Amino acid chemoreceptors of Bacillus subtilis

Abstract

Specificities of chemoreceptors for the 20 common amino acids, toward which B. subtilis shows chemotaxis, were assessed by competition (jamming) experiments using a modification of the traditional capillary assay, called the sensitivity capillary assay. Many amino acids were sensed by at least 2 chemoreceptors. All the highest affinity chemoreceptors for the amino acids were distinct, except glutamate and aspartate, which may share 1 chemoreceptor, and tyrosine, for which the data could not be collected due to low solubility. The data suggest that each amino acid-chemoreceptor complex binds to a different signaler (from which signals travel to the flagella to modify behavior appropriately), and that many of the signalers can also bind other attractant-chemoreceptor complexes as antagonists (no signals to flagella).