Horn Carsten, Jenewein Stefan, Sohn-Bösser Linda, Bremer Erhard, Schmitt Lutz
Institute of Biochemistry, Heinrich Heine University Düsseldorf, Düsseldorf, Germany.
J Mol Microbiol Biotechnol. 2005;10(2-4):76-91. doi: 10.1159/000091556.
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.
对大多数微生物来说，适应不断变化的渗透条件是其生存和细胞活力的先决条件。在革兰氏阳性土壤细菌枯草芽孢杆菌中，有五种转运系统催化相容性溶质跨质膜的摄取，使枯草芽孢杆菌能够在广泛的渗透条件下生长。本综述的重点是渗透保护剂摄取A（OpuA）转运蛋白，它是底物结合蛋白（SBP）依赖性ATP结合盒（ABC）转运蛋白家族的成员，介导相容性溶质甘氨酸甜菜碱和脯氨酸甜菜碱的摄取。OpuA由三个亚基组成：位于胞质溶胶中的核苷酸结合结构域（OpuAA）、跨膜结构域（OpuAB）和SBP（OpuAC），后者以高特异性结合甘氨酸甜菜碱和脯氨酸甜菜碱，并将其靶向OpuAB，以便通过ATP依赖性转运穿过质膜。在简要介绍细菌渗透适应领域后，我们将总结我们最近关于OpuA系统各组分生化和结构分析的发现。我们的研究涵盖了OpuA转运蛋白的分离亚基以及对整个转运蛋白的初步体外研究。
