Activation of the ATPase activity of heat-shock proteins Hsc70/Hsp70 by cysteine-string protein
Activation of the ATPase activity of heat-shock proteins Hsc70/Hsp70 by cysteine-string protein
复制标题
DOI：
10.1042/bj3220853
复制
发表时间：
1997-03-15
影响因子：
4.1
通讯作者：
Burgoyne, RD
中科院分区：
文献类型：
--
作者：
Chamberlain, LH;Burgoyne, RD
DnaJ蛋白具有一个与大肠杆菌蛋白DnaJ同源的“J”结构域。DnaJ已被证明与伴侣蛋白DnaK相互作用，并且许多真核DnaJ样蛋白已被发现与70 kDa热休克蛋白/70 kDa热休克同源蛋白（Hsp70/Hsc70）相互作用，这是DnaK的真核同源物。半胱氨酸弦蛋白（Csps）被认为在钙刺激的胞吐中起作用，在本文中，我们描述了Csp （Csp1）和Hsc70/Hsp70之间特定的atp依赖的相互作用。我们还发现，Csp1可以刺激Hsc70和Hsp70的atp酶活性数倍。此外，研究人员发现，在肾上腺染色质细胞中发现的Csp变体Csp2可以提高Hsc70的atp酶活性，其程度与Csp1相似，而Csp(137-198)，缺乏Csp1的“J”结构域的截断蛋白不能刺激Hsc70的atp酶活性。这表明除了与Hsc70相互作用外，Csp1和Csp2的功能肯定在某些方面有所不同。从DnaJ/Hsc70相互作用的总体角度来看，这项研究也很重要，因为Csps缺乏富含G/ f的区域，该区域被认为是DnaJ激活DnaK的atp酶活性所必需的。因此，这项工作将暗示富含G/ f的区域并不是DnaJ蛋白刺激Hsp70蛋白atp酶活性的基本特征。
DnaJ proteins are characterized by a 'J' domain which is homologous to a region of the Escherichia coli protein DnaJ. DnaJ has been shown to interact with the chaperone protein DnaK, and a number of eukaryotic DnaJ-like proteins have been found to interact with the 70 kDa heat-shock protein/70 kDa heat-shock cognate protein (Hsp70/Hsc70), the eukaryotic homologues of DnaK. Cysteine-string proteins (Csps) are believed to function in calcium-stimulated exocytosis and in this paper we describe a specific ATP-dependent interaction between a Csp (Csp1) and Hsc70/Hsp70. We also show that Csp1 can stimulate the ATPase activity of both Hsc70 and Hsp70 several-fold. Furthermore, we demonstrate that Csp2, a Csp variant found in adrenal chromaffin cells, can enhance the ATPase activity of Hsc70 to a similar extent as Csp1, whereas Csp(137-198), a truncated protein lacking the 'J' domain of Csp1 is unable to stimulate the ATPase activity of Hsc70. This suggests that the functions of Csp1 and Csp2 must differ in some aspect other than interaction with Hsc70. This study is also important from a general view of DnaJ/Hsc70 interactions, as Csps lack a G/F-rich region which has been suggested to be essential for activation of the ATPase activity of DnaK by DnaJ. Thus, this work would imply that a G/F-rich region is not an essential feature of DnaJ proteins for stimulation of the ATPase activity of Hsp70 proteins.