STKP controls stress-induced autolysis in Streptococcus pneumoniae by phosphorylation of ComE

PIÑAS GE, CIAN ME, CORTES PR, ALBARRACIN ORIO AG, ECHENIQUE J.

POTRERO DE LOS FUNES

Encuentro; Reunión Anual de la Sociedad Argentina de Investigación en Bioquímica y Biología Molecular; 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 crosstalk mechanism. To study the possibility that phosphorylation of ComE by an alternative phosphodonor could be required for ASIL, we created a D58A comE mutant, in which the phosphorylable aspartate residue at D58A position 58 was replaced by alanine. The comE 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 ASILpathway, 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. These findings support the idea that upon acidic stress StkPactivates ComE by phosphorylation and triggers the autolytic response.