Absence of RstA results in delayed initiation of DNA replication in Escherichia coli

作者：Yao, Yuan; Ma, Yong; Chen, Xiuli; Bade, Rengui; Lv, Cuilan; Zhu, Runxiu^*

来源：PLos One, 2018, 13(7): e0200688.

DOI：10.1371/journal.pone.0200688

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• ORIGIN
• HU

RstB/RstA is an uncharacterized Escherichia co/itwo-component system, the regulatory effects of which on the E. coli cell cycle remain unclear. We found that the doubling time and average number of replication origins per cell in an Delta rstB mutant were the same as the wild-type, and the average number of replication origins in an Delta rstA mutant was 18.2% lower than in wild-type cells. The doubling times were 34 min, 35 min, and 40 min for the wild-type, Delta rstB, and Delta rstA strains, respectively. Ectopic expression of RstA from plasmid pACYCrstA partly reversed the Delta rstA mutant phenotypes. The amount of initiator protein DnaA per cell was reduced by 40% in the Delta rstA mutant compared with the wild-type, but the concentration of DnaA did not change as the total amount of cellular protein was also reduced in these cells. Deletion or overproduction of RstA does not change the temperature sensitivity of dnaA46, dnaB252 and dnaC2. The expression of hupA was decreased by 0.53-fold in Delta rstA. RstA interacted with Topoisomerase I weakly in vivo and increased its activity of relaxing the negative supercoiled plasmid. Our data suggest that deletion of RstA leads to delayed initiation of DNA replication, and RstA may affect initiation of replication by controlling expression of dnaA or hupA. Furthermore, the delayed initiation may by caused by the decreased activity of topoisomerase I in RstA mutant.

• 出版日期2018-7-16
• 单位内蒙古大学; 内蒙古科技大学包头医学院; 内蒙古科技大学包头师范学院