title: A tyrosine aminotransferase involved in tocopherol synthesis in Arabidopsis.
abstract: The metabolic function of the predicted Arabidopsis tyrosine aminotransferase (TAT) encoded by the At5g53970 gene was studied using two independent knock-out mutants. Gas chromatography-mass spectrometry based metabolic profiling revealed a specific increase in tyrosine levels, supporting the proposed function of At5g53970 as a tyrosine-specific aminotransferase not involved in tyrosine biosynthesis, but rather in utilization of tyrosine for other metabolic pathways. The TAT activity of the At5g53970-encoded protein was verified by complementation of the Escherichia coli tyrosine auxotrophic mutant DL39, and in vitro activity of recombinantly expressed and purified At5g53970 was found to be specific for tyrosine. To investigate the physiological role of At5g53970, the consequences of reduction in tyrosine utilization on metabolic pathways having tyrosine as a substrate were analysed. We found that tocopherols were substantially reduced in the mutants and we conclude that At5g53970 encodes a TAT important for the synthesis of tocopherols in Arabidopsis.
authors.affiliation: Department of Molecular Genetics, Leibniz Institute of Plant Genetics and Crop Plant Research-IPK, Corrensstrasse 3, 06466 Gatersleben, Germany. riewe@ipk-gatersleben.de
authors.forename: David
authors.initials: D
authors.lastname: Riewe
authors.forename: Mehrana
authors.initials: M
authors.lastname: Koohi
authors.forename: Jan
authors.initials: J
authors.lastname: Lisec
authors.forename: Markus
authors.initials: M
authors.lastname: Pfeiffer
authors.forename: Rico
authors.initials: R
authors.lastname: Lippmann
authors.forename: Judith
authors.initials: J
authors.lastname: Schmeichel
authors.forename: Lothar
authors.initials: L
authors.lastname: Willmitzer
authors.forename: Thomas
authors.initials: T
authors.lastname: Altmann
mesh_terms: D017360:Arabidopsis / Q000201:enzymology* / Q000254:growth & development; D029681:Arabidopsis Proteins / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics; D055786:Gene Knockout Techniques; D005816:Genetic Complementation Test; D024505:Tocopherols / Q000378:metabolism*; D014443:Tyrosine / Q000378:metabolism; D014444:Tyrosine Transaminase / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D014443:Tyrosine; D014444:Tyrosine Transaminase; D024505:Tocopherols