Protein serine/threonine kinase StkP positively controls virulence and competence in Streptococcus pneumoniae

In the Streptococcus pneumoniae genome, stkP, encoding a membrane-associated serine/threonine kinase, is not redundant (L. Novakova, S. Romao, J. Echenique, P. Branny, and M.-C. Trombe, unpublished results). The data presented here demonstrate that StkP belongs to the signaling network involved in competence triggering in vitro and lung infection and bloodstream invasion in vivo. In competence, functional StkP is required for activation of comCDE upstream of the autoregulated ring orchestrated by the competence-stimulating peptide. This is the first description of positive regulation of comCDE transcription in balance with its repression by CiaRH.