title: Maturation of functional type III secretion machinery by activation of anaerobic respiration in enterohaemorrhagic Escherichia coli.
abstract: Enterohaemorrhagic Escherichia coli (EHEC) is a gastrointestinal pathogen that causes diarrhoea and more severe diseases in humans. A key feature of EHEC is the type III secretion system (TTSS), which translocates virulence factors (effectors) directly into host cells. In this study, the expression and secretion of effectors in EHEC grown under anaerobic conditions were examined. The secretion of effectors was greatly enhanced, without an increase in their expression levels, when EHEC was grown in the presence of specific electron acceptors, such as trimethylamine N-oxide (TMAO) and nitrate, for anaerobic respiration. The activation of the TTSS was dependent on the activity of respiratory systems, including electron-acceptor-specific signalling systems and reductases. Although de novo protein synthesis was not required for TTSS activation, the inhibition of respiratory activity abolished secretion. EHEC grown with either TMAO or nitrate possessed a more intact type III secretion (TTS) apparatus, including the needle protein EscF and the translocator protein EspA, than EHEC grown without an electron acceptor. These observations suggest that activation of either the TMAO- or the nitrate-specific respiratory system accelerates the maturation of functional TTS apparatus under anaerobic growth conditions.
authors.affiliation: Division of Applied Bacteriology, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Ando
authors.affiliation: Division of Applied Bacteriology, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Abe
authors.affiliation: Division of Applied Bacteriology, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors.forename: Nakaba
authors.initials: N
authors.lastname: Sugimoto
authors.affiliation: Division of Applied Bacteriology, Graduate School of Medicine, Osaka University, 2-2 Yamadaoka, Suita, Osaka 565-0871, Japan.
authors.forename: Toru
authors.initials: T
authors.lastname: Tobe
mesh_terms: D000693:Anaerobiosis; D004926:Escherichia coli / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism / Q000502:physiology; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D006801:Humans; D008744:Methylamines / Q000378:metabolism*; D009566:Nitrates / Q000378:metabolism*; D016877:Oxidants / Q000378:metabolism*; D010101:Oxygen Consumption
chemical_list: D029968:Escherichia coli Proteins; D008744:Methylamines; D009566:Nitrates; D016877:Oxidants; C005855:trimethyloxamine