title: Externally suppressible frameshift mutant of Salmonella typhimurium.
abstract: Prototrophic revertants of ICR-191A-induced frameshift mutant hisD3018 have been induced spontaneously by ICR-191A and N-methyl-N'-nitro-N-nitrosoguanidine (NG) treatment. In each case two genetically distinct prototroph classes were differentiated by transducibility into his deletion recipients: (i) transducible, generally fast-growing revertants within the hisD gene producing from 10 to 100% of normal amounts of histidinol dehydrogenase and (ii) nontransducible slow-growing prototrophs with very low levels of enzyme activity of which at least some arose by external suppression. These nontransducible revertants, whether arising spontaneously or in the presence of ICR-191A or NG, contain histidinol dehydrogenase which is electrophoretically similar to the wild-type enzyme.
mesh_terms: D000166:Acridines / Q000494:pharmacology; D000429:Alcohol Oxidoreductases / Q000378:metabolism; D004586:Electrophoresis; D005827:Genetics, Microbial; D006147:Guanine / Q000494:pharmacology; D009154:Mutation; D012486:Salmonella typhimurium / Q000187:drug effects / Q000201:enzymology; D014161:Transduction, Genetic
chemical_list: D000166:Acridines; D006147:Guanine; D000429:Alcohol Oxidoreductases