Role of signal transduction systems in biofilm formation of Streptococcus pneumoniae

CIAN MB; PIÑAS GE; CORTES PR; ALBARRACIN ORIO AG; ECHENIQUE JR,

SAN MIGUEL DE TUCUMAN

Encuentro; XLV REUNION ANUAL SOCIEDAD ARGENTINA DE INVESTIGACION EN BIOQUIMICA Y BIOLOGIA MOLECULAR; 2009

SAIB

Biofilm formation plays an important role in bacterial pathogenesis. In Streptococcus pneumoniae, it has been demonstrated that biofilm development is associated with nasopharyngeal carriage and otitis media pathogenesis. In the present work, we studied the contribution of signal transduction systems to biofilm development of S. pneumoniae. For this purpose, we constructed knock-out mutants of the 14 twocomponent systems and the unique serine/threonine kinase (StkP) and its cognate phosphatase (PhpP). Biofilm formation was evaluated by crystal violet staining of cells growing statically in polystyrene plates. The ritR and the ciaH mutants showed significantly less biofilm formation than the wild-type strain. On the other hand, the php mutant also showed decreased biofilm formation, while the stkP mutant displayed a wild-type strain phenotype. These results indicated that RitR, an orphan response regulator involved in iron metabolism, and CiaH, a histidine kinase, together with the phosphatase PhpP, are required for biofilm development. Because it has been recently reported that PhpP can interact with RitR and positively regulate ritR transcription, we suggest a connection between PhpP, RitR and iron metabolism for the control of biofilm development in S. Pneumoniae.