The hydroxyl of threonine 13 of the bovine 70-kDa heat shock cognate protein is essential for transducing the ATP-induced conformational change.Sousa, M.C., McKay, D.B.
(1998) Biochemistry 37: 15392-15399
- PubMed: 9799500
- DOI: 10.1021/bi981510x
- Primary Citation of Related Structures:
- PubMed Abstract:
- Structural Basis of the 70-Kilodalton Heat Shock Cognate Protein ATP Hydrolytic Activity
Flaherty, K.M.,Wilbanks, S.M.,Deluca-Flaherty, C.,Mckay, D.B.
(1994) J.Biol.Chem. 269: 12899
- Three-Dimensional Structure of the ATPase Fragment of a 70K Heat-Shock Cognate Protein
Flaherty, K.M.,Deluca-Flaherty, C.,Mckay, D.B.
(1990) Nature 346: 623
The mechanism by which ATP binding transduces a conformational change in 70-kDa heat shock proteins that results in release of bound peptides remains obscure. Wei and Hendershot demonstrated that mutating Thr37 of hamster BiP to glycine impeded the A ...
The mechanism by which ATP binding transduces a conformational change in 70-kDa heat shock proteins that results in release of bound peptides remains obscure. Wei and Hendershot demonstrated that mutating Thr37 of hamster BiP to glycine impeded the ATP-induced conformational change, as monitored by proteolysis [(1995) J. Biol. Chem. 270, 26670-26676]. We have mutated the equivalent resitude of the bovine heat shock cognate protein (Hsc70), Thr13, to serine, valine, and glycine. Solution small-angle X-ray scattering experiments on a 60-kDa fragment of Hsc70 show that ATP binding induces a conformational change in the T13S mutant but not the T13V or T13G mutants. The kinetics of ATP-induced tryptophan fluorescence intensity changes in the 60-kDa proteins is biphasic for the T13S mutant but monophasic for T13V or T13G, consistent with a conformational change following initial ATP binding in the T13S mutant but not the other two. Crystallographic structures of the ATPase fragments of the T13S and T13G mutants at 1.7 A resolution show that the mutations do not disrupt the ATP binding site and that the serine hydroxyl mimics the threonine hydroxyl in the wild-type structure. We conclude that the hydroxyl of Thr13 is essential for coupling ATP binding to a conformational change in Hsc70. Molecular modeling suggests this may result from the threonine hydroxyl hydrogen-bonding to a gamma-phosphate oxygen of ATP, thereby inducing a structural shift within the ATPase domain that couples to its interactions with the peptide binding domain.
Beckman Laboratories for Structural Biology, Department of Structural Biology, Stanford University School of Medicine, California 94305-5400, USA.