Department of Biochemistry, University of Zurich, Zurich, Switzerland.
Institute of Biochemistry, Biocenter, Goethe-University Frankfurt, Frankfurt am Main, Germany.
Nat Struct Mol Biol. 2015 Oct;22(10):803-8. doi: 10.1038/nsmb.3091. Epub 2015 Sep 14.
The SLC26 family of membrane proteins combines a variety of functions within a conserved molecular scaffold. Its members, besides coupled anion transporters and channels, include the motor protein Prestin, which confers electromotility to cochlear outer hair cells. To gain insight into the architecture of this protein family, we characterized the structure and function of SLC26Dg, a facilitator of proton-coupled fumarate symport, from the bacterium Deinococcus geothermalis. Its modular structure combines a transmembrane unit and a cytoplasmic STAS domain. The membrane-inserted domain consists of two intertwined inverted repeats of seven transmembrane segments each and resembles the fold of the unrelated transporter UraA. It shows an inward-facing, ligand-free conformation with a potential substrate-binding site at the interface between two helix termini at the center of the membrane. This structure defines the common framework for the diverse functional behavior of the SLC26 family.
SLC26 家族的膜蛋白在保守的分子支架内结合了多种功能。其成员除了偶联阴离子转运体和通道外，还包括赋予耳蜗外毛细胞电动性的运动蛋白 Prestin。为了深入了解该蛋白家族的结构，我们对来自嗜热栖热菌的 SLC26Dg（促进质子偶联延胡索酸盐协同转运）的结构和功能进行了表征。它的模块化结构结合了一个跨膜单元和一个细胞质 STAS 结构域。膜插入结构域由两个相互交织的七次跨膜片段的反向重复组成，类似于无关转运体 UraA 的折叠。它呈现出一个向内的、无配体的构象，在膜中心两个螺旋末端之间的界面处具有潜在的底物结合位点。该结构定义了 SLC26 家族多样化功能行为的共同框架。
