Thomson, NH orcid.org/0000-0001-7332-790X, Santos, S, Mitchenall, LA et al. (3 more authors) (2014) DNA G-segment bending is not the sole determinant of topology simplification by type II DNA topoisomerases. Scientific Reports, 4. ARTN 6158. ISSN 2045-2322
Abstract
DNA topoisomerases control the topology of DNA. Type II topoisomerases exhibit topology simplification, whereby products of their reactions are simplified beyond that expected based on thermodynamic equilibrium. The molecular basis for this process is unknown, although DNA bending has been implicated. To investigate the role of bending in topology simplification, the DNA bend angles of four enzymes of different types (IIA and IIB) were measured using atomic force microscopy (AFM). The enzymes tested were Escherichia coli topo IV and yeast topo II (type IIA enzymes that exhibit topology simplification), and Methanosarcina mazei topo VI and Sulfolobus shibatae topo VI (type IIB enzymes, which do not). Bend angles were measured using the manual tangent method from topographical AFM images taken with a novel amplitude-modulated imaging mode: small amplitude small set-point (SASS), which optimises resolution for a given AFM tip size and minimises tip convolution with the sample. This gave improved accuracy and reliability and revealed that all 4 topoisomerases bend DNA by a similar amount: ~120° between the DNA entering and exiting the enzyme complex. These data indicate that DNA bending alone is insufficient to explain topology simplification and that the ‘exit gate’ may be an important determinant of this process.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | (c) 2014 The Authors. This work is licensed under a Creative Commons Attribution 4.0 International License. The images or other third party material in this article are included in the article’s Creative Commons license, unless indicated otherwise in the credit line; if the material is not included under the Creative Commons license, users will need to obtain permission from the license holder in order to reproduce the material. |
Keywords: | Enzyme mechanisms; Imaging techniques |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Medicine and Health (Leeds) > School of Dentistry (Leeds) > Oral Biology (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 29 Oct 2014 09:04 |
Last Modified: | 10 May 2019 10:57 |
Published Version: | http://dx.doi.org/10.1038/srep06158 |
Status: | Published |
Publisher: | Nature Publishing Group |
Identification Number: | 10.1038/srep06158 |
Related URLs: | |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:80823 |