National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.
Structure. 2010 Oct 13;18(10):1270-9. doi: 10.1016/j.str.2010.07.009.
Thermosomes are group II chaperonins responsible for protein refolding in an ATP-dependent manner. Little is known regarding the conformational changes of thermosomes during their functional cycle due to a lack of high-resolution structure in the open state. Here, we report the first complete crystal structure of thermosome (rATcpnβ) in the open state from Acidianus tengchongensis. There is a ∼30° rotation of the apical and lid domains compared with the previous closed structure. Besides, the structure reveals a conspicuous hydrophobic patch in the lid domain, and residues locating in this patch are conserved across species. Both the closed and open forms of rATcpnβ were also reconstructed by electron microscopy (EM). Structural fitting revealed the detailed conformational change from the open to the closed state. Structural comparison as well as protease K digestion indicated only ATP binding without hydrolysis does not induce chamber closure of thermosome.
热休克蛋白是 II 类伴侣蛋白，负责以 ATP 依赖的方式进行蛋白质重折叠。由于缺乏开放状态下的高分辨率结构，因此对于热休克蛋白在其功能循环过程中的构象变化知之甚少。在这里，我们报道了来自腾格里沙漠嗜热球菌的热休克蛋白（rATcpnβ）在开放状态下的首个完整晶体结构。与之前的封闭结构相比，顶端和盖子结构域发生了约 30°的旋转。此外，该结构还揭示了盖子结构域中一个明显的疏水区，并且位于该区域的残基在不同物种中是保守的。通过电子显微镜（EM）还重建了 rATcpnβ 的封闭和开放两种形式。结构拟合揭示了从开放到封闭状态的详细构象变化。结构比较和蛋白酶 K 消化表明，ATP 结合而不水解不会诱导热休克蛋白腔的关闭。
