(Georgia Institute of Technology, 2006-12-15)
Epperson, Erin; Kirby, John
Myxococcus xanthus is a Gram negative soil bacterium that utilizes eight
chemosensory systems of interacting proteins, most of which are homologous to the E.coli
chemotaxis proteins, in order to regulate its two types of gliding motility (A and S),
predation of other organisms, and multicellular fruiting body formation. The M. xanthus
Che7 system, which has not been thoroughly characterized to date, is of specific interest
because it is thought to regulate A motility through exopolysaccharide (EPS) production,
contain a completely cytoplasmic Mcp (methyl-accepting chemotaxis protein), and have
two functioning non-chemotaxis proteins: Cpc7 and Des7. In this study, we explored the
protein-protein interactions of the Che7 system of M. xanthus through yeast two-hybrid
and beta-galactosidase assays. In addition to the expected interactions between the Che7
chemotaxis homologs, we found that Cpc7 interacted with both Des7 and Mcp7. This
suggests that Cpc7 is cytoplasmic and that several possibilities for the mechanism of signal
transduction in the Che7 system of M. xanthus exist. From these results, we propose a new
protein interaction model for the Che7 chemosensory two-component signal transduction
system.