Strub Christine, Schlieker Christian, Bukau Bernd, Mogk Axel
Institut für Biochemie und Molekularbiologie, Universität Freiburg, Freiburg, Germany.
FEBS Lett. 2003 Oct 9;553(1-2):125-30. doi: 10.1016/s0014-5793(03)00985-2.
The Hsp100 protein ClpB is a member of the AAA+ protein family that mediates the solubilization of aggregated proteins in cooperation with the DnaK chaperone system. Unstructured polypeptides such as casein or poly-L-lysine have been shown to stimulate the ATPase activity of ClpB and thus may both act as substrates. Here we compared the effects of alpha-casein and poly-L-lysine on the ATPase and chaperone activities of ClpB. alpha-Casein stimulated ATP hydrolysis by both AAA domains of ClpB and inhibited the ClpB-dependent solubilization of aggregated proteins if present in excess. In contrast, poly-L-lysine stimulated exclusively the ATPase activity of the second AAA domain and increased the disaggregation activity of ClpB. Thus poly-L-lysine does not act as substrate, but rather represents an effector molecule, which enhances the chaperone activity of ClpB.
热休克蛋白100（Hsp100）家族的ClpB蛋白是AAA +蛋白家族的成员，它与DnaK伴侣系统协同作用，介导聚集蛋白的溶解。已证明诸如酪蛋白或聚-L-赖氨酸之类的无结构多肽可刺激ClpB的ATP酶活性，因此两者都可能充当底物。在这里，我们比较了α-酪蛋白和聚-L-赖氨酸对ClpB的ATP酶活性和伴侣活性的影响。α-酪蛋白刺激ClpB的两个AAA结构域的ATP水解，如果过量存在，则抑制ClpB依赖的聚集蛋白的溶解。相反，聚-L-赖氨酸仅刺激第二个AAA结构域的ATP酶活性，并增加ClpB的解聚活性。因此，聚-L-赖氨酸不是底物，而是一种效应分子，可增强ClpB的伴侣活性。
