Relative Spatial Positions of Tryptophan and Cationic Residues in Helical Membrane-active Peptides Determine Their Cytotoxicity
Relative Spatial Positions of Tryptophan and Cationic Residues in Helical Membrane-active Peptides Determine Their Cytotoxicity
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DOI：
10.1074/jbc.m111.279281
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发表时间：
2012-01-02
影响因子：
4.8
通讯作者：
Vogel, Hans J.
中科院分区：
文献类型：
--
作者：
Rekdal, Oystein;Haug, Bengt Erik;Vogel, Hans J.
已经研究了理想化的两亲性螺旋21-mer肽（KAAKKAA）（3）的10种类似物的细胞毒性活性，其中在不同位置的三个Ala残基已经被Trp残基取代。肽的细胞毒活性被发现是显着依赖于一个理想化的α-螺旋的疏水部门内的色氨酸残基的位置。与色氨酸残基位于相反的阳离子部门的肽显示没有抗肿瘤活性，而那些肽与两个或三个色氨酸残基位于相邻的阳离子部门表现出高的细胞毒活性时，测试对三种不同的癌细胞系。染料释放实验显示，与具有位于阳离子部分对面的Trp残基的肽相反，Trp残基位于阳离子部分附近的肽诱导了由两性离子磷脂酰胆碱和带负电荷的磷脂酰丝氨酸的混合物组成的脂质体的强透化活性（1-棕榈酰基-2-油酰基-sn-甘油基-3-磷酸胆碱（POPC）/1-棕榈酰基-2-油酰基-sn-甘油基-3-磷酸-L-丝氨酸（POPS））（2：1），但不来自由两性离子磷脂酰胆碱POPC组成的脂质体。荧光蓝移和淬灭实验表明，Trp残基插入到POPC/POPS脂质体的疏水环境中更深，具有高细胞毒活性的肽。通过圆二色性研究，建立了细胞毒性活性与α螺旋倾向之间的相关性。一个非活性和两个活性肽在胶束的存在下，使用NMR光谱的结构研究表明，只有活性肽采用高度卷曲螺旋结构时，绑定到膜表面。
The cytotoxic activity of 10 analogs of the idealized amphipathic helical 21-mer peptide (KAAKKAA)(3), where three of the Ala residues at different positions have been replaced with Trp residues, has been investigated. The peptide's cytotoxic activity was found to be markedly dependent upon the position of the Trp residues within the hydrophobic sector of an idealized alpha-helix. The peptides with Trp residues located opposite the cationic sector displayed no antitumor activity, whereas those peptides with two or three Trp residues located adjacent to the cationic sector exhibited high cytotoxic activity when tested against three different cancer cell lines. Dye release experiments revealed that in contrast to the peptides with Trp residues located opposite the cationic sector, the peptides with Trp residues located adjacent to the cationic sector induced a strong permeabilizing activity from liposomes composed of a mixture of zwitterionic phosphatidylcholine and negatively charged phosphatidylserine (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC)/1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-L-serine (POPS)) (2:1) but not from liposomes composed of zwitterionic phosphatidylcholine, POPC. Fluorescence blue shift and quenching experiments revealed that Trp residues inserted deeper into the hydrophobic environment of POPC/POPS liposomes for peptides with high cytotoxic activity. Through circular dichroism studies, a correlation between the cytotoxic activity and the alpha-helical propensity was established. Structural studies of one inactive and two active peptides in the presence of micelles using NMR spectroscopy showed that only the active peptides adopted highly coiled to helical structures when bound to a membrane surface.