Amino Acids Sample Clauses

Amino Acids. The amino acid arginine promotes swarming under non-permissive conditions, particularly those of low pH, but arginine biosynthesis mutants swarm normally indicating the intracellular production of this amino acid does not contribute to swarming under normal laboratory conditions (23). However, the mechanism by which extracellular arginine and SpeA (arginine decarboxylase) contribute to swarming was later elucidated. The SpeA-mediated conversion of arginine to agmatine consumes intracellular protons, conserving the proton gradient and proton motive force during swarming in low pH environments (282). Glutamine is required for swarming, and P. mirabilis encodes genes specific for glutamine synthesis and transport (23, 25). On media non-permissive for swarming motility, only glutamine was able to initiate differentiation (25). Mutants in glnA encoding glutamine synthetase are completely unable to swarm on rich media, and only L-glutamine restored swarming in this mutant. However, no data exists suggesting exogenous glutamine triggers differentiation, though cells migrate for slightly longer distances prior to consolidation (23). Glutamine may promote migration but it does not seem to trigger differentiation. Overall, amino acids have been shown to trigger differentiation and promote migration. They may be sensed by P. mirabilis to determine if surroundings are ideal for the initiation of swarming or if entry into consolidation phase is warranted.