4bwl

Structure of the Y137A mutant of E. coli N-acetylneuraminic acid lyase in complex with pyruvate, N-acetyl-D-mannosamine and N- acetylneuraminic acidStructure of the Y137A mutant of E. coli N-acetylneuraminic acid lyase in complex with pyruvate, N-acetyl-D-mannosamine and N- acetylneuraminic acid

Structural highlights 4bwl is a 4 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: , , , Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function NANA_ECOLI Catalyzes the cleavage of N-acetylneuraminic acid (sialic acid) to form pyruvate and N-acetylmannosamine via a Schiff base intermediate.[HAMAP-Rule:MF_01237] Publication Abstract from PubMed N-Acetylneuraminic acid lyase (NAL) is a Class I aldolase that catalyzes the reversible condensation of pyruvate with N-acetyl-d-mannosamine (ManNAc) to yield the sialic acid N-acetylneuraminic acid (Neu5Ac). Aldolases are finding increasing use as biocatalysts for the stereospecific synthesis of complex molecules. Incomplete understanding of the mechanism of catalysis in aldolases, however, can hamper development of new enzyme activities and specificities, including control over newly generated stereocenters. In the case of NAL, it is clear that the enzyme catalyzes a Bi-Uni ordered condensation reaction in which pyruvate binds first to the enzyme to form a catalytically important Schiff base. The identity of the residues required for catalysis of the condensation step and the nature of the transition state for this reaction, however, have been a matter of conjecture. In order to address, this we crystallized a Y137A variant of the E. coli NAL in the presence of Neu5Ac. The three-dimensional structure shows a full length sialic acid bound in the active site of subunits A, B, and D, while in subunit C, discontinuous electron density reveals the positions of enzyme-bound pyruvate and ManNAc. These 'snapshot' structures, representative of intermediates in the enzyme catalytic cycle, provided an ideal starting point for QM/MM modeling of the enzymic reaction of carbon-carbon bond formation. This revealed that Tyr137 acts as the proton donor to the aldehyde oxygen of ManNAc during the reaction, the activation barrier is dominated by carbon-carbon bond formation, and proton transfer from Tyr137 is required to obtain a stable Neu5Ac-Lys165 Schiff base complex. The results also suggested that a triad of residues, Tyr137, Ser47, and Tyr110 from a neighboring subunit, are required to correctly position Tyr137 for its function, and this was confirmed by site-directed mutagenesis. This understanding of the mechanism and geometry of the transition states along the C-C bond-forming pathway will allow further development of these enzymes for stereospecific synthesis of new enzyme products. Reaction Mechanism of N-Acetylneuraminic Acid Lyase Revealed by a Combination of Crystallography, QM/MM Simulation, and Mutagenesis.,Daniels AD, Campeotto I, van der Kamp MW, Bolt AH, Trinh CH, Phillips SE, Pearson AR, Nelson A, Mulholland AJ, Berry A ACS Chem Biol. 2014 Feb 21. PMID:24521460 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also N-acetylneuraminate lyase 3D structures

spinqualitylabelsall models 4bwl, resolution 2.00Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image