Chromosomal domains of supercoiling in Salmonella typhimurium.
The chromosomes of enteric bacteria are divided into about 50 independently supercoiled domains. It is not known whether the net level of DNA supercoiling is similar in each domain, or whether the domains are differentially supercoiled. We have addressed this question genetically, using a supercoiling-sensitive promoter to probe the relative levels of supercoiling at defined points around the Salmonella typhimurium chromosome. We conclude that, within the limits of resolution of this approach, the level of supercoiling does not differ significantly between chromosomal domains, and that each domain responds in a similar fashion to factors that perturb supercoiling. These findings have implications for the organization of the bacterial genome.
Imperial Cancer Research Fund Laboratories, University of Oxford, John Radcliffe Hospital, UK.
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D026905:Amino Acid Transport Systems; D001426:Bacterial Proteins / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D002352:Carrier Proteins / Q000235:genetics; D002876:Chromosomes, Bacterial / Q000648:ultrastructure*; D004250:DNA Topoisomerases, Type II / Q000378:metabolism; D004269:DNA, Bacterial / Q000235:genetics; D004278:DNA, Superhelical / Q000235:genetics; D015964:Gene Expression Regulation, Bacterial; D008156:Luciferases / Q000096:biosynthesis / Q000235:genetics; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D009675:Novobiocin / Q000494:pharmacology; D011401:Promoter Regions, Genetic; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis; D012486:Salmonella typhimurium / Q000235:genetics / Q000648:ultrastructure*; D059005:Topoisomerase II Inhibitors
D026905:Amino Acid Transport Systems; D001426:Bacterial Proteins; D002352:Carrier Proteins; D004269:DNA, Bacterial; D004278:DNA, Superhelical; C060774:ProU protein, Bacteria; D011993:Recombinant Fusion Proteins; D059005:Topoisomerase II Inhibitors; D009675:Novobiocin; D008156:Luciferases; D004250:DNA Topoisomerases, Type II