Graduate School of Pharmaceutical Sciences, The University of Tokyo, Tokyo, Japan.
PLoS One. 2011;6(7):e22253. doi: 10.1371/journal.pone.0022253. Epub 2011 Jul 14.
Group II chaperonins found in archaea and in eukaryotic cytosol mediate protein folding without a GroES-like cofactor. The function of the cofactor is substituted by the helical protrusion at the tip of the apical domain, which forms a built-in lid on the central cavity. Although many studies on the change in lid conformation coupled to the binding and hydrolysis of nucleotides have been conducted, the molecular mechanism of lid closure remains poorly understood. Here, we performed a single-molecule polarization modulation to probe the rotation of the helical protrusion of a chaperonin from a hyperthermophilic archaeum, Thermococcus sp. strain KS-1. We detected approximately 35° rotation of the helical protrusion immediately after photorelease of ATP. The result suggests that the conformational change from the open lid to the closed lid state is responsible for the approximately 35° rotation of the helical protrusion.
在古菌和真核细胞质中发现的 II 类分子伴侣在没有 GroES 样辅助因子的情况下介导蛋白质折叠。辅助因子的功能被顶端结构域尖端的螺旋突出物取代，该突出物在中央腔上形成内置盖。尽管已经进行了许多关于与核苷酸结合和水解偶联的盖构象变化的研究，但盖关闭的分子机制仍知之甚少。在这里，我们进行了单分子偏振调制，以探测来自嗜热古菌 Thermococcus sp. strain KS-1 的分子伴侣的螺旋突出物的旋转。我们在光解 ATP 后立即检测到螺旋突出物约 35°的旋转。结果表明，从开盖状态到闭盖状态的构象变化负责螺旋突出物约 35°的旋转。
