title: Mutagenesis by normal metabolites in Escherichia coli: phenylalanine mutagenesis is dependent on error-prone DNA repair.
abstract: In search of a model for the production of 'spontaneous' mutations induced by DNA damage produced during normal metabolism, 19 amino acids were tested for mutagenicity in Escherichia coli K-12 uvrB. Cystine, and, to a lesser extent, arginine and threonine were found to be antimutagenic; only phenylalanine was found to be mutagenic. At 2 mM, phenylalanine induced mutants at 1.5-2-fold above background [lacZ53(amber)----Lac+, rifampicin resistance (missense), and bacteriophage T6 resistance]. Tyrosine and, to a lesser extent, tryptophan (each at 2 mM) inhibited the mutagenicity of phenylalanine. Phenylalanine mutagenesis was detected in the uvrB strain, but not in the wild-type, uvrB umuC or uvrB lexA strains. Thus, phenylalanine seems to cause the production of excisable lesions ('UV-like'?) in DNA, which, if not excised, can induce mutations via error-prone DNA repair.
mesh_terms: D000596:Amino Acids / Q000494:pharmacology*; D011088:DNA Ligases / Q000235:genetics; D004260:DNA Repair; D004269:DNA, Bacterial / Q000378:metabolism; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics*; D009154:Mutation; D010649:Phenylalanine / Q000494:pharmacology*
chemical_list: D000596:Amino Acids; D004269:DNA, Bacterial; D010649:Phenylalanine; D011088:DNA Ligases