Target type: biologicalprocess
The process in which the nucleoprotein complex (composed of the broken single-strand DNA and the recombinase) searches and identifies a region of homology in intact duplex DNA. The broken single-strand DNA displaces the like strand and forms Watson-Crick base pairs with its complement, forming a duplex in which each strand is from one of the two recombining DNA molecules. [GOC:elh, PMID:10357855]
DNA strand invasion is a crucial step in homologous recombination, a process that repairs DNA double-strand breaks (DSBs) and facilitates genetic exchange. This intricate process involves the following steps:
1. **DSB formation:** A DNA double-strand break occurs, leaving a gap in the DNA molecule.
2. **5' end resection:** Enzymes such as exonucleases degrade the 5' ends of the broken DNA strands, generating 3' single-stranded tails.
3. **Strand invasion:** The 3' single-stranded tail from the broken DNA (the invading strand) searches for a homologous sequence in an intact DNA molecule (the donor DNA). This search is aided by proteins like Rad51, which forms a nucleoprotein filament on the invading strand and promotes the pairing of homologous sequences.
4. **D-loop formation:** The invading strand displaces one of the strands in the donor DNA, forming a displacement loop (D-loop). The D-loop is stabilized by the interaction between the invading strand and the donor DNA, and by proteins that bind to the single-stranded DNA.
5. **DNA synthesis:** Once the D-loop is formed, DNA polymerase can use the invading strand as a template to synthesize a new strand that is complementary to the donor DNA. This process is called branch migration, and it extends the D-loop, leading to the incorporation of genetic information from the donor DNA into the broken DNA molecule.
6. **Resolution:** The invading strand and the displaced donor strand can be ligated together, completing the repair process.
Strand invasion is essential for maintaining genome integrity and facilitating genetic diversity. The process ensures that the broken DNA is repaired with the correct sequence, preventing mutations and preventing loss of genetic information. This exchange of genetic information contributes to the evolution of species.'
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| Protein | Definition | Taxonomy |
|---|---|---|
| DNA repair protein RAD51 homolog 1 | A DNA repair protein RAD51 homolog 1 that is encoded in the genome of human. [PRO:DNx] | Homo sapiens (human) |
| Compound | Definition | Classes | Roles |
|---|---|---|---|
| 5-hydroxyindole | hydroxyindoles | human metabolite | |
| methyl tryptophan, (l-trp)-isomer | |||
| 3-chloro-1-(2-chlorophenyl)-4-(4-morpholinyl)pyrrole-2,5-dione | maleimides | ||
| 3-chloro-1-(3,4-dichlorophenyl)-4-(4-morpholinyl)-1h-pyrrole-2,5-dione | 3-chloro-1-(3,4-dichlorophenyl)-4-(4-morpholinyl)-1H-pyrrole-2,5-dione: an inhibitor of RAD51 that disrupts homologous recombination in human cells; structure in first source |