title: Structure of Salmonella FlhE, conserved member of a flagellar type III secretion operon.
abstract: The bacterial flagellum is assembled by a multicomponent transport apparatus categorized as a type III secretion system. The secretion of proteins that assemble into the flagellum is driven by the proton motive force. The periplasmic protein FlhE is a member of the flhBAE operon in the majority of bacteria where FlhE is found. FlhA and FlhB are established components of the flagellar type III secretion system. The absence of FlhE results in a proton leak through the flagellar system, inappropriate secretion patterns, and cell death, indicating that FlhE regulates an important aspect of proper flagellar biosynthesis. We isolated FlhE from the periplasm of Salmonella and solved its structure to 1.5Å resolution. The structure reveals a β-sandwich fold, with no close structural homologs. Possible roles of FlhE, including that of a chaperone, are discussed.
authors.affiliation: Department of Molecular Biosciences and Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA.
authors.forename: Jaemin
authors.initials: J
authors.lastname: Lee
authors.affiliation: Department of Molecular Biosciences and Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA.
authors.forename: Arthur F
authors.initials: AF
authors.lastname: Monzingo
authors.affiliation: Department of Molecular Biosciences and Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA.
authors.forename: Adrian T
authors.initials: AT
authors.lastname: Keatinge-Clay
authors.affiliation: Department of Molecular Biosciences and Institute for Cellular and Molecular Biology, University of Texas at Austin, Austin, TX 78712, USA. Electronic address: rasika@austin.utexas.edu.
authors.forename: Rasika M
authors.initials: RM
authors.lastname: Harshey
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism; D058947:Bacterial Secretion Systems; D002850:Chromatography, Gel; D018360:Crystallography, X-Ray; D005407:Flagella / Q000378:metabolism*; D008969:Molecular Sequence Data; D009876:Operon; D011487:Protein Conformation; D012486:Salmonella typhimurium / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid
chemical_list: D001426:Bacterial Proteins; D058947:Bacterial Secretion Systems; C091067:FlhE protein, Salmonella typhimurium
keywords: flagellar motility; proton leak; proton motive force