Virion-associated uracil DNA glycosylase-2 and apurinic/apyrimidinic endonuclease are involved in the degradation of APOBEC3G-edited nascent HIV-1 DNA

J Biol Chem. 2007 Apr 20;282(16):11667-75. doi: 10.1074/jbc.M606864200. Epub 2007 Feb 1.

Abstract

Cellular cytidine deaminases APOBEC3 family is a group of potent inhibitors for many exogenous and endogenous retroviruses. It has been demonstrated that they induce G to A hypermutations in the nascent retroviral DNA, resulting from the cytosine (C) to uracil (U) conversions in minus-stranded viral DNA. In this report, we have demonstrated that the result of C to U conversion in minus-stranded DNA of human immunodeficiency virus type 1 (HIV-1) could trigger a degradation of nascent viral DNA mediated by uracil DNA glycosylases-2 (UNG2) and apurinic/apyrimidinic endonuclease (APE). Since antiviral activity of APOBEC3G is partially affected by UNG2 inhibitor Ugi or UNG2-specific short-interfering RNA in virus-producing cells but not target cells, the virion-associated UNG2 most likely mediates this process. Interestingly, as APE-specific short-interfering RNA can also partially inhibit the anti-HIV-1 activity of APOBEC3G in virus-producing cells but not in target cells and APE molecules can be detected within HIV-1 virions, it seems that the required APE is also virion-associated. Furthermore, the in vitro cleavage experiment using uracil-containing single-stranded DNA as a template has demonstrated that the uracil-excising catalytic activity of virion-associated UNG2 can remove dU from the uracil-containing viral DNA and leave an abasic site, which could be further cleaved by virion-associated APE. Based upon our observations, we propose that the degradation of APOBEC3G-edited viral DNA mediated by virion-associated UNG2 and APE during or after reverse transcription could be partially responsible for the potent anti-HIV-1 effect by APOBEC3G in the absence of vif.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • APOBEC-3G Deaminase
  • Base Sequence
  • Catalysis
  • Cell Line
  • Cytidine Deaminase
  • DNA Glycosylases / metabolism
  • DNA Glycosylases / physiology*
  • DNA, Viral / genetics*
  • DNA-(Apurinic or Apyrimidinic Site) Lyase / metabolism
  • Gene Products, vif / metabolism
  • HIV-1 / metabolism*
  • Humans
  • Molecular Sequence Data
  • Mutation
  • Nucleoside Deaminases / metabolism*
  • Plasmids / metabolism
  • RNA, Small Interfering / metabolism
  • Repressor Proteins / metabolism*
  • Virion / metabolism*
  • vif Gene Products, Human Immunodeficiency Virus

Substances

  • DNA, Viral
  • Gene Products, vif
  • RNA, Small Interfering
  • Repressor Proteins
  • vif Gene Products, Human Immunodeficiency Virus
  • CCNO protein, human
  • DNA Glycosylases
  • Nucleoside Deaminases
  • APOBEC-3G Deaminase
  • APOBEC3G protein, human
  • Cytidine Deaminase
  • APEX1 protein, human
  • DNA-(Apurinic or Apyrimidinic Site) Lyase