The N Terminus of ClpB from Thermus thermophilus Is Not Essential for the Chaperone Activity*
The N Terminus of ClpB from Thermus thermophilus Is Not Essential for the Chaperone Activity*
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嗜热栖热菌 ClpB 的 N 末端对于分子伴侣活性不是必需的*
DOI：
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发表时间：
2002
影响因子：
4.8
通讯作者：
J. Reinstein
中科院分区：
文献类型：
--
作者：
P. Beinker;S. Schlee;Y. Groemping;R. Seidel;J. Reinstein
来自嗜热栖热菌的ClpB属于Clp/Hsp 100蛋白家族，并与DnaK伴侣系统合作再活化蛋白质聚集体。蛋白质再活化和与DnaK系统相互作用的机制仍不清楚。ClpB具有两个核苷酸结合结构域，这对功能至关重要，并显示出复杂的变构行为。在第一个核苷酸结合结构域之前的N-末端结构域的作用在很大程度上是未知的。我们纯化并表征了N-末端缩短的ClpB变体（ClpBΔN;氨基酸140-854），其在用三种不同底物蛋白的重折叠测定中保持活性。此外，N-末端截短没有显著改变蛋白的核苷酸结合亲和力、核苷酸依赖性寡聚化和变构行为。相反，酪蛋白结合和κ-酪蛋白对ATP酶活性的刺激受到影响。这些结果表明，N-末端结构域是不是必不可少的伴侣功能，不影响核苷酸的结合，并不参与分子间接触的形成。它有助于ClpB的酪蛋白结合位点，但其他底物蛋白不一定与N末端相互作用。这表明κ-酪蛋白的结合模式存在实质性差异，κ-酪蛋白通常用作ClpB和其他可能更合适的底物蛋白的模型底物。
ClpB from Thermus thermophilusbelongs to the Clp/Hsp100 protein family and reactivates protein aggregates in cooperation with the DnaK chaperone system. The mechanism of protein reactivation and interaction with the DnaK system remains unclear. ClpB possesses two nucleotide binding domains, which are essential for function and show a complex allosteric behavior. The role of the N-terminal domain that precedes the first nucleotide binding domain is largely unknown. We purified and characterized an N-terminal shortened ClpB variant (ClpBΔN; amino acids 140–854), which remained active in refolding assays with three different substrate proteins. In addition the N-terminal truncation did not significantly change the nucleotide binding affinities, the nucleotide-dependent oligomerization, and the allosteric behavior of the protein. In contrast casein binding and stimulation of the ATPase activity by κ-casein were affected. These results suggest that the N-terminal domain is not essential for the chaperone function, does not influence the binding of nucleotides, and is not involved in the formation of intermolecular contacts. It contributes to the casein binding site of ClpB, but other substrate proteins do not necessarily interact with the N terminus. This indicates a substantial difference in the binding mode of κ-casein that is often used as model substrate for ClpB and other possibly more suitable substrate proteins.
影响因子：
7
作者：
A. F. Neuwald;L. Aravind;J. Spouge;E. Koonin
通讯作者：
A. F. Neuwald;L. Aravind;J. Spouge;E. Koonin
DOI：
10.1016/s0021-9258(17)41804-7
发表时间：
1994-02
期刊：
The Journal of biological chemistry
影响因子：
--
作者：
D. Parsell;A. Kowal;S. Lindquist
通讯作者：
D. Parsell;A. Kowal;S. Lindquist