Structural basis of signaling between bacterial chemoreceptors and flagella

描述（由申请人提供）：细菌靠近或远离化学物质的运动（趋化性）对细胞生长和存活很重要，也可能在许多传染病的进展中起重要作用。大肠杆菌是了解跨膜信号传导、运动和细胞行为机制的卓越模型系统。大肠杆菌趋化/运动途径是生物学中研究得最好的感觉信号转导系统之一，但在分子水平上仍有待充分认识。我们的长期目标是阐明活细胞中趋化信号和鞭毛转换的结构基础。这一建议的总体目标是将化学受体复合物和鞭毛运动细胞在不同信号状态下的结构变化联系起来。通过对由mreB突变体产生的鞭毛小细胞（直径约0.2 um）进行成像，我们将能够使用低温电子断层扫描来确定在同一单个小细胞内处于不同信号状态的受体阵列和鞭毛马达的高分辨率结构。创新的微流体技术将使我们能够记录这些微型细胞的行为。结构和功能可以在相同的条件下以前所未有的方式观察到。因此，我们将能够测试关于受体阵列和运动复合物结构变化如何表现为行为变化的假设。

DESCRIPTION (provided by applicant): The movement of bacteria toward or away from chemicals (chemotaxis) is important for cell growth and survival and may also play a major role in the progression of many infectious diseases. Escherichia coli is the pre-eminent model system for understanding the mechanisms underlying transmembrane signaling, motility and cellular behavior. E. coli chemotaxis/motility pathway is one of the best-studied sensory signal transduction systems in biology, yet it remains to be fully understood at the molecular level. Our long-term goal is to elucidate the structural basis of chemotactic signaling and flagellar switchin in living cells. The overall objective of this proposal is to correlate structural changes in the chemoreceptor complex and the flagellar motor of cells in different signaling states. By imaging flagellated minicells (~ 0.2 um diameter) generated from a skinny mreB mutant, we will be able to use cryo-electron tomography to determine high-resolution structures of the receptor array and flagellar motor trapped in different signaling states within the same individual minicells. Innovative microfluidic techniques will enable us to record the behavior of these minicells. Structure and function can be observed under identical conditions in an unprecedented manner. Thus, we will be able to test hypotheses about how changes in the structure of receptor arrays and motor complexes are manifested as changes in behavior.