title: A cytotoxic type III secretion effector of Vibrio parahaemolyticus targets vacuolar H+-ATPase subunit c and ruptures host cell lysosomes.
abstract: Vibrio parahaemolyticus is one of the human pathogenic vibrios. During the infection of mammalian cells, this pathogen exhibits cytotoxicity that is dependent on its type III secretion system (T3SS1). VepA, an effector protein secreted via the T3SS1, plays a major role in the T3SS1-dependent cytotoxicity of V. parahaemolyticus. However, the mechanism by which VepA is involved in T3SS1-dependent cytotoxicity is unknown. Here, we found that protein transfection of VepA into HeLa cells resulted in cell death, indicating that VepA alone is cytotoxic. The ectopic expression of VepA in yeast Saccharomyces cerevisiae interferes with yeast growth, indicating that VepA is also toxic in yeast. A yeast genome-wide screen identified the yeast gene VMA3 as essential for the growth inhibition of yeast by VepA. Although VMA3 encodes subunit c of the vacuolar H(+)-ATPase (V-ATPase), the toxicity of VepA was independent of the function of V-ATPases. In HeLa cells, knockdown of V-ATPase subunit c decreased VepA-mediated cytotoxicity. We also demonstrated that VepA interacted with V-ATPase subunit c, whereas a carboxyl-terminally truncated mutant of VepA (VepAΔC), which does not show toxicity, did not. During infection, lysosomal contents leaked into the cytosol, revealing that lysosomal membrane permeabilization occurred prior to cell lysis. In a cell-free system, VepA was sufficient to induce the release of cathepsin D from isolated lysosomes. Therefore, our data suggest that the bacterial effector VepA targets subunit c of V-ATPase and induces the rupture of host cell lysosomes and subsequent cell death.
authors: Laboratory of Genomic Research on Pathogenic Bacteria, International Research Center for Infectious Diseases, Research Institute for Microbial Diseases, Osaka University, Suita, Osaka, Japan.
authors: Shigeaki
authors: S
authors: Matsuda
authors: Natsumi
authors: N
authors: Okada
authors: Toshio
authors: T
authors: Kodama
authors: Takeshi
authors: T
authors: Honda
authors: Tetsuya
authors: T
authors: Iida
mesh_terms: D017209:Apoptosis; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism; D058947:Bacterial Secretion Systems; D002402:Cathepsin D / Q000378:metabolism; D045744:Cell Line, Tumor; D006367:HeLa Cells; D006801:Humans; D008247:Lysosomes / Q000378:metabolism*; D008264:Macrophages / Q000378:metabolism; D034622:RNA Interference; D034741:RNA, Small Interfering; D012441:Saccharomyces cerevisiae / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism; D025262:Vacuolar Proton-Translocating ATPases / Q000235:genetics / Q000378:metabolism*; D014736:Vibrio parahaemolyticus / Q000378:metabolism* / Q000472:pathogenicity; D037521:Virulence Factors / Q000096:biosynthesis / Q000378:metabolism*
chemical_list: C541389:ATP6V0C protein, human; D001426:Bacterial Proteins; D058947:Bacterial Secretion Systems; D034741:RNA, Small Interfering; D029701:Saccharomyces cerevisiae Proteins; C479898:VMA3 protein, S cerevisiae; D037521:Virulence Factors; D002402:Cathepsin D; D025262:Vacuolar Proton-Translocating ATPases