RecA4142 causes SOS constitutive expression by loading onto reversed replication forks in Escherichia coli K-12.
RecA4142 causes SOS constitutive expression by loading onto reversed replication forks in Escherichia coli K-12.
复制标题
RecA4142 通过加载到大肠杆菌 K-12 中的反向复制叉上，引起 SOS 组成型表达。
DOI：
10.1128/jb.01623-09
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发表时间：
2010
影响因子：
3.2
通讯作者：
Sandler,StevenJ
中科院分区：
文献类型：
--
作者：
Long,JarukitEdward;Massoni,ShawnC;Sandler,StevenJ
当 DNA 损伤产生的单链 DNA (ssDNA) 与 RecA 结合并形成 RecA-DNA 丝时，大肠杆菌启动 SOS 反应。recASOS 组成型 [recA(Con)] 突变体在没有 DNA 损伤的情况下诱导 SOS 反应。有人提出recA(Con)突变体在复制叉处与ssDNA结合，但具体机制尚不清楚。此前，研究表明recA4142(F217Y)是一种新型recA(Con)突变体，其高SOS组成型[SOS(Con)]表达依赖于RecBCD。这可能是因为 RecA4142 被加载到 DNA 的双链末端 (DSE)。在此，表明recA4142SOS(Con)表达另外依赖于ruvAB(仅复制叉逆转[RFR]活性)和recJ(5'→3'核酸外切酶)、xonA(3'→5'核酸外切酶)并部分依赖于recQ(解旋酶)。最后，recA4142菌株中的sbcCD突变（Mre11/Rad50同源物）导致SOS（Con）以独立于ruvAB、recBCD、recJ和xonA的方式完全表达。假设RuvAB催化RFR，RecJ和XonA钝化DSE（由RFR产生），然后RecBCD将RecA4142加载到该末端以产生SOS（Con）表达。 InsbcCD 突变体，RecA4142 本身可以结合其他通常被 SbcCD 核酸酶降解的 DNA 底物。
Escherichia coliinitiates the SOS response when single-stranded DNA (ssDNA) produced by DNA damage is bound by RecA and forms a RecA-DNA filament.recASOS constitutive [recA(Con)] mutants induce the SOS response in the absence of DNA damage. It has been proposed thatrecA(Con) mutants bind to ssDNA at replication forks, although the specific mechanism is unknown. Previously, it had been shown thatrecA4142(F217Y), a novelrecA(Con) mutant, was dependent on RecBCD for its high SOS constitutive [SOS(Con)] expression. This was presumably because RecA4142 was loaded at a double-strand end (DSE) of DNA. Herein, it is shown thatrecA4142SOS(Con) expression is additionally dependent onruvAB(replication fork reversal [RFR] activity only) andrecJ(5′→3′ exonuclease),xonA(3′→5′ exonuclease) and partially dependent onrecQ(helicase). Lastly,sbcCDmutations (Mre11/Rad50 homolog) inrecA4142strains caused full SOS(Con) expression in anruvAB-,recBCD-,recJ-, andxonA-independent manner. It is hypothesized that RuvAB catalyzes RFR, RecJ and XonA blunt the DSE (created by the RFR), and then RecBCD loads RecA4142 onto this end to produce SOS(Con) expression. InsbcCDmutants, RecA4142 can bind other DNA substrates by itself that are normally degraded by the SbcCD nuclease.