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Issue 44, 2010
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Atomic force microscopy of DNA at high humidity: irreversible conformational switching of supercoiled molecules

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Abstract

Three topologically different double-stranded DNA molecules of the same size (bps) have been imaged in air on mica using amplitude modulation atomic force microscopy (AM AFM) under controlled humidity conditions. At very high relative humidity (>90% RH), localized conformational changes of the DNA were observed, while at lower RH, the molecules remained immobile. The conformational changes occurred irreversibly and were driven principally by superhelical stress stored in the DNA molecules prior to binding to the mica surface. The binding mechanism of the DNA to the mica (surface equilibration versus kinetic trapping) modulated the extent of the conformational changes. In cases where DNA movement was observed, increased kinking of the DNA was seen at high humidity when more surface water was present. Additionally, DNA condensation behavior was also present in localized regions of the molecules. This study illustrates that changes in the tertiary structure of DNA can be induced during AFM imaging at high humidity on mica. We propose that AM AFM in high humidity will be a useful technique for probing DNA topology without some of the drawbacks of imaging under bulk solution.

Graphical abstract: Atomic force microscopy of DNA at high humidity: irreversible conformational switching of supercoiled molecules

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Publication details

The article was received on 28 Jul 2010, accepted on 09 Sep 2010 and first published on 07 Oct 2010


Article type: Paper
DOI: 10.1039/C0CP01347A
Citation: Phys. Chem. Chem. Phys., 2010,12, 14727-14734
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    Atomic force microscopy of DNA at high humidity: irreversible conformational switching of supercoiled molecules

    D. J. Billingsley, J. Kirkham, W. A. Bonass and N. H. Thomson, Phys. Chem. Chem. Phys., 2010, 12, 14727
    DOI: 10.1039/C0CP01347A

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