2bup: Difference between revisions
New page: left|200px<br /><applet load="2bup" size="450" color="white" frame="true" align="right" spinBox="true" caption="2bup, resolution 1.70Å" /> '''T13G MUTANT OF THE A... |
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[[Image:2bup.jpg|left|200px]]<br /><applet load="2bup" size=" | [[Image:2bup.jpg|left|200px]]<br /><applet load="2bup" size="350" color="white" frame="true" align="right" spinBox="true" | ||
caption="2bup, resolution 1.70Å" /> | caption="2bup, resolution 1.70Å" /> | ||
'''T13G MUTANT OF THE ATPASE FRAGMENT OF BOVINE HSC70'''<br /> | '''T13G MUTANT OF THE ATPASE FRAGMENT OF BOVINE HSC70'''<br /> | ||
==Overview== | ==Overview== | ||
The mechanism by which ATP binding transduces a conformational change in | 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. | ||
==About this Structure== | ==About this Structure== | ||
2BUP is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Bos_taurus Bos taurus] with PO4, MG, K, CL, ADP and ATP as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http:// | 2BUP is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Bos_taurus Bos taurus] with <scene name='pdbligand=PO4:'>PO4</scene>, <scene name='pdbligand=MG:'>MG</scene>, <scene name='pdbligand=K:'>K</scene>, <scene name='pdbligand=CL:'>CL</scene>, <scene name='pdbligand=ADP:'>ADP</scene> and <scene name='pdbligand=ATP:'>ATP</scene> as [http://en.wikipedia.org/wiki/ligands ligands]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2BUP OCA]. | ||
==Reference== | ==Reference== | ||
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[[Category: Bos taurus]] | [[Category: Bos taurus]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
[[Category: Mckay, D | [[Category: Mckay, D B.]] | ||
[[Category: Sousa, M | [[Category: Sousa, M C.]] | ||
[[Category: ADP]] | [[Category: ADP]] | ||
[[Category: ATP]] | [[Category: ATP]] | ||
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[[Category: molecular chaperone]] | [[Category: molecular chaperone]] | ||
''Page seeded by [http:// | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 16:41:57 2008'' | ||
Revision as of 17:42, 21 February 2008
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T13G MUTANT OF THE ATPASE FRAGMENT OF BOVINE HSC70
OverviewOverview
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.
About this StructureAbout this Structure
2BUP is a Single protein structure of sequence from Bos taurus with , , , , and as ligands. Full crystallographic information is available from OCA.
ReferenceReference
The hydroxyl of threonine 13 of the bovine 70-kDa heat shock cognate protein is essential for transducing the ATP-induced conformational change., Sousa MC, McKay DB, Biochemistry. 1998 Nov 3;37(44):15392-9. PMID:9799500
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