A molecular sensor that allows a gut commensal to control its nutrient foundation in a competitive ecosystem

摘要

Little is known about how members of the indigenous microflora interact with their mammalian hosts to establish mutually beneficial relationships. We have used a gnotobiotic mouse model to show that Bacterondes thetaiotaomi- cron, a component of the intestinal microflora of mice and humans, uses a repressor, FucR, as a iuolecular sensor of L-fucose availability. FucR coordinates expression of an operon encoding enzymes in the L-fucose metabolic pathway with ex- pression of another locus that regulates production of fucosy lated glycans in intestinal enterocytes. Genetic and biochemical studies indicate that FucR does this by using fucose as an inducer at one locus and as a corepressor at the other locus. Coordinating this commensal's immediate nutritional requirements with pro- duction of a host-derived energy source is consistent with its need to enter and persist within a competitive ecosystem.