GyrI: a counter-defensive strategy against proteinaceous inhibitors of DNA gyrase

Chatterji, Monalisa and Nagaraja, Valakunja (2002) GyrI: a counter-defensive strategy against proteinaceous inhibitors of DNA gyrase. In: EMBO Reports, 3 (3). pp. 261-267.

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Abstract

DNA gyrase is the target of two plasmid-encoded toxins CcdB and microcin B17, which ensure plasmid maintenance. These proteins stabilize gyrase-DNA covalent complexes leading to double-strand breaks in the genome. In contrast, the physiological role of chromosomally encoded inhibitor of DNA gyrase (Gyrl) in Escherichia coli is unclear and its mechanism of inhibition has not been established. We demonstrate that the mode of inhibition of GyrI is distinct from all other gyrase inhibitors. It inhibits DNA gyrase prior to, or at the step of, binding of DNA by the enzyme. Gyrl reduces intrinsic as well as toxin-stabilized gyrase-DNA covalent complexes. Furthermore, Gyri reduces microcin B17-mediated double-strand breaks in vivo, imparting protection to the cells against the toxin, substantiating the in vitro results. Thus, Gyrl is an antidote to DNA gyrase-specific proteinaceous poisons encoded by plasmid addiction systems.

Item Type:	Journal Article
Publication:	EMBO Reports
Publisher:	Nature Publishing Group
Additional Information:	Copyright of this article belongs to Nature Publishing Group.
Department/Centre:	Division of Biological Sciences > Microbiology & Cell Biology
Date Deposited:	19 Jul 2011 04:58
Last Modified:	19 Jul 2011 04:58
URI:	http://eprints.iisc.ac.in/id/eprint/39225

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