The 70-kDa heat shock protein chaperone nucleotide-binding domain in solution unveiled as a molecular machine that can reorient its functional subdomains.
The 70-kDa heat shock protein chaperone nucleotide-binding domain in solution unveiled as a molecular machine that can reorient its functional subdomains.
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溶液中的 70 kDa 热休克蛋白伴侣核苷酸结合结构域被揭示为一种分子机器，可以重新定位其功能子结构域。
DOI：
10.1073/pnas.0401313101
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发表时间：
2004
期刊：
影响因子：
--
通讯作者：
Zuiderweg,ErikRP
中科院分区：
文献类型：
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作者：
Zhang,Yongbo;Zuiderweg,ErikRP
分子量为70 kDa的热休克同源蛋白（Hsc 70）分子伴侣在哺乳动物细胞质中的蛋白质（重）折叠和分类中起着至关重要的作用。在这里，我们研究，通过NMR，44-kDa的核苷酸结合结构域（NBD）的这个分子，它变构调节，通过结合ADP或ATP在两个主叶之间的裂缝，伴侣的亲和力连接的底物结合结构域。NBD也是与耦合到变构中的辅伴侣相互作用的中心。通过NMR测量残余偶极耦合，我们发现溶液中Hsc 70 NBD的两个叶的取向与它们在14个叠加X射线结构中的位置偏离高达10°。叶内亚结构域的额外取向差异揭示了溶液中的Hsc 70 NBD作为一种灵活的分子机器，可以调节其所有四个亚结构域的相对位置。因为与核苷酸相互作用的残基来自所有四个亚结构域，所以亚结构域方向的调整应该影响核苷酸化学，反之亦然。我们的数据表明一个假设，cochaperone或底物结构域结合扰动的相对亚结构域的方向，从而在功能上和变构耦合的NBD的核苷酸状态。
The 70-kDa heat shock cognate (Hsc70) chaperone plays a crucial role in protein (re-)folding and triage in the mammalian cytosol. Here we study, by NMR, the 44-kDa nucleotide-binding domain (NBD) of this molecule, which allosterically regulates, by binding either ADP or ATP in a cleft between the two main lobes, the chaperoning affinity of the attached substrate-binding domain. The NBD is also a center of interaction with cochaperones that couple into the allostery. By measuring residual dipolar couplings by NMR, we show that the orientation of two lobes of the Hsc70 NBD in solution deviates up to 10° from their positions in 14 superimposing x-ray structures. Additional orientational differences of subdomains within the lobes unveil the Hsc70 NBD in solution as a flexible molecular machine that can adjust the relative positions of all of its four subdomains. Because the residues interacting with the nucleotide emanate from all four subdomains, adjustments in subdomain orientation should affect the nucleotide chemistry and vice versa. Our data suggest a hypothesis that cochaperone or substrate domain binding perturbs the relative subdomain orientations, thereby functionally and allosterically coupling to the nucleotide state of the NBD.