Chromosome segregation proteins of Vibrio cholerae as transcription regulators.
Chromosome segregation proteins of Vibrio cholerae as transcription regulators.
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DOI：
10.1128/mbio.01061-14
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发表时间：
2014-05-06
期刊：
影响因子：
6.4
通讯作者：
Chattoraj DK
中科院分区：
文献类型：
--
作者：
Baek JH;Rajagopala SV;Chattoraj DK
细菌帕拉和ParB蛋白质最为人所知的是它们对质粒和染色体分离的贡献，但它们也可能对其他细胞功能有贡献。在分离中，帕拉A与帕拉B相互作用，帕拉B结合到帕拉S着丝粒类似位点。在转录中，质粒Par蛋白可以通过特异性结合其自身的启动子来充当阻遏物，另外，在ParB的情况下，通过从parS位点扩散到附近的启动子。在这里，我们已经问过染色体Par蛋白是否同样可以控制转录。霍乱弧菌全基因组ParB1结合分析显示，优先结合到三个已知的parS1位点和有限的传播ParB1超越parS1位点。将野生型转录组与ΔparA1、ΔparB1和ΔparAB1突变体的转录组进行比较，发现ParB1扩散覆盖的20个基因中有2个（VC 0067和VC 0069）受到ParB1和ParA1的抑制。第三个基因（VC 0076）在扩散区的边缘和几个基因进一步远离也被抑制，特别是外膜蛋白，ompU（VC 0633）的基因。由于ParA1或ParB1结合在VC 0076和ompU基因附近不明显，因此抑制可能需要其他因子的参与。事实上，在细菌和酵母双杂交筛选中发现ParA1和ParB1蛋白都与几种霍乱弧菌蛋白相互作用。这些研究表明，染色体Par蛋白可以抑制与parS无关的基因，并且可以在不直接结合同源启动子DNA的情况下这样做。染色体的定向分离对于它们在分裂细胞中的维持是必不可少的。许多细菌具有被认为专门用于分离的基因（par），这与它们在质粒维持中的作用类似。越来越清楚的是，染色体par基因是多效性的，它们有助于不同的过程，如DNA复制，细胞分裂，细胞生长和运动。解释多效性的一种方法是认为Par蛋白充当或控制其他转录因子。我们通过确定Par蛋白如何影响全基因组转录活性来测试该模型。我们发现与耐药性、应激反应和发病机制有关的基因被Par抑制。出乎意料的是，阻遏不涉及直接Par结合同源启动子DNA，表明阻遏可能涉及Par与其他调节剂的相互作用。这种多效性突出了染色体Par蛋白整合到细胞控制电路中的程度。
Bacterial ParA and ParB proteins are best known for their contribution to plasmid and chromosome segregation, but they may also contribute to other cell functions. In segregation, ParA interacts with ParB, which binds to parS centromere-analogous sites. In transcription, plasmid Par proteins can serve as repressors by specifically binding to their own promoters and, additionally, in the case of ParB, by spreading from a parS site to nearby promoters. Here, we have asked whether chromosomal Par proteins can likewise control transcription. Analysis of genome-wide ParB1 binding in Vibrio cholerae revealed preferential binding to the three known parS1 sites and limited spreading of ParB1 beyond the parS1 sites. Comparison of wild-type transcriptomes with those of ΔparA1, ΔparB1, and ΔparAB1 mutants revealed that two out of 20 genes (VC0067 and VC0069) covered by ParB1 spreading are repressed by both ParB1 and ParA1. A third gene (VC0076) at the outskirts of the spreading area and a few genes further away were also repressed, particularly the gene for an outer membrane protein, ompU (VC0633). Since ParA1 or ParB1 binding was not evident near VC0076 and ompU genes, the repression may require participation of additional factors. Indeed, both ParA1 and ParB1 proteins were found to interact with several V. cholerae proteins in bacterial and yeast two-hybrid screens. These studies demonstrate that chromosomal Par proteins can repress genes unlinked to parS and can do so without direct binding to the cognate promoter DNA. Directed segregation of chromosomes is essential for their maintenance in dividing cells. Many bacteria have genes (par) that were thought to be dedicated to segregation based on analogy to their roles in plasmid maintenance. It is becoming clear that chromosomal par genes are pleiotropic and that they contribute to diverse processes such as DNA replication, cell division, cell growth, and motility. One way to explain the pleiotropy is to suggest that Par proteins serve as or control other transcription factors. We tested this model by determining how Par proteins affect genome-wide transcription activity. We found that genes implicated in drug resistance, stress response, and pathogenesis were repressed by Par. Unexpectedly, the repression did not involve direct Par binding to cognate promoter DNA, indicating that the repression may involve Par interactions with other regulators. This pleiotropy highlights the degree of integration of chromosomal Par proteins into cellular control circuitries.