The mechanism of bistable motility gene expression in Bacillus subtilis.

描述(申请人提供)：细菌种群曾经被认为是一致的，实际上是不同细胞类型的异质混合物，当在单个细胞水平上研究时，这一点变得明显。双稳态(开/关)基因表达在表观遗传上导致细胞类型分化，并创造易于利用/生存环境变化的亚群。在这里，我们探索运动基因在枯草芽孢杆菌中双稳态表达的独特特征，它通过表观遗传机制产生单个运动细胞和非运动链的混合种群。我们将测量在运动开启和运动关闭状态之间的切换动力学，以及在生长过程中每种状态的遗传。我们将确定另一种sigma因子CD的调控机制，即沿27kb操纵子转录水平的逐渐下降，以及对鞭毛组装的调控，以产生双稳定基因表达。最后，我们将确定未知功能的发育调节因子SWRA偏向处于开启或关闭状态的人口比例的机制。在革兰氏阴性菌中，运动性及其控制已经研究了很长时间，我们打算将进化上遥远的革兰氏阳性枯草杆菌提升为一个主要的模型系统，以发现运动性基因调控的新范例。双稳性是原核生物研究的一个重要新领域，它改变了我们对细菌种群的看法。我们收集的信息将与细菌发育、抗生素治疗、毒力基因表达和细菌发病机制直接相关。

DESCRIPTION (provided by applicant): Bacterial populations, once thought to be uniform, are in fact heterogeneous mixtures of distinct cell types that become apparent when studied at the level of individual cells. Bistable (ON/OFF) gene expression epigenetically results in cell type differentiation and creates subpopulations predisposed to exploit/survive environmental change. Here we explore the unique features of the bistable expression of motility genes in Bacillus subtilis that generates mixed populations of single motile cells and non-motile chains through an epigenetic mechanism. We will measure the kinetics of switching between motility-ON and motility-OFF states and the inheritance of each state during growth. We will determine the mechanism by which the alternative sigma factor CD is controlled by both a gradual decline in transcript levels along a 27 kb operon, and regulation in response to flagellar assembly, to produce bistable gene expression. Finally, we will determine the mechanism by which a developmental regulator of unknown function, SwrA, biases the proportion of the population that is in an ON or OFF state. Motility and its control has been long-studied in Gram negative bacteria like E. coli and we intend to elevate the evolutionarily distant Gram positive B. subtilis to a premiere model system for the discovery of new paradigms of motility gene regulation. Bistability is an important new area of prokaryotic research that changes the way we think about bacterial populations. The information we gather will be directly relevant to bacterial development, antibiotic therapy, virulence gene expression, and bacterial pathogenesis.