title: Contact-Dependent Growth Inhibition (CDI) and CdiB/CdiA Two-Partner Secretion Proteins.
abstract: Bacteria have developed several strategies to communicate and compete with one another in complex environments. One important mechanism of inter-bacterial competition is contact-dependent growth inhibition (CDI), in which Gram-negative bacteria use CdiB/CdiA two-partner secretion proteins to suppress the growth of neighboring target cells. CdiB is an Omp85 outer-membrane protein that exports and assembles CdiA exoproteins onto the inhibitor cell surface. CdiA binds to receptors on susceptible bacteria and subsequently delivers its C-terminal toxin domain (CdiA-CT) into the target cell. CDI systems also encode CdiI immunity proteins, which specifically bind to the CdiA-CT and neutralize its toxin activity, thereby protecting CDI(+) cells from auto-inhibition. Remarkably, CdiA-CT sequences are highly variable between bacteria, as are the corresponding CdiI immunity proteins. Variations in CDI toxin/immunity proteins suggest that these systems function in bacterial self/non-self recognition and thereby play an important role in microbial communities. In this review, we discuss recent advances in the biochemistry, structural biology and physiology of CDI.
authors.affiliation: Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA 93106-9625, USA.
authors.forename: Julia L E
authors.initials: JL
authors.lastname: Willett
authors.affiliation: Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA 93106-9625, USA.
authors.forename: Zachary C
authors.initials: ZC
authors.lastname: Ruhe
authors.affiliation: Department of Molecular Biology and Biochemistry, University of California, Irvine, Irvine, CA 92697, USA; Department of Pharmaceutical Sciences, University of California, Irvine, Irvine, CA 92697, USA.
authors.forename: Celia W
authors.initials: CW
authors.lastname: Goulding
authors.affiliation: Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA 93106-9625, USA; Biomolecular Science and Engineering Program, University of California, Santa Barbara, Santa Barbara, CA 93106-9625, USA.
authors.forename: David A
authors.initials: DA
authors.lastname: Low
authors.affiliation: Department of Molecular, Cellular and Developmental Biology, University of California, Santa Barbara, Santa Barbara, CA 93106-9625, USA; Biomolecular Science and Engineering Program, University of California, Santa Barbara, Santa Barbara, CA 93106-9625, USA.
authors.forename: Christopher S
authors.initials: CS
authors.lastname: Hayes
mesh_terms: D000595:Amino Acid Sequence; D001419:Bacteria / Q000254:growth & development* / Q000276:immunology / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D001427:Bacterial Toxins / Q000737:chemistry / Q000378:metabolism; D018441:Biofilms; D029968:Escherichia coli Proteins / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D016680:Genome, Bacterial; D006094:Gram-Positive Bacteria / Q000254:growth & development / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D059013:Microbial Consortia; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary
chemical_list: D001426:Bacterial Proteins; D001427:Bacterial Toxins; C503242:CdiA protein, E coli; C513104:CdiB protein, E coli; D029968:Escherichia coli Proteins; D008565:Membrane Proteins
keywords: biofilms; self/non-self recognition; toxin/immunity proteins; type V secretion