title: DNA is more negatively supercoiled in bacterial plasmids than in minichromosomes isolated from budding yeast.
abstract: A series of circular shuttle vectors were constructed that could replicate and transcribe in the cells of both Escherichia coli and Saccharomyces cerevisiae. 2-D agarose gel electrophoresis run without or in the presence of different concentrations of chloroquine (CHL) revealed that bacterial plasmids were more negatively (-) supercoiled than minichromosomes isolated from budding yeast. Attempts to increase (-) supercoiling in S. cerevisiae or to reduce it in E. coli have deleterious biological consequences. These observations indicate that DNA supercoiling can vary in different species but cells are exquisitely sensitive to sudden changes in supercoiling. In E. coli, the observation that cell growth as well as ColE1 plasmid copy number decrease when DNA relaxes suggests that supercoiling could affect cell viability by regulating the initiation of both transcription and replication.
authors.affiliation: Departamento de Biología Celular y del Desarrollo, Centro de Investigaciones Biológicas (CSIC), Madrid, Spain.
authors.forename: María-Dolores
authors.initials: MD
authors.lastname: Mayán-Santos
authors.forename: María-Luisa
authors.initials: ML
authors.lastname: Martínez-Robles
authors.forename: Pablo
authors.initials: P
authors.lastname: Hernández
authors.forename: Dora
authors.initials: D
authors.lastname: Krimer
authors.forename: Jorge B
authors.initials: JB
authors.lastname: Schvartzman
mesh_terms: D002470:Cell Survival / Q000187:drug effects; D002738:Chloroquine / Q000737:chemistry* / Q000494:pharmacology; D004261:DNA Replication / Q000187:drug effects; D004269:DNA, Bacterial / Q000737:chemistry*; D004271:DNA, Fungal / Q000737:chemistry*; D004278:DNA, Superhelical / Q000737:chemistry*; D004587:Electrophoresis, Agar Gel / Q000379:methods; D015180:Electrophoresis, Gel, Two-Dimensional / Q000379:methods; D004926:Escherichia coli / Q000235:genetics*; D010957:Plasmids; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D014158:Transcription, Genetic
chemical_list: D004269:DNA, Bacterial; D004271:DNA, Fungal; D004278:DNA, Superhelical; D002738:Chloroquine