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Mycobacterium tuberculosis RuvX is a Holliday junction resolvase formed by dimerisation of the monomeric YqgF nuclease domain

Nautiyal, Astha and Rani, Sandhya P and Sharples, Gary J and Muniyappa, K (2016) Mycobacterium tuberculosis RuvX is a Holliday junction resolvase formed by dimerisation of the monomeric YqgF nuclease domain. In: MOLECULAR MICROBIOLOGY, 100 (4). pp. 656-674.

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Official URL: http://dx.doi.org /10.1111/mmi.13338

Abstract

The Mycobacterium tuberculosis genome possesses homologues of the ruvC and yqgF genes that encode putative Holliday junction (HJ) resolvases. However, their gene expression profiles and enzymatic properties have not been experimentally defined. Here we report that expression of ruvC and yqgF is induced in response to DNA damage. Protein-DNA interaction assays with purified M. tuberculosis RuvC (MtRuvC) and YqgF (MtRuvX) revealed that both associate preferentially with HJ DNA, albeit with differing affinities. Although both MtRuvC and MtRuvX cleaved HJ DNA in vitro, the latter displayed robust HJ resolution activity by symmetrically related, paired incisions. MtRuvX showed a higher binding affinity for the HJ structure over other branched recombination and replication intermediates. An MtRuvX(D28N) mutation, eliminating one of the highly conserved catalytic residues in this class of endonucleases, dramatically reduced its ability to cleave HJ DNA. Furthermore, a unique cysteine (C38) fulfils a crucial role in HJ cleavage, consistent with disulfide-bond mediated dimerization being essential for MtRuvX activity. In contrast, E. coli YqgF is monomeric and exhibits no branched DNA binding or cleavage activity. These results fit with a functional modification of YqgF in M. tuberculosis so that it can act as a dimeric HJ resolvase analogous to that of RuvC.

Item Type: Journal Article
Additional Information: Copy right for this article belongs to the WILEY-BLACKWELL, 111 RIVER ST, HOBOKEN 07030-5774, NJ USA
Department/Centre: Division of Biological Sciences > Biochemistry
Depositing User: Id for Latest eprints
Date Deposited: 24 Aug 2016 09:18
Last Modified: 24 Aug 2016 09:18
URI: http://eprints.iisc.ac.in/id/eprint/54423

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