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Holliday Junction Binding and Resolution by the Rap Structure-specific Endonuclease of Phage Lambda

Sharples, Gary and Curtis, Fiona and McGlynn, Peter and Bolt, Edward (2004) Holliday Junction Binding and Resolution by the Rap Structure-specific Endonuclease of Phage Lambda. Journal of Molecular Biology, 340 (4). pp. 739-751.

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Abstract

Rap endonuclease targets recombinant joint molecules arising from phage λ Red-mediated genetic exchange. Previous studies revealed that Rap nicks DNA at the branch point of synthetic Holliday junctions and other DNA structures with a branched component. However, on X junctions incorporating a three base-pair core of homology or with a fixed crossover, Rap failed to make the bilateral strand cleavages characteristic of a Holliday junction resolvase. Here, we demonstrate that Rap can mediate symmetrical resolution of 50 bp and χ Holliday structures containing larger homologous cores. On two different mobile 50 bp junctions Rap displays a weak preference for cleaving the phosphodiester backbone between 5′-GC dinucleotides. The products of resolution on both large and small DNA substrates can be sealed by T4 DNA ligase, confirming the formation of nicked duplexes. Rap protein was also assessed for its capacity to influence the global conformation of junctions in the presence or absence of magnesium ions. Unlike the known Holliday junction binding proteins, Rap does not affect the angle of duplex arms, implying an unorthodox mode of junction binding. The results demonstrate that Rap can function as a Holliday junction resolvase in addition to eliminating other branched structures that may arise during phage recombination.

Item Type: Article
Journal or Publication Title: Journal of Molecular Biology
Uncontrolled Keywords: genetic recombination ; bacteriophage lambda ; Holliday junction resolvase
Subjects: UNSPECIFIED
Departments: Faculty of Health and Medicine > Medicine
ID Code: 51950
Deposited By: ep_importer_pure
Deposited On: 09 Dec 2011 11:17
Refereed?: Yes
Published?: Published
Last Modified: 09 Apr 2014 22:56
Identification Number:
URI: http://eprints.lancs.ac.uk/id/eprint/51950

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