Molecular and mechanistic basis for spatiotemporal organization of polar flagella

许多细菌通过鞭毛运动，这为它们在环境增殖中提供了显著的优势。鞭毛是由复杂的纳米机器旋转的蛋白质纤维，它允许细菌按照化学梯度移动。长期以来，人们一直认为鞭毛的位置和数量（鞭毛模式）在物种之间存在差异。有两种基本的鞭毛模式存在：一个或多个丝状体出现在细胞的一个或两个极或它们发生在侧的位置远离细胞极。鞭毛的数量，鞭毛定位模式和鞭毛活性在大量的细菌物种中以时空的方式由两个相互作用的蛋白质，SRP型GTATPFlhF和MinD样ATP酶FlhG调节。这两种蛋白质的作用机制仍然是难以捉摸的。在这项研究中，我们将联合收割机的互补专业知识的两个参与小组，进一步研究如何FlhF和FlhG建立非常常见的单极鞭毛模式，使用我们发达的模式物种希瓦氏菌腐败。更具体地说，我们将进一步确定如何FlhG链接鞭毛组装与转录控制相应的积木，以及如何及时鞭毛合成的调节。此外，我们将研究如何FlhF指导新生鞭毛结构的指定细胞极，以及如何FlhF和FlhG之间的直接相互作用是时空控制。我们预计，这些方法将能够生成FlhF/FlhG介导的细菌机制的第一个全面的模型，并深入了解这两种蛋白质如何发挥作用，以建立其他不同的鞭毛模式。

Many bacteria are motile by flagella, which provides them with a significant advantage in environmental proliferation. Flagella are proteinaceous fibers rotated by intricate sophisticated nanomachines, which allow bacteria to move in accordance with chemical gradients. It has long been established that place and number of flagella (flagellation pattern) vary among the species. There are two basic flagellation patterns existing: either one or more filaments emerge at one both cell poles or they occur at lateral positions away from the cell pole. The number of flagella, flagellar localization pattern and flagellar activity in a huge number of bacterial species is regulated in a spatiotemporal fashion by two interacting proteins, the SRP-type GTPase FlhF and the MinD-like ATPase FlhG. The mechanism by which the two proteins act are still mostly elusive. In this study, we will combine the complementary expertises of the two participating groups to further investigate how FlhF and FlhG establish the very common monopolar flagellation pattern using our well-developed model species Shewanella putrefaciens. More specifically, we will further determine how FlhG links flagella assembly with transcriptional control of the corresponding building blocks, and how timely flagella synthesis is regulated. Furthermore, we will investigate how FlhF directs the nascent flagellar structure to the designated cell pole, and how direct interaction between FlhF and FlhG is spatiotemporally controlled. We expect that the approaches will enable to generate the first comprehensive model of an FlhF/FlhG-mediated mechanism in bacteria and to give insights into how the two proteins may function to establish other, different flagellar patterns.