Conserved Amplification of Chemotactic Responses through Chemoreceptor Interactions

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Abstract
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.