Salmonella flagellar regulon is controlled by a nutrient-tunable bistable switch

摘要

Motility is a common strategy used by diverse organisms to adapt to changes in their environment. For instance, when proximal sources of nutrients are depleted, one simple strategy is to seek out new ones. This process has been extensively studied in the enteric bacteria Escherichia coli and Salmonella enterica serovar Typhimurium. Both employ flagella to move. Both swim towards nutrients and away from toxins by altering the rotational bias of their flagella. Both regulate the expression of their flagellar genes in response to nutrient availability, independently of chemotaxis. Interestingly, this response is quite different despite otherwise close similarities between the two motility systems. In particular, nutrients repress flagellar gene expression in E. coli whereas they enhance it in Salmonella.