title: Intercellular communication by related bacterial protein toxins: colicins, contact-dependent inhibitors, and proteins exported by the type VI secretion system.
abstract: Bacteria are in constant conflict with competing bacterial and eukaryotic cells. To cope with the various challenges, bacteria developed distinct strategies, such as toxins that inhibit the growth or kill rivals of the same ecological niche. In recent years, two toxin systems have been discovered - the type VI secretion system and the contact-dependent growth inhibition (CDI) system. These systems have structural and functional similarities and share features with the long-known gram-negative bacteriocins, such as small immunity proteins that bind to and inactivate the toxins, and target sites on DNA, tRNA, rRNA, murein (peptidoglycan), or the cytoplasmic membrane. Colicins, CdiA proteins, and certain type VI toxins have a modular design with the transport functions localized in the N-terminal region and the activity functions localized in the C-terminal region. Despite these common properties, the sequences of toxins and immunity proteins of colicins, CDI systems, and type VI systems show little similarity.
authors.affiliation: Department of Protein Evolution, Max Planck Institute for Developmental Biology, Tübingen, Germany. volkmar.braun@tuebingen.mpg.de
authors.forename: Volkmar
authors.initials: V
authors.lastname: Braun
authors.forename: Silke I
authors.initials: SI
authors.lastname: Patzer
mesh_terms: D001419:Bacteria / Q000254:growth & development / Q000378:metabolism*; D058947:Bacterial Secretion Systems; D001427:Bacterial Toxins / Q000235:genetics / Q000378:metabolism*; D003087:Colicins / Q000235:genetics / Q000378:metabolism*; D003260:Contact Inhibition; D021381:Protein Transport
chemical_list: D058947:Bacterial Secretion Systems; D001427:Bacterial Toxins; D003087:Colicins
keywords: CDI systems; colicins; type VI secretion systems