Chaperonin-Catalyzed Rescue of Kinetically Trapped States in Protein Folding
Chaperonin-Catalyzed Rescue of Kinetically Trapped States in Protein Folding
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DOI：
10.1016/j.cell.2010.05.027
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发表时间：
2010-07-09
期刊：
影响因子：
64.5
通讯作者：
Hayer-Hartl, Manajit
中科院分区：
文献类型：
--
作者：
Chakraborty, Kausik;Chatila, Manal;Hayer-Hartl, Manajit
GroEL和GroES形成了一个伴侣蛋白纳米笼，使单个蛋白质分子可以在隔离状态下折叠。使蛋白质依赖伴侣蛋白的折叠特性尚不清楚。在这里，我们使用麦芽糖结合蛋白DM-MBP的双突变体作为底物来解决这个问题。在自发的再折叠中，DM-MBP填充了一个动力学捕获的中间体，该中间体塌陷但结构紊乱。在DM-MBP中引入两个远程二硫键，降低了该中间体的熵折叠势垒，并大大加速了天然态的形成。引人注目的是，伴侣蛋白笼中蛋白质的空间限制模仿了约束二硫化物对折叠的动力学效应，以笼壁负电荷团簇介导的方式。这些发现表明伴侣蛋白依赖与蛋白质填充熵稳定折叠中间体的倾向相关。从这种折叠陷阱中拯救蛋白质的能力可能解释了伴侣蛋白笼在细胞伴侣蛋白网络中的独特重要作用。
GroEL and GroES form a chaperonin nano-cage for single protein molecules to fold in isolation. The folding properties that render a protein chaperonin dependent are not yet understood. Here, we address this question using a double mutant of the maltose-binding protein DM-MBP as a substrate. Upon spontaneous refolding, DM-MBP populates a kinetically trapped intermediate that is collapsed but structurally disordered. Introducing two long-range disulfide bonds into DM-MBP reduces the entropic folding barrier of this intermediate and strongly accelerates native state formation. Strikingly, steric confinement of the protein in the chaperonin cage mimics the kinetic effect of constraining disulfides on folding, in a manner mediated by negative charge clusters in the cage wall. These findings suggest that chaperonin dependence correlates with the tendency of proteins to populate entropically stabilized folding intermediates. The capacity to rescue proteins from such folding traps may explain the uniquely essential role of chaperonin cages within the cellular chaperone network.