csgA Gene and Cell Interactions in Myxococcus xanthus

黄粘球菌的发育受Csg细胞间通讯系统的调控。C信号可能是csgA基因的多肽产物。初步结果为今后的工作提出了四个方向。首先，对csgA进行随机诱变，然后对发育突变体进行DNA测序，以确定该蛋白的重要功能域。其次，研究csgA对营养水平调节的反应，有望揭示营养水平如何在这种生物体中被评估并用于调节基因表达。该项目将涉及a)随机诱变和调控区域的DNA测序，以确定在调控中起关键作用的核苷酸；b)使用识别位点探针克隆编码调控蛋白的基因；c)用凝胶迁移位移法和DNA足迹法表征蛋白质-DNA相互作用。d)使用报告基因座定量体内表达水平。第三，对csgA抑制基因突变的持续分析有望揭示信号传导过程中的其他步骤。几个抑制等位基因已经被克隆出来，这些基因将被测序并通过其他功能试验进行研究。粘菌的生命周期包含了高等生物发育的基本要素，包括定向细胞运动、多细胞形态发生、调节基因表达和细胞分化。因此，它可以作为研究这些过程的实验模型。

Myxococcus xanthus development is regulated by the Csg intercellular communication system. The C signal appears to be the polypeptide product of the csgA gene. The preliminary results suggest four directions for future work. First, random mutagenesis of csgA followed by DNA sequencing of developmental mutants is expected to determine the important functional domains of the protein. Second, examination of the regulation of csgA in response to moderated levels of nutrients is expected to reveal how nutrient levels are assessed in this organism and used to regulate gene expression. This project will involve a) random mutagenesis and DNA sequencing of the regulatory region to identify nucleotides that play a critical role in regulation, b) cloning of genes encoding regulatory proteins using recognition site probes, c) characterization of the protein-DNA interactions with gel mobility shift assays and DNA foot printing, and d) quantitation of the expression levels in vivo using a reporter locus. Third, continued analysis of the csgA suppressor mutations is expected to reveal other steps in the signaling process. Several suppressor alleles have been cloned and these will be sequenced and studied by other functional assays. %%% The life cycle of the myxobacterium, Myxococcus xanthus, contains the basic elements found in the development of higher organisms including directed cell movement, multicellular morphogenesis, regulated gene expression and cellular differentiation. It can therefore serve as an experimentally accessible model for the study of these processes.