Characterization of Vibrio parahaemolyticus manganese-resistant mutants in reference to the function of the ferric uptake regulatory protein

T. Funahashi, C. Fujiwara, M. Okada, S. I. Miyoshi, S. Shinoda, S. Narimatsu, S. Yamamoto

Research output: Contribution to journalArticlepeer-review

12 Citations (Scopus)

Abstract

In many bacteria, the ferric uptake regulatory protein (Fur) has a central role in the negative regulation of genes affected by iron limitation. In this study, Vibrio parahaemolyticus strains carrying mutations in the fur gene encoding Fur were isolated by the manganese selection method to assess the function of Fur in connection with alternations in the coordinate expression of the siderophore vibrioferrin (VF) and iron-repressible outer membrane proteins (IROMPs). Ten out of 25 manganese-resistant mutants constitutively produced VF and expressed at least two IROMPs irrespective of the iron concentration in the medium. PCR-direct DNA sequencing of the fur genes in these mutants identified four different point mutations causing amino acid changes. Moreover, a fur overexpressing plasmid was constructed to prepare antiserum against V. parahaemolyticus Fur. Western blotting with this antiserum revealed that the intracellular abundance of the wild-type Fur was not significantly affected by the iron concentrations in the growth medium, and that the Fur proteins of the mutant strains occurred at substantially smaller amounts and/or migrated more rapidly in sodium dodecyl sulfate-polyacrylamide gel electrophoresis than the wild-type Fur. These data afford an additional insight into the structure-function relationship of Fur and imply its involvement in the iron acquisition systems of V. parahaemolyticus, although it is yet unknown whether its action on the target genes is direct or indirect.

Original languageEnglish
Pages (from-to)963-970
Number of pages8
JournalMICROBIOLOGY and IMMUNOLOGY
Volume44
Issue number12
DOIs
Publication statusPublished - 2000

Keywords

  • Fur mutation
  • Iron-repressible gene
  • Manganese-resistant mutant
  • Vibrio parahaemolyticus

ASJC Scopus subject areas

  • Microbiology
  • Immunology
  • Virology

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