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Abstract Detail


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Williams, Matthew R. [1], Showalter, Allan M. [2], Faik, Ahmed [2].

Biochemical Characterization of Putative Fucosyltransferases for Arabinogalactan-proteins.

Arabinogalactan-proteins (AGPs) are hyperglycosylated members of the hydroxyproline-rich glycoprotein family (HRGPs). AGPs are found in the cell walls, plasma membranes and extracellular secretions of plants. Due to the complexity of the arabinogalactan polysaccharide moiety on AGPs, we anticipate that 16 enzyme activities are required for synthesis in Arabidopsis. None of these enzymes have been cloned. Arabidopsis AGPs contain α-1,2-linked fucose residues. We have identified and characterized 9 Arabidopsis genes homologous to the xyloglucan-α-1,2-fucosyltransferase gene (AtFUT1) that fucosylates xyloglucans (Sarria et al., 2001 Plant Phys. 127:1595-1606). These 10 Arabidopsis fucosyltransferases (FUTs) are grouped in family GT37 according to the Carbohydrate-Active enZymes (CAZy) database. Among these enzymes, only AtFUT1s function is known. Based on our preliminary data, we hypothesize that AtFUT4 (At2g15390) and AtFUT6 (At1g14080) encode enzymes that are AGP-specific FUTs. Work on the mur1 mutant showed that the fucose residues of AGPs are important in root cell elongation (van Hengel, Roberts, 2002 Plant J. 32:105-113). The predicted amino acid sequences for AtFUT4 and AtFUT6 show 57.2% and 61.8% similarity with AtFUT1 respectively, and share three conserved motifs with AtFUT1 and known α-1,2 or α-1,6 FUTs from humans, nematodes and bacteria. Bioinformatic analysis predicted AtFUT4 and AtFUT6 to be type II membrane proteins consistent with a Golgi localization. We cloned both genes and made his-tagged and untagged constructs for heterologous expression in Drosophila S2 and Pichia cells. A biochemical assay will be optimized using microsomes from roots and non-fucosylated AGPs. The assays will be used to evaluate the biochemical function of these putative AGP-FUTs.


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Matthew R. Williams
Allan M. Showalter
Ahmed Faik


1 - Ohio University, Environmental and Plant Biology, Athens, OH, 45701, United States
2 - Ohio University, Environmental and Plant Biology, Molecular and Cellular Biology Program, Athens, OH, 45701, United States

Keywords:
fucosyltransferase
glycosyltransferase
AGPs
arabinogalactan-proteins
HRGPs
hyperglycosylated hydoxyproline-rich glycoproteins
fucose
fucosylation.

Presentation Type: Plant Biology Abstract
Session: P
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM
Number: P17016
Abstract ID:536


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