Wang Dan, Song Yuande, Li Jiantao, Wang Chunyu, Li Fei
State Key Laboratory of Supramolecular Structure and Materials, Jilin University, Changchun, People's Republic of China.
Biochim Biophys Acta. 2011 Jun;1808(6):1639-44. doi: 10.1016/j.bbamem.2010.11.005. Epub 2010 Nov 11.
DMT1 is an integral membrane protein with 12 putative transmembrane domains. As a divalent metal ion transporter, it plays an important role in metal ion homeostasis from bacteria to human. Loss-function mutations at the conserved motif DPGN located within the first transmembrane domain (TMD1) of DMT1 indicate the significance of TMD1 in the biological function of the protein. In the present work, we study the structure, topology and metal ion binding of DMT1-TMD1 peptide by nuclear magnetic resonance using sodium dodecyl sulfate and dodecylphosphocholine micelles as membrane mimics. We find that the peptide forms an α-helix-extended segment-α-helix configuration in which the motif DPGN locates at the central flexible region. The N-terminal part of the peptide is deeply embedded in micelles, while the motif section and the C-terminal part are close to the surface of micelles. The peptide can bind to Mn2+ and Co2+ ions by the side chains of the negatively charged residues in the motif section and the C-terminal part of TMD1. The crucial role of the central flexible region and the C-terminal part of TMD1 in metal ion capture is confirmed by the binding of the N-terminal part truncated TMD1 to metal ions.
二价金属离子转运蛋白1（DMT1）是一种具有12个假定跨膜结构域的整合膜蛋白。作为一种二价金属离子转运体，它在从细菌到人类的金属离子稳态中发挥着重要作用。位于DMT1第一个跨膜结构域（TMD1）内保守基序DPGN处的功能丧失突变表明TMD1在该蛋白生物学功能中的重要性。在本研究中，我们以十二烷基硫酸钠和十二烷基磷酰胆碱胶束作为膜模拟物，通过核磁共振研究了DMT1 - TMD1肽段的结构、拓扑结构和金属离子结合情况。我们发现该肽段形成了α - 螺旋 - 延伸段 - α - 螺旋结构，其中基序DPGN位于中央柔性区域。肽段的N端部分深深嵌入胶束中，而基序部分和C端部分靠近胶束表面。该肽段可通过TMD1基序部分和C端部分带负电荷残基的侧链与Mn2 +和Co2 +离子结合。TMD1中央柔性区域和C端部分在金属离子捕获中的关键作用通过截短N端部分的TMD1与金属离子的结合得到证实。
