Department of Biology, Johns Hopkins University, 144 Mudd Hall, 3400 North Charles Street, Baltimore, Maryland 21218, United States.
Department of Chemistry, The University of Texas at Austin, Austin, Texas 78712, United States.
Biochemistry. 2021 Feb 16;60(6):460-464. doi: 10.1021/acs.biochem.0c00903. Epub 2021 Jan 19.
The ATP-consuming chaperonin machinery, a complex between GroEL and GroES, has evolved to facilitate folding of substrate proteins (SPs) that cannot do so spontaneously. A series of kinetic experiments show that the SPs are encapsulated in the GroEL/ES nanocage for a short duration. If confinement of the SPs is the mechanism by which GroEL/ES facilitates folding, it follows that the assisted folding rate, relative to the bulk value, should always be enhanced. Here, we show that this is not the case for the folding of rhodanese in the presence of the full machinery of GroEL/ES and ATP. The assisted folding rate of rhodanese decreases. On the basis of our finding and those reported in other studies, we suggest that the ATP-consuming chaperonin machinery has evolved to optimize the product of the folding rate and the yield of the folded SPs on the biological time scale. Neither the rate nor the yield is separately maximized.
ATP 消耗分子伴侣机制，即 GroEL 和 GroES 之间的复合物，已经进化为促进不能自发折叠的底物蛋白 (SPs) 的折叠。一系列动力学实验表明，SPs 被短暂地包裹在 GroEL/ES 纳米笼中。如果 SP 的限制是 GroEL/ES 促进折叠的机制，那么相对于体相值，辅助折叠速率应该始终得到增强。在这里，我们表明，对于在完整的 GroEL/ES 和 ATP 机器存在下的 rhodanese 的折叠，情况并非如此。rhodanese 的辅助折叠速率降低。基于我们的发现和其他研究的报告，我们建议，ATP 消耗分子伴侣机制已经进化为在生物时间尺度上优化折叠速率和折叠 SP 的产量的乘积。折叠速率和产率都没有被单独最大化。
