
Holliday Junction

Molecular structure of a Holliday junction. From .
A 'Holliday junction' is a mobile junction between four strands of
DNA. The structure is named after
Robin Holliday, who proposed it in 1964
[1][2] to account for a particular type of exchange of genetic information in
yeast known as
homologous recombination.
Because these junctions are between homologous sequences they can slide up and down the DNA. In
bacteria, this sliding (or branch migration) is facilitated by the
RuvABC complex or
RecG protein, molecular motors that use the energy of
ATP hydrolysis to push the junction around. The junction must then be resolved, split up, to restore 2 linear duplexes. This can be done to either restore the parental configuration or to establish a crossed over configuration. Resolution can occur in either a horizontal or vertical fashion during homologous recombination, giving patch products (if in same orientation during double strand break repair) or splice products (if in different orientations during double strand break repair).
Holliday junctions are important in maintaining genomic integrity.
See also
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Genetic recombination
References
1. Happy Hollidays: 40th anniversary of the Holliday junction, Liu Y, West S, , , Nat Rev Mol Cell Biol, 2004
2. {{cite journal |title=Caution! DNA Crossing: Crystal Structures of Holliday Junctions |author=Hays FA, Watson J, Ho PS |journal=J Biol Chem |volume=278 |issue=50 |pages=49663–49666 |date=2003 |id=
External links
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Conformational Change of Holliday Junction
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Holliday Structure in tetrahedral form
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Analysis of branch migration activites of proteins using synthetic DNA substrates (a protocol)