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Recycling of pyridoxine (vitamin B6) by PUP 1 in A rabidopsis
Author(s) -
Szydlowski Nicolas,
Bürkle Lukas,
Pourcel Lucille,
Moulin Michael,
Stolz Jürgen,
Fitzpatrick Teresa B.
Publication year - 2013
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/tpj.12195
Subject(s) - pyridoxine , biochemistry , mutant , permease , glutamine , biosynthesis , yeast , vitamin , biology , chemistry , amino acid , enzyme , gene
Summary Vitamin 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 A rabidopsis purine permeases ( PUP s) to transport vitamin B6. Several members of the family complement the growth phenotype of a S accharomyces cerevisiae mutant strain impaired in both de novo biosynthesis of vitamin B6 as well as its uptake. The strongest activity was observed with PUP 1 and was confirmed by direct measurement of uptake in yeast as well as in planta , defining PUP 1 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 PUP 1 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 PUP 1 is involved in the uptake of the vitamin.