title: Interaction between vitamin B6 metabolism, nitrogen metabolism and autoimmunity.
abstract: The essential micronutrient vitamin B6 is best known in its enzymatic cofactor form, pyridoxal 5'-phosphate (PLP). However, vitamin B6 comprises the amine pyridoxamine 5'-phosphate (PMP) and the alcohol pyridoxine 5'-phosphate (PNP) in addition to PLP, as well as their corresponding non-phosphorylated forms. The different B6 forms (called vitamers) are enzymatically interconverted in a ubiquitous salvage pathway. Recently, we have shown that balancing the ratio of the different B6 vitamers in particular PMP by the PMP/PNP oxidase PDX3 is essential for growth and development in Arabidopsis thaliana. Intriguingly, nitrate to ammonium conversion is impaired in pdx3 mutants, such that the mutants become ammonium-dependent, suggesting an interaction between vitamin B6 and nitrogen metabolism. In addition, we found a strong up-regulation of genes related to plant defense. Here, we further show that pdx3 mutants display a temperature-sensitive phenotype that is typical of autoimmune mutants and is possibly connected to the impaired nitrogen metabolism.
authors.affiliation: a Department of Botany and Plant Biology , University of Geneva , Geneva , Switzerland.
authors.forename: Maite
authors.initials: M
authors.lastname: Colinas
authors.affiliation: a Department of Botany and Plant Biology , University of Geneva , Geneva , Switzerland.
authors.forename: Teresa B
authors.initials: TB
authors.lastname: Fitzpatrick
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000276:immunology; D029681:Arabidopsis Proteins / Q000378:metabolism; D015551:Autoimmunity; D018506:Gene Expression Regulation, Plant; D009584:Nitrogen / Q000378:metabolism*; D010641:Phenotype; D012098:Reproduction; D013696:Temperature; D025101:Vitamin B 6 / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D025101:Vitamin B 6; D009584:Nitrogen
keywords: Arabidopsis thaliana; PDX3; autoimmunity; nitrogen metabolism; plant defense; pyridoxamine/pyridoxine phosphate oxidase; vitamin B6; vitamin B6 salvage