Recycling of pyridoxine (vitamin B6) by PUP1 in Arabidopsis

• DOI: 10.1111/tpj.12195
• Publication Date: 2013-04-01T15:18:39Z
• Authors: Nicolas Szydlowski; Lukas Bürkle; Lucille Pourcel; Michael Moulin; Jürgen Stolz; Teresa B. Fitzpat...
• Keywords: Plant Exudates; Recombinant Fusion Proteins; info:eu-repo/classification/ddc/580; Arabidopsis; Gene Expression; Genetically Modified; Saccharomyces cerevisiae; Arabidopsis/genetics/metabolism/ultrastructure; Nucleobase Transport Proteins/genetics/metabolism; Plant Roots; Plant Epidermis; 12. Responsible consumption; 03 medical and health sciences; Gene Expression Regulation, Plant; Nucleobase Transport Proteins; [SDV.BV]Life Sciences [q-bio]/Vegetal Biology; [SDV.BBM]Life Sciences [q-bio]/Biochemistry, Molecular Biology; Plant Roots/genetics/metabolism/ultrastructure; Plant Exudates/analysis; Arabidopsis Proteins/genetics/metabolism; Microscopy; 0303 health sciences; Pyridoxine/chemistry/metabolism; Microscopy, Confocal; Arabidopsis Proteins; Cell Membrane/metabolism; Cell Membrane; Genetic Complementation Test; Pyridoxine; Biological Transport; Plant; Plants; Plants, Genetically Modified; Plant Epidermis/genetics/metabolism/ultrastructure; ddc:580; Phenotype; Gene Expression Regulation; Confocal; Multigene Family; Mutation; Saccharomyces cerevisiae/genetics/metabolism

SummaryVitamin B6 is a cofactor for more than 140 essential enzymatic reactions and was recently proposed as a potent antioxidant, playing a role in the photoprotection of plants. De novo biosynthesis of the vitamin has been described relatively recently and is derived from simple sugar precursors as well as glutamine. In addition, the vitamin can be taken up from exogenous sources in a broad range of organisms, including plants. However, specific transporters have been identified only in yeast. Here we assess the ability of the family of Arabidopsis purine permeases (PUPs) to transport vitamin B6. Several members of the family complement the growth phenotype of a Saccharomyces cerevisiae mutant strain impaired in both de novo biosynthesis of vitamin B6 as well as its uptake. The strongest activity was observed with PUP1 and was confirmed by direct measurement of uptake in yeast as well as in planta, defining PUP1 as a high affinity transporter for pyridoxine. At the tissue level the protein is localised to hydathodes and here we use confocal microscopy to illustrate that at the cellular level it is targeted to the plasma membrane. Interestingly, we observe alterations in pyridoxine recycling from the guttation sap upon overexpression of PUP1 and in a pup1 mutant, consistent with the role of the protein in retrieval of pyridoxine. Furthermore, combining the pup1 mutant with a vitamin B6 de novo biosynthesis mutant (pdx1.3) corroborates that PUP1 is involved in the uptake of the vitamin.