title: Vesicle-mediated export and assembly of pore-forming oligomers of the enterobacterial ClyA cytotoxin.
abstract: The ClyA protein is a pore-forming cytotoxin expressed by Escherichia coli and some other enterobacteria. It confers cytotoxic activity toward mammalian cells, but it has remained unknown how ClyA is surface exposed and exported from bacterial cells. Outer-membrane vesicles (OMVs) released from the bacteria were shown to contain ClyA protein. ClyA formed oligomeric pore assemblies in the OMVs, and the cytotoxic activity toward mammalian cells was considerably higher than that of ClyA protein purified from the bacterial periplasm. The redox status of ClyA correlated with its ability to form the oligomeric pore assemblies. In bacterial cells with a defective periplasmic disulphide oxidoreductase system, the ClyA protein was phenotypically expressed in a constitutive manner. The results define a vesicle-mediated transport mechanism in bacteria, and our findings show that the localization of proteins to OMVs directly may contribute to the activation and delivery of pathogenic effector proteins.
authors.affiliation: Department of Molecular Biology, Umeå University, S-901 87 Umeå, Sweden. sun.nyunt.wai@molbiol.umu.se
authors.forename: Sun Nyunt
authors.initials: SN
authors.lastname: Wai
authors.forename: Barbro
authors.initials: B
authors.lastname: Lindmark
authors.forename: Tomas
authors.initials: T
authors.lastname: Söderblom
authors.forename: Akemi
authors.initials: A
authors.lastname: Takade
authors.forename: Marie
authors.initials: M
authors.lastname: Westermark
authors.forename: Jan
authors.initials: J
authors.lastname: Oscarsson
authors.forename: Jana
authors.initials: J
authors.lastname: Jass
authors.forename: Agneta
authors.initials: A
authors.lastname: Richter-Dahlfors
authors.forename: Yoshimitsu
authors.initials: Y
authors.lastname: Mizunoe
authors.forename: Bernt Eric
authors.initials: BE
authors.lastname: Uhlin
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D001427:Bacterial Toxins / Q000737:chemistry / Q000378:metabolism; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism; D003603:Cytotoxins / Q000737:chemistry / Q000378:metabolism; D004926:Escherichia coli / Q000378:metabolism* / Q000648:ultrastructure; D006367:HeLa Cells; D006460:Hemolysin Proteins / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism; D010084:Oxidation-Reduction; D011108:Polymers / Q000737:chemistry / Q000378:metabolism; D019704:Protein Disulfide-Isomerases / Q000378:metabolism; D012475:Salmonella / Q000378:metabolism; D022161:Transport Vesicles / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: D001426:Bacterial Proteins; D001427:Bacterial Toxins; D003603:Cytotoxins; C079503:DsbB protein, Bacteria; D006460:Hemolysin Proteins; D008565:Membrane Proteins; D011108:Polymers; C087744:ApxI toxin, Bacteria; D019704:Protein Disulfide-Isomerases