Dual regulatory pathways integrating the RcsC-RcsD-RcsB signalling system control enterohaemorrhagic Escherichia coli pathogenicity.
Bacterial pathogenesis is strictly regulated in response to changes in environmental conditions. A His-Asp phosphorelay system consisting of a sensor kinase and response regulator is used by Gram-positive and Gram-negative bacteria to control gene expression in response to environmental stimuli. We screened His-Asp phosphorelay systems for their effect on virulence expression in enterohaemorrhagic Escherichia coli (EHEC), and found rcsD or rcsB overexpression enhanced locus for enterocyte effacement (LEE) gene transcription and adherence to Caco-2 cells through transcriptional activation of the ler regulatory gene. An EHEC-specific regulator GrvA, encoded by ECs1274, was required for ler transcription activation by RcsB. Furthermore, GrvA activated ler transcription in E. coli K12. Stimulation of the RcsDCB regulatory system by RcsF overexpression slightly increased EspB expression in the wild type but not the ECs1274 mutant. However, EspB expression in an rcsB deletion mutant increased compared with wild type, suggesting that RcsB negatively regulates LEE gene expression and that active RcsB protein is present under normal growth conditions. Deletion of pchA, which encodes a positive regulator for ler, abolished the effect of the rcsB deletion, suggesting that pchA mediated the negative RcsB effect. pchA transcript levels decreased when RcsB expression increased. Thus, LEE gene transcription may be regulated by RcsB through two oppositely regulated O157-specific regulators, PchA and GrvA.
Tobe
Toru
T
Division of Applied Bacteriology, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan. torutobe@bact.med.osaka-u.ac.jp
Ando
Hiroki
H
Ishikawa
Hiroko
H
Abe
Hiroyuki
H
Tashiro
Kosuke
K
Hayashi
Tetsuya
T
Kuhara
Satoru
S
Sugimoto
Nakaba
N
D000222:Adaptation, Physiological; D018938:Caco-2 Cells; D019453:Escherichia coli O157 / Q000235:genetics / Q000378:metabolism / Q000472:pathogenicity*; D029968:Escherichia coli Proteins / Q000032:analysis / Q000235:genetics / Q000502:physiology*; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D005809:Genes, Regulator / Q000235:genetics / Q000502:physiology; D017930:Genes, Reporter; D006801:Humans; D009097:Multienzyme Complexes / Q000235:genetics / Q000502:physiology*; D010749:Phosphoprotein Phosphatases / Q000235:genetics / Q000502:physiology*; D010750:Phosphoproteins / Q000032:analysis; D010770:Phosphotransferases / Q000235:genetics / Q000502:physiology*; D011494:Protein Kinases / Q000235:genetics / Q000502:physiology*; D012329:RNA, Bacterial / Q000032:analysis; D012333:RNA, Messenger / Q000032:analysis; D015398:Signal Transduction / Q000235:genetics; D015534:Trans-Activators / Q000235:genetics / Q000502:physiology; D014157:Transcription Factors / Q000235:genetics / Q000502:physiology*; D014158:Transcription, Genetic; D014774:Virulence / Q000235:genetics / Q000502:physiology; D001616:beta-Galactosidase / Q000235:genetics
D029968:Escherichia coli Proteins; C457340:LEE protein, E coli; C465556:Ler protein, E coli; D009097:Multienzyme Complexes; D010750:Phosphoproteins; D012329:RNA, Bacterial; D012333:RNA, Messenger; C489568:RcsB protein, E coli; D015534:Trans-Activators; D014157:Transcription Factors; C489728:rcsC protein, E coli; D010770:Phosphotransferases; D011494:Protein Kinases; C434271:rcsD protein, E coli; D010749:Phosphoprotein Phosphatases; D001616:beta-Galactosidase