Swarming differentiation of vibrio vulnificus downregulates the expression of the vvhBA hemolysin gene via the LuxS quorum-sensing system.
Swarming has proven to be a good in vitro model for bacterial surface adherence and colonization, and the swarming differentiation of a bacterium has been shown to be coupled with changes in the expression of virulence factors associated with its invasiveness, particularly in the early stages of infection. In this study, we attempted to determine whether the expression of vvhA, which encodes for hemolysin/cytolysin (VvhA), is either upregulated or downregulated during the swarming differentiation of V. vulnificus. The insertional inactivation of vvhA itself exerted no detectable effect on the expression of V. vulnificus swarming motility. However, in our lacZ-fused vvhA transcriptional reporter assay, vvhA expression decreased in swarming V. vulnificus as compared to non-swarming or planktonic V. vulnificus. The reduced expression of vvhA in swarming V. vulnificus increased as a result of the deletional inactivation of luxS, a gene associated with quorum sensing. These results show that vvhA expression in swarming V. vulnificus is downregulated via the activity of the LuxS quorum-sensing system, suggesting that VvhA performs no essential role in the invasiveness of V. vulnificus via the adherence to and colonization on the body surfaces required in the early stages of the infection. However, VvhA may play a significant role in the pathophysiological deterioration occurring after swarming V. vulnificus is differentiated into planktonic V. vulnificus.
Kim
Moon-Young
MY
Research Center for Resistant Cells, Chosun University Medical School, Gwangju 501-759, Republic of Korea.
Park
Ra-Young
RY
Choi
Mi-Hwa
MH
Sun
Hui-Yu
HY
Kim
Choon-Mee
CM
Kim
Soo-Young
SY
Rhee
Joon-Haeng
JH
Shin
Sung-Heui
SH
D001422:Bacterial Adhesion / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology*; D013437:Carbon-Sulfur Lyases; D002454:Cell Differentiation; D002465:Cell Movement / Q000235:genetics*; D015536:Down-Regulation; D015964:Gene Expression Regulation, Bacterial; D017930:Genes, Reporter / Q000235:genetics; D009154:Mutation; D015854:Up-Regulation; D041261:Vibrio vulnificus / Q000166:cytology / Q000235:genetics / Q000472:pathogenicity*
D001426:Bacterial Proteins; C470630:VvhA protein, Vibrio vulnificus; D013437:Carbon-Sulfur Lyases; C117753:LuxS protein, Bacteria