Sialic acid recognition by Vibrio cholerae neuraminidase

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Title Sialic acid recognition by Vibrio cholerae neuraminidase
Author Moustafa, Ibrahim; Connaris, Helen; Taylor, Margaret; Zaitsev, Viateslav; Wilson, Jenny; Kiefel, Milton; von Itzstein, Mark; Taylor, Garry
Journal Name Journal of Biological Chemistry
Editor Herbert Tabor
Year Published 2004
Place of publication USA
Publisher American Society for Biochemistry and molecular Biology Inc
Abstract Vibrio cholerae neuraminidase (VCNA) plays a significant role in the pathogenesis of cholera by removing sialic acid from higher order gangliosides to unmask GM1, the receptor for cholera toxin. We previously showed that the structure of VCNA is composed of a central ?-propeller catalytic domain flanked by two lectin-like domains, however the nature of the carbohydrates recognised by these lectin domains has remained unknown. We present here structures of the enzyme in complex with two substrates, ?2,3-sialyllactose and ?-2,6-sialyllactose. Both substrate complexes reveal the ?-anomer of N-acetylneuraminic acid (Neu5Ac, NANA) bound to the Nterminal lectin domain, thereby revealing the role of this domain. The large number of interactions suggest a relatively high binding affinity for sialic acid, which was confirmed by calorimetry, which gave a Kd~30?M. Saturation transfer difference (STD) NMR using a non-hydrolysable substrate, Neu5,9Ac2-2-S-(?-2,6)-GlcNAc?1Me, was also used to map the ligand interactions at the VCNA lectin binding site. It is well known that VCNA can hydrolyse both ?-2,3- and ?-2,6-linked sialic acid substrates. In this study using ?-2,3-sialyllactose co-crystallised with VCNA it was revealed that the inhibitor 2-deoxy-2,3-didehydro-N-acetylneuraminic acid (Neu5Ac2en, DANA) was bound at the catalytic site. This observation supports the notion that VCNA can produce its own inhibitor and has been further confirmed by 1H NMR analysis. The discovery of the sialic acid-binding site in the N-lectin-like domain suggests that this might help target VCNA to sialic acid-rich environments, thereby enhancing the catalytic efficiency of the enzyme.
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Copyright Statement Copyright 2004 American Society for Biochemistry and Molecular Biology. Please refer to the journal website for access to the definitive, published version.
Volume 279
Issue Number 39
Page from 40819
Page to 40826
ISSN 0021-9258
Date Accessioned 2005-03-22
Language en_US
Research Centre Institute for Glycomics
Faculty Institute for Glycomics
Subject PRE2009-Science & Technology
Publication Type Journal Articles (Refereed Article)
Publication Type Code c1

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