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Updated: Sep 8, 2026

Iterative Optimization of DNA Duplexes for Crystallization of SeqA-DNA Complexes
Published on: November 1, 2012
Crystal structure of an octameric RuvA-Holliday junction complex
1Department of Biochemistry and Molecular Biology, University College London, United Kingdom.
Abstract:
Holliday junctions occur as intermediates in homologous recombination and DNA repair. In bacteria, resolution of Holliday junctions is accomplished by the RuvABC system, consisting of a junction-specific helicase complex RuvAB, which promotes branch migration, and a junction-specific endonuclease RuvC, which nicks two strands. The crystal structure of a complex between the RuvA protein of M. leprae and a synthetic four-way junction has now been determined. Rather than binding on the open surface of a RuvA tetramer as previously suggested, the DNA is sandwiched between two RuvA tetramers, which form a closed octameric shell, stabilized by a conserved tetramer-tetramer interface. Interactions between the DNA backbone and helix-hairpin-helix motifs from both tetramers suggest a mechanism for strand separation promoted by RuvA.
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