title: Native structure of a type IV secretion system core complex essential for Legionella pathogenesis.
abstract: Bacterial type IV secretion systems are evolutionarily related to conjugation systems and play a pivotal role in infection by delivering numerous virulence factors into host cells. Using transmission electron microscopy, we report the native molecular structure of the core complex of the Dot/Icm type IV secretion system encoded by Legionella pneumophila, an intracellular human pathogen. The biochemically isolated core complex, composed of at least five proteins--DotC, DotD, DotF, DotG, and DotH--has a ring-shaped structure. Intriguingly, morphologically distinct premature complexes are formed in the absence of DotG or DotF. Our data suggest that DotG forms a central channel spanning inner and outer membranes. DotF, a component dispensable for type IV secretion, plays a role in efficient embedment of DotG into the functional core complex. These results highlight a common scheme for the biogenesis of transport machinery.
authors: Laboratory of Combined Research on Microbiology and Immunology, Research Institute for Microbial Diseases, Osaka University, Yamadaoka 3-1, Suita, Osaka 565-0871, Japan; and.
authors: Tomoko
authors: T
authors: Kubori
authors: Laboratory of Combined Research on Microbiology and Immunology, Research Institute for Microbial Diseases, Osaka University, Yamadaoka 3-1, Suita, Osaka 565-0871, Japan; and.
authors: Masafumi
authors: M
authors: Koike
authors: Laboratory of Combined Research on Microbiology and Immunology, Research Institute for Microbial Diseases, Osaka University, Yamadaoka 3-1, Suita, Osaka 565-0871, Japan; and.
authors: Xuan Thanh
authors: XT
authors: Bui
authors: Faculty of Life and Environmental Sciences, Prefectural University of Hiroshima, Shobara, Hiroshima 727-0023, Japan.
authors: Saori
authors: S
authors: Higaki
authors: Faculty of Life and Environmental Sciences, Prefectural University of Hiroshima, Shobara, Hiroshima 727-0023, Japan.
authors: Shin-Ichi
authors: S
authors: Aizawa
authors: Laboratory of Combined Research on Microbiology and Immunology, Research Institute for Microbial Diseases, Osaka University, Yamadaoka 3-1, Suita, Osaka 565-0871, Japan; and hnagai@biken.osaka-u.ac.jp.
authors: Hiroki
authors: H
authors: Nagai
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology / Q000648:ultrastructure; D058947:Bacterial Secretion Systems / Q000235:genetics / Q000502:physiology*; D002462:Cell Membrane / Q000502:physiology / Q000648:ultrastructure; D005798:Genes, Bacterial; D054884:Host-Pathogen Interactions; D006801:Humans; D016952:Legionella pneumophila / Q000472:pathogenicity* / Q000502:physiology / Q000648:ultrastructure*; D046529:Microscopy, Electron, Transmission; D008954:Models, Biological; D008958:Models, Molecular; D046912:Multiprotein Complexes / Q000235:genetics / Q000502:physiology / Q000648:ultrastructure; D055503:Protein Multimerization; D014774:Virulence / Q000235:genetics / Q000502:physiology
chemical_list: D001426:Bacterial Proteins; D058947:Bacterial Secretion Systems; D046912:Multiprotein Complexes
keywords: assembly pathway; effector translocation; membrane proteins; nanomachine