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| {{STRUCTURE_2bup| PDB=2bup | SCENE= }} | | {{STRUCTURE_2bup| PDB=2bup | SCENE= }} |
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| '''T13G MUTANT OF THE ATPASE FRAGMENT OF BOVINE HSC70'''
| | ===T13G MUTANT OF THE ATPASE FRAGMENT OF BOVINE HSC70=== |
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| ==Overview==
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| 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. | | The line below this paragraph, {{ABSTRACT_PUBMED_9799500}}, adds the Publication Abstract to the page |
| | (as it appears on PubMed at http://www.pubmed.gov), where 9799500 is the PubMed ID number. |
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| | {{ABSTRACT_PUBMED_9799500}} |
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| ==About this Structure== | | ==About this Structure== |
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| [[Category: Atpase]] | | [[Category: Atpase]] |
| [[Category: Molecular chaperone]] | | [[Category: Molecular chaperone]] |
| ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 20:49:27 2008'' | | |
| | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 29 07:30:01 2008'' |
