The Erwinia chrysanthemi 3937 PhoQ sensor kinase regulates several virulence determinants.
The PhoPQ two-component system regulates virulence factors in Erwinia chrysanthemi, a pectinolytic enterobacterium that causes soft rot in several plant species. We characterized the effect of a mutation in phoQ, the gene encoding the sensor kinase PhoQ of the PhoPQ two-component regulatory system, on the global transcriptional profile of E. chrysanthemi using cDNA microarrays and further confirmed our results by quantitative reverse transcription-PCR analysis. Our results indicate that a mutation in phoQ affects transcription of at least 40 genes, even in the absence of inducing conditions. Enhanced expression of several genes involved in iron metabolism was observed in the mutant, including that of the acs operon that is involved in achromobactin biosynthesis and transport. This siderophore is required for full virulence of E. chrysanthemi, and its expression is governed by the global repressor protein Fur. Changes in gene expression were also observed for membrane transporters, stress-related genes, toxins, and transcriptional regulators. Our results indicate that the PhoPQ system governs the expression of several additional virulence factors and may also be involved in interactions with other regulatory systems.
Laboratory of Plant Pathology, Faculty of Agriculture, Shizuoka University, 836 Ohya, Suruga-Ku, Shizuoka 422-8529, Japan.
Balakrishnan
B
Venkatesh
Lavanya
L
Babujee
Hui
H
Liu
Pete
P
Hedley
Takashi
T
Fujikawa
Paul
P
Birch
Ian
I
Toth
Shinji
S
Tsuyumu
D001426:Bacterial Proteins / Q000502:physiology*; D001427:Bacterial Toxins / Q000235:genetics; D016974:Dickeya chrysanthemi / Q000235:genetics / Q000472:pathogenicity / Q000502:physiology*; D017353:Gene Deletion; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D005798:Genes, Bacterial; D005809:Genes, Regulator; D026901:Membrane Transport Proteins / Q000235:genetics; D016254:Mutagenesis, Insertional; D020411:Oligonucleotide Array Sequence Analysis; D009876:Operon; D020133:Reverse Transcriptase Polymerase Chain Reaction; D017262:Siderophores / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D037521:Virulence Factors / Q000096:biosynthesis* / Q000235:genetics
D001426:Bacterial Proteins; D001427:Bacterial Toxins; D026901:Membrane Transport Proteins; C079792:PhoQ protein, Bacteria; D017262:Siderophores; D037521:Virulence Factors