STRUCTURES OF TERNARY COMPLEXES OF RAT DNA-POLYMERASE-BETA, A DNA TEMPLATE-PRIMER, AND DDCTP
STRUCTURES OF TERNARY COMPLEXES OF RAT DNA-POLYMERASE-BETA, A DNA TEMPLATE-PRIMER, AND DDCTP
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DOI：
10.1126/science.7516580
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发表时间：
1994-06-24
期刊：
影响因子：
56.9
通讯作者：
KRAUT, J
中科院分区：
文献类型：
--
作者：
PELLETIER, H;SAWAYA, MR;KRAUT, J
大鼠 DNA 聚合酶 beta (pol beta)、DNA 模板引物和双脱氧胞苷三磷酸 (ddCTP) 的两个三元复合物已分别在 2.9 埃和 3.6 埃分辨率下测定，ddCTP 是双脱氧胞苷 (ddC) 的三磷酸盐，双脱氧胞苷是一种靶向人类逆转录酶的核苷类似物 免疫缺陷病毒（HIV），目前用于治疗艾滋病，虽然两种复合物的晶体属于不同的空间群，但结构相似，表明聚合酶-DNA-ddCTP相互作用不受晶体堆积力的影响。在 pol beta 活性位点，延伸引物的攻击 3'-OH、ddCTP 磷酸盐和两个 Mg2+ 离子均聚集在 Asp(190)、Asp(192) 和 Asp(256) 周围。其中两个残基 Asp(190) 和 Asp(256) 存在于迄今为止研究的所有聚合酶的氨基酸序列中，并且在四种聚合酶（大肠杆菌 DNA 聚合酶 I 的 Klenow 片段、HIV-1 逆转录酶、T7 RNA 聚合酶和大鼠 DNA pol beta）中空间相似，其晶体结构现已已知。描述了核苷酸转移反应的双金属离子机制，并且可以适用于所有聚合酶。在分析的三元复合物结构中，pol beta 与 DNA 模板引物的结合方式与最近提出的其他聚合酶 DNA 模型不同。
Two ternary complexes of rat DNA polymerase beta (pol beta), a DNA template-primer, and dideoxycytidine triphosphate (ddCTP) have been determined at 2.9 Angstrom and 3.6 Angstrom resolution, respectively, ddCTP is the triphosphate of dideoxycytidine (ddC), a nucleoside analog that targets the reverse transcriptase of human immunodeficiency virus (HIV) and is at present used to treat AIDS, Although crystals of the two complexes belong to different space groups, the structures are similar, suggesting that the polymerase-DNA-ddCTP interactions are not affected by crystal packing forces. In the pol beta active site, the attacking 3'-OH of the elongating primer, the ddCTP phosphates, and two Mg2+ ions are all clustered around Asp(190), Asp(192), and Asp(256). Two of these residues, Asp(190) and Asp(256), are present in the amino acid sequences of all polymerases so far studied and are also spatially similar in the four polymerases-the Klenow fragment of Escherichia coli DNA polymerase I, HIV-1 reverse transcriptase, T7 RNA polymerase, and rat DNA pol beta-whose crystal structures are now known. A two-metal ion mechanism is described for the nucleotidyl transfer reaction and may apply to all polymerases. In the ternary complex structures analyzed, pol beta binds to the DNA template-primer in a different manner from that recently proposed for other polymerase-DNA models.