Feedback-resistant Phosphoribosyl-ATP Pyrophosphorylase in L-Histidine-producing Mutants of Corynebacterium glutarnicum

Phosphoribosyl-ATP pyrophosphorylase of two l-histidine-producers of Corynebacterium glutamicum, each selected as a 2-thiazolealanine (TA)-resistant and a 1,2,4-triazole-3-alanine (TRA)-resistant, was found to be 100-fold resistant to l-histidine-inhibition in comparison with wild-type enzyme. It was also resistant to the inhibition by TA, but still as sensitive as the wild-type enzyme to the inhibition by α-methylhistidine. Formation of the pyrophosphorylase in these mutants was not significantly derepressed. However, two-fold derepression was noted with a further improved l-histidine producer KY-10522, a derivative of the above TRA-resistant. KY-10522 is an improved strain in l-histidine-productivity through the additions of resistance markers including increased resistance to TRA. Phosphoribosyl-ATP pyrophosphorylase of KY-10522 was found to be resistant to the feedback inhibition, like it’s parent strain.