Genetic and Biochemical Analysis of the Isoenzymes Concerned in the First Reaction of Aromatic Biosynthesis in Escherichia coli

Abstract

Mutant strains of Escherichia coli K-12 were isolated possessing mutations which affected the tyrosine-inhibitable 3-deoxy- d -arabinoheptulosonic acid-7-phosphate (DAHP) synthetase, the phenylalanine-inhibitable DAHP synthetase, or the tryptophan-repressible DAHP synthetase. The mutations causing the loss of each of these activities have been mapped and are widely separated from each other on the E. coli chromosome. Chromatography on diethylaminoethyl cellulose columns allowed the recognition of four peaks of activity.