The Regulation of Biosynthesis of Aromatic Amino Acids and Vitamins

Abstract

This chapter discusses the regulation of biosynthesis of aromatic compounds. The biosynthesis of aromatic amino acids and vitamins is proving a particularly interesting model system for the study of regulation. Animals are incapable of synthesizing benzene rings, but microorganisms and plants may form aromatic compounds by several pathways. The shikimate pathway is the important pathway for the biosynthesis of aromatic amino acids and vitamins in all organisms. Similar isoenzymes to those in E. coli occur in Salmonella typhimurium. In Saccharomyces cerevisiae it appears that there are only two DAHP synthetases, one inhibited by tyrosine and other inhibited by phenylalanine. Mutants lacking one isoenzyme have been isolated and the growth of these strains is inhibited by either phenylalanine or tyrosine, indicating that only two isoenzymes exist.