four-way junction helicase activity

Definition

Target type: molecularfunction

Unwinding a DNA helix of DNA containing four-way junctions, including Holliday junctions, driven by ATP hydrolysis. [GOC:al, PMID:22723423, PMID:9442895]

Four-way junction helicases are enzymes that specifically recognize and unwind four-way DNA junctions, also known as Holliday junctions. These junctions are crucial intermediates in homologous recombination, a DNA repair process that allows for the exchange of genetic information between two homologous DNA molecules. The molecular function of four-way junction helicases involves several steps:

1. **Junction Recognition**: The helicase binds to the four-way junction, recognizing the unique structural features of the junction. This recognition often involves specific interactions with the DNA bases and the sugar-phosphate backbone of the junction.
2. **Strand Separation**: Once bound, the helicase uses ATP hydrolysis to provide energy for the unwinding of the junction. This process involves breaking the hydrogen bonds between the base pairs within the junction, leading to the separation of the four DNA strands.
3. **Translocation**: The helicase then translocates along the separated strands, moving in a specific direction to further unwind the junction. This movement can be either 5' to 3' or 3' to 5', depending on the specific helicase.
4. **Branch Migration**: In some cases, four-way junction helicases can promote branch migration, a process that shifts the point of crossing between the DNA strands. This can lead to the formation of new Holliday junctions or the resolution of existing ones.

The ability of four-way junction helicases to unwind and resolve these complex DNA structures is essential for maintaining genomic stability. It allows for accurate DNA repair, reduces the risk of mutations, and contributes to the proper segregation of chromosomes during cell division.'
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Proteins (3)

Compounds (2)