The loss in hydrophobic surface area resulting from a Leu to Val mutation at the N-terminus of the aldehyde dehydrogenase presequence prevents import of the protein into mitochondria.
The loss in hydrophobic surface area resulting from a Leu to Val mutation at the N-terminus of the aldehyde dehydrogenase presequence prevents import of the protein into mitochondria.
复制标题
醛脱氢酶前序列 N 末端的 Leu 突变为 Val 导致疏水表面积的损失，从而阻止蛋白质输入线粒体。
DOI：
10.1110/ps.8.4.890
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发表时间：
1999
期刊：
影响因子：
--
通讯作者：
Weiner,H
中科院分区：
文献类型：
--
作者：
Hammen,PK;Heard,TS;Waltner,M;Weiner,H
大鼠肝脏线粒体乙醛脱氢酶 (ALDH) 前序列第二个残基处的明显保守突变（Leu 突变为 Val）导致前体蛋白未输入线粒体。制备了另外的突变体以用非极性侧链取代 Leu2 的各种氨基酸。 Ile、Phe 和 Trp 突变体的输入程度与天然前体相似，但 Ala 突变体的输入程度也仅为大约四分之一。结果表明，在甲硫氨酸氨肽酶催化的反应中，N-末端甲硫氨酸从L2V突变体中被去除。天然 pALDH 和其他突变体前序列的 N 端甲硫氨酸被阻断，可能是通过乙酰化作用。由于共翻译修饰的差异，L2V 突变体前序列的可用疏水表面持续显着损失。当使用未删除 Met1 的系统进行翻译时，L2V 突变体的导入能力得到恢复。从 L2V 突变体中去除 Arg-Gly-Pro 螺旋接头片段（残基 11-14），将三个亮氨酸残基移向 N 末端，也恢复了导入能力。这些结果得出这样的结论：线粒体前序列 N 末端附近的最小疏水表面积是决定其输入能力的重要特性。因此，在试图了解前体蛋白和线粒体输入装置的蛋白质之间的相互作用时，必须考虑静电和疏水成分。
An apparent conservative mutation, Leu to Val, at the second residue of the rat liver mitochondrial aldehyde dehydrogenase (ALDH) presequence resulted in a precursor protein that was not imported into mitochondria. Additional mutants were made to substitute various amino acids with nonpolar side chains for Leu2. The Ile, Phe, and Trp mutants were imported to an extent similar to that of the native precursor, but the Ala mutant was imported only about one-fourth as well. It was shown that the N-terminal methionine was removed from the L2V mutant in a reaction catalyzed by methionine aminopeptidase. The N-terminal methionine of native pALDH and the other mutant presequences was blocked, presumably by acetylation. Because of the difference in co-translational modification, the L2V mutant sustained a significant loss in the available hydrophobic surface of the presequence. Import competence was restored to the L2V mutant when it was translated using a system that did not remove Met1. The removal of an Arg-Gly-Pro helix linker segment (residues 11–14) from the L2V mutant, which shifted three leucine residues toward the N-terminus, also restored import competence. These results lead to the conclusion that a minimum amount of hydrophobic surface area near the N-termini of mitochondrial presequences is an essential property to determine their ability to be imported. As a result, both electrostatic and hydrophobic components must be considered when trying to understand the interactions between precursor proteins and proteins of the mitochondrial import apparatus.