title: Structure of Rhodococcus equi virulence-associated protein B (VapB) reveals an eight-stranded antiparallel β-barrel consisting of two Greek-key motifs.
abstract: Members of the virulence-associated protein (Vap) family from the pathogen Rhodococcus equi regulate virulence in an unknown manner. They do not share recognizable sequence homology with any protein of known structure. VapB and VapA are normally associated with isolates from pigs and horses, respectively. To contribute to a molecular understanding of Vap function, the crystal structure of a protease-resistant VapB fragment was determined at 1.4 Å resolution. The structure was solved by SAD phasing employing the anomalous signal of one endogenous S atom and two bound Co ions with low occupancy. VapB is an eight-stranded antiparallel β-barrel with a single helix. Structural similarity to avidins suggests a potential binding function. Unlike other eight- or ten-stranded β-barrels found in avidins, bacterial outer membrane proteins, fatty-acid-binding proteins and lysozyme inhibitors, Vaps do not have a next-neighbour arrangement but consist of two Greek-key motifs with strand order 41238567, suggesting an unusual or even unique topology.
authors.affiliation: Department of Chemistry, Bielefeld University, Universitaetsstrasse 25, 33615 Bielefeld, Germany.
authors.forename: Christina
authors.initials: C
authors.lastname: Geerds
authors.affiliation: Institute for Cell Biology, University of Bonn, Ulrich-Haberland Strasse 61a, 53121 Bonn, Germany.
authors.forename: Jens
authors.initials: J
authors.lastname: Wohlmann
authors.affiliation: Institute for Cell Biology, University of Bonn, Ulrich-Haberland Strasse 61a, 53121 Bonn, Germany.
authors.forename: Albert
authors.initials: A
authors.lastname: Haas
authors.affiliation: Department of Chemistry, Bielefeld University, Universitaetsstrasse 25, 33615 Bielefeld, Germany.
authors.forename: Hartmut H
authors.initials: HH
authors.lastname: Niemann
mesh_terms: D020816:Amino Acid Motifs; D001360:Avidin / Q000737:chemistry; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D018360:Crystallography, X-Ray; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D015870:Gene Expression; D008562:Membrane Glycoproteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D008969:Molecular Sequence Data; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D016929:Rhodococcus equi / Q000737:chemistry* / Q000378:metabolism; D040681:Structural Homology, Protein
chemical_list: D001426:Bacterial Proteins; D004268:DNA-Binding Proteins; D008562:Membrane Glycoproteins; D011994:Recombinant Proteins; D001360:Avidin; C077517:VapB protein, Bacteria
keywords: Greek-key motif; Rhodococcus equi; Vap protein family; antiparallel β-barrel; single-wavelength anomalous dispersion