Role of methionine in bacterial chemotaxis.

The effect of methionine starvation on the motility and behavior of normal and nonchemotactic mutants of Salmonella typhimurium was investigated. Methionine starvation eliminates tumbling in the wild type, but fails to do so in an uncoordinated (frequent tumbling) mutant. In the mutant, methionine starvation significantly extends the period of smooth motility that follows a sharp temporal increase of attractant. These results suggest that methionine metabolism is not tightly coupled to the generation of tumbles, but rather is necessary for the return of some tumble-regulating parameter to a steady-state level.