title: The blueprint of the type-3 injectisome.
abstract: Type-3 secretion systems are sophisticated syringe-like nanomachines present in many animal and plant Gram-negative pathogens. They are capable of translocating an arsenal of specific bacterial toxins (effector proteins) from the prokaryotic cytoplasm across the three biological membranes directly into the eukaryotic cytosol, some of which modulate host cell mechanisms for the benefit of the pathogen. They populate a particular biological niche, which is maintained by specific, pathogen-dependent effectors. In contrast, the needle complex, which is the central component of this specialized protein delivery machine, is structurally well-conserved. It is a large supramolecular cylindrical structure composed of multiple copies of a relatively small subset of proteins, is embedded in the bacterial membranes and protrudes from the pathogen's surface with a needle filament. A central channel traverses the entire needle complex, and serves as a hollow conduit for proteins destined to travel this secretion pathway. In the past few years, there has been a tremendous increase in an understanding on both the structural and the mechanistic level. This review will thus focus on new insights of this remarkable molecular machine.
authors.affiliation: Research Institute of Molecular Pathology, Dr. Bohr Gasse 7, A-1030 Vienna,  Austria.
authors.forename: Agata
authors.initials: A
authors.lastname: Kosarewicz
authors.forename: Lisa
authors.initials: L
authors.lastname: Königsmaier
authors.forename: Thomas C
authors.initials: TC
authors.lastname: Marlovits
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry; D058947:Bacterial Secretion Systems; D006090:Gram-Negative Bacteria / Q000737:chemistry* / Q000472:pathogenicity; D016905:Gram-Negative Bacterial Infections / Q000382:microbiology; D054884:Host-Pathogen Interactions; D008565:Membrane Proteins / Q000737:chemistry*; D046912:Multiprotein Complexes / Q000737:chemistry; D017434:Protein Structure, Tertiary; D021381:Protein Transport; D013329:Structure-Activity Relationship
chemical_list: D001426:Bacterial Proteins; D058947:Bacterial Secretion Systems; D008565:Membrane Proteins; D046912:Multiprotein Complexes