Molecular Mechanism of Bacterial Chromosome Partitioning dependent on a Centromere like site migS

我们在大肠杆菌基因组上发现了一个着丝粒样元素（migS）。我们寻找与migS基因相互作用的基因产物。phoU的转座子（Tn）插入突变在migS缺失突变下表现出生长缺陷。据报道，PhoU在磷酸盐摄取和细胞间磷酸盐代谢中起作用，尽管一些人认为这些不是它的主要功能。phoU Tn插入突变体（phoU:: Tn）缺少phoU基因羧基末端的一些氨基酸残基，零突变体不表现出与migS突变体相同的合成致死表型。phoU::Tn细胞的类核位于细胞中心，而野生型细胞的类核位于细胞中心。突变体细胞分裂时子类核不明显分离。事实上，在phoU突变体中，dna缺失细胞的频率增加了。这种表型在slmA缺陷细胞中被夸大，在未分离的细胞核上隔膜抑制机制缺失。在ΔslmA、phoU:: Tn双突变细胞中，与野生型细胞相比，无核细胞的频率增加，出现了断头台型细胞。我们得出结论，截断的PhoU蛋白干扰了子类核的正确定位，这可能导致有丝分裂灾难。此外，我们希望重点研究细菌细胞中DNA双极性迁移的分子机制。虽然在原核生物中发现了肌动蛋白样蛋白，但在染色体的双极性迁移中尚未发现将染色体分割成子细胞的运动功能。据推测，马达蛋白在这一过程中产生了驱动力。对migS依赖性迁移的分子机制的研究为推测运动蛋白如何参与染色体分裂提供了重要的新线索。蛋白质组学方法已经确定了两种蛋白质为migS结合蛋白。已经对编码migS结合蛋白的基因进行了进一步的研究，结果表明这些基因可能参与了migS Less的双极迁移

We have found a centromere-like element (migS) on the Escherichia coli genome. We searched gene products that genetically interact with migS. Transposon (Tn) insertion mutations of phoU showed a growth defect under migS deletion mutation. It was reported that PhoU functions in phosphate uptake and intercellular phosphate metabolism, although several group claimed those were not its primary functions. The phoU Tn insertion mutant (phoU : : Tn) lacked a few amino acid residues from the carboxyl terminal of phoU gene, and the null mutant did not show the synthetic lethal phenotype with migS mutant. phoU::Tn cells showed mislocated nucleoid from centre of the cells, while in wild type cells have the nucleoid at central region of the cell. Daughter nucleoids were not clearly separated at cell division in the mutant. In fact, frequency of DNA-less cells increased in the phoU mutant. This phenotype was exaggerated in slmA deficient cells where septum inhibition mechanism over unseparated nucl … More eoids was absent. In ΔslmA, phoU : : Tn double mutant cells, frequency of anucleate cells were increased compared to the wild type cells and guillotine typed cells were appeared. We concluded that the truncated PhoU protein perturbed correct positioning of daughter nucleoids and this could lead mitotic catastroph. Furthermore, we would like to focus on study of the molecular mechanism for bipolar migration of DNA in a bacterial cell. Although actin-like proteins have been found in prokaryotes, a motor function to partition chromosomes into daughter cells has not yet been identified on bipolar migration of the chromsome. Presumably, a motor protein works on the process to generate a driving force. Investigation of the molecular mechanism of migS dependent migration is providing vital new clues as how the putative motor protein contributes to chromosome partitioning. Proteomics approaches have already been identified two proteins as migS binding proteins. Further investigation of the genes that encode the migS binding proteins have already been carried out, and the results indicates the genes would be involved in bipolar migration of migS Less