title: Activation of contact-dependent antibacterial tRNase toxins by translation elongation factors.
abstract: Contact-dependent growth inhibition (CDI) is a mechanism by which bacteria exchange toxins via direct cell-to-cell contact. CDI systems are distributed widely among Gram-negative pathogens and are thought to mediate interstrain competition. Here, we describetsfmutations that alter the coiled-coil domain of elongation factor Ts (EF-Ts) and confer resistance to the CdiA-CTEC869tRNase toxin from enterohemorrhagicEscherichia coliEC869. Although EF-Ts is required for toxicity in vivo, our results indicate that it is dispensable for tRNase activity in vitro. We find that CdiA-CTEC869binds to elongation factor Tu (EF-Tu) with high affinity and this interaction is critical for nuclease activity. Moreover, in vitro tRNase activity is GTP-dependent, suggesting that CdiA-CTEC869only cleaves tRNA in the context of translationally active GTP·EF-Tu·tRNA ternary complexes. We propose that EF-Ts promotes the formation of GTP·EF-Tu·tRNA ternary complexes, thereby accelerating substrate turnover for rapid depletion of target-cell tRNA.
authors.affiliation: Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, CA 93106.
authors.forename: Allison M
authors.initials: AM
authors.lastname: Jones
authors.affiliation: Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, CA 93106.
authors.forename: Fernando
authors.initials: F
authors.lastname: Garza-Sánchez
authors.affiliation: Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, CA 93106.
authors.forename: Jaime
authors.initials: J
authors.lastname: So
authors.affiliation: Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, CA 93106.|Biomolecular Science and Engineering Program, University of California, Santa Barbara, CA 93106.
authors.forename: Christopher S
authors.initials: CS
authors.lastname: Hayes
authors.affiliation: Department of Molecular, Cellular, and Developmental Biology, University of California, Santa Barbara, CA 93106; david.low@lifesci.ucsb.edu.|Biomolecular Science and Engineering Program, University of California, Santa Barbara, CA 93106.
authors.forename: David A
authors.initials: DA
authors.lastname: Low
mesh_terms: D000898:Antibiosis / Q000235:genetics; D001483:Base Sequence; D001665:Binding Sites; D003260:Contact Inhibition / Q000235:genetics; D018360:Crystallography, X-Ray; D004722:Endoribonucleases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D054324:Enterohemorrhagic Escherichia coli / Q000235:genetics* / Q000378:metabolism / Q000472:pathogenicity; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D006160:Guanosine Triphosphate / Q000737:chemistry / Q000378:metabolism; D008565:Membrane Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D009690:Nucleic Acid Conformation; D010444:Peptide Elongation Factor Tu / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D010445:Peptide Elongation Factors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D014176:Protein Biosynthesis; D000072756:Protein Conformation, alpha-Helical; D000072757:Protein Conformation, beta-Strand; D054730:Protein Interaction Domains and Motifs; D012343:RNA, Transfer / Q000737:chemistry* / Q000378:metabolism; D013379:Substrate Specificity
chemical_list: C503242:CdiA protein, E coli; D029968:Escherichia coli Proteins; D008565:Membrane Proteins; D010445:Peptide Elongation Factors; C023512:elongation factor Ts; D006160:Guanosine Triphosphate; D012343:RNA, Transfer; D004722:Endoribonucleases; D010444:Peptide Elongation Factor Tu
keywords: bacterial competition; cell communication; protein synthesis; ribonuclease; toxin-immunity proteins