title: DNA supercoiling and suppression of the leu-500 promoter mutation.
abstract: top mutations (formerly supX) eliminate DNA topoisomerase I activity and suppress the leu-500 promoter mutation in Salmonella typhimurium (K. M. Overbye, S. K. Basu, and P. Margolin, Cold Spring Harbor Symp. Quant. Biol. 47:785-791, 1983). Sublethal doses of coumermycin which reduce intracellular levels of supercoiling activity in a top mutant eliminated suppression of the leu-500 mutation. This result provides evidence that increased DNA supercoiling suppresses the leu-500 promoter mutation in top mutants.
mesh_terms: D049933:Aminocoumarins; D003374:Coumarins / Q000494:pharmacology; D003470:Culture Media; D004264:DNA Topoisomerases, Type I / Q000235:genetics; D004269:DNA, Bacterial / Q000378:metabolism*; D004278:DNA, Superhelical / Q000378:metabolism*; D005798:Genes, Bacterial; D007930:Leucine / Q000096:biosynthesis / Q000494:pharmacology; D009154:Mutation; D011401:Promoter Regions, Genetic; D012486:Salmonella typhimurium / Q000187:drug effects / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D013489:Suppression, Genetic
chemical_list: D049933:Aminocoumarins; D003374:Coumarins; D003470:Culture Media; D004269:DNA, Bacterial; D004278:DNA, Superhelical; D004264:DNA Topoisomerases, Type I; D007930:Leucine; C004628:coumermycin