title: DNA supercoiling by gyrase is linked to nucleoid compaction.
abstract: The genes of E. coli are located on a circular chromosome of 4.6 million basepairs. This 1.6 mm long molecule is compressed into a nucleoid to fit inside the 1-2 microm cell in a functional format. To examine the role of DNA supercoiling as nucleoid compaction force we modulated the activity of DNA gyrase by electronic, genetic, and chemical means. A model based on physical properties of DNA and other cell components predicts that relaxation of supercoiling expands the nucleoid. Nucleoid size did not increase after reduction of DNA gyrase activity by genetic or chemical means, but nucleoids did expand upon chemical inhibition of gyrase in chloramphenicol-treated cells, indicating that supercoiling may help to compress the genome.
authors.affiliation: Molecular Cell Physiology, Free University, Amsterdam, The Netherlands.
authors.forename: Rogier
authors.initials: R
authors.lastname: Stuger
authors.forename: Conrad L
authors.initials: CL
authors.lastname: Woldringh
authors.forename: Coen C
authors.initials: CC
authors.lastname: van der Weijden
authors.forename: Norbert O E
authors.initials: NO
authors.lastname: Vischer
authors.forename: Barbara M
authors.initials: BM
authors.lastname: Bakker
authors.forename: Rob J M
authors.initials: RJ
authors.lastname: van Spanning
authors.forename: Jacky L
authors.initials: JL
authors.lastname: Snoep
authors.forename: Hans V
authors.initials: HV
authors.lastname: Westerhoff
mesh_terms: D027081:DNA Gyrase / Q000235:genetics / Q000378:metabolism*; D004269:DNA, Bacterial / Q000378:metabolism*; D004278:DNA, Superhelical / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics* / Q000378:metabolism; D010316:Particle Size
chemical_list: D004269:DNA, Bacterial; D004278:DNA, Superhelical; D027081:DNA Gyrase