[Phenotypic analysis of luxS gene deletion mutants and its application in virulence regulation research in group B Streptococcus].
OBJECTIVE
To explore the mechanism of virulence regulation in group B streptococcus (BGS) by studying LuxS-related AI-2 quorum-sensing pathway in GBS.


METHODS
luxS gene deletion mutants of GBS (Delta lusX) were characterized by reverse transcription (RT)-PCR, colony immunoblot analysis, growth curve measurement, and cAMP determination. Functional analysis of luxS in the deletion mutants was conducted by bioluminescence assay.


RESULTS
Genetic analysis results showed that the luxS deletion in the mutant 515-Delta lusX caused upregulation of scpB gene expression. Phenotypic analysis revealed that, in comparison with the wild strain, 515-Delta lusX mutant grew slowly in DCM media but quickly in THY media. An approximately two-fold decrement in bioluminescence was detected in the luxS deletion mutants as compared with the wild strain.


CONCLUSIONS
This study confirms the importance of LuxS molecule in the AI-2 quorum-sensing pathway in GBS and provides new insights into the virulence regulation mechanism of GBS.
Ouyang
Qian
Q
Institute of Genetic Engineering, Southern Medical University, Guangzhou 510515, China.
Ma
Wen-li
WL
Liu
Cui-hua
CH
Shi
Rong
R
Zheng
Wen-ling
WL
D001426:Bacterial Proteins / Q000235:genetics*; D013437:Carbon-Sulfur Lyases / Q000235:genetics*; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial; D008029:Lighting; D010641:Phenotype; D013292:Streptococcus agalactiae / Q000235:genetics* / Q000472:pathogenicity*; D014774:Virulence
D001426:Bacterial Proteins; D013437:Carbon-Sulfur Lyases; C117753:LuxS protein, Bacteria