Bakhanashvili M, Hizi A
Department of Cell Biology and Histology, Sackler School of Medicine, Tel Aviv University, Israel.
FEBS Lett. 1992 Jun 15;304(2-3):289-93. doi: 10.1016/0014-5793(92)80640-3.
HIV reverse transcriptases (RTs) have few cysteine residues relative to other RTs and retain their DNA polymerization functions following chemical modification by thiol-specific reagents. The functional role of the cysteines in the fidelity of the DNA-dependent DNA synthesis of HIV RTs has been addressed by chemical modification of the wild-type enzymes in combination with the analysis of an enzymatically active mutant HIV-1 RT in which all cysteines were modified to serines. We have observed an increase in 3'-terminal mispair extension efficiency exhibited by chemically modified HIV-1 and HIV-2 RTs. The possible involvement of cysteine residues was further substantiated using the cysteine-free mutant HIV-1 RT that displays an increased efficiency of mispair extension. These results provide evidence for a possible role of cysteine residues in the fidelity of DNA synthesis catalyzed by HIV RTs.
与其他逆转录酶相比，HIV逆转录酶（RTs）含有的半胱氨酸残基较少，并且在经硫醇特异性试剂化学修饰后仍保留其DNA聚合功能。通过对野生型酶进行化学修饰，并结合对一种酶活性突变型HIV-1 RT（其中所有半胱氨酸均被修饰为丝氨酸）的分析，研究了半胱氨酸在HIV RTs依赖DNA的DNA合成保真度中的功能作用。我们观察到，经化学修饰的HIV-1和HIV-2 RTs表现出3'末端错配延伸效率增加。使用无半胱氨酸的突变型HIV-1 RT进一步证实了半胱氨酸残基可能的参与，该突变型显示出更高的错配延伸效率。这些结果为半胱氨酸残基在HIV RTs催化的DNA合成保真度中可能发挥的作用提供了证据。
