Identification and functional analysis of vibrio vulnificus SmcR, a novel global regulator.
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 LD50 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.
Department of Food Science and Technology, Center for Agricultural Biomaterials, Seoul National University, Seoul 151-742, Korea.
Jeong Hyun
JH
Lee
Jee Eun
JE
Rhee
Uryung
U
Park
Hyun-Mok
HM
Ju
Byung Cheol
BC
Lee
Tae Sung
TS
Kim
Hye Sook
HS
Jeong
Sang Ho
SH
Choi
D000818:Animals; D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology*; D018441:Biofilms; D003001:Cloning, Molecular; D005260:Female; D051379:Mice; D008813:Mice, Inbred ICR; D009154:Mutation; D015534:Trans-Activators / Q000235:genetics / Q000502:physiology*; D041261:Vibrio vulnificus / Q000472:pathogenicity; D014774:Virulence
D001426:Bacterial Proteins; D015534:Trans-Activators; C410093:smcR protein, Vibrio vulnificus