Biochemisches Institut, Universität Zürich, Winterthurerstrasse 190, 8057 Zürich, Switzerland.
Proc Natl Acad Sci U S A. 2010 Jun 29;107(26):11793-8. doi: 10.1073/pnas.1002356107. Epub 2010 Jun 14.
Molecular chaperones are known to be essential for avoiding protein aggregation in vivo, but it is still unclear how they affect protein folding mechanisms. We use single-molecule Förster resonance energy transfer to follow the folding of a protein inside the GroEL/GroES chaperonin cavity over a time range from milliseconds to hours. Our results show that confinement in the chaperonin decelerates the folding of the C-terminal domain in the substrate protein rhodanese, but leaves the folding rate of the N-terminal domain unaffected. Microfluidic mixing experiments indicate that strong interactions of the substrate with the cavity walls impede the folding process, but the folding hierarchy is preserved. Our results imply that no universal chaperonin mechanism exists. Rather, a competition between intra- and intermolecular interactions determines the folding rates and mechanisms of a substrate inside the GroEL/GroES cage.
分子伴侣被认为对于避免体内蛋白质聚集是必不可少的，但它们如何影响蛋白质折叠机制仍不清楚。我们使用单分子Förster 共振能量转移技术，在从毫秒到小时的时间范围内，跟踪 GroEL/GroES 分子伴侣腔体内的蛋白质折叠。我们的结果表明，在分子伴侣腔体内的限制会降低底物蛋白硫氧还蛋白 C 端结构域的折叠速度，但对 N 端结构域的折叠速度没有影响。微流混合实验表明，底物与腔壁的强相互作用会阻碍折叠过程，但折叠层次结构得以保留。我们的结果表明，不存在普遍的分子伴侣机制。相反，是分子内和分子间相互作用之间的竞争决定了底物在 GroEL/GroES 笼内的折叠速度和机制。
