Conserved Amplification of Chemotactic Responses through Chemoreceptor Interactions

Many bacteria concentrate their chemoreceptors at the cell poles. Chemoreceptor location is important in Escherichia coli, since chemosensory responses are sensitive to receptor proximity. It is not known, however, whether chemotaxis in other bacteria is similarly regulated. To investigate the importance of receptor-receptor interactions in other bacterial species, we synthesized saccharide-bearing multivalent ligands that are designed to cluster relevant chemoreceptors. As has been shown with E. coli, we demonstrate that the behaviors of Bacillus subtilis, Spirochaete aurantia, and Vibrio furnissii are sensitive to the valence of the chemoattractant. Moreover, in B. subtilis, chemotactic responses to serine were increased by pretreatment with saccharide-bearing multivalent ligands. This result indicates that, as in E. coli, signaling information is transferred among chemoreceptors in B. subtilis. These results suggest that interreceptor communication may be a general mechanism for modulating chemotactic responses in bacteria.