THE MITOCHONDRIAL CHAPERONIN HSP60 IS REQUIRED FOR ITS OWN ASSEMBLY
THE MITOCHONDRIAL CHAPERONIN HSP60 IS REQUIRED FOR ITS OWN ASSEMBLY
复制标题
DOI：
10.1038/348455a0
复制
发表时间：
1990-11-29
期刊：
影响因子：
64.8
通讯作者：
HORWICH, AL
中科院分区：
文献类型：
--
作者：
CHENG, MY;HARTL, FU;HORWICH, AL
线粒体基质中的热休克蛋白60（hsp 60）对于新输入的蛋白质的折叠和组装至关重要1。Hsp 60属于一类结构相关的伴侣蛋白，存在于内共生起源的细胞器和细菌胞质中2 -9。Hsp 60单体形成排列为两个堆叠的7-mer环的复合物6。这种14-mer复合物在其表面结合未折叠的蛋白质，然后似乎在ATP依赖性过程中催化它们的折叠10。问题是这样一个装配机器本身是如何折叠和装配的。Hsp 60亚基由核基因编码，在胞质溶胶中翻译为转运体7，转运到线粒体中并进行蛋白水解加工。在完整的细胞和分离的hsp 60缺陷的酵母突变体mif 4的线粒体中，没有观察到新输入的野生型亚基的自组装。为了形成新的组装的14聚体，需要功能性预先存在的hsp 60复合物。进口的亚基以令人惊讶的5-10分钟的快速半衰期组装，表明催化反应。这些发现进一步证明，自组装可能不是蛋白质在完整细胞中获得其功能构象的主要机制。
HEATSHOCK protein 60 (hsp60) in the matrix of mitochondria is essential for the folding and assembly of newly imported proteins1. Hsp60 belongs to a class of structurally related chaperonins found in organelles of endosymbiotic origin and in the bacterial cytosol2–9. Hsp60 monomers form a complex arranged as two stacked 7-mer rings6. This 14-mer complex binds unfolded proteins at its surface, then seems to catalyse their folding in an ATP-dependent process10. The question arises as to how such an assembly machinery is itself folded and assembled. Hsp60 subunits are encoded by a nuclear gene and translated in the cytosol as precursors7which are translocated into mitochondria and proteolytically processed. In both intact cells and isolated mitochondria of the hsp60-defective yeast mutant mif4, self-assembly of newly imported wild-type subunits is not observed. Functional pre-existing hsp60 complex is required in order to form new, assembled, 14-mer. Subunits imported invitroare assembled with a surprisingly fast half-time of 5–10 min, indicative of a catalysed reaction. These findings are further evidence that self-assembly may not be the principal mechanism by which proteins attain their functional conformation in the intact cell.