Conjugational hyperrecombination achieved by derepressing the LexA regulon, altering the properties of RecA protein and inactivating mismatch repair in Escherichia coli K-12.
Conjugational hyperrecombination achieved by derepressing the LexA regulon, altering the properties of RecA protein and inactivating mismatch repair in Escherichia coli K-12.
复制标题
通过去抑制 LexA 调节子、改变 RecA 蛋白的特性以及灭活大肠杆菌 K-12 中的错配修复来实现接合超重组。
DOI：
10.1093/genetics/163.4.1243
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发表时间：
2003
期刊：
影响因子：
3.3
通讯作者：
Clark,AlvinJ
中科院分区：
文献类型：
--
作者：
Lanzov,VladislavA;Bakhlanova,IrinaV;Clark,AlvinJ
重组交换（FRE）的频率，破坏共遗传的转移供体标记inEscherichia coliHfr的F-杂交的差异高达两个因素，这取决于生理因素和培养条件。在标准条件下，我们发现AB 1157系野生型菌株的FRE为5.01 ± 0.43次交换/100分钟单位的DNA长度。使用这些条件，我们显示了各种突变对FRE的累积效应。lexA基因失活（lexA 71：：Tn 5）和recA基因突变（recA 730）的组成型SOS表达分别显示FRE增加1.4倍和7倍。doublelexA 71 recA 730组合使FRE增加了10.17倍。在双exA recA突变体中加入mutS 215：：Tn 10，使错配修复系统失活，使FRE增加到野生型FRE的26倍。最后，我们发现另一个recA突变产生的SOS表达与recA 730一样多，但FRE仅增加3倍。我们的结论是，三个因素有助于正常低FRE在标准条件下：镇压的莱克萨调节子，野生型RecA蛋白的性质，和一个功能MutSHL错配修复系统。我们讨论了exA、recA和mutS突变累积提高FRE以获得超重组的机制。
The frequency of recombinational exchanges (FRE) that disrupt co-inheritance of transferred donor markers inEscherichia coliHfr by F-crosses differs by up to a factor of two depending on physiological factors and culture conditions. Under standard conditions we found FRE to be 5.01 ± 0.43 exchanges per 100-min units of DNA length for wild-type strains of the AB1157 line. Using these conditions we showed a cumulative effect of various mutations on FRE. Constitutive SOS expression bylexAgene inactivation (lexA71::Tn5) andrecAgene mutation (recA730) showed, respectively, ∼4- and 7-fold increases of FRE. The doublelexA71 recA730combination gave an ∼17-fold increase in FRE. Addition ofmutS215::Tn10, inactivating the mismatch repair system, to the doublelexA recAmutant increased FRE to ∼26-fold above wild-type FRE. Finally, we showed that anotherrecAmutation produced as much SOS expression asrecA730but increased FRE only 3-fold. We conclude that three factors contribute to normally low FRE under standard conditions: repression of the LexA regulon, the properties of wild-type RecA protein, and a functioning MutSHL mismatch repair system. We discuss mechanisms by which thelexA, recA, andmutSmutations may elevate FRE cumulatively to obtain hyperrecombination.