title: [Regulation of purine biosynthetic genes expression in Salmonella typhimurium. II. Isolation and characterization of Oc mutants].
abstract: Purine repressor protein, encoded by purR has shown to effect expression of purine structure genes except purB in de novo pathway in Salmonella typhimurium. However, up to date there is no direct evidence of the repressor binding to operator DNA of these genes. Report here is the isolation and characterization of purine Oc mutants in Salmonella typhimurium. purD:: MudJ (lacZ Kanr) and purG:: MudJ (lacZ Kanr) were used as starting strains Both strains were mutagenized by NTG, and derepressed mutants were selected on the MacConkey plate containing an excess of adenosine (2mmol/L). 8 independent depressed mutants were obtained from purD:: MudJ (lacZ Kanr), 9 were obtained from purG:: MudJ (lacZ Kanr). Transduction analysis and trans-acting or cis-acting test of the genes with merochromosome DNA tandem genetic duplication strains proved that 1 mutant for each group exert the constitute expression by cis-acting. This is first purine Oc mutant obtained from Salmonella typhimurium.
authors.affiliation: Institute of microbiology, Academia Sinica, Beijing.
authors.forename: A
authors.initials: A
authors.lastname: Wang
authors.forename: X
authors.initials: X
authors.lastname: Dai
authors.forename: X
authors.initials: X
authors.lastname: Chen
authors.forename: G
authors.initials: G
authors.lastname: Tang
mesh_terms: D015964:Gene Expression Regulation, Bacterial; D009154:Mutation; D011687:Purines / Q000378:metabolism*; D012486:Salmonella typhimurium / Q000235:genetics*
chemical_list: D011687:Purines