3atu | pdb_00003atu

Crystal structure of human Hsp70 NBD in the ADP- and Mg ion-bound state

spinqualitylabelsall models 3atu, resolution 1.65Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 3atu is a 1 chain structure with sequence from Homo sapiens. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: ADP, MG, NA, PG0, PO4 Related: 2e88, 2e8a, 3a8y, 3atv Gene: Hsp70, HSPA1, HSPA1A, HSPA1B (Homo sapiens) Resources: FirstGlance, OCA, RCSB, PDBsum Publication Abstract from PubMed The molecular chaperone 70-kDa heat shock protein (Hsp70) is driven by ATP hydrolysis and ADP-ATP exchange. ADP dissociation from Hsp70 is reportedly slow in the presence of inorganic phosphate (P(i) ). In this study, we investigated the interaction of Hsp70 and its nucleotide-binding domain (NBD) with ADP in detail, by isothermal titration calorimetry measurements and found that Mg(2+) ion dramatically elevates the affinity of Hsp70 for ADP. On the other hand, P(i) increased the affinity in the presence of Mg(2+) ion, but not in its absence. Thus, P(i) enhances the effect of the Mg(2+) ion on the ADP binding. Next, we determined the crystal structures of the ADP-bound NBD with and without Mg(2+) ion. As compared with the Mg(2+) ion-free structure, the ADP- and Mg(2+) ion-bound NBD contains one Mg(2+) ion, which is coordinated with the beta-phosphate group of ADP and associates with Asp10, Glu175, and Asp199, through four water molecules. The Mg(2+) ion is also coordinated with one P(i) molecule, which interacts with Lys71, Glu175, and Thr204. In fact, the mutations of Asp10 and Asp199 reduced the affinity of the NBD for ADP, in both the presence and the absence of P(i) . Therefore, the Mg(2+) ion-mediated network, including the P(i) and water molecules, increases the affinity of Hsp70 for ADP, and thus the dissociation of ADP is slow. In ADP-ATP exchange, the slow ADP dissociation might be rate-limiting. However, the nucleotide-exchange factors actually enhance ADP release by disrupting the Mg(2+) ion-mediated network. Biochemical and structural studies on the high affinity of Hsp70 for ADP.,Arakawa A, Handa N, Shirouzu M, Yokoyama S Protein Sci. 2011 May 23. doi: 10.1002/pro.663. PMID:21608060 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Heat Shock Proteins

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