6abp
From Proteopedia
(New page: 200px<br /><applet load="6abp" size="450" color="white" frame="true" align="right" spinBox="true" caption="6abp, resolution 1.67Å" /> '''SUGAR-BINDING AND CR...) |
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| - | [[Image:6abp.gif|left|200px]]<br /><applet load="6abp" size=" | + | [[Image:6abp.gif|left|200px]]<br /><applet load="6abp" size="350" color="white" frame="true" align="right" spinBox="true" |
caption="6abp, resolution 1.67Å" /> | caption="6abp, resolution 1.67Å" /> | ||
'''SUGAR-BINDING AND CRYSTALLOGRAPHIC STUDIES OF AN ARABINOSE-BINDING PROTEIN MUTANT (MET108LEU) WHICH EXHIBITS ENHANCED AFFINITY AND ALTERED SPECIFICITY'''<br /> | '''SUGAR-BINDING AND CRYSTALLOGRAPHIC STUDIES OF AN ARABINOSE-BINDING PROTEIN MUTANT (MET108LEU) WHICH EXHIBITS ENHANCED AFFINITY AND ALTERED SPECIFICITY'''<br /> | ||
==Overview== | ==Overview== | ||
| - | In addition to hydrogen bonds, van der Waals forces contribute to the | + | In addition to hydrogen bonds, van der Waals forces contribute to the affinity of protein-carbohydrate interactions. Nonpolar van der Waals contacts in the complexes of the L-arabinose-binding protein (ABP) with monosaccharides have been studied by means of site-directed mutagenesis, equilibrium and rapid kinetic binding techniques, and X-ray crystallography. ABP, a periplasmic transport receptor of Escherichia coli, binds L-arabinose, D-galactose, and D-fucose with preferential affinity in the order of Ara greater than Gal much greater than Fuc. Well-refined, high-resolution structures of ABP complexed with the three sugars revealed that the structural differences in the ABP-sugar complexes are localized around C5 of the sugars, where the equatorial H of Ara has been substituted for CH3 (Fuc) or CH2OH (Gal). The side chain of Met108 undergoes a sterically dictated, ligand-specific, conformational change to optimize nonpolar interactions between its methyl group and the sugar. We found that the Met108Leu ABP binds Gal tighter than wild-type ABP binds Ara and exhibits a preference for ligand in the order of Gal much greater than Fuc greater than Ara. The differences in affinity can be attributed to differences in the dissociation rates of the ABP-sugar complexes. We have refined at better than 1.7-A resolution the crystal structures of the Met108Leu ABP complexed with each of the sugars and offer a molecular explanation for the altered binding properties. |
==About this Structure== | ==About this Structure== | ||
| - | 6ABP is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli]. Full crystallographic information is available from [http:// | + | 6ABP is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=6ABP OCA]. |
==Reference== | ==Reference== | ||
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[[Category: Escherichia coli]] | [[Category: Escherichia coli]] | ||
[[Category: Single protein]] | [[Category: Single protein]] | ||
| - | [[Category: Quiocho, F | + | [[Category: Quiocho, F A.]] |
| - | [[Category: Tesmer, J | + | [[Category: Tesmer, J J.G.]] |
| - | [[Category: Vermersch, P | + | [[Category: Vermersch, P S.]] |
[[Category: binding proteins]] | [[Category: binding proteins]] | ||
| - | ''Page seeded by [http:// | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 19:16:01 2008'' |
Revision as of 17:16, 21 February 2008
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SUGAR-BINDING AND CRYSTALLOGRAPHIC STUDIES OF AN ARABINOSE-BINDING PROTEIN MUTANT (MET108LEU) WHICH EXHIBITS ENHANCED AFFINITY AND ALTERED SPECIFICITY
Overview
In addition to hydrogen bonds, van der Waals forces contribute to the affinity of protein-carbohydrate interactions. Nonpolar van der Waals contacts in the complexes of the L-arabinose-binding protein (ABP) with monosaccharides have been studied by means of site-directed mutagenesis, equilibrium and rapid kinetic binding techniques, and X-ray crystallography. ABP, a periplasmic transport receptor of Escherichia coli, binds L-arabinose, D-galactose, and D-fucose with preferential affinity in the order of Ara greater than Gal much greater than Fuc. Well-refined, high-resolution structures of ABP complexed with the three sugars revealed that the structural differences in the ABP-sugar complexes are localized around C5 of the sugars, where the equatorial H of Ara has been substituted for CH3 (Fuc) or CH2OH (Gal). The side chain of Met108 undergoes a sterically dictated, ligand-specific, conformational change to optimize nonpolar interactions between its methyl group and the sugar. We found that the Met108Leu ABP binds Gal tighter than wild-type ABP binds Ara and exhibits a preference for ligand in the order of Gal much greater than Fuc greater than Ara. The differences in affinity can be attributed to differences in the dissociation rates of the ABP-sugar complexes. We have refined at better than 1.7-A resolution the crystal structures of the Met108Leu ABP complexed with each of the sugars and offer a molecular explanation for the altered binding properties.
About this Structure
6ABP is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.
Reference
Sugar-binding and crystallographic studies of an arabinose-binding protein mutant (Met108Leu) that exhibits enhanced affinity and altered specificity., Vermersch PS, Lemon DD, Tesmer JJ, Quiocho FA, Biochemistry. 1991 Jul 16;30(28):6861-6. PMID:2069949
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