telomere maintenance via recombination

Definition

Target type: biologicalprocess

Any recombinational process that contributes to the maintenance of proper telomeric length. [GOC:elh, PMID:11850777]

Telomere maintenance via recombination is a crucial process in maintaining genome stability and preventing cellular senescence. It is particularly important in organisms that lack telomerase, an enzyme that adds repetitive DNA sequences to telomeres, the protective caps at the ends of chromosomes. Unlike telomerase-based extension, recombination-based telomere maintenance relies on homologous recombination (HR) between existing telomere sequences.

Here's a detailed description of the process:

1. **Initiation:** The process begins with the recognition of a critically short telomere. This shortness can trigger a DNA damage response, activating DNA repair pathways.

2. **Homology Search:** The short telomere, often with a single-stranded overhang, initiates a search for homologous sequences. This search is facilitated by the formation of a 3’ single-stranded overhang that can invade a homologous region.

3. **Invasion and Pairing:** The overhang invades a homologous sequence, often located on a sister chromatid or a homologous chromosome. This pairing forms a displacement loop (D-loop).

4. **Strand Invasion and Extension:** DNA synthesis occurs, using the invading strand as a template. This extends the short telomere, restoring its length.

5. **Resolution:** The newly synthesized DNA is incorporated into the telomere. The invading strand is displaced, and the process can be repeated to further extend the telomere.

6. **Alternative Mechanisms:** Alternative pathways, such as break-induced replication (BIR), have also been implicated in telomere maintenance through recombination. BIR allows for the replication of a broken DNA molecule using a homologous template, effectively restoring a missing portion of the telomere.

This recombination-based telomere maintenance process involves a complex interplay of DNA repair factors, including nucleases, helicases, and recombinases. The precise details of the process can vary depending on the specific organism and cellular context. However, the overall principle of using existing telomere sequences as templates for extension remains consistent.'
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Proteins (1)

Compounds (4)