Virion-associated uracil DNA glycosylase-2 and apurinic/apyrimidinic endonuclease are involved in the degradation of APOBEC3G-edited nascent HIV-1 DNA.
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.
Yang
Bin
B
Center for Human Virology, Division of Infectious Diseases, Department of Medicine, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA.
Chen
Keyang
K
Zhang
Chune
C
Huang
Sophia
S
Zhang
Hui
H
D000071480:APOBEC-3G Deaminase; D001483:Base Sequence; D002384:Catalysis; D002460:Cell Line; D003564:Cytidine Deaminase; D045647:DNA Glycosylases / Q000378:metabolism / Q000502:physiology*; D004279:DNA, Viral / Q000235:genetics*; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase / Q000378:metabolism; D016346:Gene Products, vif / Q000378:metabolism; D015497:HIV-1 / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D009154:Mutation; D009700:Nucleoside Deaminases / Q000378:metabolism*; D010957:Plasmids / Q000378:metabolism; D034741:RNA, Small Interfering / Q000378:metabolism; D012097:Repressor Proteins / Q000378:metabolism*; D014771:Virion / Q000378:metabolism*; D054320:vif Gene Products, Human Immunodeficiency Virus
D004279:DNA, Viral; D016346:Gene Products, vif; D034741:RNA, Small Interfering; D012097:Repressor Proteins; D054320:vif Gene Products, Human Immunodeficiency Virus; C492570:CCNO protein, human; D045647:DNA Glycosylases; D009700:Nucleoside Deaminases; D000071480:APOBEC-3G Deaminase; C464924:APOBEC3G protein, human; D003564:Cytidine Deaminase; C085108:APEX1 protein, human; D043603:DNA-(Apurinic or Apyrimidinic Site) Lyase