Abstract
Regulatory properties of the enzymes in L-tyrosine and L-phenylalanine terminal pathway in Corynebacterium glutamicum were investigated. Prephenate dehydrogenase was partially feedback inhibited by L-tyrosine. Prephenate dehydratase was strongly inhibited by L-phenylalanine and L-tryptophan and 100% inhibition was attained at the concentrations of 5×10-2mM and 10-1mM, respectively. L-Tyrosine stimulated prephenate dehydratase activity (6-fold stimulation at 1mM) and restored the enzyme activity inhibited by L-phenylalanine or L-tryptophan. These regulations seem to give the balanced synthesis of L-tyrosine and L-phenylalanine. Prephenate dehydratase from C. glutamicum was stimulated by L-methionine and L-leucine similarly to the enzyme in Bacillus subtilis and moreover by L-isoleucine and L-histidine. C. glutamicum mutant No. 66, an L-phenylalanine producer resistant to p-fluorophenylalanine, had a prephenate dehydratase completely resistant to the inhibition by L-phenylalanine and L-tryptophan.
