The acyl-homoserine lactone-type quorum-sensing system modulates cell motility and virulence of Erwinia chrysanthemi pv. zeae.
Erwinia chrysanthemi pv. zeae is one of the Erwinia chrysanthemi pathovars that infects on both dicotyledons and monocotyledons. However, little is known about the molecular basis and regulatory mechanisms of its virulence. By using a transposon mutagenesis approach, we cloned the genes coding for an E. chrysanthemi pv. zeae synthase of acyl-homoserine lactone (AHL) quorum-sensing signals (expI(Ecz)) and a cognate response regulator (expR(Ecz)). Chromatography analysis showed that expI(Ecz) encoded production of the AHL signal N-(3-oxo-hexanoyl)-homoserine lactone (OHHL). Null mutation of expI(Ecz) in the E. chrysanthemi pv. zeae strain EC1 abolished AHL production, increased bacterial swimming and swarming motility, disabled formation of multicell aggregates, and attenuated virulence of the pathogen on potato tubers. The mutation also marginally reduced the inhibitory activity of E. chrysanthemi pv. zeae on rice seed germination. The mutant phenotypes were rescued by either exogenous addition of AHL signal or in trans expression of expI(Ecz). These data demonstrate that the AHL-type QS signal plays an essential role in modulation of E. chrysanthemi pv. zeae cell motility and the ability to form multicell aggregates and is involved in regulation of bacterial virulence.
Hussain
Mumtaz B B M
MB
Institute of Molecular and Cell Biology, 61 Biopolis Drive, Singapore 138673.
Zhang
Hai-Bao
HB
Xu
Jin-Ling
JL
Liu
Qiongguang
Q
Jiang
Zide
Z
Zhang
Lian-Hui
LH
D054742:Acyl-Butyrolactones / Q000378:metabolism*; D000595:Amino Acid Sequence; D001422:Bacterial Adhesion; D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D002465:Cell Movement; D016974:Dickeya chrysanthemi / Q000235:genetics / Q000378:metabolism / Q000472:pathogenicity* / Q000502:physiology*; D015964:Gene Expression Regulation, Bacterial; D008969:Molecular Sequence Data; D012275:Oryza / Q000382:microbiology; D053038:Quorum Sensing; D012639:Seeds / Q000382:microbiology; D017422:Sequence Analysis, DNA; D011198:Solanum tuberosum / Q000382:microbiology; D015534:Trans-Activators / Q000235:genetics / Q000378:metabolism; D014774:Virulence
D054742:Acyl-Butyrolactones; D001426:Bacterial Proteins; C115748:ExpR protein, Erwinia; D015534:Trans-Activators; C081685:expI protein, Erwinia