title: Vibrio cholerae MARTX toxin heterologous translocation of beta-lactamase and roles of individual effector domains on cytoskeleton dynamics.
abstract: The Vibrio cholerae MARTXVc toxin delivers three effector domains to eukaryotic cells. To study toxin delivery and function of individual domains, the rtxA gene was modified to encode toxin with an in-frame beta-lactamase (Bla) fusion. The hybrid RtxA::Bla toxin was Type I secreted from bacteria; and then Bla was translocated into eukaryotic cells and delivered by autoprocessing, demonstrating that the MARTXVc toxin is capable of heterologous protein transfer. Strains that produce hybrid RtxA::Bla toxins that carry one effector domain in addition to Bla were found to more efficiently translocate Bla. In cell biological assays, the actin cross-linking domain (ACD) and Rho-inactivation domain (RID) are found to cross-link actin and inactivate RhoA, respectively, when other effector domains are absent, with toxin autoprocessing required for high efficiency. The previously unstudied alpha-beta hydrolase domain (ABH) is shown here to activate CDC42, although the effect is ameliorated when RID is also present. Despite all effector domains acting on cytoskeleton assembly, the ACD was sufficient to rapidly inhibit macrophage phagocytosis. Both the ACD and RID independently disrupted polarized epithelial tight junction integrity. The sufficiency of ACD but strong selection for retention of RID and ABH suggests these two domains may primarily function by modulating cell signaling.
authors.affiliation: Department of Microbiology-Immunology, Northwestern University, Feinberg School of Medicine, Chicago, IL, 60611, USA.
authors.forename: Jazel S
authors.initials: JS
authors.lastname: Dolores
authors.forename: Shivani
authors.initials: S
authors.lastname: Agarwal
authors.forename: Martina
authors.initials: M
authors.lastname: Egerer
authors.forename: Karla J F
authors.initials: KJ
authors.lastname: Satchell
mesh_terms: D000199:Actins / Q000378:metabolism; D000668:Ampicillin Resistance; D001427:Bacterial Toxins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism* / Q000633:toxicity; D002460:Cell Line; D045744:Cell Line, Tumor; D016764:Cell Polarity; D003001:Cloning, Molecular; D003599:Cytoskeleton / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D008870:Microtubules / Q000378:metabolism; D010587:Phagocytosis; D054730:Protein Interaction Domains and Motifs; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D014734:Vibrio cholerae / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D001618:beta-Lactamases / Q000235:genetics / Q000378:metabolism*; D020764:cdc42 GTP-Binding Protein / Q000378:metabolism; D020742:rhoA GTP-Binding Protein / Q000378:metabolism
chemical_list: D000199:Actins; D001427:Bacterial Toxins; C434464:RtxA protein, Vibrio cholerae; D001618:beta-Lactamases; D020764:cdc42 GTP-Binding Protein; D020742:rhoA GTP-Binding Protein