[Biosynthesis of phenylalanine and tyrosine in Streptomycetes]

The biosynthesis of phenylalanine and tyrosine from prephenic acid may proceed via phenylpyruvic acid or p-hydroxyphenylpyruvic acid or via arogenate. The enzymes necessary for these biosynthetic steps have been tested in a variety of Streptomycetes. Tyrosine is synthesized exclusively via arogenate, while phenylalanine is synthesized via phenylpyruvic acid. The feedback inhibition pattern of the corresponding enzymes has been determined. The organisms may be divided into four groups according to the properties of the phenylalanine and tyrosine biosynthetic enzymes and their regulation patterns.