Gässler C S, Buchberger A, Laufen T, Mayer M P, Schröder H, Valencia A, Bukau B
Institut für Biochemie und Molekularbiologie, Universität Freiburg, Hermann-Herder-Strasse 7, D-79104 Freiburg, Germany.
Proc Natl Acad Sci U S A. 1998 Dec 22;95(26):15229-34. doi: 10.1073/pnas.95.26.15229.
Hsp70 chaperones assist protein folding by ATP-controlled cycles of substrate binding and release. ATP hydrolysis is the rate-limiting step of the ATPase cycle that causes locking in of substrates into the substrate-binding cavity of Hsp70. This key step is strongly stimulated by DnaJ cochaperones. We show for the Escherichia coli Hsp70 homolog, DnaK, that stimulation by DnaJ requires the linked ATPase and substrate-binding domains of DnaK. Functional interaction with DnaJ is affected by mutations in an exposed channel located in the ATPase domain of DnaK. It is proposed that binding to this channel, possibly involving the J-domain, allows DnaJ to couple substrate binding with ATP hydrolysis by DnaK. Evolutionary conservation of the channel and the J-domain suggests conservation of the mechanism of action of DnaJ proteins.
热休克蛋白70（Hsp70）伴侣蛋白通过由ATP控制的底物结合和释放循环来协助蛋白质折叠。ATP水解是ATP酶循环的限速步骤，该步骤会导致底物锁定在Hsp70的底物结合腔中。这一关键步骤受到DnaJ共伴侣蛋白的强烈刺激。我们发现，对于大肠杆菌Hsp70同源物DnaK而言，DnaJ的刺激作用需要DnaK的ATP酶结构域和底物结合结构域相连接。与DnaJ的功能相互作用会受到位于DnaK的ATP酶结构域中一个暴露通道上的突变的影响。有人提出，与该通道的结合，可能涉及J结构域，使得DnaJ能够将底物结合与DnaK的ATP水解偶联起来。该通道和J结构域在进化上的保守性表明DnaJ蛋白的作用机制具有保守性。
