resolution of DNA recombination intermediates

Definition

Target type: biologicalprocess

The cleavage and rejoining of intermediates, such as Holliday junctions, formed during DNA recombination to produce two intact molecules in which genetic material has been exchanged. [GOC:elh, GOC:mah, GOC:vw]

Resolution of DNA recombination intermediates is a crucial step in the process of homologous recombination, a vital mechanism for repairing DNA double-strand breaks (DSBs). DSBs are highly damaging lesions that can lead to cell death or genomic instability if left unrepaired. Homologous recombination utilizes a homologous template, such as a sister chromatid, to repair the DSB, ensuring accurate replication of the genetic information.

During recombination, the broken ends of the DNA molecule are processed to generate single-stranded DNA tails, which invade the homologous template and form a structure called a Holliday junction. The Holliday junction is a four-way DNA junction where two strands of DNA from different duplexes are crossed over.

Resolution of Holliday junctions is essential for completing the recombination process and separating the newly synthesized DNA from the template. It is achieved by specialized enzymes called resolvases, which cleave the Holliday junction at one of the two crossover points.

The resolution of Holliday junctions can occur in two different ways:

1. **Isomerization:** This process involves the rotation of the Holliday junction, allowing the resolvase to cleave the junction at a different location. Isomerization can result in either crossover or non-crossover products, depending on the orientation of the junction before cleavage.
2. **Cleavage:** Resolvase enzymes bind to the Holliday junction and cleave the DNA strands at specific sites. The cleavage sites determine the outcome of the recombination event.

The cleavage of Holliday junctions by resolvases is a highly regulated process that involves a complex interplay of protein-protein interactions and DNA sequence recognition. Different resolvases have distinct recognition sequences, and their activity is tightly regulated to ensure accurate and efficient resolution of recombination intermediates.

After cleavage, the Holliday junction is resolved into two separate DNA duplexes, which can then be ligated together to form two complete DNA molecules. The final products of recombination can be either crossover or non-crossover, depending on the orientation of the Holliday junction at the time of resolution.

Crossover products result in the exchange of genetic material between the two homologous chromosomes, leading to genetic diversity and increased recombination frequency. Non-crossover products, on the other hand, do not result in genetic exchange but are still essential for repairing DSBs and maintaining genomic stability.

In summary, the resolution of DNA recombination intermediates is a critical step in homologous recombination that ensures accurate repair of DSBs and maintains genomic integrity. This process involves the cleavage of Holliday junctions by resolvases, which can result in either crossover or non-crossover products. The outcome of resolution is tightly regulated by a complex interplay of protein-protein interactions and DNA sequence recognition.'
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Proteins (1)

Compounds (2)