Buchberger A, Schröder H, Büttner M, Valencia A, Bukau B
Zentrum für Molekulare Biologie, Universität Heidelberg, FRG.
Nat Struct Biol. 1994 Feb;1(2):95-101. doi: 10.1038/nsb0294-95.
The activity of DnaK (Hsp70) chaperones in assisting protein folding relies on DnaK binding and ATP-controlled release of protein substrates. The ATPase activity of DnaK is tightly controlled by the nucleotide exchange factor GrpE. We find that GrpE interacts stably with the amino-terminal ATPase domain of DnaK. Analysis of the mutant DnaK756 protein, which has a lower affinity for GrpE, reveals a role for residue Gly 32 in GrpE binding. Gly 32 is located in an exposed loop near the nucleotide binding site of DnaK. Deletion of this loop prevents stable GrpE binding, ATPase stimulation by GrpE, and DnaK chaperone activity. Conservation of this loop within the Hsp70 family suggests that cooperation between Hsp70 and GrpE-like proteins may be a general feature of this class of chaperone.
DnaK（热休克蛋白70，Hsp70）伴侣蛋白在协助蛋白质折叠过程中的活性依赖于DnaK与蛋白质底物的结合以及由ATP控制的底物释放。DnaK的ATP酶活性受核苷酸交换因子GrpE的严格调控。我们发现，GrpE与DnaK的氨基末端ATP酶结构域稳定相互作用。对与GrpE亲和力较低的突变体DnaK756蛋白的分析表明，甘氨酸残基32在GrpE结合中发挥作用。甘氨酸32位于DnaK核苷酸结合位点附近的一个暴露环中。缺失该环会阻止GrpE的稳定结合、GrpE对ATP酶的刺激以及DnaK伴侣蛋白的活性。Hsp70家族中该环的保守性表明，Hsp70与类GrpE蛋白之间的协作可能是这类伴侣蛋白的一个普遍特征。
