Biological Chemistry, and Lifesciences Institute, University of Michigan, Ann Arbor, MI 48109, USA.
Proc Natl Acad Sci U S A. 2011 Nov 22;108(47):18966-71. doi: 10.1073/pnas.1111220108. Epub 2011 Nov 7.
The heat shock protein 70 kDa (Hsp70)/DnaJ/nucleotide exchange factor system assists in intracellular protein (re)folding. Using solution NMR, we obtained a three-dimensional structure for a 75-kDa Hsp70-DnaJ complex in the ADP state, loaded with substrate peptide. We establish that the J domain (residues 1-70) binds with its positively charged helix II to a negatively charged loop in the Hsp70 nucleotide-binding domain. The complex shows an unusual "tethered" binding mode which is stoichiometric and saturable, but which has a dynamic interface. The complex represents part of a triple complex of Hsp70 and DnaJ both bound to substrate protein. Mutagenesis data indicate that the interface is also of relevance for the interaction of Hsp70 and DnaJ in the ATP state. The solution complex is completely different from a crystal structure of a disulfide-linked complex of homologous proteins [Jiang, et al. (2007) Mol Cell 28:422-433].
热休克蛋白 70 kDa（Hsp70）/DnaJ/核苷酸交换因子系统有助于细胞内蛋白质（再）折叠。我们使用溶液 NMR 获得了 ADP 状态下负载底物肽的 75 kDa Hsp70-DnaJ 复合物的三维结构。我们确定 J 结构域（残基 1-70）通过其带正电荷的螺旋 II 与 Hsp70 核苷酸结合域中的带负电荷的环结合。该复合物显示出一种不寻常的“束缚”结合模式，这种模式是化学计量的和饱和的，但具有动态界面。该复合物代表 Hsp70 和 DnaJ 与底物蛋白结合的三重复合物的一部分。突变体数据表明，该界面对于 Hsp70 和 DnaJ 在 ATP 状态下的相互作用也很重要。该溶液复合物与同源蛋白的二硫键连接复合物的晶体结构完全不同[Jiang 等人，（2007）Mol Cell 28:422-433]。
