RpoN of the fish pathogen Vibrio (Listonella) anguillarum is essential for flagellum production and virulence by the water-borne but not intraperitoneal route of inoculation

Microbiology. 1997 Dec;143 ( Pt 12):3849-59. doi: 10.1099/00221287-143-12-3849.


To investigate the involvement of RpoN in flagellum production and pathogenicity of Vibrio (Listonella) anguillarum, the rpoN gene was cloned and sequenced. The deduced product of the rpoN gene displayed strong homology to the alternative sigma 54 factor (RpoN) of numerous species of bacteria. In addition, partial sequencing of rpoN-linked ORFs revealed a marked resemblance to similarly located ORFs in other bacterial species. A polar insertion or an in-frame deletion in the coding region of rpoN abolished expression of the flagellin subunits and resulted in loss of motility. Introduction of the rpoN gene of V. anguillarum or Pseudomonas putida into the rpoN mutants restored flagellation and motility. The rpoN mutants were proficient in the expression of other proposed virulence determinants of V. anguillarum, such as ability to grow under low available iron conditions, and expression of the LPS O-antigen and of haemolytic and proteolytic extracellular products. The infectivity of the rpoN mutants with respect to the wild-type strain was unaffected following intraperitoneal injection of fish but was reduced significantly when fish were immersed in bacteria-containing water. Thus, RpoN does not appear to regulate any factors required for virulence subsequent to penetration of the fish epithelium, but is important in the infection of fish by water-borne V. anguillarum.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Bacterial Proteins / biosynthesis
  • Bacterial Proteins / chemistry
  • Bacterial Proteins / genetics
  • Base Sequence
  • Cell Movement
  • Cloning, Molecular
  • DNA-Binding Proteins*
  • DNA-Directed RNA Polymerases / biosynthesis
  • DNA-Directed RNA Polymerases / genetics*
  • Fishes / microbiology*
  • Flagella / physiology*
  • Flagella / ultrastructure
  • Flagellin / biosynthesis
  • Genes, Bacterial
  • Genetic Complementation Test
  • Molecular Sequence Data
  • Mutagenesis, Insertional
  • Open Reading Frames
  • RNA Polymerase Sigma 54
  • Recombinant Proteins / biosynthesis
  • Recombinant Proteins / chemistry
  • Sequence Deletion
  • Sigma Factor / biosynthesis
  • Sigma Factor / genetics*
  • Vibrio / genetics
  • Vibrio / pathogenicity*
  • Vibrio / physiology*
  • Virulence


  • Bacterial Proteins
  • DNA-Binding Proteins
  • Recombinant Proteins
  • Sigma Factor
  • Flagellin
  • DNA-Directed RNA Polymerases
  • RNA Polymerase Sigma 54

Associated data

  • GENBANK/U86585