title: Biochemical and structural analysis of the Bacillus subtilis ABC transporter OpuA and its isolated subunits.
abstract: Adaptation of microorganisms to changing osmotic conditions is a prerequisite for survival and cellular vitality for most microorganisms. In the Gram-positive soil bacterium Bacillus subtilis, five transport systems catalyze the uptake of compatible solutes across the plasma membrane that allow the growth of B. subtilis over a wide range of osmotic conditions. Focus of this review is the osmoprotectant uptake A (OpuA) transporter, a member of the family of substrate-binding protein (SBP)-dependent ATP-binding cassette (ABC) transporters that mediates the uptake of the compatible solutes glycine betaine and proline betaine. OpuA is composed of three subunits: a nucleotide-binding domain (OpuAA) located in the cytosol, a transmembrane domain (OpuAB), and a SBP (OpuAC), which binds glycine betaine and proline betaine with high specificity and targets it to OpuAB for ATP-dependent translocation across the plasma membrane. After a brief introduction in the field of bacterial osmoadaptation, we will summarize our recent findings about the biochemical and structural analysis of the components of the OpuA systems. Our studies covered both the isolated subunits of the OpuA transporter and initial investigations of the whole transporter in vitro.
authors.affiliation: Institute of Biochemistry, Heinrich Heine University Düsseldorf, Düsseldorf, Germany.
authors.forename: Carsten
authors.initials: C
authors.lastname: Horn
authors.forename: Stefan
authors.initials: S
authors.lastname: Jenewein
authors.forename: Linda
authors.initials: L
authors.lastname: Sohn-Bösser
authors.forename: Erhard
authors.initials: E
authors.lastname: Bremer
authors.forename: Lutz
authors.initials: L
authors.lastname: Schmitt
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000737:chemistry / Q000378:metabolism*; D000595:Amino Acid Sequence; D001412:Bacillus subtilis / Q000378:metabolism*; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D001665:Binding Sites; D019281:Dimerization; D008958:Models, Molecular; D008969:Molecular Sequence Data; D021122:Protein Subunits / Q000737:chemistry / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid
chemical_list: D018528:ATP-Binding Cassette Transporters; D001426:Bacterial Proteins; D021122:Protein Subunits