An insect gut environment reveals the induction of a new sugar-phosphate sensor system in Bacillus cereus.

Bacteria survive under various conditions by sensing stimuli triggering specific adaptive physiological responses, which are often based on membrane-integrated sensors connected to a cytoplasmic regulator. Recent studies reveal that mucus glycans may act as signal molecules for two-component systems involved in intestinal colonization. Bacillus cereus, a human and insect opportunistic pathogen was used to identify bacterial factors expressed in an insect gut infection model. The screen revealed a promoter involved in the expression of a gene with so far unknown functions. A search for gut-related compounds, inducing its transcription, identified glucose-6-phosphate as an activation signal. The gene is part of a five-gene cluster, including a two-component system. Interestingly such five gene loci are conserved in the pathogenic Bacillus group as well as in various Clostridia bacteria and are with analogy to other multi-component sensor systems in enteropathogenic bacteria, such as E. coli. Thus our results provide insights into the function of two-component and auxiliary sensor systems in host-microbe interactions and opens up possible investigations of such systems in other gut associated bacteria.