What is Holliday junction and what is its purpose?
Holliday junction, cross-shaped structure that forms during the process of genetic recombination, when two double-stranded DNA molecules become separated into four strands in order to exchange segments of genetic information.
Which enzyme is important in the resolution of a Holliday junction?
HJ resolvases
Holliday junction cleavage, which generates two unconnected DNA duplexes, is catalyzed by a group of structure-selective endonucleases called HJ resolvases. These nucleases have been isolated from bacteria, bacteriophages, archaea, viruses, yeasts, plants, and mammals (Table 1) and share a number of common properties.
What is Heteroduplex in Holliday model?
The key features of the Holliday model are the formation of heteroduplex DNA; the creation of a cross bridge; its migration along the two heteroduplex strands, termed branch migration; the occurrence of mismatch repair; and the subsequent resolution, or splicing, of the intermediate structure to yield different types …
What can the Holliday model help explain?
In 1964, Robin Holliday proposed a model that accounted for heteroduplex formation and gene conversion during recombination. It illustrates the critical steps of pairing of homologous duplexes, formation of a heteroduplex, formation of the recombination joint, branch migration and resolution.
Which enzyme resolves the Holliday junction?
(B) Canonical Holliday junction resolvases are dimeric enzymes that induce structural changes to the junction on binding, causing the junction to unfold. Resolution occurs by the introduction of two coordinated and symmetrically related nicks in strands of like polarity at, or very near, the branchpoint.
What enzyme cuts Holliday junctions during homologous recombination?
The double Holliday junctions are then converted into recombination products by nicking endonucleases, a type of restriction endonuclease which cuts only one DNA strand.
What process does the Holliday model help explain?