Bubonic plague, one of the most virulent of bacterial infections, is spread by the bites of fleas persistently colonized by Yersinia pestis. The bacteria form a biofilm in the digestive tract of the flea that blocks the insect's feeding. This stimulates the flea to bite repeatedly in futile attempts to feed, thus spreading bacteria to new mammalian hosts. The biofilm is crucial to persistent flea colonization and maintenance of the bacterium enzootically in wild rodents and their fleas. Biofilms are also made by a wide variety of other bacterial pathogens. Some of these, like Y. pestis, use biofilms to colonize vectors and other environmental niches, while others make biofilms in human infections. The goal of this research is to understand how Y. pestis regulates biofilm formation. A multi-component phosphorelay is part of the biofilm regulatory network. RcsD, one of the components, is unusual in that the gene encoding it contains a single nucleotide deletion that appears to frameshift the protein upstream of its phosphotransferase domain. Nevertheless, genetic tests indicate that Y. pestis RcsD is functional. RcsD will be analyzed with a genetic structure-function study as well as in vitro phosphotransferase assays. Results will be compared to those from Y. pseudotuberculosis, a closely related organism in which rcsD is not frameshifted, to make inferences about Y. pestis evolution. The second messenger cyclic-di-GMP is an important biofilm regulator in Y. pestis and numerous other bacteria. HmsT is a diguanylate cyclase that synthesizes c-di-GMP to promote biofilms. Transcriptional regulation of hmsT and a novel post-translational mechanism that regulates the protein's stability will be investigated. HmsP is a c-di-GMP phosphodiesterase that degrades the second messenger to downregulate biofilms. A second HmsP function in addition to phosphodiesterase activity has been identified, and this will be analyzed in a structure-function study. The role of oligomerization and proteolysis in post-translational regulation of HmsP will be investigated.
Bubonic plague, one of the most deadly of bacterial infections, is spread by flea bites. The causative bacteria, Yersinia pestis, form a tight plug known as a biofilm in the flea's digestive tract, which stimulates it to bite and spread the infection. The goal of this research is to understand how the biofilm is formed.
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| Sun, Yi-Cheng; Koumoutsi, Alexandra; Jarrett, Clayton et al. (2011) Differential control of Yersinia pestis biofilm formation in vitro and in the flea vector by two c-di-GMP diguanylate cyclases. PLoS One 6:e19267 |
| Drace, Kevin; McLaughlin, Stephanie; Darby, Creg (2009) Caenorhabditis elegans BAH-1 is a DUF23 protein expressed in seam cells and required for microbial biofilm binding to the cuticle. PLoS One 4:e6741 |
| Sun, Yi-Cheng; Koumoutsi, Alexandra; Darby, Creg (2009) The response regulator PhoP negatively regulates Yersinia pseudotuberculosis and Yersinia pestis biofilms. FEMS Microbiol Lett 290:85-90 |
