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Direct regulation of topoisomerase activity by a nucleoid-associated protein

Ghosh, Soumitra and Mallick, Bratati and Nagaraja, Valakunja (2014) Direct regulation of topoisomerase activity by a nucleoid-associated protein. In: NUCLEIC ACIDS RESEARCH, 42 (17). pp. 11156-11165.

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Official URL: http://dx.doi.org/ 10.1093/nar/gku804


The topological homeostasis of bacterial chromosomes is maintained by the balance between compaction and the topological organization of genomes. Two classes of proteins play major roles in chromosome organization: the nucleoid-associated proteins (NAPs) and topoisomerases. The NAPs bind DNA to compact the chromosome, whereas topoisomerases catalytically remove or introduce supercoils into the genome. We demonstrate that HU, a major NAP of Mycobacterium tuberculosis specifically stimulates the DNA relaxation ability of mycobacterial topoisomerase I (TopoI) at lower concentrations but interferes at higher concentrations. A direct physical interaction between M. tuberculosis HU (MtHU) and TopoI is necessary for enhancing enzyme activity both in vitro and in vivo. The interaction is between the amino terminal domain of MtHU and the carboxyl terminal domain of TopoI. Binding of MtHU did not affect the two catalytic trans-esterification steps but enhanced the DNA strand passage, requisite for the completion of DNA relaxation, a new mechanism for the regulation of topoisomerase activity. An interaction-deficient mutant of MtHU was compromised in enhancing the strand passage activity. The species-specific physical and functional cooperation between MtHU and TopoI may be the key to achieve the DNA relaxation levels needed to maintain the optimal superhelical density of mycobacterial genomes.

Item Type: Journal Article
Additional Information: Copyright for this article belongs to the OXFORD UNIV PRESS, GREAT CLARENDON ST, OXFORD OX2 6DP, ENGLAND
Department/Centre: Division of Biological Sciences > Microbiology & Cell Biology
Date Deposited: 12 Jan 2015 05:54
Last Modified: 12 Jan 2015 05:54
URI: http://eprints.iisc.ac.in/id/eprint/50591

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