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

T Funahashi1, C Fujiwara, M Okada

  • 1Faculty of Pharmaceutical Sciences, Okayama University, Okayama, Japan.

Microbiology and Immunology
|February 28, 2001
PubMed

Insights

Mutations in the ferric uptake regulatory protein (Fur) gene in Vibrio parahaemolyticus disrupt iron acquisition. These Fur mutations lead to constitutive production of siderophores and iron-repressible outer membrane proteins, impacting bacterial iron homeostasis.

Area of Science:

  • Microbiology
  • Bacterial Physiology
  • Molecular Biology

Background:

  • The ferric uptake regulatory protein (Fur) is a key transcriptional repressor controlling iron-regulated genes in many bacteria.
  • Understanding Fur's function is crucial for deciphering bacterial iron acquisition mechanisms.

Purpose of the Study:

  • To investigate the role of Fur in regulating iron uptake systems in Vibrio parahaemolyticus.
  • To characterize mutations in the fur gene and their effects on vibrioferrin (VF) and iron-repressible outer membrane proteins (IROMPs) expression.

Main Methods:

  • Isolation of manganese-resistant mutants of V. parahaemolyticus.
  • Analysis of VF production and IROMP expression under varying iron concentrations.
  • PCR-direct DNA sequencing of fur genes.
  • Construction of a fur overexpressing plasmid and Western blotting using anti-Fur antiserum.

Main Results:

  • Ten manganese-resistant mutants constitutively produced VF and expressed at least two IROMPs, independent of iron levels.
  • Four distinct point mutations in the fur gene were identified, leading to amino acid substitutions.
  • Western blot analysis showed reduced amounts and/or altered migration of mutant Fur proteins compared to wild-type Fur.

Conclusions:

  • The study provides insights into the structure-function relationship of Fur in V. parahaemolyticus.
  • Mutations in Fur significantly impact the expression of iron acquisition systems, suggesting its involvement in regulating VF and IROMPs.
  • The precise mechanism of Fur's action on target genes in V. parahaemolyticus remains to be elucidated.

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