Temperature is one of the important parameters regulating the expression of virulence factors in bacteria. The global regulator, a histone-like nucleoid structuring protein (H-NS), is known to play a crucial role in this regulation. In the present study, we first clarified the role of H-NS in the temperature-dependent regulation of virulence factor production in
Vibrio vulnificus, including that of the cytolytic toxin (
V. vulnificus hemolysin: VVH) and the proteolytic enzyme (
V. vulnificus protease: VVP). The expression of
hns itself was subjected to temperature regulation, where
hns was expressed more at 26℃ than at 37℃. VVH production and the expression of its gene
vvhA were increased by disruption of the
hns gene. H-NS appeared to affect the
vvhA expression by the well-documented transcriptional silencing mechanism. On the other hand,
hns disruption resulted in the reduction of VVP production and the expression of its gene
vvpE. H-NS was suggested to positively regulate
vvpE expression through the increase in the level of the
rpoS mRNA. Moreover, H-NS was found to contribute to the survival of
V. vulnificus in stressful environments. When compared to the wild type strain, the
hns mutant exhibited reduced survival rates when subjected to acidic pH, hyperosmotic and oxidative stress.
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