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Effect of supercoiling on the λ switch
The Niels Bohr Institute; University of Copenhagen; Copenhagen, Denmark.
Umeå University, Faculty of Science and Technology, Department of Physics. (The Biophysics and Biophotonics group)
The Niels Bohr Institute; University of Copenhagen; Copenhagen, Denmark.
Department of Cellular and Molecular Medicine; Faculty of Health and Sciences; Copenhagen, Denmark.
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2014 (English)In: Bacteriophage, ISSN 2159-7081, Vol. 4, no 1, e27517-1-e27517-5 p.Article in journal (Refereed) Accepted
Abstract [en]

The lysogenic state of the λ switch is exceptionally stable, still, it is capable of responding to DNA-damage and rapidly enter the lytic state. We invented an assay where PNA mediated tethering of a plasmid allowed for single molecule investigations of the effect of supercoiling on the efficiency of the epigenetic λ switch. Compared with non-supercoiled DNA, the presence of supercoils enhances the CI-mediated DNA looping probability and renders the transition between the looped and unlooped states steeper, thus increasing the Hill coefficient. Interestingly, the transition occurs exactly at the CI concentration corresponding to the minimum number of CI molecules capable of maintaining the pRM-repressed state. Based on these results we propose that supercoiling maintains the pRM-repressible state as CI concentration decline during induction and thus prevent autoregulation of cI from interfering with induction.

Place, publisher, year, edition, pages
2014. Vol. 4, no 1, e27517-1-e27517-5 p.
Keyword [en]
supercoiling, λ switch, epigenetics, PNA, cooperativity, CI protein, tethered particle motion
National Category
Biophysics Other Physics Topics
URN: urn:nbn:se:umu:diva-84026DOI: 10.4161/bact.27517OAI: diva2:678773
Available from: 2013-12-12 Created: 2013-12-12 Last updated: 2015-11-11Bibliographically approved

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Andersson, Magnus
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