Effect of Leucine to Phenylalanine Substitution on the Nonpolar Face of a Class A Amphipathic Helical Peptide on Its Interaction with Lipid HIGH RESOLUTION SOLUTION NMR STUDIES OF 4F-DIMYRISTOYLPHOSPHATIDYLCHOLINE DISCOIDAL COMPLEX
Effect of Leucine to Phenylalanine Substitution on the Nonpolar Face of a Class A Amphipathic Helical Peptide on Its Interaction with Lipid HIGH RESOLUTION SOLUTION NMR STUDIES OF 4F-DIMYRISTOYLPHOSPHATIDYLCHOLINE DISCOIDAL COMPLEX
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DOI：
10.1074/jbc.m806384200
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发表时间：
2008-12-05
影响因子：
4.8
通讯作者：
Anantharamaiah, G. M.
中科院分区：
文献类型：
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作者：
Mishra, Vinod K.;Palgunachari, Mayakonda N.;Anantharamaiah, G. M.
模型A类两亲性螺旋肽模拟载脂蛋白A-I（apoA-I）（高密度脂蛋白的主要蛋白质组分）的若干性质。先前，我们报道了Ac-18A-NH2（由于两个苯丙氨酸而重新命名为2F）的NMR结构，Ac-18A-NH2是在脂质存在下的基线模型A类两亲性螺旋肽（Mishra，V.K.，Anantharamaiah，G. M.，Segrest，J. P.，Palgunachari，M. N.，Chaddha，M.，沈国放，S. W.，和Krishna，N. R.（2006）J Biol. Chem. 281，6511 - 6519）。用Phe残基取代非极性表面上的两个Leu残基（Leu3和Leu（14））产生肽4F（因四个苯丙氨酸而如此命名），其抗炎和抗动脉粥样硬化特性已被广泛研究。与2F一样，4F也与1，2-二肉豆蔻酰甘油-3-磷酸胆碱（DMPC）形成盘状新生高密度脂蛋白样颗粒。由于肽-脂质复合物中的细微结构变化已被证明是其抗动脉粥样硬化性质的原因，因此我们进行了高分辨率NMR研究以推断4F中心点DMPC圆盘中4F的详细结构。与2F一样，4F采用明确的两亲性α-螺旋结构，以1：1的肽/脂质重量比与脂质结合。核Overhauser效应（NOE）光谱揭示了一些分子间的紧密接触的芳香族残基之间的疏水性面对的螺旋和脂酰基链质子。与2F相似，观察到的肽-脂质NOE的模式与圆盘边缘上两亲性α螺旋相对于脂质双层平面的平行取向一致（带模型）。然而，与2F α DMPC中的2F相反，4F α DMPC复合物中的4F更靠近脂质头基，如4F和DMPC头基质子之间的NOE数所证明。这些NOE在2F中心点DMPC复合物中不存在。此外，4F中心点DMPC复合物中DMPC sn-3链的构象与2F中心点DMPC复合物中不同，如4F中心点DMPC中脂质2.CH和β CH2质子之间的NOE所证明，但在2F中心点DMPC复合物中并非如此。基于本研究的结果，我们推断4F的抗动脉粥样硬化性质可能是由于其优先与脂质头基相互作用。
Model class A amphipathic helical peptides mimic several properties of apolipoprotein A-I (apoA-I), the major protein component of high density lipoproteins. Previously, we reported the NMR structures of Ac-18A-NH2 (renamed as 2F because of two phenylalanines), the base-line model class A amphipathic helical peptide in the presence of lipid (Mishra, V. K., Anantharamaiah, G. M., Segrest, J. P., Palgunachari, M. N., Chaddha, M., Simon Sham, S. W., and Krishna, N. R. ( 2006) J Biol. Chem. 281, 6511-6519). Substitution of two Leu residues on the nonpolar face (Leu3 and Leu(14)) with Phe residues produced the peptide 4F (so named because of four phenylalanines), which has been extensively studied for its anti-inflammatory and antiatherogenic properties. Like 2F, 4F also forms discoidal nascent high density lipoprotein-like particles with 1,2-dimyristoylsn-glycero-3-phosphocholine (DMPC). Since subtle structural changes in the peptide-lipid complexes have been shown to be responsible for their antiatherogenic properties, we undertook high resolution NMR studies to deduce detailed structure of 4F in 4F center dot DMPC discs. Like 2F, 4F adopts a well defined amphipathic alpha-helical structure in association with the lipid at a 1:1 peptide/lipid weight ratio. Nuclear Overhauser effect (NOE) spectroscopy revealed a number of intermolecular close contacts between the aromatic residues in the hydrophobic face of the helix and the lipid acyl chain protons. Similar to 2F, the pattern of observed peptide-lipid NOEs is consistent with a parallel orientation of the amphipathic alpha helix, with respect to the plane of the lipid bilayer, on the edge of the disc (the belt model). However, in contrast to 2F in 2F alpha DMPC, 4F in the 4F alpha DMPC complex is located closer to the lipid headgroup as evidenced by a number of NOEs between 4F and DMPC headgroup protons. These NOEs are absent in the 2F center dot DMPC complex. In addition, the conformation of the DMPC sn-3 chain in 4F center dot DMPC complex is different than in the 2F center dot DMPC complex as evidenced by the NOE between lipid 2.CH and beta CH2 protons in 4F center dot DMPC, but not in 2F center dot DMPC, complex. Based on the results of this study, we infer that the antiatherogenic properties of 4F may result from its preferential interaction with lipid headgroups.