Nucleic Acids Research Advance Access originally published online on September 16, 2008
Nucleic Acids Research 2008 36(18):5882-5895; doi:10.1093/nar/gkn587
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Nucleic Acids Research, 2008, Vol. 36, No. 18 5882-5895
© 2008 The Author(s)
This is an Open Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/2.0/uk/) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited.
Nucleic Acid Enzymes |
The reverse gyrase helicase-like domain is a nucleotide-dependent switch that is attenuated by the topoisomerase domain
University of Basel, Biozentrum, Biophysical Chemistry, Klingelbergstrasse 70, 4056 Basel, Switzerland
*To whom correspondence should be addressed. Tel: +41 61 267 2381; Fax: +41 61 267 2189; Email: dagmar.klostermeier{at}unibas.ch
Received July 9, 2008. Revised September 1, 2008. Accepted September 1, 2008.
Reverse gyrase is a topoisomerase that introduces positive supercoils into DNA in an ATP-dependent manner. It is unique to hyperthermophilic archaea and eubacteria, and has been proposed to protect their DNA from damage at high temperatures. Cooperation between its N-terminal helicase-like and the C-terminal topoisomerase domain is required for positive supercoiling, but the precise role of the helicase-like domain is currently unknown. Here, the characterization of the isolated helicase-like domain from Thermotoga maritima reverse gyrase is presented. We show that the helicase-like domain contains all determinants for nucleotide binding and ATP hydrolysis. Its intrinsic ATP hydrolysis is significantly stimulated by ssDNA, dsDNA and plasmid DNA. During the nucleotide cycle, the helicase-like domain switches between high- and low-affinity states for dsDNA, while its affinity for ssDNA in the ATP and ADP states is similar. In the context of reverse gyrase, the differences in DNA affinities of the nucleotide states are smaller, and the DNA-stimulated ATPase activity is strongly reduced. This inhibitory effect of the topoisomerase domain decelerates the progression of reverse gyrase through the nucleotide cycle, possibly providing optimal coordination of ATP hydrolysis with the complex reaction of DNA supercoiling.
The authors wish it to be known that, in their opinion, the first two authors should be regarded as joint First Authors.
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