Absence of the BaeR protein leads to the early initiation of DNA replication in Escherichia coli
Absence of the BaeR protein leads to the early initiation of DNA replication in Escherichia coli
复制标题
BaeR 蛋白的缺失导致大肠杆菌 DNA 复制提前启动
DOI：
10.4238/2015.december.14.16
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发表时间：
2015-01-01
影响因子：
0.4
通讯作者：
Morigen
中科院分区：
文献类型：
--
作者：
Yao, Y.;Wunier;Morigen
大肠杆菌细胞有几十个双组分系统来感知和响应各种刺激，从而应对不断变化的环境。Baes/Baer就是一种这样的双组分系统，它处理各种包络应力。有趣的是，Arca/ArcB和Tors/TorR双组分系统已知与DNA复制的启动有关；然而，Baes/Baer对DNA复制的启动的影响尚不清楚。流式细胞仪分析表明，Delta Baer突变体的每个细胞的平均复制起始数(ORCs)比野生型细胞高约30%。Delta Baer细胞的生长速度也是如此。PbaeR中Baer的异位表达逆转了Delta Baer突变表型。结果表明，Baer的缺失导致DNA复制的早期启动。此外，Baer的缺失导致每个细胞的Dna A量增加，但不改变作为启动子蛋白的Dna A的浓度。在Delta spy突变体中，每个细胞的平均oriC数与在野生型细胞中发现的相同，尽管spy基因的表达受Baer控制。这些结果表明，Baer可能通过控制Dna A基因的表达而间接影响复制的启动。
Escherichia coli cells have dozens of two-component systems to sense and respond to various stimuli, and thereby cope with changing environments. BaeS/BaeR is one such two-component system, and it deals with a variety of envelope stresses. Interestingly, the ArcA/ArcB and TorS/TorR two-component systems are known to be associated with initiation of DNA replication; however, the effects of BaeS/BaeR on initiation of DNA replication remain unknown. Flow cytometry analysis revealed that the average number of replication origins (oriCs) per cell in Delta baeR mutants was approximately 30% higher than that in wild-type cells. So was the growth rate of Delta baeR cells. Ectopic expression of BaeR from the pbaeR plasmid reversed the Delta baeR mutant phenotypes. The results indicate that absence of BaeR leads to the early initiation of DNA replication. Further, deletion of BaeR caused an increase in the amount of DnaA per cell, but did not change concentration of DnaA, which is the initiator protein. The average number of oriCs per cell in Delta spy mutants was the same as that found in the wild-type cells although spy gene expression is controlled by BaeR. These results suggest that BaeR may indirectly affect initiation of replication by controlling expression of the dnaA gene.