DNA Supercoiling by Gyrase is Linked to Nucleoid Compaction

Authors: Stuger R.¹; Woldringh C.L.²; van der Weijden C.C.¹; Vischer N.O.E.²; Bakker B.M.¹; van Spanning R.J.M.¹; Snoep J.L.¹; Weterhoff H.V.^{1, 2, 3}

Source: Molecular Biology Reports, Volume 29, Numbers 1-2, 2002 , pp. 79-82(4)

Publisher: Springer

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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 mgr m 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.

Keywords: DNA gyrase; Escherichia coli; nucleoid; supercoiling; topoisomerase

Language: English

Document Type: Research article

Affiliations: 1: Molecular Cell Physiology, Free University, Amsterdam, The Netherlands 2: Swammerdam Institute for Life Sciences, University of Amsterdam, The Netherlands 3: Stellenbosch Institute for Advanced Study, South Africa

Publication date: 2002-01-01