Autogenous and global control of the flagellar master operon, flhD, in Salmonella typhimurium

K. Kutsukake

Research output: Contribution to journalArticle

104 Citations (Scopus)

Abstract

Expression of the flagellar master operon, flhD, is known to be affected by growth conditions and by mutations in a variety of genes. In the present work, the transcriptional control of the Salmonella typhimurium flhD operon was investigated in various genetic backgrounds. First, we examined the effect of mutations in the global regulators cAMP-CRP, H-NS, OmpR and RpoS. Mutations in the cya, crp or hns gene reduced but did not eliminate flhD expression. However, expression was completely inhibited in the cya hns and crp hns double mutants. These results indicate that cAMP-CRP and H-NS independently activate the flhD operon and that maximal expression is attained in the presence of both regulators. On the other hand, the ompR and rpoS mutations did not affect either the motility phenotype or flhD expression. We next examined the expression of a chromosomal flhD-lac fusion gene in the presence of a plasmid carrying the wild-type flhD operon. It was found that under this condition the chromosomal flhD operon was repressed or activated, depending on the intracellular activity of FliA, an alternative sigma factor specific for late flagellar operons. In the absence of FliA or in the presence of both FliA and its cognate anti-sigma factor FlgM, the flhD operon was autogenously repressed, whereas in the flgM mutant background it was autogenously activated in the presence of FliA. This autoregulation was still observed in the crp or hns mutant background, indicating that the autogenous control is achieved by a mechanism that is independent of the cAMP-CRP and H-NS regulatory pathways.

Original languageEnglish
Pages (from-to)440-448
Number of pages9
JournalMGG Molecular & General Genetics
Volume254
Issue number4
DOIs
Publication statusPublished - 1997
Externally publishedYes

Fingerprint

Salmonella typhimurium
Operon
Sigma Factor
Mutation
Lac Operon
Genes
Plasmids
Homeostasis
Phenotype
Growth

Keywords

  • Autogenous regulation
  • cAMP-CRP
  • Flagellar master operon
  • FliA-FlgM regulatory system
  • H-NS

ASJC Scopus subject areas

  • Genetics

Cite this

Autogenous and global control of the flagellar master operon, flhD, in Salmonella typhimurium. / Kutsukake, K.

In: MGG Molecular & General Genetics, Vol. 254, No. 4, 1997, p. 440-448.

Research output: Contribution to journalArticle

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