title: Autoprocessing of the Vibrio cholerae RTX toxin by the cysteine protease domain.
abstract: Vibrio cholerae RTX is a large multifunctional bacterial toxin that causes actin crosslinking. Due to its size, it was predicted to undergo proteolytic cleavage during translocation into host cells to deliver activity domains to the cytosol. In this study, we identified a domain within the RTX toxin that is conserved in large clostridial glucosylating toxins TcdB, TcdA, TcnA, and TcsL; putative toxins from V. vulnificus, Yersinia sp., Photorhabdus sp., and Xenorhabdus sp.; and a filamentous/hemagglutinin-like protein FhaL from Bordetella sp. In vivo transfection studies and in vitro characterization of purified recombinant protein revealed that this domain from the V. cholerae RTX toxin is an autoprocessing cysteine protease whose activity is stimulated by the intracellular environment. A cysteine point mutation within the RTX holotoxin attenuated actin crosslinking activity suggesting that processing of the toxin is an important step in toxin translocation. Overall, we have uncovered a new mechanism by which large bacterial toxins and proteins deliver catalytic activities to the eukaryotic cell cytosol by autoprocessing after translocation.
authors.affiliation: Department of Microbiology-Immunology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA.
authors.forename: Kerri-Lynn
authors.initials: KL
authors.lastname: Sheahan
authors.forename: Christina L
authors.initials: CL
authors.lastname: Cordero
authors.forename: Karla J Fullner
authors.initials: KJ
authors.lastname: Satchell
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001427:Bacterial Toxins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D019556:COS Cells; D002522:Chlorocebus aethiops; D016384:Consensus Sequence; D003546:Cysteine Endopeptidases / Q000737:chemistry*; D005798:Genes, Bacterial; D006868:Hydrolysis; D008954:Models, Biological; D008969:Molecular Sequence Data; D010802:Phylogeny; D017354:Point Mutation; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D014734:Vibrio cholerae / Q000737:chemistry / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity
chemical_list: D001427:Bacterial Toxins; D011994:Recombinant Proteins; D003546:Cysteine Endopeptidases