title: Type III Secretion: Building and Operating a Remarkable Nanomachine.
abstract: The Type III secretion system (T3SS) is a protein export pathway that is widespread in Gram-negative bacteria and delivers effector proteins directly into eukaryotic cells. At its core lie the injectisome (a sophisticated transmembrane secretion apparatus) and a complex network of specialized chaperones that target secretory proteins to the antechamber of the injectisome. The assembly of the system, and the subsequent secretion of proteins through it, undergo fine-tuned, hierarchical regulation. Here, we present the current understanding of the injectisome assembly process, secretion hierarchy, and the role of chaperones. We discuss these events in light of available structural and biochemical dissection and propose future directions essential to revealing mechanistic insight into this fascinating nanomachine.
authors.affiliation: KU Leuven, Rega Institute for Medical Research, Department of Microbiology and Immunology, Laboratory of Molecular Bacteriology, 3000 Leuven, Belgium; Institute of Molecular Biology and Biotechnology, FORTH, University of Crete, PO Box 1385, Iraklio, Crete, GR-711 10 Greece; Department of Biology, University of Crete, PO Box 1385, GR-711 10 Iraklio, Crete, Greece.
authors.forename: Athina G
authors.initials: AG
authors.lastname: Portaliou
authors.affiliation: KU Leuven, Rega Institute for Medical Research, Department of Microbiology and Immunology, Laboratory of Molecular Bacteriology, 3000 Leuven, Belgium; Institute of Molecular Biology and Biotechnology, FORTH, University of Crete, PO Box 1385, Iraklio, Crete, GR-711 10 Greece; Department of Biology, University of Crete, PO Box 1385, GR-711 10 Iraklio, Crete, Greece.
authors.forename: Konstantinos C
authors.initials: KC
authors.lastname: Tsolis
authors.affiliation: KU Leuven, Rega Institute for Medical Research, Department of Microbiology and Immunology, Laboratory of Molecular Bacteriology, 3000 Leuven, Belgium; Institute of Molecular Biology and Biotechnology, FORTH, University of Crete, PO Box 1385, Iraklio, Crete, GR-711 10 Greece.
authors.forename: Maria S
authors.initials: MS
authors.lastname: Loos
authors.affiliation: KU Leuven, Rega Institute for Medical Research, Department of Microbiology and Immunology, Laboratory of Molecular Bacteriology, 3000 Leuven, Belgium.
authors.forename: Valentina
authors.initials: V
authors.lastname: Zorzini
authors.affiliation: KU Leuven, Rega Institute for Medical Research, Department of Microbiology and Immunology, Laboratory of Molecular Bacteriology, 3000 Leuven, Belgium; Institute of Molecular Biology and Biotechnology, FORTH, University of Crete, PO Box 1385, Iraklio, Crete, GR-711 10 Greece; Department of Biology, University of Crete, PO Box 1385, GR-711 10 Iraklio, Crete, Greece. Electronic address: tassos.economou@rega.kuleuven.be.
authors.forename: Anastassios
authors.initials: A
authors.lastname: Economou
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism; D006090:Gram-Negative Bacteria / Q000378:metabolism*; D036103:Nanotechnology
chemical_list: D001426:Bacterial Proteins
keywords: Type III secretion (T3S); Type III secretion system (T3SS); chaperones; energy requirements; injectisome assembly; secretion regulation