Bruand C, Ehrlich S D
Laboratoire de G¿en¿etique Microbienne, INRA, Domaine de Vilvert, 78352 Jouy-en-Josas cedex, France.
Mol Microbiol. 2000 Jan;35(1):204-10. doi: 10.1046/j.1365-2958.2000.01700.x.
The Escherichia coli UvrD helicase (or helicase II) is known for its involvement in DNA repair. We report that UvrD is required for DNA replication of several different rolling-circle plasmids in E. coli, whereas its homologue, the Rep helicase, is not. Lack of UvrD helicase does not impair the first step of plasmid replication, nicking of the double-stranded origin by the plasmid initiator protein. However, replication proceeds no further without UvrD. Indeed, the nicked plasmid molecules accumulate to a high level in uvrD mutants. We conclude that UvrD is the replicative helicase of various rolling-circle plasmids. This is the first description of a direct implication of UvrD in DNA replication in vivo.
大肠杆菌UvrD解旋酶（或解旋酶II）因其参与DNA修复而闻名。我们报告称，UvrD是大肠杆菌中几种不同滚环质粒DNA复制所必需的，而其同源物Rep解旋酶则不是。缺乏UvrD解旋酶不会损害质粒复制的第一步，即质粒起始蛋白对双链起点的切口形成。然而，没有UvrD，复制就无法进一步进行。事实上，在uvrD突变体中，带切口的质粒分子会积累到很高的水平。我们得出结论，UvrD是各种滚环质粒的复制性解旋酶。这是首次描述UvrD在体内DNA复制中的直接作用。
