A hierarchical quorum-sensing system in Yersinia pseudotuberculosis is involved in the regulation of motility and clumping.
In cell-free Yersinia pseudotuberculosis culture supernatants, we have chemically characterized three N-acyl homoserine lactone (AHL) molecules, N-octanoyl homoserine lactone (C8-HSL), N-(3-oxohexanoyl)homoserine lactone (3-oxo-C6-HSL) and N-hexanoyl homoserine lactone (C6-HSL). We have identified, cloned and sequenced two pairs of LuxR/I homologues termed YpsR/I and YtbR/I. In Escherichia coli at 37 degrees C, YpsI and YtbI both synthesize C6-HSL, although YpsI is responsible for 3-oxo-C6-HSL and YtbI for C8-HSL synthesis respectively. However, in a Y. pseudotuberculosis ypsI-negative background, YtbI appears capable of adjusting the AHL profile from all three AHLs at 37 degrees C and 22 degrees C to the absence of 3-oxo-C6-HSL at 28 degrees C. Insertion deletion mutagenesis of ypsR leads to the loss of C8-HSL at 22 degrees C, which suggests that at this temperature the YpsR protein is involved in the hierarchical regulation of the ytbR/I locus. When compared with the parent strain, the ypsR and ypsI mutants exhibit a number of phenotypes, including clumping (ypsR mutant), overexpression of a major flagellin subunit (ypsR mutant) and increased motility (both ypsR and ypsI mutants). The clumping and motility phenotypes are both temperature dependent. These data are consistent with a hierarchical quorum-sensing cascade in Y. pseudotuberculosis that is involved in the regulation of clumping and motility.
Atkinson
S
S
School of Pharmaceutical Sciences, University of Nottingham, University Park, Nottingham NG7 2RD, UK.
Throup
J P
JP
Stewart
G S
GS
Williams
P
P
D015107:4-Butyrolactone / Q000031:analogs & derivatives / Q000378:metabolism; D000595:Amino Acid Sequence; D001422:Bacterial Adhesion; D001426:Bacterial Proteins / Q000235:genetics; D001483:Base Sequence; D002450:Cell Communication; D017931:DNA Primers / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics; D005798:Genes, Bacterial; D008969:Molecular Sequence Data; D009068:Movement; D009154:Mutation; D010641:Phenotype; D012097:Repressor Proteins / Q000235:genetics; D017386:Sequence Homology, Amino Acid; D015534:Trans-Activators / Q000235:genetics; D015011:Yersinia pseudotuberculosis / Q000235:genetics / Q000502:physiology*
D001426:Bacterial Proteins; D017931:DNA Primers; D012097:Repressor Proteins; D015534:Trans-Activators; C084289:luxL protein, Vibrio harveyi; C064778:LuxR autoinducer binding proteins; C088386:homoserine lactone; D015107:4-Butyrolactone