Kanno Ryo, Koike-Takeshita Ayumi, Yokoyama Ken, Taguchi Hideki, Mitsuoka Kaoru
Department of Biophysics, Faculty of Science, Kyoto University, Oiwake, Kitashirakawa, Sakyo-ku, Kyoto 606-8502, Japan.
Structure. 2009 Feb 13;17(2):287-93. doi: 10.1016/j.str.2008.12.012.
The chaperonin GroEL interacts with various proteins, leading them to adopt their correct conformations with the aid of GroES and ATP. The actual mechanism is still being debated. In this study, by use of cryo-electron microscopy, we determined the solution structure of the Thermus thermophilus GroEL-GroES complex encapsulating its substrate proteins. We observed the averaged density of substrate proteins in the center of the GroEL-GroES cavity. The position of the averaged substrate density in the cavity suggested a repulsive interaction between a majority of the substrate proteins and the interior wall of the cavity, which is suitable for substrate release. In addition, we observed a distortion of the cis-GroEL ring, especially at the position near the substrate, which indicated that the interaction between the encapsulated proteins and the GroEL ring results in an adjustment in the cavity's shape to accommodate the substrate.
伴侣蛋白GroEL与多种蛋白质相互作用，借助GroES和ATP引导它们形成正确的构象。其实际机制仍在争论中。在本研究中，我们利用冷冻电子显微镜确定了嗜热栖热菌GroEL - GroES复合物包裹其底物蛋白时的溶液结构。我们观察到GroEL - GroES腔中心底物蛋白的平均密度。腔内平均底物密度的位置表明大多数底物蛋白与腔内壁之间存在排斥相互作用，这有利于底物释放。此外，我们观察到顺式GroEL环的扭曲，特别是在靠近底物的位置，这表明被包裹蛋白与GroEL环之间的相互作用导致腔的形状发生调整以容纳底物。
