Reassessing APOBEC3G Inhibition by HIV-1 Vif-Derived Peptides

J Mol Biol. 2017 Jan 6;429(1):88-96. doi: 10.1016/j.jmb.2016.11.012. Epub 2016 Nov 22.


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.

Keywords: DNA cytosine deamination; Evolvability; HIV-1; Mutation; Vif-derived peptides.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, N.I.H., Extramural

MeSH terms

  • APOBEC-3G Deaminase / antagonists & inhibitors*
  • Enzyme Inhibitors / metabolism*
  • Peptides / genetics
  • Peptides / metabolism*
  • vif Gene Products, Human Immunodeficiency Virus / genetics
  • vif Gene Products, Human Immunodeficiency Virus / metabolism*


  • Enzyme Inhibitors
  • Peptides
  • vif Gene Products, Human Immunodeficiency Virus
  • vif protein, Human immunodeficiency virus 1
  • APOBEC-3G Deaminase
  • APOBEC3G protein, human