Quorum sensing in Staphylococci is regulated via phosphorylation of three conserved histidine residues.
Staphylococcus aureus cause infections by producing toxins, a process regulated by cell-cell communication (quorum sensing) through the histidine-phosphorylation of the target of RNAIII-activating protein (TRAP). We show here that TRAP is highly conserved in staphylococci and contains three completely conserved histidine residues (His-66, His-79, His-154) that are phosphorylated and essential for its activity. This was tested by constructing a TRAP(-) strain with each of the conserved histidine residues changed to alanine by site-directed mutagenesis. All mutants were tested for pathogenesis in vitro (expression of RNAIII and hemolytic activity) and in vivo (murine cellulitis model). Results show that RNAIII is not expressed in the TRAP(-) strain, that it is non hemolytic, and that it does not cause disease in vivo. These pathogenic phenotypes could be rescued in the strain containing the recovered traP, confirming the importance of TRAP in S. aureus pathogenesis. The phosphorylation of TRAP mutated in any of the conserved histidine residues was significantly reduced, and mutants defective in any one of these residues were non-pathogenic in vitro or in vivo, whereas those mutated in a non-conserved histidine residue (His-124) were as pathogenic as the wild type. These results confirm the importance of the three conserved histidine residues in TRAP activity. The phosphorylation pattern, structure, and gene organization of TRAP deviates from signaling molecules known to date, suggesting that TRAP belongs to a novel class of signal transducers.
Gov
Yael
Y
Department of Human Microbiology, Sackler School of Medicine, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel.
Borovok
Ilya
I
Korem
Moshe
M
Singh
Vineet K
VK
Jayaswal
Radheshyam K
RK
Wilkinson
Brian J
BJ
Rich
Stephen M
SM
Balaban
Naomi
N
D000595:Amino Acid Sequence; D000818:Animals; D015152:Blotting, Northern; D002450:Cell Communication; D004247:DNA / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000378:metabolism; D006639:Histidine / Q000737:chemistry*; D051379:Mice; D008969:Molecular Sequence Data; D016296:Mutagenesis; D016297:Mutagenesis, Site-Directed; D009154:Mutation; D010641:Phenotype; D010766:Phosphorylation; D010802:Phylogeny; D010957:Plasmids / Q000378:metabolism; D017434:Protein Structure, Tertiary; D016372:RNA, Antisense / Q000737:chemistry; D012329:RNA, Bacterial / Q000737:chemistry; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction; D013211:Staphylococcus aureus / Q000378:metabolism*; D013997:Time Factors
D016372:RNA, Antisense; D012329:RNA, Bacterial; C096035:RNAIII, Staphylococcus aureus; D006639:Histidine; D004247:DNA