1qm5

Phosphorylase recognition and phosphorylysis of its oligosaccharide substrate: answers to a long outstanding question

spinqualitylabelsall models 1qm5, resolution 2.00Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1qm5 is a 2 chain structure with sequence from Escherichia coli. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2Å Ligands: GLC, PLP, PO4, SGC Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function PHSM_ECOLI Phosphorylase is an important allosteric enzyme in carbohydrate metabolism. Enzymes from different sources differ in their regulatory mechanisms and in their natural substrates. However, all known phosphorylases share catalytic and structural properties. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed Phosphorylases are key enzymes of carbohydrate metabolism. Structural studies have provided explanations for almost all features of control and substrate recognition of phosphorylase but one question remains unanswered. How does phosphorylase recognize and cleave an oligosaccharide substrate? To answer this question we turned to the Escherichia coli maltodextrin phosphorylase (MalP), a non-regulatory phosphorylase that shares similar kinetic and catalytic properties with the mammalian glycogen phosphorylase. The crystal structures of three MalP-oligosaccharide complexes are reported: the binary complex of MalP with the natural substrate, maltopentaose (G5); the binary complex with the thio-oligosaccharide, 4-S-alpha-D-glucopyranosyl-4-thiomaltotetraose (GSG4), both at 2.9 A resolution; and the 2.1 A resolution ternary complex of MalP with thio-oligosaccharide and phosphate (GSG4-P). The results show a pentasaccharide bound across the catalytic site of MalP with sugars occupying sub-sites -1 to +4. Binding of GSG4 is identical to the natural pentasaccharide, indicating that the inactive thio compound is a close mimic of the natural substrate. The ternary MalP-GSG4-P complex shows the phosphate group poised to attack the glycosidic bond and promote phosphorolysis. In all three complexes the pentasaccharide exhibits an altered conformation across sub-sites -1 and +1, the site of catalysis, from the preferred conformation for alpha(1-4)-linked glucosyl polymers. Phosphorylase recognition and phosphorolysis of its oligosaccharide substrate: answers to a long outstanding question.,Watson KA, McCleverty C, Geremia S, Cottaz S, Driguez H, Johnson LN EMBO J. 1999 Sep 1;18(17):4619-32. PMID:10469642 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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