title: A method for isolating nonsense suppressors in enterobacteriaceae using an amber mutant of the drug resistance factor R1.
abstract: We describe here the isolation of a mutant derivative of the drug resistance factor R1 (Meynell and Datta, 1966) that carries a nonsense mutation in a gene determining resistance to penicillins.  We have used this mutant R1 to isolate derivatives of Escherichia coli and Klebsiella pneumoniae that contain nonsense suppressors (Sup- strains) by screening penicillin-resistant revertants of strains containing the mutant R factor for the presence of such suppressors.  This obviates the need to have known nonsense mutations in chromosomal genes.  Theoretically, suppressor-containing derivatives of any bacterial species that can maintain and express R1 can be constructed.
mesh_terms: D004926:Escherichia coli; D007711:Klebsiella pneumoniae; D009154:Mutation; D010403:Penicillin Resistance; D010406:Penicillins; D011815:R Factors; D013489:Suppression, Genetic
chemical_list: D010406:Penicillins