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Literature summary for 5.6.2.3 extracted from
- Homologous DNA strand exchange activity of the human mitochondrial DNA helicase TWINKLE (2016), Nucleic Acids Res., 44, 4200-4210 .
Cloned(Commentary)
| Cloned (Comment) | Organism |
|---|---|
| recombinant expression of C-terminally His6-tagged wild-type TWINKLE and truncated mutant in Escherichia coli strain Rosetta (DE3) | Homo sapiens |
Protein Variants
| Protein Variants | Comment | Organism |
|---|---|---|
| additional information | generation of a TWINKLE mutant lacking the first 42 amino acids | Homo sapiens |
Localization
| Localization | Comment | Organism | GeneOntology No. | Textmining |
|---|---|---|---|---|
| mitochondrion | - |
Homo sapiens | 5739 | - |
| additional information | helicase TWINKLE is a phage T7-gene 4-like protein expressed in the nucleus and localized in the human mitochondria | Homo sapiens | - |
- |
Metals/Ions
| Metals/Ions | Comment | Organism | Structure |
|---|---|---|---|
| Mg2+ | required | Homo sapiens |  |
Natural Substrates/ Products (Substrates)
| Natural Substrates | Organism | Comment (Nat. Sub.) | Natural Products | Comment (Nat. Pro.) | Rev. | Reac. |
|---|---|---|---|---|---|---|
| ATP + H2O | Homo sapiens | - |
ADP + phosphate | - |
? | |
Organism
| Organism | UniProt | Comment | Textmining |
|---|---|---|---|
| Homo sapiens | Q96RR1 | - |
- |
Purification (Commentary)
| Purification (Comment) | Organism |
|---|---|
| recombinant C-terminally His6-SUMO-tagged wild-type TWINKLE and truncated mutant from Escherichia coli strain Rosetta (DE3) by nickel affinity chromatography, tag cleavage through Sumo-protease, anion exchange chromatography, and gel filtration | Homo sapiens |
Substrates and Products (Substrate)
| Substrates | Comment Substrates | Organism | Products | Comment (Products) | Rev. | Reac. |
|---|---|---|---|---|---|---|
| ATP + H2O | - |
Homo sapiens | ADP + phosphate | - |
? | |
| additional information | TWINKLE uses DNA annealing function to actively catalyze strand-exchange reaction between the unwinding substrate and a homologous single-stranded DNA. The mechanism of strand-exchange involves active coupling of unwinding and annealing reactions by the TWINKLE. Unlike strand-annealing, the strand-exchange reaction requires nucleotide hydrolysis and is greatly stimulated by short region of homology between the recombining DNA strands that promote joint molecule formation to initiate strand-exchange. ssDNA and dsDNA oligodeoxynucleotides of different sizes are used as helicase substrates for unwinding and strand-exchange reaction assay, substrate specificity for unwinding, strand-exchange, and branch migration with UTP as cosubstrate, detailed overview. Complementarity between the recombining strands is crucial for TWINKLE catalyzed strand-exchange reaction. TWINKLE is catalyzing the reactions of strand-exchange and joint molecule formation by using its DNA unwinding and annealing activities. TWINKLE translocates on the 5'-strand of the fork DNA to catalyze the strand-exchange reaction, and it catalyzes homologous branch migration reaction | Homo sapiens | ? | - |
- |
|
| UTP + H2O | - |
Homo sapiens | UDP + phosphate | - |
? | |
Subunits
| Subunits | Comment | Organism |
|---|---|---|
| hexamer | TWINKLE is a ring-shaped hexameric helicase | Homo sapiens |
Synonyms
| Synonyms | Comment | Organism |
|---|---|---|
| human mitochondrial DNA helicase | - |
Homo sapiens |
| mitochondrial DNA helicase | - |
Homo sapiens |
| TWINKLE | - |
Homo sapiens |
| TWNK | - |
Homo sapiens |
Temperature Optimum [°C]
| Temperature Optimum [°C] | Temperature Optimum Maximum [°C] | Comment | Organism |
|---|---|---|---|
| 25 | 30 | assay at | Homo sapiens |
pH Optimum
| pH Optimum Minimum | pH Optimum Maximum | Comment | Organism |
|---|---|---|---|
| 7.5 | - |
assay at | Homo sapiens |
General Information
| General Information | Comment | Organism |
|---|---|---|
| metabolism | human mitochondrial (mt) DNA is replicated by a minimal T7-like replisome that consists of the nuclear-encoded DNA polymerase gamma, DNA helicase TWINKLE, and single strand DNA binding protein (mtSSB) | Homo sapiens |
| physiological function | the human mitochondrial DNA replisome is the ring-shaped helicase TWINKLE, which catalyzes branch migration by resolving homologous four-way junction DNA. Despite being a helicase, TWINKLE has unique DNA annealing activity. TWINKLE uses DNA annealing function to actively catalyze strand-exchange reaction between the unwinding substrate and a homologous single-stranded DNA. The mechanism of strand-exchange involves active coupling of unwinding and annealing reactions by the TWINKLE. TWINKLE catalyzes branch migration by resolving homologous four-way junction DNA. These four DNA modifying activities of TWINKLE: strand-separation, strand-annealing, strand-exchange, and branch migration suggesting a dual role of TWINKLE in mitochondrial DNA maintenance. In addition to playing a major role in fork progression during leading strand DNA synthesis, TWINKLE is involved in recombinational repair of the human mitochondrial DNA | Homo sapiens |
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Release 2023.1 (January 2023)
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