The third and fourth transmembrane domains of Slc11a1: Comparison of their structures and positioning in phospholipid model membranes
The third and fourth transmembrane domains of Slc11a1: Comparison of their structures and positioning in phospholipid model membranes
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DOI：
10.1002/bip.21115
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发表时间：
2009
期刊：
影响因子：
2.4
通讯作者：
Haiyan Qi;Lei Yang;Rong Xue;Yuande Song;Shuo Wang;Fei Li
中科院分区：
文献类型：
--
作者：
Haiyan Qi;Lei Yang;Rong Xue;Yuande Song;Shuo Wang;Fei Li
两个肽 TM3 和 TM4（分别对应于二价金属离子转运蛋白 Slc11a1 的第三和第四跨膜结构域）与磷脂模型膜（包括两性离子二肉豆蔻酰磷脂酰胆碱（DMPC）和阴离子二肉豆蔻酰磷脂酰甘油（DMPG））的相互作用，在各种肽与脂质（P:L）比例下进行了研究，使用差示扫描量热法 (DSC)、圆二色性 (CD) 和荧光技术分析肽在脂质双层中的二级结构和定位。 DSC 和荧光结果表明两种肽均插入磷脂双层中。 TM4埋入双层较深，插入位置受pH值影响较小，而TM3嵌入较浅，随着pH值的增加，位置明显向双层表面方向移动。与 TM3 相比，两种脂质中 TM4 的掺入对脂质疏水链的堆积造成更多干扰。此外，TM3 对脂质堆积的扰动与 pH 相关，而 TM4 的扰动与 pH 依赖性较小，但与 pH 4 和 7 相比，pH 5.5 时主转变的焓变化异常大。CD 数据表明，TM4 和 TM3 二级结构之间的主要区别在于 α 螺旋含量，两种脂质中 TM4 的螺旋度高于 TM3。肽的折叠也受到磷脂的组成的影响。对于这两种肽，阴离子脂质 DMPG 比中性脂质 DMPC 诱导更多的 α 螺旋折叠。 © 2008 Wiley periodicals, Inc. 生物聚合物（Pept Sci）92：52–64，2009。
Interactions of two peptides TM3 and TM4, corresponding to the third and fourth transmembrane domains of a divalent metal‐ion transporter Slc11a1, respectively, with phospholipid model membranes, including zwitterionic dimyristoylphosphatidylcholine (DMPC) and anionic dimyristoylphosphatidylglycerol (DMPG), are studied in a wide range of peptide‐to‐lipid (P:L) ratios, and the secondary structures and positioning of the peptides in the lipid bilayers are analyzed, using differential scanning calorimetry (DSC), circular dichroism (CD), and fluorescence techniques. DSC and fluorescence results indicate that both peptides are inserted in the phospholipid bilayers. TM4 is buried in the bilayers more deeply and the insertion position is less affected by pH values, whereas TM3 is less deeply embedded and the position is remarkably shifted toward the direction of the bilayer surface with increasing pH value. The incorporation of TM4 in both lipids causes more perturbation to the packing of the hydrophobic chains of the lipids than TM3. Moreover, the perturbation of TM3 to the lipid packing is pH dependent, whereas the perturbation of TM4 is less pH dependent but with an unusually larger change in the enthalpy of the main transition at pH 5.5 than those at pH 4 and 7. CD data demonstrate that the main discrimination between the secondary structures of TM4 and TM3 is the α‐helix content, more helicity for TM4 than TM3 in both lipids. The folding of the peptides is also affected by the composition of the phospholipids. Anionic lipid DMPG induces more α‐helical folding than neutral lipid DMPC for both peptides. © 2008 Wiley Periodicals, Inc. Biopolymers (Pept Sci) 92: 52–64, 2009.