Intercellular signaling in Myxococcus xanthus

黄粘球菌细胞在营养生长和多细胞子实体形成过程中在固体表面表现出协调的细胞运动。这些复杂的社会行为使这种细菌成为研究细胞间信号传导和微生物发育的良好模型系统。我们的研究重点是了解社会滑行运动（S-motility）的机械和生理基础以及子实体形成过程中运动的趋化控制。在最后的资助期间，我们发现了社会运动所需的两种细胞表面附属物的一些重要分子功能：IV型毛和原纤维。基于这些发现，我们假设黄顶草的定向运动涉及到frz化学感觉系统对毛开关频率的控制。我们还假设原纤维是一种自生的细胞外基质物质，是黄原菌的主要化学引诱剂，并为黄原菌的子实体形成提供了重要的信号。我们提出以下具体目标来检验这些假设：1。获得毛菌依赖运动的直接物理证据，并研究其与FRZ化学感觉系统的相互作用；2. 获得子实体形成过程中原纤维引导的趋化运动的直观证据；3. 鉴定参与纤维梯度自生的分子成分。这些研究将有助于我们了解社会群体、社会狩猎、细胞间信号传导和子实体形成的分子机制。它还将提供对滑翔运动和细菌运动/趋化系统进化的分子理解。由于M. xanthus的s -运动性和聚集性与假单胞菌和奈瑟菌等致病菌的抽搐运动性和生物膜形成非常相似，因此该研究也可能为这些事件的进一步分子表征提供线索，从而导致针对这些致病菌的新治疗方法。

Myxococcus xanthus cells exhibit coordinated cell movements on a solid surface during vegetative growth and multicellular fruiting body formation. These complex social behaviors make this bacterium an excellent model system for studying intercellular signaling and microbial development. The focus of our research is to understand the mechanical and physiological basis of social gliding motility (S-motility) and the chemotactic control of motility during fruiting body formation. During the last grant period, we discovered some important molecular functions of two cell surface appendages that are required for social motility: the type IV pili and fibrils. Based on these findings, we hypothesize that directed motility in M.xanthus involves the control of pilus switching frequency by the frz chemosensory system. We also hypothesize that fibril, a self-generated extracellular matrix material, is a major chemoattractant for M. xanthus and provides an important signal for fruiting body formation in M. xanthus. We propose the following specific aims to test these hypotheses: 1. to obtain direct physical evidence of pilus dependent motility and study its interaction with the frz chemosensory system; 2. to obtain direct visual evidence of fibril-guided chemotactic movement during fruiting body formation; 3. to identify molecular components involved in self-generation of fibril gradient. The studies will help us to understand the molecular mechanisms of social swarming, social hunting, intercellular signaling, and fruiting body formation. It will also provide a molecular understanding of gliding motility and the evolution of bacterial motility/chemotaxis systems. Since the S-motility and aggregation of M. xanthus are very similar to twitching motility and biofilm formation in pathogenic bacteria like Pseudomonas and Neisseria, the studies may also provide clues for further molecular characterization of these events, leading to new treatments against these pathogenic bacteria.