Peptide alarmone signalling triggers an auto-active bacteriocin necessary for genetic competence.
The induction of genetic competence is a strategy used by bacteria to increase their genetic repertoire under stressful environmental conditions. Recently, Streptococcus pneumoniae has been shown to co-ordinate the uptake of transforming DNA with fratricide via increased expression of the peptide pheromone responsible for competence induction. Here, we document that environmental stress-induced expression of the peptide pheromone competence-stimulating peptide (CSP) in the oral pathogen Streptococcus mutans. We showed that CSP is involved in the stress response and determined the CSP-induced regulon in S. mutans by microarray analysis. Contrary to pneumococcus, S. mutans responds to increased concentrations of CSP by cell lysis in only a fraction of the population. We have focused on the mechanism of cell lysis and have identified a novel bacteriocin as the 'death effector'. Most importantly, we showed that this bacteriocin causes cell death via a novel mechanism of action: intracellular action against self. We have also identified the cognate bacteriocin immunity protein, which resides in a separate unlinked genetic locus to allow its differential regulation. The role of the lytic response in S. mutans competence is also discussed. Together, these findings reveal a novel autolytic pathway in S. mutans which may be involved in the dissemination of fitness-enhancing genes in the oral biofilm.
Perry
Julie A
JA
Dental Research Institute, Faculty of Dentistry, University of Toronto, Toronto, ON, Canada.
Jones
Marcus B
MB
Peterson
Scott N
SN
Cvitkovitch
Dennis G
DG
Lévesque
Céline M
CM
D001426:Bacterial Proteins / Q000378:metabolism*; D001430:Bacteriocins / Q000378:metabolism*; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D020411:Oligonucleotide Array Sequence Analysis; D010675:Pheromones / Q000378:metabolism*; D018085:Regulon; D013295:Streptococcus mutans / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism
D001426:Bacterial Proteins; D001430:Bacteriocins; D010675:Pheromones; C423628:competence factor, Streptococcus