title: Analysis of the Arabidopsis rsr4-1/pdx1-3 mutant reveals the critical function of the PDX1 protein family in metabolism, development, and vitamin B6 biosynthesis.
abstract: Vitamin B6 represents a highly important group of compounds ubiquitous in all living organisms. It has been demonstrated to alleviate oxidative stress and in its phosphorylated form participates as a cofactor in >100 biochemical reactions. By means of a genetic approach, we have identified a novel mutant, rsr4-1 (for reduced sugar response), with aberrant root and leaf growth that requires supplementation of vitamin B6 for normal development. Cloning of the mutated gene revealed that rsr4-1 carries a point mutation in a member of the PDX1/SOR1/SNZ (for Pyridoxine biosynthesis protein 1/Singlet oxygen resistant 1/Snooze) family that leads to reduced vitamin B6 content. Consequently, metabolism is broadly altered, mainly affecting amino acid, raffinose, and shikimate contents and trichloroacetic acid cycle constituents. Yeast two-hybrid and pull-down analyses showed that Arabidopsis thaliana PDX1 proteins can form oligomers. Interestingly, the mutant form of PDX1 has severely reduced capability to oligomerize, potentially suggesting that oligomerization is important for function. In summary, our results demonstrate the critical function of the PDX1 protein family for metabolism, whole-plant development, and vitamin B6 biosynthesis in higher plants.
authors.affiliation: Angewandte Genetik, Freie Universität Berlin, 14195 Berlin, Germany.
authors.forename: Susan
authors.initials: S
authors.lastname: Wagner
authors.forename: Anne
authors.initials: A
authors.lastname: Bernhardt
authors.forename: Jan Erik
authors.initials: JE
authors.lastname: Leuendorf
authors.forename: Christel
authors.initials: C
authors.lastname: Drewke
authors.forename: Anna
authors.initials: A
authors.lastname: Lytovchenko
authors.forename: Nader
authors.initials: N
authors.lastname: Mujahed
authors.forename: Cristian
authors.initials: C
authors.lastname: Gurgui
authors.forename: Wolf B
authors.initials: WB
authors.lastname: Frommer
authors.forename: Eckhard
authors.initials: E
authors.lastname: Leistner
authors.forename: Alisdair R
authors.initials: AR
authors.lastname: Fernie
authors.forename: Hanjo
authors.initials: H
authors.lastname: Hellmann
mesh_terms: D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000033:anatomy & histology / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D019759:Carbon-Nitrogen Lyases; D032461:Chromosomes, Plant; D004734:Energy Metabolism; D035264:Flowers / Q000033:anatomy & histology / Q000254:growth & development; D020869:Gene Expression Profiling; D005816:Genetic Complementation Test; D008969:Molecular Sequence Data; D019884:Nitrogenous Group Transferases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D010641:Phenotype; D018515:Plant Leaves / Q000033:anatomy & histology / Q000254:growth & development; D030821:Plants, Genetically Modified; D017354:Point Mutation; D020836:Protein Structure, Quaternary; D011736:Pyridoxine / Q000378:metabolism; D020798:Two-Hybrid System Techniques; D025101:Vitamin B 6 / Q000096:biosynthesis*; D014803:Vitamin B Complex / Q000096:biosynthesis*
chemical_list: D029681:Arabidopsis Proteins; D014803:Vitamin B Complex; D025101:Vitamin B 6; D019884:Nitrogenous Group Transferases; D019759:Carbon-Nitrogen Lyases; C505161:At2g38230 protein, Arabidopsis; D011736:Pyridoxine