Study on structure and assembly of the third transmembrane domain of Slc11a1
Study on structure and assembly of the third transmembrane domain of Slc11a1
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DOI：
10.1002/psc.1230
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发表时间：
2010-05
影响因子：
2.1
通讯作者：
Shuyan Xiao;Yuxia Wang;Lei Yang;Haiyan Qi;Chunyu Wang;Fei Li
中科院分区：
文献类型：
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作者：
Shuyan Xiao;Yuxia Wang;Lei Yang;Haiyan Qi;Chunyu Wang;Fei Li
利用NMR和CD实验研究了Slc 11 a1及其E139 A突变体的第三跨膜结构域（TMD 3）肽段在1，1，1，3，3，3-六氟-2-丙醇（HFIP）水溶液中的结构和自组装。Slc 11 a1是一种整合的膜蛋白，具有12个推定的TMD，并作为pH偶联的二价金属阳离子转运蛋白发挥作用。Slc 11 a1的Glu 139在预测的Slc 11蛋白家族的TMD 3内高度保守并且功能相关。在这里，我们使用CD和NMR光谱为Slc 11 a1及其E139 A突变体在60% HFIP-d2水溶液中对应于TMD 3的两个24残基肽的结构特征提供了第一个直接的实验证据。我们的研究表明，跨膜肽从Ile 5到Met 20折叠为典型的两亲性α螺旋结构，亲水残基Glu 12（Slc 11 a1中的Glu 139）和Asp 19位于螺旋的同一侧。Glu 139被丙氨酸残基取代对肽的结构几乎没有影响，但增加了疏水性并促进了肽的自组装。虽然野生型肽在HFIP水溶液中是单体，但E139 A突变体形成二聚体。E139 A突变引起的跨膜肽疏水性的增加和/或跨膜片段之间相互作用的改变可能会影响蛋白质的金属离子转运。版权所有© 2010欧洲肽协会和约翰威利父子有限公司。
The structure and self‐assembly of the peptide corresponding to the third transmembrane domain (TMD3) of Slc11a1 and its E139A mutant are studied in 1,1,1,3,3,3‐hexafluoro‐2‐propanol (HFIP) aqueous solution by NMR and CD experiments. Slc11a1 is an integral membrane protein with 12 putative TMDs and functions as a pH‐coupled divalent metal cation transporter. Glu139 of Slc11a1 is highly conserved within predicted TMD3 of the Slc11 protein family and function‐associated. Here, we provide the first direct experimental evidence for the structural features of two 24‐residue peptides corresponding to TMD3 of Slc11a1 and its E139A mutant in 60% HFIP‐d2 aqueous solution using CD and NMR spectroscopies. Our study shows that the membrane‐spanning peptide folds as a typical amphipathic α‐helix structure from Ile5 to Met20 with hydrophilic residues Glu12 (Glu139 in Slc11a1) and Asp19 lying on the same side of the helix. The substitution of Glu139 by an alanine residue has little effect on the structure of the peptide, but increases hydrophobicity and facilitates self‐assembly of the peptide. Although the wildtype peptide is monomeric in HFIP aqueous solution, the E139A mutant forms a dimer. The increase in hydrophobicity of the membrane‐spanning peptide and/or change in the interactions between transmembrane segments induced by E139A mutation may affect the metal ion transport of the protein. Copyright © 2010 European Peptide Society and John Wiley & Sons, Ltd.