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

Norambuena, L; Marchant, L; Berninsone, P; Hirschberg, CB; Silva H.; Orellana, A

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.

Más información

Título según WOS: Transport of UDP-galactose in plants - Identification and functional characterization of AtUTr1, an Arabidopsis thaliana UDP-galactose/UDP-glucose transporter
Título según SCOPUS: Transport of UDP-galactose in plants. Identification and functional characterization of AtUTr1, an Arabidopsis thaliana UDP-galactose/UDP-glucose transporter
Título de la Revista: JOURNAL OF BIOLOGICAL CHEMISTRY
Volumen: 277
Número: 36
Editorial: AMER SOC BIOCHEMISTRY MOLECULAR BIOLOGY INC
Fecha de publicación: 2002
Página de inicio: 32923
Página final: 32929
Idioma: English
URL: http://www.jbc.org/cgi/doi/10.1074/jbc.M204081200
DOI:

10.1074/jbc.M204081200

Notas: ISI, SCOPUS