Institute for Molecular Virology, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA; Division of Basic Sciences, School of Dentistry, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA.
Institute for Molecular Virology, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA; Veterinary Medicine Graduate Program, University of Minnesota - Twin Cities, Minneapolis, MN 55455, USA.
J Mol Biol. 2021 Sep 3;433(18):167111. doi: 10.1016/j.jmb.2021.167111. Epub 2021 Jun 18.
5-aza-cytidine (5-aza-C) has been shown to be a potent human immunodeficiency virus type 1 (HIV-1) mutagen that induces G-to-C hypermutagenesis by incorporation of the reduced form (i.e., 5-aza-dC, 5-aza-dCTP). Evidence to date suggests that this lethal mutagenesis is the primary antiretroviral mechanism for 5-aza-C. To investigate the breadth of application of 5-aza-C as an antiretroviral mutagen, we have conducted a comparative, parallel analysis of the antiviral mechanism of 5-aza-C between HIV-1 and gammaretroviruses - i.e., murine leukemia virus (MuLV) and feline leukemia virus (FeLV). Intriguingly, in contrast to the hallmark G-to-C hypermutagenesis observed with HIV-1, MuLV and FeLV did not reveal the presence of a significant increase in mutational burden, particularly that of G-to-C transversion mutations. The effect of 5-aza-dCTP on DNA synthesis revealed that while HIV-1 RT was not inhibited by 5-aza-dCTP even at 100 µM, 5-aza-dCTP was incorporated and significantly inhibited MuLV RT, generating pause sites and reducing the fully extended product. 5-aza-dCTP was found to be incorporated into DNA by MuLV RT or HIV-1 RT, but only acted as a non-obligate chain terminator for MuLV RT. This biochemical data provides an independent line of experimental evidence in support of the conclusion that HIV-1 and MuLV have distinct primary mechanisms of antiretroviral action with 5-aza-C. Taken together, our data provides striking evidence that an antiretroviral mutagen can have strong potency via distinct mechanisms of action among closely related viruses, unlinking antiviral activity from antiviral mechanism of action.
5-氮杂胞苷（5-aza-C）已被证明是一种有效的人类免疫缺陷病毒 1 型（HIV-1）诱变剂，通过整合其还原形式（即 5-氮杂-dC、5-氮杂-dCTP）诱导 G-to-C 高突变率。迄今为止的证据表明，这种致死性诱变是 5-aza-C 的主要抗逆转录病毒机制。为了研究 5-aza-C 作为抗逆转录病毒诱变剂的广泛应用，我们对 5-aza-C 在 HIV-1 和γ逆转录病毒（即鼠白血病病毒（MuLV）和猫白血病病毒（FeLV））中的抗病毒机制进行了比较和并行分析。有趣的是，与 HIV-1 观察到的标志性 G-to-C 高突变率相反，MuLV 和 FeLV 并没有显示出突变负荷的显著增加，特别是 G-to-C 颠换突变的增加。5-aza-dCTP 对 DNA 合成的影响表明，尽管 HIV-1 RT 甚至在 100μM 时也不受 5-aza-dCTP 抑制，但 5-aza-dCTP 被整合并显著抑制 MuLV RT，产生暂停位点并减少完全延伸产物。发现 MuLV RT 或 HIV-1 RT 将 5-aza-dCTP 整合到 DNA 中，但仅作为 MuLV RT 的非必需链终止剂起作用。这些生化数据提供了独立的实验证据，支持 HIV-1 和 MuLV 具有 5-aza-C 的不同主要抗逆转录病毒作用机制的结论。综上所述，我们的数据提供了引人注目的证据，表明一种抗逆转录病毒诱变剂可以通过密切相关的病毒之间不同的作用机制发挥强大的效力，将抗病毒活性与抗病毒作用机制脱钩。
