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Literature summary for 5.6.2.3 extracted from
- The Dictyostelium discoideum homologue of Twinkle, Twm1, is a mitochondrial DNA helicase, an active primase and promotes mitochondrial DNA replication (2018), BMC Mol. Biol., 19, 12 .
Activating Compound
| Activating Compound | Comment | Organism | Structure |
|---|---|---|---|
| DNA | the presence of DNA, especially linear DNA, increases the nucleoside triphosphatase activity of the enzyme | Dictyostelium discoideum |  |
Cloned(Commentary)
| Cloned (Comment) | Organism |
|---|---|
| gene twm1, Twinkle homologue (Twm1) in Dictyostelium discoideum is encoded by the nuclear twm1 gene and targeted to mitochondria, quantitative PCR enzyme expression analysis, recombinant expression of truncated enzyme in Dictyostelium discoideum AX2 cells and of His-tagged enzyme in Escherichia coli strain BL21 (DE3) | Dictyostelium discoideum |
Protein Variants
| Protein Variants | Comment | Organism |
|---|---|---|
| additional information | recombinant expression of antisence Twm1 construct in Dictyostelium discoideum AX2 cells leading to mitochondrial dysfunction and reduced mtDNA copy number. Ethidium bromide exposure increases twm1 expression and results in mtDNA loss from which antisense transformants are less able to recover. Generation of a truncated Twm1 with 599 amino acids and 68 kDa, lacking the first 154 and last 19 amino acids of the full length protein (772 amino acids) | Dictyostelium discoideum |
Localization
| Localization | Comment | Organism | GeneOntology No. | Textmining |
|---|---|---|---|---|
| mitochondrion | Twinkle homologue (Twm1) in Dictyostelium discoideum is encoded by the nuclear twm1 gene and targeted to mitochondria | Dictyostelium discoideum | 5739 | - |
Organism
| Organism | UniProt | Comment | Textmining |
|---|---|---|---|
| Dictyostelium discoideum | Q54J94 | - |
- |
Purification (Commentary)
| Purification (Comment) | Organism |
|---|---|
| recombinant His-tagged enzyme from Escherichia coli strain BL21 (DE3) by nickel affinity chromatography, dialysis, and ultrafiltration | Dictyostelium discoideum |
Substrates and Products (Substrate)
| Substrates | Comment Substrates | Organism | Products | Comment (Products) | Rev. | Reac. |
|---|---|---|---|---|---|---|
| ATP + H2O | best substrate | Dictyostelium discoideum | ADP + phosphate | - |
? | |
| CTP + H2O | - |
Dictyostelium discoideum | CDP + phosphate | - |
? | |
| dATP + H2O | high activity | Dictyostelium discoideum | dADP + phosphate | - |
? | |
| dCTP + H2O | - |
Dictyostelium discoideum | dCDP + phosphate | - |
? | |
| dGTP + H2O | - |
Dictyostelium discoideum | dGDP + phosphate | - |
? | |
| dTTP + H2O | - |
Dictyostelium discoideum | dTDP + phosphate | - |
? | |
| GTP + H2O | - |
Dictyostelium discoideum | GDP + phosphate | - |
? | |
| additional information | heterologously expressed recombinant Twm1 possesses nucleoside triphosphatase (NTPase), helicase and primase activity in vitro. Twm1 functions as a 5'->3' helicase which requires open fork-like DNA substrates. Nucleotide phosphate substrate specificity, overview. NTPase activity of Twm1 is also measured in the presence of linear dsDNA (FHA0), circular ssDNA (M13mp18) or linear ssDNA (FHA3.1) | Dictyostelium discoideum | ? | - |
- |
|
| UTP + H2O | - |
Dictyostelium discoideum | UDP + phosphate | - |
? | |
Synonyms
| Synonyms | Comment | Organism |
|---|---|---|
| DDB0187832 | locus name | Dictyostelium discoideum |
| TWINKLE | - |
Dictyostelium discoideum |
| Twm1 | - |
Dictyostelium discoideum |
Temperature Optimum [°C]
| Temperature Optimum [°C] | Temperature Optimum Maximum [°C] | Comment | Organism |
|---|---|---|---|
| 21 | - |
assay at | Dictyostelium discoideum |
pH Optimum
| pH Optimum Minimum | pH Optimum Maximum | Comment | Organism |
|---|---|---|---|
| 7.5 | - |
assay at | Dictyostelium discoideum |
Expression
| Organism | Comment | Expression |
|---|---|---|
| Dictyostelium discoideum | ethidium bromide exposure increases twm1 expression | up |
General Information
| General Information | Comment | Organism |
|---|---|---|
| malfunction | Twm1 gene antisense inhibition leads to mitochondrial dysfunction and reduced mtDNA copy number | Dictyostelium discoideum |
| physiological function | Twm1 is a replicative mitochondrial DNA helicase which is capable of priming DNA for replication. Non-metazoan Twinkle functions in the initiation of mitochondrial DNA replication. Twm1 is important for mitochondrial function as it maintains mitochondrial DNA copy number in vivo. Twm1 is a helicase which unwinds DNA resembling open forks, although it can act upon substrates with a single 3' overhang, albeit less efficiently. Furthermore, unlike human Twinkle, Twm1 has primase activity in vitro. Twinkle helicases function as 5'->3' helicases and, similar to other replicative helicases, form ring-shaped hexamers to unwind dsDNA at the replication fork | Dictyostelium discoideum |
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