Identification and Functional Analysis of Vibrio vulnificus SmcR, a Novel Global Regulator

  • Lee, Jeojng-Hyun (Department of Food Science and Technology, Department of Agricultural Biotechnology, and Center for Agricultural Biomaterials, Seoul National University) ;
  • Rhee, Jee-Eun (Department of Food Science and Technology, Department of Agricultural Biotechnology, and Center for Agricultural Biomaterials, Seoul National University) ;
  • Park, U-Ryung (Department of Food Science and Technology, Department of Agricultural Biotechnology, and Center for Agricultural Biomaterials, Seoul National University) ;
  • Ju, Hyun-Mok (Department of Food Science and Technology, Department of Agricultural Biotechnology, and Center for Agricultural Biomaterials, Seoul National University) ;
  • Lee, Byung-Cheol (School of Life Sciences and Biotechnology, Korea University) ;
  • Kim, Tae-Sung (School of Life Sciences and Biotechnology, Korea University) ;
  • Jeong, Hye-Sook (Laboratory of Enteric Infections, Department of Microbiology, National Institute of Health Korea) ;
  • Choi, Sang-Ho (Department of Food Science and Technology, Department of Agricultural Biotechnology, and Center for Agricultural Biomaterials, Seoul National University)
  • Published : 2007.02.28

Abstract

Recently, quorum sensing has been implicated as an important global regulator controlling the production of numerous virulence factors such as capsular polysaccharides in bacterial pathogens. The nucleotide and deduced amino acid sequences of smcR, a homolog of V. harveyi luxR identified from V. vulnificus ATCC29307, were analyzed. The amino acid sequence of SmcR from V. vulnificus was 72 to 92% similar to those of LuxR homologs from Vibrio spp. Functions of SmcR were assessed by the construction of an isogenic mutant, whose smcR gene was inactivated by allelic exchanges, and by evaluating its phenotype changes in vitro and in mice. The disruption of smcR resulted in a significant alteration in biofilm formation, in type of colony morphology, and in motility. When compared with the wild-type, the smcR mutant exhibited reduced survival under adverse conditions, such as acidic pH and hyperosmotic stress. The smcR mutant exhibited decreased cytotoxic activity toward INT 407 cells in vitro. Furthermore, the intraperitoneal $LD_{50}$ of the smcR mutant was approximately $10^2$ times higher than that of parental wild-type. Therefore, it appears that SmcR is a novel global regulator, controlling numerous genes contributing to the pathogenesis as well as survival of V. vulnificus.

Keywords

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