Identification and Partial Characterization of an L-Tyrosine Aminotransferase (TAT) fromArabidopsis thaliana

Abstract

The aminotransferase gene family in the model plantArabidopsis thalianaconsists of 44 genes. Twenty six of these enzymes are classified as characterized meaning that the reaction(s) that the enzyme catalyzes are documented using experimental means. The remaining 18 enzymes are uncharacterized and are therefore deemed putative. Our laboratory is interested in elucidating the function(s) of the remaining putative aminotransferase enzymes. To this end, we have identified and partially characterized an aminotransferase (TAT) enzyme from Arabidopsis annotated by the locus tag At5g36160. The full-length cDNA was cloned and the purified recombinant enzyme was characterized usingin vitroandin vivoexperiments.In vitroanalysis showed that the enzyme is capable of interconverting L-Tyrosine and 4-hydroxyphenylpyruvate, and L-Phenylalanine and phenylpyruvate.In vivoanalysis by functional complementation showed that the gene was able to complement anE. coliwith a background of aminotransferase mutations that confers auxotrophy for L-Tyrosine and L-Phenylalanine.