Bakhanashvili M, Avidan O, Hizi A
Department of Cell Biology and Histology, Sackler School of Medicine, Tel Aviv University, Israel.
FEBS Lett. 1996 Aug 12;391(3):257-62. doi: 10.1016/0014-5793(96)00747-8.
The high error rates characteristic of human immunodeficiency virus type-1 reverse transcriptase (HIV-1 RT) are a presumptive source of the viral hypermutability that impedes prevention and therapy of acquired immunodeficiency syndrome (AIDS). We have analyzed two mutants of HIV-1 RT by conducting a comparative study of the accuracy of DNA synthesis. Each mutant bears a single amino acid substitution adjacent to the two aspartic acid residues at positions 185 and 186 in the highly conserved DNA polymerase active site. The first mutant, Met 184-->Leu (M184L), displays a marked reduction in both misinsertion and mispair extension, suggesting a fidelity of DNA synthesis significantly higher than that of the wild-type HIV-1 RT. The second mutant, Tyr 183-->Phe (Y183F), shows a decrease in mispair extension with no significant change in misincorporation. Thus, the overall pattern of error-proneness of DNA synthesis is: wild-type HIV-1 RT > Y183F > M184L. Taken together, it is possible that residues 183 and 184 contribute to the low fidelity of DNA synthesis characteristic of the reverse transcriptases of HIV-1, HIV-2 and possibly, of other lentiviruses. Our observations may bear on the nature of potential mutations responsible for resistance to the nucleoside analogs used in chemotherapy of AIDS.
人类免疫缺陷病毒1型逆转录酶（HIV-1 RT）具有高错误率，这可能是病毒高度变异性的来源，而这种变异性阻碍了获得性免疫缺陷综合征（AIDS）的预防和治疗。我们通过对DNA合成准确性进行比较研究，分析了HIV-1 RT的两个突变体。每个突变体在高度保守的DNA聚合酶活性位点的185和186位的两个天冬氨酸残基附近有一个单一氨基酸取代。第一个突变体，Met 184→Leu（M184L），在错配插入和错配延伸方面均显著降低，这表明其DNA合成保真度明显高于野生型HIV-1 RT。第二个突变体，Tyr 183→Phe（Y183F），错配延伸减少，而错配掺入无显著变化。因此，DNA合成错误倾向的总体模式为：野生型HIV-1 RT＞Y183F＞M184L。综合来看，183和184位残基可能导致了HIV-1、HIV-2以及可能其他慢病毒逆转录酶DNA合成保真度低的特性。我们的观察结果可能与艾滋病化疗中使用的核苷类似物耐药相关潜在突变的性质有关。
