Structure analysis and conformational transitions of the cell penetrating peptide transportan 10 in the membrane-bound state.
Structure analysis and conformational transitions of the cell penetrating peptide transportan 10 in the membrane-bound state.
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DOI：
10.1371/journal.pone.0099653
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发表时间：
2014
期刊：
影响因子：
3.7
通讯作者：
Ulrich AS
中科院分区：
文献类型：
--
作者：
Fanghänel S;Wadhwani P;Strandberg E;Verdurmen WP;Bürck J;Ehni S;Mykhailiuk PK;Afonin S;Gerthsen D;Komarov IV;Brock R;Ulrich AS
细胞穿透肽转运蛋白10（TP 10）的结构分析揭示了在膜结合状态下的不同构象的示例性范围。发现二分肽（N-末端来源于甘丙肽，C-末端来源于mastoparan）表现出（i）两亲性α-螺旋，（ii）内在无序肽以及（iii）β-折叠淀粉样蛋白原纤维的突出特征，并且这些构象状态作为浓度的函数相互转化。我们使用了一种互补的方法，固态19 F-NMR和圆二色性取向膜样品的结构和动力学行为的特征TP 10在其单体和聚集的形式。用3-（三氟甲基）-双环[1.1.1]-1-基甘氨酸（CF 3-Bpg）的L -或D -对映体作为19 F-NMR的报告基团选择性地取代肽中的九个不同位置。使用L -差向异构体类似物，在低肽浓度下在脂质双层中进行全面的三维结构分析，其中TP 10是单体。虽然N-末端区域是柔性的，并且在脂质双层的平面内本质上是非结构化的，但C-末端α-螺旋以1.55 °的倾斜角嵌入膜中，并且与其两亲性特征一致。将空间阻塞性D-CF 3-Bpg报告基团并入螺旋区中导致膜结合肽的局部解折叠。在高浓度下，这些螺旋失稳的C-末端取代促进聚集成不动的β-折叠，其类似于淀粉样蛋白原纤维。另一方面，阻碍性D-CF 3-Bpg取代可以容纳在TP 10的柔性N-末端，在那里它们在高浓度下不促进聚集。因此，TP 10的两个区域之间的串扰对其构象转换施加了微妙的平衡，因为α-螺旋的存在抵消了未折叠的N-末端自组装成β-折叠原纤维的趋势。
Structure analysis of the cell-penetrating peptide transportan 10 (TP10) revealed an exemplary range of different conformations in the membrane-bound state. The bipartite peptide (derived N-terminally from galanin and C-terminally from mastoparan) was found to exhibit prominent characteristics of (i) amphiphilic α-helices, (ii) intrinsically disordered peptides, as well as (iii) β-pleated amyloid fibrils, and these conformational states become interconverted as a function of concentration. We used a complementary approach of solid-state 19F-NMR and circular dichroism in oriented membrane samples to characterize the structural and dynamical behaviour of TP10 in its monomeric and aggregated forms. Nine different positions in the peptide were selectively substituted with either the L - or D -enantiomer of 3-(trifluoromethyl)-bicyclopent-[1.1.1]-1-ylglycine (CF3 -Bpg) as a reporter group for 19F-NMR. Using the L -epimeric analogs, a comprehensive three-dimensional structure analysis was carried out in lipid bilayers at low peptide concentration, where TP10 is monomeric. While the N-terminal region is flexible and intrinsically unstructured within the plane of the lipid bilayer, the C-terminal α-helix is embedded in the membrane with an oblique tilt angle of ∼55° and in accordance with its amphiphilic profile. Incorporation of the sterically obstructive D -CF3 -Bpg reporter group into the helical region leads to a local unfolding of the membrane-bound peptide. At high concentration, these helix-destabilizing C-terminal substitutions promote aggregation into immobile β-sheets, which resemble amyloid fibrils. On the other hand, the obstructive D -CF3 -Bpg substitutions can be accommodated in the flexible N-terminus of TP10 where they do not promote aggregation at high concentration. The cross-talk between the two regions of TP10 thus exerts a delicate balance on its conformational switch, as the presence of the α-helix counteracts the tendency of the unfolded N-terminus to self-assemble into β-pleated fibrils.
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