Kinetic measurement of the step size of DNA unwinding by Escherichia coli UvrD helicase
Kinetic measurement of the step size of DNA unwinding by Escherichia coli UvrD helicase
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DOI：
10.1126/science.275.5298.377
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发表时间：
1997-01-17
期刊：
影响因子：
56.9
通讯作者：
Lohman, TM
中科院分区：
文献类型：
--
作者：
Ali, JA;Lohman, TM
利用一系列具有10 - 40个碱基对的双链区的寡脱氧核苷酸，研究了大肠杆菌DNA修复解旋酶UvrD解旋双链DNA的动力学机制。单营业额解旋实验表明，不同的滞后阶段，增加了双链体的长度，因为部分解旋的DNA中间状态是高度填充在解旋。对这些动力学的分析表明，UvrD以不连续的步骤解旋双链DNA，平均“步长”为4至5个碱基对（约为DNA螺旋的半圈）。这表明了一种解旋机制，其中二聚体解旋酶的交替亚基直接与双链体DNA相互作用。
The kinetic mechanism by which the DNA repair helicase UvrD of Escherichia coli unwinds duplex DNA was examined with the use of a series of oligodeoxynucleotides with duplex regions ranging from 10 to 40 base pairs. Single-turnover unwinding experiments showed distinct lag phases that increased with duplex length because partially unwound DNA intermediate states are highly populated during unwinding. Analysis of these kinetics indicates that UvrD unwinds duplex DNA in discrete steps, with an average ''step size'' of 4 to 5 base pairs (approximately one-half turn of the DNA helix). This suggests an unwinding mechanism in which alternating subunits of the dimeric helicase interact directly with duplex DNA.