A model for the mechanism of human topoisomerase I
A model for the mechanism of human topoisomerase I
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DOI：
10.1126/science.279.5356.1534
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发表时间：
1998-03-06
期刊：
影响因子：
56.9
通讯作者：
Champoux, JJ
中科院分区：
文献类型：
--
作者：
Stewart, L;Redinbo, MR;Champoux, JJ
70千道尔顿氨基末端截短形式的人拓扑异构酶I与22个碱基对的双链体寡核苷酸复合的三维结构，确定为2.8埃的分辨率，揭示了与DNA接触的酶的所有结构元件。连接酶的中心核心与羧基末端结构域的接头区呈现卷曲螺旋构型，并远离酶的其余部分突出。接头的带正电荷的DNA近端表面仅与切割位点下游的DNA进行少量接触。结合DNA切割前后重构的人拓扑异构酶的晶体结构，该信息表明哪些氨基酸残基参与催化磷酸二酯键断裂和再连接。这些结构也导致了拓扑异构化步骤通过一种称为“受控旋转”的机制发生的建议。"
The three-dimensional structure of a 70-kilodalton amino terminally truncated form of human topoisomerase I in complex with a 22-base pair duplex oligonucleotide, determined to a resolution of 2.8 angstroms, reveals all of the structural elements of the enzyme that contact DNA. The linker region that connects the central core of the enzyme to the carboxyl-terminal domain assumes a coiled-coil configuration and protrudes away from the remainder of the enzyme, The positively charged DNA-proximal surface of the linker makes only a few contacts with the DNA downstream of the cleavage site. In combination with the crystal structures of the reconstituted human topoisomerase before and after DNA cleavage, this information suggests which amino acid residues are involved in catalyzing phosphodiester bond breakage and religation. The structures also lead to the proposal that the topoisomerization step occurs by a mechanism termed "controlled rotation."