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spinqualitylabelsall models 1qwj, resolution 2.8Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

The Crystal Structure of Murine CMP-5-N-Acetylneuraminic Acid Synthetase

Overview

Sialic acids are activated by CMP-5-N-acetylneuraminic acid synthetase prior to their transfer onto oligo- or polysaccharides. Here, we present the crystal structure of the N-terminal catalytically active domain of the murine 5-N-acetylneuraminic acid synthetase in complex with the reaction product. In contrast to the previously solved structure of 5-N-acetylneuraminic acid synthetase from Neisseria meningitidis and the related CMP-KDO-synthetase of Escherichia coli, the murine enzyme is a tetramer, which was observed with the active sites closed. In this conformation a loop is shifted by 6A towards the active site and thus an essential arginine residue can participate in catalysis. Furthermore, a network of intermolecular salt-bridges and hydrogen bonds in the dimer as well as hydrophobic interfaces between two dimers indicate a cooperative behaviour of the enzyme. In addition, a complex regulation of the enzyme activity is proposed that includes phosphorylation and dephosphorylation.

About this Structure

1QWJ is a Single protein structure of sequence from Mus musculus with as ligand. Active as N-acylneuraminate cytidylyltransferase, with EC number 2.7.7.43 Full crystallographic information is available from OCA.

Reference

The crystal structure of murine CMP-5-N-acetylneuraminic acid synthetase., Krapp S, Munster-Kuhnel AK, Kaiser JT, Huber R, Tiralongo J, Gerardy-Schahn R, Jacob U, J Mol Biol. 2003 Dec 5;334(4):625-37. PMID:14636592

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