THE MOLECULAR CHAPERONE CLPL IS INVOLVED IN THE ACID-STRESS INDUCED AUTOLYSIS OF PNEUMOCOCCUS

PIÑAS G; CORTES P; ALBARRACIN ORIO, A; J. ECHENIQUE

Pinamar-Buenos Aires, Argentina

Congreso; XLI Annual Meeting Argentine Society for Biochemistry and Molecular Biology (SAIB); 2005

Sociedad Argentina de Investigaciones en Bioquímica y Biología Molecular (SAIB)

ClpL belongs to the Hsp100 family of heat shock proteins. It carries out a chaperone function and probably is also involved in proteolysis, when it is associated with ClpP, removing damaged and denatured proteins. During studies of acid tolerance response in S. pneumoniae, we found that ClpL was highly induced at pH 5,6 (Cortes et al., SAIB 2003). This pH value was also responsible for the autolysis observed in the wild type strain after 2 hours of incubation at 37ºC (Piñas et al., SAIB 2003). To evaluate the role of ClpL in acid-stress induced autolysis, we constructed a clpL mutant and studied its lytic phenotype when incubated at pH 5,6. We found that the clpL mutant did not undergo autolysis after 6 hours of incubation compared with the wild type strain. We further investigated the penicillin-induced autolysis of this mutant, and we observed lysis in both the mutant and the wild-type strains. These results suggest that ClpL is involved in the acid-induced autolysis and that its chaperone function is not essential for the activity of the major pneumococcal autolysin, LytA, since the clpL mutant could still lyse in the presence of penicillin. ClpL, acting as a chaperone, may be required to fold a protein that promotes the acid-induced autolysis, or to remove by proteolysis a protein that blocks this effect.