Arnold E, Jacobo-Molina A, Nanni R G, Williams R L, Lu X, Ding J, Clark A D, Zhang A, Ferris A L, Clark P
Center for Advanced Biotechnology and Medicine (CABM), Piscataway, New Jersey 08854-5638.
Nature. 1992 May 7;357(6373):85-9. doi: 10.1038/357085a0.
AIDS, caused by human immunodeficiency virus (HIV), is one of the world's most serious health problems, with current protocols being inadequate for either prevention or successful long-term treatment. In retroviruses such as HIV, the enzyme reverse transcriptase copies the single-stranded RNA genome into double-stranded DNA that is then integrated into the chromosomes of infected cells. Reverse transcriptase is the target of the most widely used treatments for AIDS, 3'-azido-3'-deoxythymidine (AZT) and 2',3'-dideoxyinosine (ddI), but resistant strains of HIV-1 arise in patients after a relatively short time. There are several nonnucleoside inhibitors of HIV-1 reverse transcriptase, but resistance to such agents also develops rapidly. We report here the structure at 7 A resolution of a ternary complex of the HIV-1 reverse transcriptase heterodimer, a monoclonal antibody Fab fragment, and a duplex DNA template-primer. The double-stranded DNA binds in a groove on the surface of the enzyme. The electron density near one end of the DNA matches well with the known structure of the HIV-1 reverse transcriptase RNase H domain. At the opposite end of the DNA, a mercurated derivative of UTP has been localized by difference Fourier methods, allowing tentative identification of the polymerase nucleoside triphosphate binding site. We also determined the structure of the reverse transcriptase/Fab complex in the absence of template-primer to compare the bound and free forms of the enzyme. The presence of DNA correlates with movement of protein electron density in the vicinity of the putative template-primer binding groove. These results have important implications for developing improved inhibitors of reverse transcriptase for the treatment of AIDS.
艾滋病由人类免疫缺陷病毒（HIV）引起，是世界上最严重的健康问题之一，目前的治疗方案在预防或长期成功治疗方面均显不足。在诸如HIV这样的逆转录病毒中，逆转录酶将单链RNA基因组复制成双链DNA，然后整合到被感染细胞的染色体中。逆转录酶是治疗艾滋病最广泛使用的药物3'-叠氮-3'-脱氧胸苷（AZT）和2',3'-双脱氧肌苷（ddI）的作用靶点，但在患者体内，HIV-1的耐药菌株会在相对较短的时间内出现。有几种HIV-1逆转录酶的非核苷抑制剂，但对这些药物的耐药性也迅速产生。我们在此报告HIV-1逆转录酶异二聚体、单克隆抗体Fab片段和双链DNA模板引物三元复合物在7埃分辨率下的结构。双链DNA结合在酶表面的一个凹槽中。DNA一端附近的电子密度与HIV-1逆转录酶RNase H结构域的已知结构匹配良好。在DNA的另一端，通过差值傅里叶方法定位了UTP的汞化衍生物，从而初步确定了聚合酶核苷三磷酸结合位点。我们还测定了无模板引物时逆转录酶/Fab复合物的结构，以比较酶的结合形式和游离形式。DNA的存在与假定的模板引物结合凹槽附近蛋白质电子密度的移动相关。这些结果对开发用于治疗艾滋病的改进型逆转录酶抑制剂具有重要意义。
