electronic address: rsh@umn.edu.
authors.forename: Reuben S
authors.initials: RS
authors.lastname: Harris
mesh_terms: D000071480:APOBEC-3G Deaminase / Q000037:antagonists & inhibitors*; D004791:Enzyme Inhibitors / Q000378:metabolism*; D010455:Peptides / Q000235:genetics / Q000378:metabolism*; D054320:vif Gene Products, Human Immunodeficiency Virus / Q000235:genetics / Q000378:metabolism*
chemical_list: D004791:Enzyme Inhibitors; D010455:Peptides; D054320:vif Gene Products, Human Immunodeficiency Virus; C514847:vif protein, Human immunodeficiency virus 1; D000071480:APOBEC-3G Deaminase; C464924:APOBEC3G protein, human
keywords: DNA cytosine deamination; Evolvability; HIV-1; Mutation; Vif-derived peptides