Monitoring protein conformation along the pathway of chaperonin-assisted folding
Monitoring protein conformation along the pathway of chaperonin-assisted folding
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DOI：
10.1016/j.cell.2008.01.048
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发表时间：
2008-04-04
期刊：
影响因子：
64.5
通讯作者：
Hartl, F. Ulrich
中科院分区：
文献类型：
--
作者：
Sharma, Shruti;Chakraborty, Kausik;Hartl, F. Ulrich
GroEL/GroES伴侣蛋白系统介导细菌细胞质中的蛋白质折叠。新合成的蛋白质通过上游伴侣如DnaK/DnaJ （Hsp70）的转移到达GroEL。在这里，我们使用单分子和集合FRET来监测模型底物的构象转变，因为它沿着这种伴侣途径进行。我们发现DnaK/DnaJ使蛋白质稳定在折叠极其缓慢的崩溃状态。转移到GroEL导致展开，部分分子达到局部高度膨胀的构象。atp诱导的GroEL结构域运动导致具有中等疏水性的蛋白质片段的短暂进一步展开和快速动员，从而允许GroEL表面的部分压实。更多的疏水区域被释放，随后蛋白质被GroES封装在中央GroEL腔中，完成压实并允许快速折叠。片段链释放和压实在避免由于自发疏水崩溃而无法有效折叠的蛋白质的错误折叠中可能是重要的。
The GroEL/GroES chaperonin system mediates protein folding in the bacterial cytosol. Newly synthesized proteins reach GroEL via transfer from upstream chaperones such as DnaK/DnaJ (Hsp70). Here we employed single molecule and ensemble FRET to monitor the conformational transitions of a model substrate as it proceeds along this chaperone pathway. We find that DnaK/DnaJ stabilizes the protein in collapsed states that fold exceedingly slowly. Transfer to GroEL results in unfolding, with a fraction of molecules reaching locally highly expanded conformations. ATP-induced domain movements in GroEL cause transient further unfolding and rapid mobilization of protein segments with moderate hydrophobicity, allowing partial compaction on the GroEL surface. The more hydrophobic regions are released upon subsequent protein encapsulation in the central GroEL cavity by GroES, completing compaction and allowing rapid folding. Segmental chain release and compaction may be important in avoiding misfolding by proteins that fail to fold efficiently through spontaneous hydrophobic collapse.