title: Structural model of the gas vesicle protein GvpA and analysis of GvpA mutants in vivo.
abstract: Gas vesicles are gas-filled protein structures increasing the buoyancy of cells. The gas vesicle envelope is mainly constituted by the 8 kDa protein GvpA forming a wall with a water excluding inner surface. A structure of GvpA is not available; recent solid-state NMR results suggest a coil-α-β-β-α-coil fold. We obtained a first structural model of GvpA by high-performance de novo modelling. Attenuated total reflection (ATR)-Fourier transform infrared spectroscopy (FTIR) supported this structure. A dimer of GvpA was derived that could explain the formation of the protein monolayer in the gas vesicle wall. The hydrophobic inner surface is mainly constituted by anti-parallel β-strands. The proposed structure allows the pinpointing of contact sites that were mutated and tested for the ability to form gas vesicles in haloarchaea. Mutations in α-helix I and α-helix II, but also in the β-turn affected the gas vesicle formation, whereas other alterations had no effect. All mutants supported the structural features deduced from the model. The proposed GvpA dimers allow the formation of a monolayer protein wall, also consistent with protease treatments of isolated gas vesicles.
authors.affiliation: Institute for Nanotechnology, Karlsruhe Institute of Technology, PO Box 3640, D-76021 Karlsruhe, Germany.
authors.forename: Timo
authors.initials: T
authors.lastname: Strunk
authors.forename: Kay
authors.initials: K
authors.lastname: Hamacher
authors.forename: Franziska
authors.initials: F
authors.lastname: Hoffgaard
authors.forename: Harald
authors.initials: H
authors.lastname: Engelhardt
authors.forename: Martina Daniela
authors.initials: MD
authors.lastname: Zillig
authors.forename: Karin
authors.initials: K
authors.lastname: Faist
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Wenzel
authors.forename: Felicitas
authors.initials: F
authors.lastname: Pfeifer
mesh_terms: D000595:Amino Acid Sequence; D019605:Euryarchaeota / Q000235:genetics* / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D050505:Mutant Proteins / Q000235:genetics / Q000378:metabolism; D020125:Mutation, Missense; D055503:Protein Multimerization; D020836:Protein Structure, Quaternary; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D050505:Mutant Proteins; D011506:Proteins; C038524:gas vesicle protein