1qqn
D206S MUTANT OF BOVINE 70 KILODALTON HEAT SHOCK PROTEIN
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OverviewOverview
ATP binding induces a conformational change in 70-kDa heat shock proteins, (Hsp70s) that facilitates release of bound polypeptides. Using the bovine, heat shock cognate protein (Hsc70) as a representative of the Hsp70, family, we have characterized the effect of mutations on the coupling, between ATP binding and the nucleotide-induced conformational change., Steady-state solution small-angle X-ray scattering and kinetic, fluorescence measurements on a 60-kDa fragment of Hsc70 show that point, mutations K71M, E175S, D199S, and D206S in the nucleotide binding cleft, impair the ability of ATP to induce a conformational change. A secondary, mutation in the peptide binding domain, E543K, "rescues" the ATP-induced, transition for three of these mutations (E175S/E543K, D199S/E543K, and, D206S/E543K) but not for K71M/E543K. Analysis of kinetics of the ATPase, cycle confirm that these effects do not result from unexpectedly rapid ATP, hydrolysis or slow ATP binding. Crystallographic structures of E175S, D199S, and D206S mutant ATPase fragment proteins show that the mutations, do not perturb the tertiary structure of the protein but do significantly, alter the protein-ligand interactions, due in part to an apparent charge, compensation effect whereby mutating a (probably) negatively charged, carboxyl group to a neutral serine displaces a K+ ion from the nucleotide, binding cleft in two out of three cases (E175S and D199S but not D206S).
About this StructureAbout this Structure
1QQN is a Single protein structure of sequence from Bos taurus with K, CL, MG, PO4 and ADP as ligands. Full crystallographic information is available from OCA.
ReferenceReference
Mapping the role of active site residues for transducing an ATP-induced conformational change in the bovine 70-kDa heat shock cognate protein., Johnson ER, McKay DB, Biochemistry. 1999 Aug 17;38(33):10823-30. PMID:10451379
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