Effects of p-fluorophenylalanine on the induction of mutations in bacteriophage T4. I. 5-Bromouracil mutagenesis.

The amino acid analogue rho-fluorophenylalanine (PFPA) was found to have no mutagenic activity in the gamma system of bacteriophage T4. However, under standard conditions for 5-bromouracil (5-BU) mutagenesis, PFPA depressed the induced frequencies for both forward and reverse mutations. When the folate antagonist sulphanilamide (SU) was omitted from the mutangenic treatment medium or when it was replaced by Trimethoprim (TM), another folate antagonist, this depressive effect was abolished. It was proposed that PFPA alleviated the inhibitory action of SU.