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Zechiedrich, E.L.* ; Khodursky, A.B.* ; Bachellier, S.* ; Schneider, R.* ; Chen, D.* ; Lilley, D.M.* ; Cozzarelli, N.R.*

Roles of topoisomerases in maintaining steady-state DNA supercoiling in Escherichia coli.

J. Biol. Chem. 275, 8103-8113 (2000)
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Open Access Green möglich sobald Postprint bei der ZB eingereicht worden ist.
DNA supercoiling is essential for bacterial cell survival. We demonstrated that DNA topoisomerase IV, acting in concert with topoisomerase I and gyrase, makes an important contribution to the steady-state level of supercoiling in Escherichia coli. Following inhibition of gyrase, topoisomerase IV alone relaxed plasmid DNA to a final supercoiling density (sigma) of -0.015 at an initial rate of 0.8 links min(-1). Topoisomerase I relaxed DNA at a faster rate, 5 links min(-1), but only to a sigma of -0.05. Inhibition of topoisomerase IV in wild-type cells increased supercoiling to approximately the same level as in a mutant lacking topoisomerase I activity (to sigma = -0.08). The role of topoisomerase IV was revealed by two functional assays. Removal of both topoisomerase I and topoisomerase IV caused the DNA to become hyper-negatively supercoiled (sigma = -0.09), greatly stimulating transcription from the supercoiling sensitive leu-500 promoter and increasing the number of supercoils trapped by lambda integrase site-specific recombination.
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Publikationstyp Artikel: Journalartikel
Dokumenttyp Wissenschaftlicher Artikel
ISSN (print) / ISBN 0021-9258
e-ISSN 1083-351X
Quellenangaben Band: 275, Heft: 11, Seiten: 8103-8113 Artikelnummer: , Supplement: ,
Verlag American Society for Biochemistry and Molecular Biology
Begutachtungsstatus Peer reviewed