Journal Article

<i>OeMST2</i> Encodes a Monosaccharide Transporter Expressed throughout Olive Fruit Maturation

Carlos Conde, Alice Agasse, Paulo Silva, Rémi Lemoine, Serge Delrot, Rui Tavares and Hernâni Gerós

in Plant and Cell Physiology

Published on behalf of Japanese Society of Plant Physiologists

Volume 48, issue 9, pages 1299-1308
Published in print September 2007 | ISSN: 0032-0781
Published online September 2007 | e-ISSN: 1471-9053 | DOI: http://dx.doi.org/10.1093/pcp/pcm096
OeMST2 Encodes a Monosaccharide Transporter Expressed throughout Olive Fruit Maturation

More Like This

Show all results sharing these subjects:

  • Biochemistry
  • Molecular and Cell Biology
  • Plant Sciences and Forestry

GO

Show Summary Details

Preview

In olive fruits, sugars are the main soluble components providing energy and acting as precursors for olive oil biosynthesis. Large quantities of glucose, fructose and galactose are often found in olive pulp. To analyze sugar transport processes in Olea europaea, a cDNA encoding a monosaccharide transporter, designated OeMST2 (Olea europaea monosaccharide transporter 2) was cloned. An open reading frame of 1,569 bp codes for a protein of 523 amino acids and a calculated molecular weight of 57.6 kDa. The protein is homologous to other sugar transporters identified so far in higher plants. Expression of this cDNA in an hxt-null Saccharomyces cerevisiae strain deficient in glucose transport restored its capacity to grow on and to transport glucose. The encoded protein showed high affinity for d-glucose (Km, 25 μM) and was also able to recognize d-galactose and the analogs 3-O-methyl-d-glucose and 2-deoxy-d-glucose, but not d-fructose, d-arabinose, sucrose or d-mannitol. Maximal transport activity was high at acidic pH (5.0), and the initial d-[14C]glucose uptake rates were strongly inhibited by the protonophore carbonyl cyanide m-chlorophenylhydrazone, confirming that OeMST2 is a H+/monosaccharide transporter. The expression of OeMST2 was studied during the ripening process. Transcript levels increased during fruit maturation, suggesting that OeMST2 takes part in the massive accumulation of monosaccharides in olive fruits. Monosaccharide:H+ transport system activity and OeMST2 expression were negatively regulated by glucose in suspension-cultured cells. Glucose-mediated OeMST2 repression was impaired by mannoheptulose, suggesting the involvement of a hexokinase-dependent signaling pathway.

Keywords: Glucose; Monosaccharide transport; Olea europaea; Sugar sensing

Journal Article.  6150 words.  Illustrated.

Subjects: Biochemistry ; Molecular and Cell Biology ; Plant Sciences and Forestry

Full text: subscription required

How to subscribe Recommend to my Librarian

Users without a subscription are not able to see the full content. Please, subscribe or login to access all content.