StkP controls stress induced autolysis in Streptococcus pneumoniae through phosphorylation of ComE.

PIÑAS GE; CIAN M, ; CORTES PR; ALBARRACIN ORIO AG; ECHENIQUE J

Potrero de Funes, San Luis

Congreso; SAIB; 2011

SAIB

In pneumococcus, autolysis is triggered by acidic stress. This process requires ComE, a response regulator that normally controls competence development at alkaline pH, which is activated by its cognate histidin kinase ComD by phosphorylation. We demonstrated that acidic stress-induced lysis (ASIL) was not dependent on ComD, suggesting a cross-talk mechanism between ComE and other kinases. However, we showed that no other histidine kinases were involved in the control of ASIL by a cross-talk mechanism. To study the possibility that phosphorylation of ComE by an alternative phosphodonor could be required for ASIL, we created a comED58A mutant, in which the phosphorylable aspartate residue at position 58 was replaced by alanine. The comED58A mutant autolysed like the wt strain (R801) at acidic pH, demonstrating that phosphorylation in this residue was not necessary for ASIL activation. We had described that the serine threonine kinase StkP controls competence, virulence, and autolysis. We also found that StkP was participating in the ComE-controlled ASIL pathway, being required for induction of comE transcripts. In vitro phosphorylation assays revealed that ComE is a target of StkP, being phosphorylated exclusively at threonine residues. This findings support the idea that upon acidic stress StkP activates ComE through phosphorylation and triggers the autolytic response.