Phenylalanine and Tyrosine Biosynthesis in Sporeforming Members of the Order Actinomycetales

Abstract

Abstract The enzymes of the terminal steps of phenylalanine and tyrosine biosynthesis, chorismate mutase, prephenate dehydratase, arogenate dehydratase, prephenate dehydrogenase and aroge­ nate dehydrogenase were studied in 13 sporeforming members of the order Actinomycetales. In these organisms tyrosine is synthesized exclusively via arogenate, phenylalanine, however, via phenylpyruvate. The regulation pattern of the corresponding enzymes was determined: No feed­ back inhibition of arogenate dehydrogenase by L-phenylalanine and ʟ-tyrosine was observed. Chorismate mutase was found to be inhibited in all organisms by ʟ-tyrosine and in most organisms by ʟ-tryptophan. ʟ-Phenylalanine was shown to inhibit prephenate dehydratase in the majority of bacteria tested and ʟ-tyrosine activated this enzyme in most cases. The elution profiles for the phenylalanine and tyrosine biosynthetic enzymes were studied in three members of the order Actinomycetales by anion exchange chromatography on DEAE-cellulose.