1up7: Difference between revisions
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==Overview== | ==Overview== | ||
The import of disaccharides by many bacteria is achieved through their, simultaneous translocation and phosphorylation by the, phosphoenolpyruvate-dependent phosphotransferase system (PEP-PTS). The, imported phospho-disaccharides are, in some cases, subsequently hydrolyzed, by members of the unusual glycoside hydrolase family GH4. The GH4 enzymes, occasionally found also in bacteria such as Thermotoga maritima that do, not utilise a PEP-PTS system, require both NAD(+) and Mn(2+) for, catalysis. A further curiosity of this family is that closely related, enzymes may show specificity for either alpha-d- or beta-d-glycosides., Here, we present, for the first time, the three-dimensional structure, (using single-wavelength anomalous dispersion methods, harnessing, extensive ... | The import of disaccharides by many bacteria is achieved through their, simultaneous translocation and phosphorylation by the, phosphoenolpyruvate-dependent phosphotransferase system (PEP-PTS). The, imported phospho-disaccharides are, in some cases, subsequently hydrolyzed, by members of the unusual glycoside hydrolase family GH4. The GH4 enzymes, occasionally found also in bacteria such as Thermotoga maritima that do, not utilise a PEP-PTS system, require both NAD(+) and Mn(2+) for, catalysis. A further curiosity of this family is that closely related, enzymes may show specificity for either alpha-d- or beta-d-glycosides., Here, we present, for the first time, the three-dimensional structure, (using single-wavelength anomalous dispersion methods, harnessing, extensive non-crystallographic symmetry) of the, 6-phospho-beta-glycosidase, BglT, from T.maritima in native and complexed, (NAD(+) and Glc6P) forms. Comparison of the active-center structure with, that of the 6-phospho-alpha-glucosidase GlvA from Bacillus subtilis, reveals a striking degree of structural similarity that, in light of, previous kinetic isotope effect data, allows the postulation of a common, reaction mechanism for both alpha and beta-glycosidases. Given that the, "chemistry" occurs primarily on the glycone sugar and features no, nucleophilic attack on the intact disaccharide substrate, modulation of, anomeric specificity for alpha and beta-linkages is accommodated through, comparatively minor structural changes. | ||
==About this Structure== | ==About this Structure== | ||
1UP7 is a | 1UP7 is a [http://en.wikipedia.org/wiki/Single_protein Single protein] structure of sequence from [http://en.wikipedia.org/wiki/Thermotoga_maritima Thermotoga maritima] with G6P, SO4 and NAD as [http://en.wikipedia.org/wiki/ligands ligands]. Active as [http://en.wikipedia.org/wiki/Endo-1,3(4)-beta-glucanase Endo-1,3(4)-beta-glucanase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.2.1.6 3.2.1.6] Structure known Active Site: AC1. Full crystallographic information is available from [http://ispc.weizmann.ac.il/oca-bin/ocashort?id=1UP7 OCA]. | ||
==Reference== | ==Reference== | ||
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[[Category: nad dependent]] | [[Category: nad dependent]] | ||
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Revision as of 15:32, 5 November 2007
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STRUCTURE OF THE 6-PHOSPHO-BETA GLUCOSIDASE FROM THERMOTOGA MARITIMA AT 2.4 ANSTROM RESOLUTION IN THE TETRAGONAL FORM WITH NAD AND GLUCOSE-6-PHOSPHATE
OverviewOverview
The import of disaccharides by many bacteria is achieved through their, simultaneous translocation and phosphorylation by the, phosphoenolpyruvate-dependent phosphotransferase system (PEP-PTS). The, imported phospho-disaccharides are, in some cases, subsequently hydrolyzed, by members of the unusual glycoside hydrolase family GH4. The GH4 enzymes, occasionally found also in bacteria such as Thermotoga maritima that do, not utilise a PEP-PTS system, require both NAD(+) and Mn(2+) for, catalysis. A further curiosity of this family is that closely related, enzymes may show specificity for either alpha-d- or beta-d-glycosides., Here, we present, for the first time, the three-dimensional structure, (using single-wavelength anomalous dispersion methods, harnessing, extensive non-crystallographic symmetry) of the, 6-phospho-beta-glycosidase, BglT, from T.maritima in native and complexed, (NAD(+) and Glc6P) forms. Comparison of the active-center structure with, that of the 6-phospho-alpha-glucosidase GlvA from Bacillus subtilis, reveals a striking degree of structural similarity that, in light of, previous kinetic isotope effect data, allows the postulation of a common, reaction mechanism for both alpha and beta-glycosidases. Given that the, "chemistry" occurs primarily on the glycone sugar and features no, nucleophilic attack on the intact disaccharide substrate, modulation of, anomeric specificity for alpha and beta-linkages is accommodated through, comparatively minor structural changes.
About this StructureAbout this Structure
1UP7 is a Single protein structure of sequence from Thermotoga maritima with G6P, SO4 and NAD as ligands. Active as Endo-1,3(4)-beta-glucanase, with EC number 3.2.1.6 Structure known Active Site: AC1. Full crystallographic information is available from OCA.
ReferenceReference
NAD+ and metal-ion dependent hydrolysis by family 4 glycosidases: structural insight into specificity for phospho-beta-D-glucosides., Varrot A, Yip VL, Li Y, Rajan SS, Yang X, Anderson WF, Thompson J, Withers SG, Davies GJ, J Mol Biol. 2005 Feb 18;346(2):423-35. Epub 2005 Jan 7. PMID:15670594
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