Involvement of sigmaS accumulation in repression of the flhDC operon in acidic phospholipid-deficient mutants of Escherichia coli.
Escherichia coli pgsA mutations, which cause acidic phospholipid deficiency, repress transcription of the flagellar master operon flhDC, and thus impair flagellar formation and motility. The molecular mechanism of the strong repression of flhDC transcription in the mutant cells, however, has not yet been clarified. In order to shed light on this mechanism we isolated genes which, when supplied in multicopy, suppress the repression of flhD, and found that three genes, gadW, metE and yeaB, were capable of suppression. Taking into account a previous report that gadW represses sigma(S) production, the level of sigma(S) in the pgsA3 mutant was examined. We found that pgsA3 cells had a high level of sigma(S) and that introduction of a gadW plasmid into pgsA3 cells did reduce the sigma(S) level. The pgsA3 cells exhibited a sharp increase in sigma(S) levels that can only be partially attributed to the slight increase in rpoS transcription; the largest part of the effect is due to a post-transcriptional accumulation of sigma(S). GadW in multicopy exerts its effect by post-transcriptionally downregulating sigma(S). YeaB and MetE in multicopy also exert their effect via sigma(S). Disruption of rpoS caused an increase of the flhD mRNA level, and induction from P(trc)-rpoS repressed the flhD mRNA level. The strong repression of flhD transcription in pgsA3 mutant cells is thus suggested to be caused by the accumulated sigma(S).
Uchiyama
Junji
J
Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University, 255 Shimo-Ohkubo, Saitama, Saitama 338-8570, Japan.
Nobue
Yuka
Y
Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University, 255 Shimo-Ohkubo, Saitama, Saitama 338-8570, Japan.
Zhao
Hong
H
Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University, 255 Shimo-Ohkubo, Saitama, Saitama 338-8570, Japan.
Matsuzaki
Hiroshi
H
Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University, 255 Shimo-Ohkubo, Saitama, Saitama 338-8570, Japan.
Nagahama
Hideki
H
Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University, 255 Shimo-Ohkubo, Saitama, Saitama 338-8570, Japan.
Matsuoka
Satoshi
S
Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University, 255 Shimo-Ohkubo, Saitama, Saitama 338-8570, Japan.
Matsumoto
Kouji
K
Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University, 255 Shimo-Ohkubo, Saitama, Saitama 338-8570, Japan.
Hara
Hiroshi
H
Department of Biochemistry and Molecular Biology, Graduate School of Science and Engineering, Saitama University, 255 Shimo-Ohkubo, Saitama, Saitama 338-8570, Japan.
D001426:Bacterial Proteins / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D005407:Flagella / Q000737:chemistry / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D009154:Mutation; D009876:Operon; D010743:Phospholipids / Q000378:metabolism; D012808:Sigma Factor / Q000378:metabolism*; D015534:Trans-Activators / Q000235:genetics*; D014157:Transcription Factors / Q000378:metabolism; D014158:Transcription, Genetic; D017855:Transferases (Other Substituted Phosphate Groups) / Q000235:genetics
D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; C474648:GadW protein, E coli; D010743:Phospholipids; D012808:Sigma Factor; D015534:Trans-Activators; D014157:Transcription Factors; C090552:flhC protein, E coli; C090553:flhD protein, E coli; C069567:sigma factor KatF protein, Bacteria; D017855:Transferases (Other Substituted Phosphate Groups); C020676:CDP-diacylglycerol-glycerol-3-phosphate 3-phosphatidyltransferase