PcrA is an essential DNA helicase of Bacillus subtilis fulfilling functions both in repair and rolling-circle replication
PcrA is an essential DNA helicase of Bacillus subtilis fulfilling functions both in repair and rolling-circle replication
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DOI：
10.1046/j.1365-2958.1998.00927.x
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发表时间：
1998-07-01
影响因子：
3.6
通讯作者：
Bruand, C
中科院分区：
文献类型：
--
作者：
Petit, MA;Dervyn, E;Bruand, C
大肠杆菌生存所必需的唯一RNA解旋酶是DnaB，即染色体复制叉解旋酶。相反，在枯草芽孢杆菌中，除了DnaB对应物DnaC外，我们还发现了第二种必需的DNA解旋酶PcrA，它与大肠杆菌的Rep和UvrD DNA解旋酶有40%的同源性。该基因与金黄色葡萄球菌（Staphylococcos aureus）的PcrA解旋酶有61%的同源性，位于染色体55 °，与连接酶基因（lig）和两个未知基因pcrB和yerH一起属于一个假定的操纵子。由于PcrA是细胞生存所必需的，因此构建了条件突变体，在这些突变体中，当PcrA缺失时，染色体DNA合成略有下降，对复制中间产物的分析表明，PcrA缺失后，质粒pT181的前导链合成受到抑制。为了直接比较PcrA与Rep和UvrD，在E.杆菌PcrA抑制uvrD突变体的紫外敏感性缺陷，但不抑制其突变表型。杆菌总之，这些结果表明，PcrA是用于质粒滚环复制的解旋酶，并表明它也参与UV修复。
The only RNA helicase essential for Escherichia coli viability is DnaB, the chromosome replication fork helicase. In contrast, in Bacillus subtilis, in addition to the DnaB counterpart called DnaC, we have found a second essential DNA helicase, called PcrA, It is 40% identical to the Rep and UvrD DNA helicases of E. coli and 61% identical to the PcrA helicase of Staphylococcos aureus, This gene is located at 55 degrees on the chromosome and belongs to a putative operon together with a ligase gene (lig) and two unknown genes named pcrB and yerH, As PcrA was essential for cell viability, conditional mutants were constructed, In such mutants, chromosomal DNA synthesis was slightly decreased upon PcrA depletion, and rolling-circle replication of the plasmid pT181 was inhibited, Analysis of the replication intermediates showed that leading-strand synthesis of pT181 was prevented upon PcrA depletion. To compare PcrA with Rep and UvrD directly, the protein was produced in rep and uvrD mutants of E. coli. PcrA suppressed the UV sensitivity defect of a uvrD mutant but not its mutator phenotype, Furthermore, it conferred a Rep(-) phenotype on E. coli. Altogether, these results show that PcrA is an helicase used for plasmid rolling-circle replication and suggest that it is also involved in UV repair.