Molecular Biology Division, Bhabha Atomic Research Centre, Mumbai 400 084, India.
J Biosci. 2013 Sep;38(3):487-97. doi: 10.1007/s12038-013-9352-5.
Bacterial genome segregation and cell division has been studied mostly in bacteria harbouring single circular chromosome and low-copy plasmids. Deinococcus radiodurans, a radiation-resistant bacterium, harbours multipartite genome system. Chromosome I encodes majority of the functions required for normal growth while other replicons encode mostly the proteins involved in secondary functions. Here, we report the characterization of putative P-loop ATPase (ParA2) encoded on chromosome II of D. radiodurans. Recombinant ParA2 was found to be a DNA-binding ATPase. E. coli cells expressing ParA2 showed cell division inhibition and mislocalization of FtsZ-YFP and those expressing ParA2-CFP showed multiple CFP foci formation on the nucleoid. Although, in trans expression of ParA2 failed to complement SlmA loss per se, it could induce unequal cell division in slmAminCDE double mutant. These results suggested that ParA2 is a nucleoid-binding protein, which could inhibits cell division in E. coli by affecting the correct localization of FtsZ and thereby cytokinesis. Helping slmAminCDE mutant to produce minicells, a phenotype associated with mutations in the 'Min' proteins, further indicated the possibility of ParA2 regulating cell division by bringing nucleoid compaction at the vicinity of septum growth.
细菌基因组的分离和细胞分裂主要在携带单链环状染色体和低拷贝质粒的细菌中进行研究。耐辐射球菌是一种抗辐射细菌，它具有多组分基因组系统。染色体 I 编码大多数正常生长所需的功能，而其他复制子则编码大多数与次要功能相关的蛋白质。在这里，我们报告了耐辐射球菌染色体 II 上编码的假定 P 环 ATP 酶 (ParA2) 的特征。发现重组 ParA2 是一种 DNA 结合 ATP 酶。表达 ParA2 的大肠杆菌细胞表现出细胞分裂抑制和 FtsZ-YFP 的定位错误，而表达 ParA2-CFP 的细胞在核区形成多个 CFP 焦点。尽管 ParA2 在转表达中本身不能弥补 SlmA 的缺失，但它可以在 slmAminCDE 双突变体中诱导不等的细胞分裂。这些结果表明 ParA2 是一种核区结合蛋白，它可以通过影响 FtsZ 的正确定位来抑制大肠杆菌的细胞分裂，从而导致细胞分裂。帮助 slmAminCDE 突变体产生小型细胞，这是与 'Min' 蛋白突变相关的表型，进一步表明 ParA2 通过在隔膜生长附近使核区紧凑来调节细胞分裂的可能性。
