tailieunhanh - Báo cáo khoa học: Cloning and functional characterization of Arabidopsis thaliana D-amino acid aminotransferase – D-aspartate behavior during germination

The understanding ofd-amino acid metabolism in higher plants lags far behind that in mammals, for which the biological functions of these unique amino acids have already been elucidated. In this article, we report on the biochemical behavior ofd-amino acids (particularly d-Asp) and relevant metabolic enzymes inArabidopsis thaliana. | ễFEBS Journal Cloning and functional characterization of Arabidopsis thaliana D-amino acid aminotransferase - D-aspartate behavior during germination Miya Funakoshi1 Masae Sekine1 z Masumi Katane1 Takemitsu Furuchi1 Masafumi Yohda2 Takafumi Yoshikawa1 and Hiroshi Homma1 1 Schoolof PharmaceuticalSciences Kitasato University Tokyo Japan 2 Tokyo University of Agriculture and Technology Japan Keywords A. thaliana D-amino acid aminotransferase D-alanine D-aspartate D-glutamate Correspondence H. Homma School of Pharmaceutical Sciences Kitasato University 5-9-1 Shirokane Minato-ku Tokyo 108-8641 Japan Fax 81 3 5791 6381 Tel 81 3 5791 6229 E-mail hommah@ These authors contributed equally to this work Received 21 September 2007 revised 25 December 2007 accepted 8 January 2008 doi The understanding of D-amino acid metabolism in higher plants lags far behind that in mammals for which the biological functions of these unique amino acids have already been elucidated. In this article we report on the biochemical behavior of D-amino acids particularly D-Asp and relevant metabolic enzymes in Arabidopsis thaliana. During germination and growth of the plant a transient increase in D-Asp levels was observed suggesting that D-Asp is synthesized in the plant. Administration of D-Asp suppressed growth although the inhibitory mechanism responsible for this remains to be clarified. Exogenous D-Asp was efficiently incorporated and metabolized and was converted to other D-amino acids D-Glu and D-Ala . We then studied the related metabolic enzymes and consequently cloned and characterized A. thaliana D-amino acid aminotransferase which is presumably involved in the metabolism of D-Asp in the plant by catalyzing transamination between D-amino acids. This is the first report of cDNA cloning and functional characterization of a D-amino acid aminotransferase in eukaryotes. The results presented here provide important information for .