Target type: biologicalprocess
Repair of a DSB made between two repeated sequences oriented in the same direction occurs primarily by the single strand annealing pathway. The ends of the break are processed by a 5' to 3' exonuclease, exposing complementary single-strand regions of the direct repeats that can anneal, resulting in a deletion of the unique DNA between the direct repeats. [PMID:11606529]
Double-strand break (DSB) repair via single-strand annealing (SSA) is a specialized pathway that operates when two broken DNA ends share a region of homology. This pathway is particularly relevant for repairing DSBs that occur within repetitive sequences, where other repair pathways might lead to incorrect rejoining. Here's a detailed breakdown of the process:
1. **Resection:** The 5' ends of the broken DNA strands are resected by nucleases, removing nucleotides and creating 3' single-stranded overhangs.
2. **Strand Invasion:** The 3' overhang of one broken end invades the complementary sequence on the other broken end, forming a displacement loop (D-loop).
3. **Annealing:** The invading strand anneals with the complementary sequence, bringing the two broken ends together.
4. **DNA Synthesis:** DNA polymerase fills in the gaps in the newly annealed strands, extending them to complete the missing sequence.
5. **Ligation:** DNA ligase seals the remaining nick in the DNA backbone, joining the two strands and completing the repair.
SSA relies on the presence of homologous sequences flanking the break, facilitating the annealing process. This pathway is highly accurate in restoring the original DNA sequence, as it relies on the complementary base pairing of the homologous regions. However, it can also lead to deletions if the homologous regions are not perfectly aligned.
SSA is an important backup pathway for DSB repair, particularly in situations where other pathways are not efficient, like in repetitive DNA sequences. However, its reliance on homologous sequences makes it less versatile than other repair pathways.'
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Protein | Definition | Taxonomy |
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DNA repair protein RAD52 homolog | A DNA repair protein RAD52 homolog that is encoded in the genome of human. [PRO:DNx] | Homo sapiens (human) |
Compound | Definition | Classes | Roles |
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aurintricarboxylic acid | aurintricarboxylic acid : A member of the class of quinomethanes that is 3-methylidene-6-oxocyclohexa-1,4-diene-1-carboxylic acid in which the methylidene hydrogens are replaced by 4-carboxy-3-hydroxyphenyl groups. The trisodium salt is the biological stain 'chrome violet CG' while the triammonium salt is 'aluminon'. Aurintricarboxylic Acid: A dye which inhibits protein biosynthesis at the initial stages. The ammonium salt (aluminon) is a reagent for the colorimetric estimation of aluminum in water, foods, and tissues. | monohydroxybenzoic acid; quinomethanes; tricarboxylic acid | fluorochrome; histological dye; insulin-like growth factor receptor 1 antagonist |
gossypol | Gossypol: A dimeric sesquiterpene found in cottonseed (GOSSYPIUM). The (-) isomer is active as a male contraceptive (CONTRACEPTIVE AGENTS, MALE) whereas toxic symptoms are associated with the (+) isomer. | ||
oxidopamine | oxidopamine : A benzenetriol that is phenethylamine in which the hydrogens at positions 2, 4, and 5 on the phenyl ring are replaced by hydroxy groups. It occurs naturally in human urine, but is also produced as a metabolite of the drug DOPA (used for the treatment of Parkinson's disease). Oxidopamine: A neurotransmitter analogue that depletes noradrenergic stores in nerve endings and induces a reduction of dopamine levels in the brain. Its mechanism of action is related to the production of cytolytic free-radicals. | benzenetriol; catecholamine; primary amino compound | drug metabolite; human metabolite; neurotoxin |
1,2,5,8-tetrahydroxy anthraquinone | 1,2,5,8-tetrahydroxy anthraquinone: structure in first source quinalizarin : A tetrahydroxyanthraquinone having the four hydroxy groups at the 1-, 2-, 5- and 8-positions. | tetrahydroxyanthraquinone | EC 2.7.11.1 (non-specific serine/threonine protein kinase) inhibitor |
epigallocatechin gallate | (-)-epigallocatechin 3-gallate : A gallate ester obtained by the formal condensation of gallic acid with the (3R)-hydroxy group of (-)-epigallocatechin. epigallocatechin gallate: a steroid 5alpha-reductase inhibitor and antimutagen in green tea (Camellia sinensis) | flavans; gallate ester; polyphenol | antineoplastic agent; antioxidant; apoptosis inducer; geroprotector; Hsp90 inhibitor; neuroprotective agent; plant metabolite |
epicatechin | (-)-epicatechin : A catechin with (2R,3R)-configuration. | catechin; polyphenol | antioxidant |
gallocatechol | (-)-epigallocatechin : A flavan-3,3',4',5,5',7-hexol having (2R,3R)-configuration. | catechin; flavan-3,3',4',5,5',7-hexol | antioxidant; food component; plant metabolite |
strictinin | strictinin: antioxidant from green tea leaves (Camellia sinensis L.); structure in first source | ||
corilagin | corilagin : An ellagitannin with a hexahydroxydiphenoyl group bridging over the 3-O and 6-O of the glucose core. corilagin: isolated from Geranii herba | ellagitannin; gallate ester | antihypertensive agent; antioxidant; EC 3.4.15.1 (peptidyl-dipeptidase A) inhibitor; non-steroidal anti-inflammatory drug |
6-hydroxydopa | 6-hydroxydopa: RN given refers to cpd without isomeric designation | non-proteinogenic alpha-amino acid | |
epicatechin gallate | (-)-epicatechin-3-O-gallate : A gallate ester obtained by formal condensation of the carboxy group of gallic acid with the (3R)-hydroxy group of epicatechin. A natural product found in Parapiptadenia rigida. epicatechin gallate: a steroid 5alpha-reductase inhibitor; RN given refers to the (cis)-isomer; structure given in first source; isolated from green tea | catechin; gallate ester; polyphenol | EC 3.2.1.1 (alpha-amylase) inhibitor; EC 3.2.1.20 (alpha-glucosidase) inhibitor; metabolite |
asiatic acid | monocarboxylic acid; pentacyclic triterpenoid; triol | angiogenesis modulating agent; metabolite | |
gossypetin | gossypetin : A hexahydroxyflavone having the hydroxy groups placed at the 3-, 3'-, 4'-, 5- 7- and 8-positions. gossypetin: inhibits activity of penicillinase enzyme in E coli | 7-hydroxyflavonol; hexahydroxyflavone | plant metabolite |
3-(4-chlorophenyl)-1-methyl-N-[3-(1-pyrrolidinyl)propyl]-5-thieno[2,3-c]pyrazolecarboxamide | pyrazoles; ring assembly | ||
cedrelone | cedrelone: from Toona ciliata; structure in first source | limonoid | |
rolitetracycline | rolitetracycline : A derivative of tetracycline in which the amide function is substituted with a pyrrolidinomethyl group. Rolitetracycline: A pyrrolidinylmethyl TETRACYCLINE. | ||
methacycline monohydrochloride |