The elaborate route for UDP-arabinose delivery into the Golgi of plants

In plants, L-arabinose (Ara) is a key component of cell wall polymers, glycoproteins, as well as flavonoids, and signaling peptides. Whereas the majority of Ara found in plant glycans occurs as a furanose ring (Araf), the activated precursor has a pyranose ring configuration (UDP-Arap). The biosynth...

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Published in:Proceedings of the National Academy of Sciences - PNAS 2017-04, Vol.114 (16), p.4261-4266
Main Authors: Rautengarten, Carsten, Birdseye, Devon, Pattathil, Sivakumar, McFarlane, Heather E., Saez-Aguayo, Susana, Orellana, Ariel, Persson, Staffan, Hahn, Michael G., Scheller, Henrik V., Heazlewood, Joshua L., Ebert, Berit
Format: Article
Language:English
Subjects:
Arabinose
BASIC BIOLOGICAL SCIENCES
Biological Sciences
Biosynthesis
Cell walls
Data processing
Enzymes
Flavonoids
Flowers & plants
Glycoproteins
Glycosylation
Golgi apparatus
membrane transport
nucleotide sugars
Peptides
Polymers
Polysaccharides
Signal transduction
Sugar
Xylose
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Summary:In plants, L-arabinose (Ara) is a key component of cell wall polymers, glycoproteins, as well as flavonoids, and signaling peptides. Whereas the majority of Ara found in plant glycans occurs as a furanose ring (Araf), the activated precursor has a pyranose ring configuration (UDP-Arap). The biosynthesis of UDP-Arap mainly occurs via the epimerization of UDP-xylose (UDP-Xyl) in the Golgi lumen. Given that the predominant Ara form found in plants is Araf, UDP-Arap must exit the Golgi to be interconverted into UDP-Araf by UDP-Ara mutases that are located outside on the cytosolic surface of the Golgi. Subsequently, UDP-Araf must be transported back into the lumen. This step is vital because glycosyltransferases, the enzymes mediating the glycosylation reactions, are located within the Golgi lumen, and UDP-Arap, synthesized within the Golgi, is not their preferred substrate. Thus, the transport of UDP-Araf into the Golgi is a prerequisite. Although this step is critical for cell wall biosynthesis and the glycosylation of proteins and signaling peptides, the identification of these transporters has remained elusive. In this study, we present data demonstrating the identification and characterization of a family of Golgilocalized UDP-Araf transporters in Arabidopsis. The application of a proteoliposome-based transport assay revealed that four members of the nucleotide sugar transporter (NST) family can efficiently transport UDP-Araf in vitro. Subsequent analysis of mutant lines affected in the function of these NSTs confirmed their role as UDP-Araf transporters in vivo.
ISSN:0027-8424
1091-6490
DOI:10.1073/pnas.1701894114