Substrate specificity of the DNA unwinding activity of the RecBC enzyme of Escherichia coli.
Substrate specificity of the DNA unwinding activity of the RecBC enzyme of Escherichia coli.
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大肠杆菌 RecBC 酶 DNA 解旋活性的底物特异性。
DOI：
10.1016/0022-2836(85)90414-0
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发表时间：
1985
影响因子：
5.6
通讯作者：
Smith,GR
中科院分区：
文献类型：
--
作者：
Taylor,AF;Smith,GR
大肠杆菌的RecBC酶促进噬菌体或细菌染色体的遗传重组。纯化的酶通过双链体DNA，解旋和重绕DNA，瞬时产生潜在的重组单链DNA。本文报道的研究旨在了解哪些染色体形式允许RecBC酶进入，因此可能发生RecBC酶介导的重组。环状双链体分子，无论是共价闭合的、带切口的还是含有10至774个核苷酸的单链缺口的，都不会被RecBC酶可检测地解绕。如果线性双链体分子具有几乎平端的末端，其5 '和3'末端偏移不超过约25个核苷酸，则它们容易解旋;具有较长单链尾部的分子与RecBC酶的结合较差，并且很少解旋。RecBC酶的单链核酸内切酶活性可以缓慢地切割有缺口的环以产生可能能够解绕的分子。这些结果为从RecBC酶和Chi位点（RecBC酶介导的DNA链切割的识别位点）的遗传研究建立的双链DNA末端的重组性提供了酶促基础。
The RecBC enzyme ofEscherichia colipromotes genetic recombination of phage or bacterial chromosomes. The purified enzyme travels through duplex DNA, unwinding and rewinding the DNA with the transient production of potentially recombinogenic single-stranded DNA. The studies reported here are aimed at understanding which chromosomal forms allow the entry of RecBC enzyme and hence may undergo RecBC enzyme-mediated recombination. Circular duplex molecules, whether covalently closed, nicked or containing single-stranded gaps of 10 to 774 nucleotides, are not detectably unwound by RecBC enzyme. Linear duplex molecules are readily unwound if they have a nearly flush-ended terminus whose 5′ and 3′ ends are offset by no more than about 25 nucleotides; molecules with longer single-stranded tails are poorly bound by RecBC enzyme and are infrequently unwound. The single-strand endonuclease activity of RecBC enzyme can slowly cleave gapped circles to produce molecules presumably capable of being unwound. These results provide an enzymatic basis for the recombinogenicity of double-stranded DNA ends established from genetic studies of RecBC enzyme and Chi sites, recognition sites for RecBC enzyme-mediated DNA strand cleavage.