Inhibition of the RNase H activity of HIV reverse transcriptase by azidothymidylate.
Inhibition of the RNase H activity of HIV reverse transcriptase by azidothymidylate.
复制标题
叠氮胸苷酸抑制 HIV 逆转录酶的 RNase H 活性。
DOI：
10.1021/bi00234a001
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发表时间：
1991
期刊：
影响因子：
2.9
通讯作者：
Downey,KM
中科院分区：
文献类型：
--
作者：
Tan,CK;Civil,R;Mian,AM;So,AG;Downey,KM
摘要：研究了AZTMP和其他核苷S '-单磷酸对重组HIV逆转录酶的RNA依赖性DNA聚合酶和RNase H活性的影响。这两种活性都对以MgCl 2作为二价阳离子活化剂的毫摩尔浓度的AZTMP的抑制敏感。Mn ~（2+）取代Mg ~（2+）可显著增强AZTMP对RNA酶H活性的抑制作用，使IC_（50）从5 mM降至0.05 mM，但Mn ~（2+）不改变AZTMP对RNA依赖性DNA聚合酶活性的抑制敏感性。增加底物poly（A）/poly（dT）的浓度可逆转AZTMP对RNase H活性的抑制作用，表明AZTMP可能与底物竞争结合RNase H的活性位点。其他核苷S ′-单磷酸在Mg 2+存在下不抑制RNA酶H。然而，在Mn 2+存在下，与异源双链体底物的DNA链互补的脱氧和双脱氧核苷S '-单磷酸具有一定的抑制性。在Mg ~（2+）或Mn ~（2+）存在下，AZTMP和ddTMP对RNA依赖的DNA聚合酶活性有轻微的抑制作用，而Mn ~（2+）取代Mg ~（2+）也能抑制ddAMP的作用。天然存在的核糖核苷或脱氧核糖核苷S '-单磷酸在浓度高达5 mM时不具有抑制作用。由于AZTTP在纳摩尔浓度时抑制HIV逆转录酶的RNA依赖性DNA聚合酶活性，因此AZTMP对该活性的抑制不太可能在AZT的抗病毒作用中起重要作用。然而，AZTMP（在体内可达到毫摩尔浓度）对RNase H活性的抑制可能是病毒对AZT敏感的部分原因。
Revised Manuscript Received March 26, 1991 abstract: The effects of AZTMP and other nucleoside S'-monophosphates on the RNA-dependent DNA polymerase and RNase H activities of a recombinant HIV reverse transcriptase have been investigated. Both activities are sensitive to inhibition by millimolar concentrations of AZTMP with MgCl2 as divalent cation activator. Substitution of Mn2+ for Mg2+ markedly potentiates the inhibitionof RNase H activity by AZTMP, reducing the IC50 from 5 to 0.05 mM. In contrast, Mn2+ does not alter the sensitivity of the RNA-dependent DNA polymerase activity to inhibition by AZTMP. The inhibition of RNase H activity by AZTMP can be reversed by increasing concentrations of the substrate poly (A)/poly (dT), suggesting that AZTMP may compete with the substrate for binding at the active site of RNase H. Other nucleosideS'-monophosphates do not inhibit RNase H in the presence of Mg2+. However, in the presence of Mn2+, deoxy-and dideoxynucleoside S'-monophosphates that are complementary to the DNA strand of the heteroduplex substrate are somewhat inhibitory. The RNA-dependent DNA polymerase activity is a slightly inhibited by AZTMP and ddTMP in either Mg2+ or Mn2+, and substitution of Mn2+ for Mg2+ results in inhibition by ddAMP as well. Naturally occurring ribo-or deoxyribonucleoside S'-monophosphates are not inhibitory at concentrations up to 5 mM. Since AZTTP inhibits the RNA-dependent DNA polymerase activity of HIV reverse transcriptase at nanomolar concentrations, it is unlikely that the inhibition of this activity by AZTMP plays a significant role in the antiviral effect of AZT. However, the inhibition of the RNase H activity by AZTMP, which can reach millimolar concentrations in vivo, may account for part of the sensitivity of the virus to AZT.