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Crystal Structures of N-Acetylmannosamine Kinase Provide Insights into Enzyme Activity and Inhibition

Sialic acids are essential components of membrane glycoconjugates. They are responsible for the interaction, structure, and functionality of all deuterostome cells and have major functions in cellular processes in health and diseases. The key enzyme of the biosynthesis of sialic acid is the bifuncti...

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Bibliographic Details
Published in:The Journal of biological chemistry 2012-04, Vol.287 (17), p.13656-13665
Main Authors: Martinez, Jacobo, Nguyen, Long Duc, Hinderlich, Stephan, Zimmer, Reinhold, Tauberger, Eva, Reutter, Werner, Saenger, Wolfram, Fan, Hua, Moniot, Sébastien
Format: Article
Language:English
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Summary:Sialic acids are essential components of membrane glycoconjugates. They are responsible for the interaction, structure, and functionality of all deuterostome cells and have major functions in cellular processes in health and diseases. The key enzyme of the biosynthesis of sialic acid is the bifunctional UDP-N-acetylglucosamine-2-epimerase/N-acetylmannosamine kinase that transforms UDP-N-acetylglucosamine to N-acetylmannosamine (ManNAc) followed by its phosphorylation to ManNAc 6-phosphate and has a direct impact on the sialylation of cell surface components. Here, we present the crystal structures of the human N-acetylmannosamine kinase (MNK) domain of UDP-N-acetylglucosamine-2-epimerase/N-acetylmannosamine kinase in complexes with ManNAc at 1.64 Å resolution, MNK·ManNAc·ADP (1.82 Å) and MNK·ManNAc 6-phosphate·ADP (2.10 Å). Our findings offer detailed insights in the active center of MNK and serve as a structural basis to design inhibitors. We synthesized a novel inhibitor, 6-O-acetyl-ManNAc, which is more potent than those previously tested. Specific inhibitors of sialic acid biosynthesis may serve to further study biological functions of sialic acid. Background: UDP-GlcNAc-2 epimerase/ManNAc kinase is the key enzyme for sialic acid biosynthesis. Results: The crystal structure of ManNAc kinase in complex with its substrate ManNAc has been determined at 1.64 Å resolution. Conclusion: Insights into the mechanism of ManNAc phosphorylation have been gained from the substrate-bound structure. Significance: The new structural information presented here offers a basis for designing potential inhibitors of sialic acid biosynthesis.
ISSN:0021-9258
1083-351X
DOI:10.1074/jbc.M111.318170