9318890 Hughes The flagella of the bacteria Salmonella typhimurium is a complex organelle which is completely dispensable and thus amenable to genetic dissection. This research will focus on how the assembly of the flagellar structure is regulated. We have characterized a gene, flg M, whose protein product regulates flagellin expression. In cells unable to make a hook-basal body complex, the FlgM protein prevents expression of flagellin genes. This inhibition occurs by interaction of FlgM with the alternative signa factor, o28, which is specific for expression of the flagellin and chemotaxis genes the details of the interaction between FlgM and o28 are being explored. In cells with a functional hook-basal body complex, the FlgM protein is transported by the flagellar-specific export pathway through the intact hook-basal body structure and into the growth medium. The specific role of FlgM in flagellar regulation remains to be determined and is a focus of this proposal. When plan to use FlgM export to initiate a general characterization of the flagellar-specific export pathway. Besides the flgM gene, three other novel regulatory loci were discovered which affect flagellin regulation. These will be further characterized as well. Finally, the role of FlgM in virulence suggests a broader role in the central Biology of S. typhimurium and we plan to explore what other pathways are regulated by FlgM. %%% This research will provide insight into a mechanism by which cells can control the assembly of structures on the surface of bacteria that have been shown to be involved in pathogenesis. ***
