Competence regulation by oxygen in Streptococcus pneumoniae: involvement of ciaRH and comCDE.
Anaerobic aerotolerant Streptococcus pneumoniae modulates its genetic transformability and its virulence in response to the oxygen concentration. The activity of a single protein encoded by nox and showing NADH oxidase activity is involved in these adaptive responses to O2. Northern blot analysis of wild-type cultures grown under aerobic and microaerobic conditions indicated transcriptional control of comCDE by O2. An O2-independent mutant strain carrying the gain-of-function mutation comE38KE was isolated and its analysis showed that ComE is a key point in competence stimulation by O2. Plasmid insertion mutations in ciaRH revealed that this two component signal-transducing system negatively regulates comCDE transcription. The level of comCDE transcripts appears as a major control point in competence regulation by O2 and also by growth phase and cell density.
Echenique
J R
JR
Laboratoire de Genétique et Physiologie Bactérienne, Centre Hospitalo Universitaire de Rangueil, Université Paul Sabatier 31403 Toulouse cedex, France.
Chapuy-Regaud
S
S
Trombe
M C
MC
D000693:Anaerobiosis; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D005838:Genotype; D000071677:Histidine Kinase; D009097:Multienzyme Complexes; D016296:Mutagenesis; D010100:Oxygen / Q000494:pharmacology; D010641:Phenotype; D017354:Point Mutation; D011494:Protein Kinases / Q000235:genetics; D013296:Streptococcus pneumoniae / Q000187:drug effects / Q000235:genetics / Q000502:physiology*; D014158:Transcription, Genetic; D014169:Transformation, Bacterial; D014774:Virulence
D001426:Bacterial Proteins; C103179:ComE protein, Streptococcus pneumoniae; D009097:Multienzyme Complexes; C061650:comC protein, Bacillus subtilis; D011494:Protein Kinases; D000071677:Histidine Kinase; D010100:Oxygen