title: Solution structure of homology region (HR) domain of type II secretion system.
abstract: The type II secretion system of Gram-negative bacteria is important for bacterial pathogenesis and survival; it is composed of 12 mostly multimeric core proteins, which build a sophisticated secretion machine spanning both bacterial membranes. OutC is the core component of the inner membrane subcomplex thought to be involved in both recognition of substrate and interaction with the outer membrane secretin OutD. Here, we report the solution structure of the HR domain of OutC and explore its interaction with the secretin. The HR domain adopts a β-sandwich-like fold consisting of two β-sheets each composed of three anti-parallel β-strands. This structure is strikingly similar to the periplasmic region of PilP, an inner membrane lipoprotein from the type IV pilus system highlighting the common evolutionary origin of these two systems and showing that all the core components of the type II secretion system have a structural or sequence ortholog within the type IV pili system. The HR domain is shown to interact with the N0 domain of the secretin. The importance of this interaction is explored in the context of the functional secretion system.
authors.affiliation: School of Biological and Chemical Sciences, Queen Mary University of London, London, United Kingdom.
authors.forename: Shuang
authors.initials: S
authors.lastname: Gu
authors.forename: Geoff
authors.initials: G
authors.lastname: Kelly
authors.forename: Xiaohui
authors.initials: X
authors.lastname: Wang
authors.forename: Tom
authors.initials: T
authors.lastname: Frenkiel
authors.forename: Vladimir E
authors.initials: VE
authors.lastname: Shevchik
authors.forename: Richard W
authors.initials: RW
authors.lastname: Pickersgill
mesh_terms: D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D058947:Bacterial Secretion Systems; D004755:Enterobacteriaceae / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary
chemical_list: D001425:Bacterial Outer Membrane Proteins; D058947:Bacterial Secretion Systems