title: Assembly and mechanisms of bacterial type IV secretion machines.
abstract: Type IV secretion occurs across a wide range of prokaryotic cell envelopes: Gram-negative, Gram-positive, cell wall-less bacteria and some archaea. This diversity is reflected in the heterogeneity of components that constitute the secretion machines. Macromolecules are secreted in an ATP-dependent process using an envelope-spanning multi-protein channel. Similar to the type III systems, this apparatus extends beyond the cell surface as a pilus structure important for direct contact and penetration of the recipient cell surface. Type IV systems are remarkably versatile in that they mobilize a broad range of substrates, including single proteins, protein complexes, DNA and nucleoprotein complexes, across the cell envelope. These machines have broad clinical significance not only for delivering bacterial toxins or effector proteins directly into targeted host cells, but also for direct involvement in phenomena such as biofilm formation and the rapid horizontal spread of antibiotic resistance genes among the microbial community.
authors.affiliation: Institute of Molecular Biosciences, University of Graz, Humboldtstrasse 50/I, Graz 8010, Austria. ellen.zechner@uni-graz.at
authors.forename: Ellen L
authors.initials: EL
authors.lastname: Zechner
authors.forename: Silvia
authors.initials: S
authors.lastname: Lang
authors.forename: Joel F
authors.initials: JF
authors.lastname: Schildbach
mesh_terms: D001419:Bacteria / Q000737:chemistry* / Q000235:genetics; D058947:Bacterial Secretion Systems; D002462:Cell Membrane / Q000737:chemistry; D003227:Conjugation, Genetic; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D036781:Fimbriae Proteins / Q000737:chemistry; D010861:Fimbriae, Bacterial / Q000737:chemistry*; D046911:Macromolecular Substances / Q000737:chemistry; D018832:Molecular Chaperones / Q000737:chemistry; D025941:Protein Interaction Mapping; D055550:Protein Stability; D021381:Protein Transport; D015398:Signal Transduction; D013379:Substrate Specificity
chemical_list: D058947:Bacterial Secretion Systems; D004269:DNA, Bacterial; D046911:Macromolecular Substances; D018832:Molecular Chaperones; D036781:Fimbriae Proteins