Abstract
CodY acts as a key regulatory protein involved in adaptive responses in low-G+C Gram-positive bacteria. This global transcriptional regulator diagnoses the nutritional status of the cell and responds by regulating transcription of genes involved in metabolism, differenciation and virulence. Phosphoproteomic studies evidenced that CodY is phosphorylated on its serine 215 in Bacillus subtilis. In Bacillus cereus, CodY is also phosphorylated by the Hanks kinases PrkC and YbdM. CodY phosphorylation negatively affects its DNA-binding properties. We constructed B. cereus mutant strains where the codY wild-type allele has been replaced by codY-S215D or codY-S215A, encoding a phosphomimetic or a phosphoablative CodY derivative, respectively. We showed that the phosphomimetic mutation leads to a notable reduction in CodY control over several critical cellular processes, including motility, biofilm formation, cytotoxic effects and pathogenicity. Lack of CodY phosphorylation and CodY overphosphorylation have opposite repercussions on gene expression, showing that CodY phosphorylation contributes to the adaptation of B. cereus to diverse environmental conditions. S215 is strictly conserved in CodY orthologs in firmicutes, suggesting that gene regulation mediated by Hanks kinase-dependent CodY phosphorylation could be a general regulatory mechanism in this phylum.