Outer membrane vesicles of Vibrio vulnificus deliver cytolysin-hemolysin VvhA into epithelial cells to induce cytotoxicity.
The Gram-negative bacterium Vibrio vulnificus produces cytotoxins that induce the acute death of host cells. However, the secretory mechanisms of such cytotoxins have not been extensively studied. Previously, we reported that substantial amounts of V. vulnificus cytolysin-hemolysin (VvhA) are produced in vivo during the bacterial infection in mice and that this cytotoxin, in conjunction with RtxA1, mediates cytotoxicity. In this study, we investigated whether V. vulnificus cells release outer membrane vesicles (OMVs), which are used by some Gram-negative bacteria to deliver virulence factors into host cells. We found that V. vulnificus produce OMVs and that these vesicles can induce host cell death. This process appears to be mediated by VvhA, as evidenced by the finding that OMVs isolated from VvhA-null mutants do not induce cytotoxicity. In addition, cholesterol sequestration in the host cells prevents OMV-mediated VvhA delivery, indicating that VvhA-bearing OMVs interact with cholesterol on the host cell surface. Furthermore, intracellular expression experiments revealed that VvhA-mediated cytotoxicity is driven by its N-terminal leukocidin domain.
Kim
Young Ran
YR
Clinical Vaccine R&D Center, Chonnam National University Medical School, Gwangju 501-746, Republic of Korea.
Kim
Bang Ul
BU
Kim
Soo Young
SY
Kim
Choon Mee
CM
Na
Hee Sam
HS
Koh
Jeong Tae
JT
Choy
Hyon E
HE
Rhee
Joon Haeng
JH
Lee
Shee Eun
SE
D000818:Animals; D017209:Apoptosis; D001426:Bacterial Proteins / Q000378:metabolism; D002462:Cell Membrane / Q000378:metabolism; D002784:Cholesterol / Q000378:metabolism; D003603:Cytotoxins / Q000378:metabolism*; D004847:Epithelial Cells / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D021381:Protein Transport; D022161:Transport Vesicles / Q000378:metabolism*; D041261:Vibrio vulnificus / Q000378:metabolism / Q000472:pathogenicity*; D037521:Virulence Factors / Q000378:metabolism*
D001426:Bacterial Proteins; D003603:Cytotoxins; D037521:Virulence Factors; C470630:VvhA protein, Vibrio vulnificus; D002784:Cholesterol