GlcNAc (N-acetylglucosamine) is an essential part of the glycan chain in N-linked glycoproteins. It is a building block for polysaccharides such as chitin, and several glucosaminoglycans and proteins can be O-GlcNAcylated. The deacetylated form, glucosamine, is an integral part of GPI (glycosylphosphatidylinositol) anchors. Both are incorporated into polymers by glycosyltransferases that utilize UDP-GlcNAc. This UDP-sugar is synthesized in a short pathway comprising four steps starting from fructose 6-phosphate. GNA (glucosamine-6-phosphate N-acetyltransferase) catalyses the second of these four reactions in the de novo synthesis in eukaryotes. A phylogenetic analysis revealed that only one GNA isoform can be found in most of the species investigated and that the most likely Arabidopsis candidate is encoded by the gene At5g15770 (AtGNA). qPCR (quantitative PCR) revealed the ubiquitous expression of AtGNA in all organs of Arabidopsis plants. Heterologous expression of AtGNA showed that it is highly active between pH 7 and 8 and at temperatures of 30–40°C. It showed Km values of 231 μM for glucosamine 6-phosphate and 33 μM for acetyl-CoA respectively and a catalytic efficiency comparable with that of other GNAs characterized. The solved crystal structure of AtGNA at a resolution of 1.5 Å (1 Å=0.1 nm) revealed a very high structural similarity to crystallized GNA proteins from Homo sapiens and Saccharomyces cerevisiae despite less well conserved protein sequence identity.
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Research Article|
March 27 2012
Crystal structure and functional characterization of a glucosamine-6-phosphate N-acetyltransferase from Arabidopsis thaliana
Heike Riegler;
*Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476 Potsdam-Golm, Germany
2To whom correspondence should be addressed (email [email protected]).
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Thomas Herter;
Thomas Herter
1
*Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476 Potsdam-Golm, Germany
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Irina Grishkovskaya;
Irina Grishkovskaya
†Department of Structural and Computational Biology, University of Vienna, Campus-Vienna-Biocenter 5, 1030 Wien, Austria
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Anja Lude;
Anja Lude
*Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476 Potsdam-Golm, Germany
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Malgorzata Ryngajllo;
Malgorzata Ryngajllo
*Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476 Potsdam-Golm, Germany
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Marie E. Bolger;
Marie E. Bolger
*Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476 Potsdam-Golm, Germany
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Bernd Essigmann;
Bernd Essigmann
‡Bayer S.A.S, Bayer CropScience, 14 impasse Pierre Baizet, 69263 Lyon, France
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Björn Usadel
Björn Usadel
*Max Planck Institute of Molecular Plant Physiology, Am Mühlenberg 1, 14476 Potsdam-Golm, Germany
§RWTH Aachen, Worringer Weg 1, 52056 Aachen, Germany
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Publisher: Portland Press Ltd
Received:
November 24 2011
Revision Received:
January 24 2012
Accepted:
January 27 2012
Accepted Manuscript online:
February 13 2012
Online ISSN: 1470-8728
Print ISSN: 0264-6021
© The Authors Journal compilation © 2012 Biochemical Society
2012
Biochem J (2012) 443 (2): 427–437.
Article history
Received:
November 24 2011
Revision Received:
January 24 2012
Accepted:
January 27 2012
Accepted Manuscript online:
February 13 2012
Citation
Heike Riegler, Thomas Herter, Irina Grishkovskaya, Anja Lude, Malgorzata Ryngajllo, Marie E. Bolger, Bernd Essigmann, Björn Usadel; Crystal structure and functional characterization of a glucosamine-6-phosphate N-acetyltransferase from Arabidopsis thaliana. Biochem J 15 April 2012; 443 (2): 427–437. doi: https://doi.org/10.1042/BJ20112071
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