UDP-GlcNAc is an essential precursor for glycoprotein and glycolipid synthesis. In the present study, a functional nucleotidyltransferase gene from Arabidopsis encoding a 58.3 kDa GlcNAc1pUT-1 (N-acetylglucosamine-1-phosphate uridylyltransferase) was identified. In the forward reaction the enzyme catalyses the formation of UDP-N-acetylglucosamine and PPi from the respective monosaccharide 1-phosphate and UTP. The enzyme can utilize the 4-epimer UDP-GalNAc as a substrate as well. The enzyme requires divalent ions (Mg2+ or Mn2+) for activity and is highly active between pH 6.5 and 8.0, and at 30–37 °C. The apparent Km values for the forward reaction were 337 μM (GlcNAc-1-P) and 295 μM (UTP) respectively. Another GlcNAc1pUT-2, which shares 86% amino acid sequence identity with GlcNAc1pUT-1, was found to convert, in addition to GlcNAc-1-P and GalNAc-1-P, Glc-1-P into corresponding UDP-sugars, suggesting that subtle changes in the UT family cause different substrate specificities. A three-dimensional protein structure model using the human AGX1 as template showed a conserved catalytic fold and helped identify key conserved motifs, despite the high sequence divergence. The identification of these strict and promiscuous gene products open a window to indentify new roles of amino sugar metabolism in plants and specifically their role as signalling molecules. The ability of GlcNAc1pUT-2 to utilize three different substrates may provide further understanding as to why biological systems have plasticity.
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Research Article|
August 13 2010
Identification and characterization of a strict and a promiscuous N-acetylglucosamine-1-P uridylyltransferase in Arabidopsis
Ting Yang;
Ting Yang
*Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602, U.S.A.
†Complex Carbohydrate Research Center (CCRC), University of Georgia, Athens, GA 30602, U.S.A.
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Merritt Echols;
Merritt Echols
†Complex Carbohydrate Research Center (CCRC), University of Georgia, Athens, GA 30602, U.S.A.
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Andy Martin;
Andy Martin
†Complex Carbohydrate Research Center (CCRC), University of Georgia, Athens, GA 30602, U.S.A.
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Maor Bar-Peled
Maor Bar-Peled
1
†Complex Carbohydrate Research Center (CCRC), University of Georgia, Athens, GA 30602, U.S.A.
‡Department of Plant Biology, University of Georgia, Athens, GA 30602, U.S.A.
1To whom correspondence should be addressed (email peled@ccrc.uga.edu).
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Publisher: Portland Press Ltd
Received:
March 01 2010
Revision Received:
June 15 2010
Accepted:
June 17 2010
Accepted Manuscript online:
June 17 2010
Online ISSN: 1470-8728
Print ISSN: 0264-6021
© The Authors Journal compilation © 2010 Biochemical Society
2010
Biochem J (2010) 430 (2): 275–284.
Article history
Received:
March 01 2010
Revision Received:
June 15 2010
Accepted:
June 17 2010
Accepted Manuscript online:
June 17 2010
Citation
Ting Yang, Merritt Echols, Andy Martin, Maor Bar-Peled; Identification and characterization of a strict and a promiscuous N-acetylglucosamine-1-P uridylyltransferase in Arabidopsis. Biochem J 1 September 2010; 430 (2): 275–284. doi: https://doi.org/10.1042/BJ20100315
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