title: Genetic modification of substrate specificity of hypoxanthine phosphoribosyltransferase in Salmonella typhimurium.
abstract: Salmonella typhimurium strain GP660 (proAB-gpt deletion, purE) lacks guanine phosphoribosyltransferase and hence cannot utilize guanine as a purine source and is resistant to inhibition by 8-azaguanine. Strain GP660 was mutagenized and a derivative strain (GP36) was isolated for utilization of guanine and hypoxanthine, but not xanthine, as purine sources. This alteration was designated sug. The strain was then sensitive to inhibition by 8-azaguanine. Column chromatographic analysis revealed the altered phosphoribosyltransferase peaks for both hypoxanthine and guanine to be located together, in the same position as hypoxanthine phosphoribosyltransferase (hpt gene product) of the wild-type strain. Genetic analysis showed the sug mutation to be allelic with hpt. Therefore sug represented a modification of the substrate specificity of the hpt gene product.
mesh_terms: D000483:Alleles; D001375:Azaguanine / Q000494:pharmacology; D002474:Cell-Free System; D002852:Chromatography, Ion Exchange; D005796:Genes; D006147:Guanine / Q000378:metabolism*; D007042:Hypoxanthines / Q000378:metabolism*; D009153:Mutagens; D009154:Mutation; D009604:Nitrosoguanidines; D010430:Pentosyltransferases / Q000378:metabolism*; D010641:Phenotype; D011995:Recombination, Genetic; D012486:Salmonella typhimurium / Q000201:enzymology* / Q000378:metabolism; D014161:Transduction, Genetic; D014970:Xanthines / Q000378:metabolism
chemical_list: D007042:Hypoxanthines; D009153:Mutagens; D009604:Nitrosoguanidines; D014970:Xanthines; D006147:Guanine; D010430:Pentosyltransferases; D001375:Azaguanine