Acidic stress induces autolysis by a CSP-independent ComE pathway in Streptococcus pneumoniae

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

Society of General Microbiology

Lugar: London; Año: 2008 vol. 154 p. 1300 - 1300

p style="TEXT-ALIGN: justify; LINE-HEIGHT: 150%; MARGIN-RIGHT: -36.8pt" class="MsoNormal">In Streptococcus pneumoniae, autolysis is considered a programmed cell-death process executed principally by the major autolysin (LytA), and the underlying mechanism causing its activation is not completely understood. It is known that autolysis is triggered by competence development at alkaline pH and regulated by a two-component system, ComDE, which senses a competence-stimulating peptide (CSP) and behaves as a quorum sensing mechanism. In this work, we found that acidic stress triggered a LytA-mediated autolysis, and curiously, this phenomenon was regulated by a CSP-independent ComE pathway. A further analysis of an hyperactive ComD mutant revealed that ComE needs to be phosphorylated to activate acidic stress-induced lysis (ASIL). The comE transcripts were induced by acidic culture conditions, suggesting that ComE could be sensing acidic stress. We also investiga