Crystal structure and functional characterization of a glucosamine-6-phosphate N-acetyltransferase from Arabidopsis thaliana
| Autor: | Thomas Herter, Małgorzata Ryngajłło, Heike Riegler, Bernd Essigmann, Björn Usadel, Marie E. Bolger, Anja Lude, Irina Grishkovskaya |
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| Rok vydání: | 2012 |
| Předmět: |
Glycan
Saccharomyces cerevisiae Molecular Sequence Data Arabidopsis Glucosamine 6-Phosphate N-Acetyltransferase Crystallography X-Ray Biochemistry Substrate Specificity chemistry.chemical_compound Glucosamine Gene Expression Regulation Plant Arabidopsis thaliana Humans Amino Acid Sequence Protein Structure Quaternary Molecular Biology Phylogeny biology Sequence Homology Amino Acid Cell Biology biology.organism_classification Protein Structure Tertiary Acetylglucosamine chemistry Structural Homology Protein biology.protein Heterologous expression Sequence Alignment |
| Zdroj: | The Biochemical journal. 443(2) |
| ISSN: | 1470-8728 |
| Popis: | 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 At GNA showed that it is highly active between pH 7 and 8 and at temperatures of 30–40°C. It showed K m 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 At GNA at a resolution of 1.5 A (1 A=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. |
| Databáze: | OpenAIRE |
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