Strong precursor-pore interactions constrain models for mitochondrial protein import
Strong precursor-pore interactions constrain models for mitochondrial protein import
复制标题
DOI：
10.1016/s0006-3495(98)77884-1
复制
发表时间：
1998-04-01
影响因子：
3.4
通讯作者：
Glick, BS
中科院分区：
文献类型：
--
作者：
Chauwin, JF;Oster, G;Glick, BS
线粒体前体蛋白通过蛋白质转运孔从胞质溶胶输入到基质隔室中。输入是由线粒体Hsp70（mHsp70），一个基质定位的ATP酶驱动的。目前有两种假设的mHsp70的这种功能的机制：1）“布朗棘轮”模型提出，前体链扩散的孔，和mHsp70的内腔部分的链的结合偏置这种扩散。2)“动力冲程”模型提出mHsp70经历了一个构象变化，主动拉动前体链通过孔。在这里，我们制定这两个模型定量，并比较它们的性能，在最近的实验证据表明，前体链相互作用强烈的壁的易位孔。在这些条件下，模拟布朗棘轮是低效的，而动力冲程机制似乎是一个合理的描述进口过程。
Mitochondrial precursor proteins are imported from the cytosol into the matrix compartment through a proteinaceous translocation pore. Import is driven by mitochondrial Hsp70 (mHsp70), a matrix-localized ATPase. There are currently two postulated mechanisms for this function of mHsp70: 1) The "Brownian ratchet" model proposes that the precursor chain diffuses within the pore, and that binding of mHsp70 to the lumenal portion of the chain biases this diffusion. 2) The "power stroke" model proposes that mHsp70 undergoes a conformational change that actively pulls the precursor chain through the pore. Here we formulate these two models quantitatively, and compare their performance in light of recent experimental evidence that precursor chains interact strongly with the walls of the translocation pore. Under these conditions the simulated Brownian ratchet is inefficient, whereas the power stroke mechanism seems to be a plausible description of the import process.