title: The interconversion of UDP-arabinopyranose and UDP-arabinofuranose is indispensable for plant development in Arabidopsis.
abstract: L-Ara, an important constituent of plant cell walls, is found predominantly in the furanose rather than in the thermodynamically more stable pyranose form. Nucleotide sugar mutases have been demonstrated to interconvert UDP-Larabinopyranose (UDP-Arap) and UDP-L-arabinofuranose (UDP-Araf) in rice (Oryza sativa). These enzymes belong to a small gene family encoding the previously named Reversibly Glycosylated Proteins (RGPs). RGPs are plant-specific cytosolic proteins that tend to associate with the endomembrane system. In Arabidopsis thaliana, the RGP protein family consists of five closely related members. We characterized all five RGPs regarding their expression pattern and subcellular localizations in transgenic Arabidopsis plants. Enzymatic activity assays of recombinant proteins expressed in Escherichia coli identified three of the Arabidopsis RGP protein family members as UDP-L-Ara mutases that catalyze the formation of UDP-Araf from UDP-Arap. Coimmunoprecipitation and subsequent liquid chromatography-electrospray ionization-tandem mass spectrometry analysis revealed a distinct interaction network between RGPs in different Arabidopsis organs. Examination of cell wall polysaccharide preparations from RGP1 and RGP2 knockout mutants showed a significant reduction in total L-Ara content (12–31%) compared with wild-type plants. Concomitant downregulation of RGP1 and RGP2 expression results in plants almost completely deficient in cell wall–derived L-Ara and exhibiting severe developmental defects.
authors.affiliation: Joint BioEnergy Institute, Feedstocks Division, Lawrence Berkeley National Laboratory, Emeryville, California 94608, USA.
authors.forename: Carsten
authors.initials: C
authors.lastname: Rautengarten
authors.forename: Berit
authors.initials: B
authors.lastname: Ebert
authors.forename: Thomas
authors.initials: T
authors.lastname: Herter
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Petzold
authors.forename: Tadashi
authors.initials: T
authors.lastname: Ishii
authors.forename: Aindrila
authors.initials: A
authors.lastname: Mukhopadhyay
authors.forename: Björn
authors.initials: B
authors.lastname: Usadel
authors.forename: Henrik Vibe
authors.initials: HV
authors.lastname: Scheller
mesh_terms: D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism; D050260:Carbohydrate Metabolism; D002241:Carbohydrates / Q000032:analysis; D002473:Cell Wall / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D018506:Gene Expression Regulation, Plant; D019751:Intramolecular Transferases / Q000378:metabolism; D046912:Multiprotein Complexes / Q000378:metabolism; D030821:Plants, Genetically Modified; D021381:Protein Transport; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013347:Subcellular Fractions / Q000378:metabolism; D014539:Uridine Diphosphate Sugars / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D002241:Carbohydrates; D046912:Multiprotein Complexes; D011993:Recombinant Fusion Proteins; D014539:Uridine Diphosphate Sugars; C040817:uridine diphosphate arabinose; D019751:Intramolecular Transferases