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件(MiGs)。我们搜索了与米格基因相互作用的基因产品。转座子(TN)插入突变的Phou在MiGs缺失突变下表现出生长缺陷。据报道，Phou在磷吸收和细胞间磷代谢中发挥作用，尽管有几个小组声称这些不是它的主要功能。Phou Tn插入突变体(Phou：：Tn)缺少Phou基因羧基末端的少量氨基酸残基，缺失突变体没有表现出与Migs突变体的合成致死表型。Phou：：TN细胞在细胞中心有错位的类核，而野生型细胞在细胞中心区域有类核。在突变体中，子核在细胞分裂时没有明显分离。事实上，Phou突变体中无DNA细胞的频率增加了。这种表型在SLMA缺乏的细胞中被夸大，其中隔膜抑制机制超过未分离的核…更多的早期遗迹缺席了。在ΔSLMA、Phou：：Tn双突变细胞中，与野生型细胞相比，无核率增加，并出现断头型细胞。我们的结论是，截短的Phou蛋白扰乱了子核的正确定位，这可能导致有丝分裂灾难。此外，我们将重点研究细菌细胞中DNA双极迁移的分子机制。虽然在原核生物中已经发现了肌动蛋白样蛋白，但在染色体的双极迁移过程中，尚未发现将染色体分割为子细胞的运动功能。据推测，一种马达蛋白质在这一过程中发挥作用，以产生驱动力。对MGs依赖迁移的分子机制的研究为推测马达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鉴定出两种蛋白质是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，结果表明这些基因将较少地参与MiGs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