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首页> 美国卫生研究院文献>The EMBO Journal >A chemically synthesized pre-sequence of an imported mitochondrial protein can form an amphiphilic helix and perturb natural and artificial phospholipid bilayers.
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A chemically synthesized pre-sequence of an imported mitochondrial protein can form an amphiphilic helix and perturb natural and artificial phospholipid bilayers.

机译：导入的线粒体蛋白的化学合成前序序列可形成两亲性螺旋扰乱天然和人工磷脂双层。

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摘要

Subunit IV of yeast cytochrome oxidase is made in the cytoplasm with a transient pre-sequence of 25 amino acids which is removed upon import of the protein into mitochondria. To study the function of this cleavable pre-sequence in mitochondrial protein import, three peptides representing 15, 25 or 33 amino-terminal residues of the subunit IV precursor were chemically synthesized. All three peptides were freely soluble in aqueous buffers, yet inserted spontaneously from an aqueous subphase into phospholipid monolayers up to an extrapolated limiting monolayer pressure of 40-50 mN/m. The two longer peptides also caused disruption of unilamellar liposomes. This effect was increased by a diffusion potential, negative inside the liposomes, and decreased by a diffusion potential of opposite polarity. The peptides, particularly the two longer ones, also uncoupled respiratory control of isolated yeast mitochondria. The 25-residue peptide had little secondary structure in aqueous buffer but became partly alpha-helical in the presence of detergent micelles. Based on the amino acid sequence of the peptides, a helical structure would have a highly asymmetric distribution of charged and apolar residues and would be surface active. Amphiphilic helicity appears to be a general feature of mitochondrial pre-sequences. We suggest that this feature plays a crucial role in transporting proteins into mitochondria.
机译：酵母细胞色素氧化酶的亚基IV是在细胞质中产生的，具有25个氨基酸的瞬时前序序列，该序列在蛋白质导入线粒体后就被除去。为了研究这种可切割的预序列在线粒体蛋白输入中的功能，化学合成了代表亚基IV前体的15、25或33个氨基末端残基的三个肽。所有这三种肽均可自由溶于水缓冲液，但自水亚相自发插入磷脂单层中，外推的极限单层压力为40-50 mN / m。两种较长的肽还引起单层脂质体的破坏。该作用通过在脂质体内部为负的扩散势而增加，而由于相反极性的扩散势而降低。这些肽，特别是两个较长的肽，还可以对分离的酵母线粒体进行非耦合的呼吸控制。在含水缓冲液中，具有25个残基的肽几乎没有二级结构，但是在去污剂胶束的存在下部分变为α-螺旋。基于肽的氨基酸序列，螺旋结构将具有高度不对称的带电和非极性残基分布，并且具有表面活性。两亲性螺旋似乎是线粒体前序列的普遍特征。我们建议该功能在将蛋白质转运到线粒体中起关键作用。

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