Feedback-insensitive mutants of the gene for the tyrosine-inhibited DAHP synthetase in yeast.

A yeast strain lacking the phenylalanine-sensitive DAHP synthetase exhibits a tyrosine-inhibited phenotype. Reversions from this phenotype were selected. They were the result of mutations affecting the tyrosine-sensitive DAHP synthetase which became insensitive to feedback inhibition, as shown by genetic and enzymatic studies. The feedback-insensitive mutations were located at five different sites scattered on the map of the aro4 gene.