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Mass spectrometry reveals that the antibiotic simocyclinone D8 binds to DNA gyrase in a "bent-over" conformation: evidence for positive cooperativity in binding

Edwards, M.J. and Williams, Mark A. and Maxwell, A. and McKay, A.R. (2011) Mass spectrometry reveals that the antibiotic simocyclinone D8 binds to DNA gyrase in a "bent-over" conformation: evidence for positive cooperativity in binding. Biochemistry 50 (17), pp. 3432-3440. ISSN 0006-2960.

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Official URL: http://dx.doi.org/10.1021/bi101691k

Abstract

DNA topoisomerases are enzymes that control DNA topology and are vital targets for antimicrobial and anticancer drugs. Here we present a mass spectrometry study of complexes formed between the A subunit of the topoisomerase DNA gyrase and the bifunctional inhibitor simocyclinone D8 (SD8), an antibiotic isolated from Streptomyces. These studies show that, in an alternative mode of interaction to that found by X-ray crystallography, each subunit binds a single bifunctional inhibitor with separate binding pockets for the two ends of SD8. The gyrase subunits form constitutive dimers, and fractional occupancies of inhibitor-bound states show that there is strong allosteric cooperativity in the binding of two bifunctional ligands to the dimer. We show that the mass spectrometry data can be fitted to a general model of cooperative binding via an extension of the “tight-binding” approach, providing a rigorous determination of the dissociation constants and degree of cooperativity. This general approach will be applicable to other systems with multiple binding sites and highlights mass spectrometry’s role as a powerful emerging tool for unraveling the complexities of biomolecular interactions.

Item Type: Article
School or Research Centre: Birkbeck Schools and Research Centres > School of Science > Biological Sciences
Depositing User: Dr Mark A. Williams
Date Deposited: 15 Nov 2012 13:52
Last Modified: 17 Apr 2013 12:26
URI: http://eprints.bbk.ac.uk/id/eprint/5660

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