Transport of UDP-galactose in plants. Identification and functional characterization of AtUTr1, an Arabidopsis thaliana UDP-galactose/UDP-glucose transporter

Lorena Norambuena, Lorena Marchant, Patricia Berninsone, Carlos B. Hirschberg, Herman Silva, Ariel Orellana

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71 Citations (Scopus)

Abstract

The synthesis of non-cellulosic polysaccharides and glycoproteins in the plant cell Golgi apparatus requires UDP-galactose as substrate. The topology of these reactions is not known, although the orientation of a plant galactosyltransferase involved in the biosynthesis of galactomannans in fenugreek is consistent with a requirement for UDP-galactose in the lumen of the Golgi cisternae. Here we provide evidence that sealed, right-sideout Golgi vesicles isolated from pea stems transport UDP-galactose into their lumen and transfer galactose, likely to polysaccharides and other acceptors. In addition, we identified and cloned AtUTr1, a gene from Arabidopsis thaliana that encodes a multitransmembrane hydrophobic protein similar to nucleotide sugar transporters. Northern analysis showed that AtUTr1 is indeed expressed in Arabidopsis. AtUTr1 is able to complement the phenotype of MDCK ricin-resistant cells; a mammalian cell line deficient in transport of UDP-galactose into the Golgi. In vitro assays using a Golgien-riched vesicle fraction obtained from Saccharomyces cerevisiae expressing AtUTr1-MycHis is able to transport UDP-galactose but also UDP-glucose. AtUTr1-MycHis does not transport GDP-mannose, GDP-fucose, CMP-sialic acid, UDP-glucuronic acid, or UDP-xylose when expressed in S. cerevisiae. AtUTr1 is the first transporter described that is able to transport UDP-galactose and UDP-glucose. Thus AtUTr1 may play an important role in the synthesis of glycoconjugates in Arabidopsis that contain galactose and glucose.

Original languageEnglish
Pages (from-to)32923-32929
Number of pages7
JournalJournal of Biological Chemistry
Volume277
Issue number36
DOIs
Publication statusPublished - 6 Sep 2002

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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