The Stress Tolerance Response of Vibrio Parahaemolyticus is Not Regulated by the Envz/Ompr Two-Component System
University of Delaware
Vibrio parahaemolyticus is a halophile present in marine environments worldwide that has an absolute requirement for NaCl and can grow in up to 10.5% NaCl in complex media. V. parahaemolyticus is also a pathogen of humans that causes gastroenteritis usually through the consumption of raw oysters. In this study, regulation of stress tolerance was investigated by examining the homologues of the EnvZ/OmpR two-component signal transduction system in V. parahaemolyticus, loci VP0155 and VP0154. In Escherichia coli, EnvZ/OmpR regulates more than 100 genes, and significantly influences cell growth, metabolism, and motility (Oshima et al., 2002). The putative EnvZ/OmpR system’s role in V. parahaemolyticus was examined by deleting most of vp0154, an ompR homologue, and by creating deletions in both vp0154 and vp0155, the envZ homologue, through splicing by overlap extension (SOE) PCR and homologous recombination. The in-frame deletions in the mutants were confirmed by PCR and sequencing. ΔompR and ΔenvZΔompR were characterized through examination of swimming, swarming, biofilm formation, and growth under salt, sucrose, and antimicrobial peptide stresses. No differences between the wild type and mutants were observed under these conditions, indicating that in V. parahaemolyticus, the function of EnvZ/OmpR has diverged significantly from that studied in E. coli.