Aromatic Amino Acid Biosynthesis in a 4-Chlorobenzoic Acid Degrading Pseudomonas Species; Phenylalanine and Tyrosine Synthesis via Arogenate

Abstract

The aromatic amino acid biosynthesis was studied in Pseudomonas sp. strain CBS 3 which is able to grow on 4-chlorobenzoic acid. The regulation patterns of anthranilate synthase, chorismate mutase, prephenate dehydratase, prephenate dehydrogenase, arogenate dehydratase and arogenate dehydrogenase were established. The synthesis of anthranilate synthase was induced by L-phenylalanine and L-tyrosine. The enzyme activity was inhibited by L-tryptophan. Chorismate mutase was neither repressed nor inhibited by phenylalanine and tyrosine, but induced by tryptophan. Prephenate dehydratase was both induced and activated by L-tyrosine. The prephenate dehydrogenase activity was inhibited by tyrosine. Arogenate, the transamination product of prephenate, was assayed as a substrate in a crude enzyme preparation. Both enzymes, arogenate dehydratase and arogenate dehydrogenase, could be identified in a crude enzyme preparation. Arogenate dehydrogenase showed the same regulatory pattern as prephenate dehydrogenase.