Myxococcus Xanthus Lipid Chemotaxis

生物膜是微生物及其相关细胞外基质的集合体。在自然环境中，细菌与覆盖生物和非生物表面的生物膜中的其他细胞联系在一起。一些生物膜在工业和医疗环境中会造成经济和健康问题。生物膜中的细胞通过细胞信号传递过程组装成醒目的三维结构。生物膜的一个经常被忽视的方面是使用共享空间，即细胞外基质，将代谢物和信号从一个细胞输送到另一个细胞，从而使种群的行为同步。不能分泌基质的黄色粘球菌突变体在生物膜的形成、运动性、趋化性和子实体发育方面受到损害。这项资助是研究任何细菌基质的遗传学和生物化学的最早尝试之一，它通过关注新发现的细胞通讯途径来实现这一点，该途径协调黄色微囊藻细胞对脂质信号磷脂酰乙醇胺(PE)的反应。这项研究将通过质谱学和合成化学来研究PE信号的基本结构特征。细胞外基质蛋白质组将被提纯，并利用新完成的黄花莲基因组序列通过质谱学进行鉴定。基因破坏将被用来识别必要的基质蛋白，并阐明细胞外基质启动信号感知并将这些信息传递到DIF化学传感系统的机制。最后，甲基化趋化受体DIFA将接受定点和随机突变，以确定与PE趋化相关的区域。

Biofilms are assemblages of microorganisms and their associated extracellular matrix. In natural settings bacteria are associated with other cells in biofilms that coat biological and abiological surfaces. Some biofilms cause economic and health problems in industrial and medical settings. Cells in biofilms assemble striking three-dimensional structures through the use of cell signaling processes. An often-ignored aspect of biofilms is the use of shared space, the extracellular matrix, to channel metabolites and signals from cell to cell that synchronize the behavior of the population. Myxococcus xanthus mutants that are unable to secrete the matrix are impaired in biofilm formation, motility, chemotaxis, and fruiting body development. This grant is one of the very first attempts to examine the genetics and biochemistry of the matrix of any bacterium, and it does so by focussing on a newly discovered cell communication pathway that coordinates M. xanthus cell motility in response to the lipid signal phosphatidylethanolamine (PE). The research will examine the essential structural features of the PE signal through mass spectrometry and synthetic chemistry. The extracellular matrix proteome will be purified and identified by mass spectrometry using the newly completed M. xanthus genome sequence. Gene disruption will be used to identify essential matrix proteins and elucidate the mechanism by which the extracellular matrix initiates signal perception and transduces this information to the Dif chemosensory system. Finally the methylated chemotaxis receptor DifA will be subjected to site-directed and random mutagenesis to identify regions involved in PE chemotaxis.