Swain Joanna F, Dinler Gizem, Sivendran Renuka, Montgomery Diana L, Stotz Mathias, Gierasch Lila M
Department of Biochemistry and Molecular Biology, University of Massachusetts, Amherst, Amherst, MA 01003, USA.
Mol Cell. 2007 Apr 13;26(1):27-39. doi: 10.1016/j.molcel.2007.02.020.
Hsp70 chaperones assist in protein folding, disaggregation, and membrane translocation by binding to substrate proteins with an ATP-regulated affinity that relies on allosteric coupling between ATP-binding and substrate-binding domains. We have studied single- and two-domain versions of the E. coli Hsp70, DnaK, to explore the mechanism of interdomain communication. We show that the interdomain linker controls ATPase activity by binding to a hydrophobic cleft between subdomains IA and IIA. Furthermore, the domains of DnaK dock only when ATP binds and behave independently when ADP is bound. Major conformational changes in both domains accompany ATP-induced docking: of particular importance, some regions of the substrate-binding domain are stabilized, while those near the substrate-binding site become destabilized. Thus, the energy of ATP binding is used to form a stable interface between the nucleotide- and substrate-binding domains, which results in destabilization of regions of the latter domain and consequent weaker substrate binding.
热休克蛋白70（Hsp70）伴侣蛋白通过以ATP调节的亲和力结合底物蛋白来协助蛋白质折叠、解聚和膜易位，这种亲和力依赖于ATP结合域和底物结合域之间的变构偶联。我们研究了大肠杆菌Hsp70（DnaK）的单结构域和双结构域版本，以探索结构域间通讯的机制。我们发现结构域间连接子通过结合亚结构域IA和IIA之间的疏水裂缝来控制ATP酶活性。此外，只有当ATP结合时，DnaK的结构域才对接，而当ADP结合时则独立发挥作用。ATP诱导的对接伴随着两个结构域的主要构象变化：特别重要的是，底物结合结构域的一些区域变得稳定，而靠近底物结合位点的区域变得不稳定。因此，ATP结合的能量用于在核苷酸结合结构域和底物结合结构域之间形成稳定的界面，这导致后者结构域区域的不稳定以及随后较弱的底物结合。
