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Literature summary for 5.6.2.4 extracted from
- The Saccharomyces cerevisiae Hrq1 and Pif1 DNA helicases synergistically modulate telomerase activity in vitro (2018), J. Biol. Chem., 293, 14481-14496 .
Protein Variants
| Protein Variants | Comment | Organism |
|---|---|---|
| K318A | site-directed mutagenesis, the mutant shows reduced activity and DNA binding, and increased KD value compared to wild-type. Neither wild-type Hrq1 nor Hrq1-K318A have any effect on overall telomerase activity, no effect on telomerase extension of the Tel15 and Tel30 primers | Saccharomyces cerevisiae |
Inhibitors
| Inhibitors | Comment | Organism | Structure |
|---|---|---|---|
| RNA-DNA hybrid | the in vitro helicase activity of Hrq1 is decreased about 4fold when unwinding a fork substrate with an RNA-DNA hybrid duplex region relative to a DNA-DNA duplex | Saccharomyces cerevisiae |
Localization
| Localization | Comment | Organism | GeneOntology No. | Textmining |
|---|---|---|---|---|
| additional information | Hrq1 is localized to telomeres | Saccharomyces cerevisiae | - |
- |
Metals/Ions
| Metals/Ions | Comment | Organism | Structure |
|---|---|---|---|
| Mg2+ | required | Saccharomyces cerevisiae |  |
Natural Substrates/ Products (Substrates)
| Natural Substrates | Organism | Comment (Nat. Sub.) | Natural Products | Comment (Nat. Pro.) | Rev. | Reac. |
|---|---|---|---|---|---|---|
| ATP + H2O | Saccharomyces cerevisiae | - |
ADP + phosphate | - |
? | |
| ATP + H2O | Saccharomyces cerevisiae ATCC 204508 | - |
ADP + phosphate | - |
? | |
Organism
| Organism | UniProt | Comment | Textmining |
|---|---|---|---|
| Saccharomyces cerevisiae | Q05549 | - |
- |
| Saccharomyces cerevisiae ATCC 204508 | Q05549 | - |
- |
Substrates and Products (Substrate)
| Substrates | Comment Substrates | Organism | Products | Comment (Products) | Rev. | Reac. |
|---|---|---|---|---|---|---|
| ATP + H2O | - |
Saccharomyces cerevisiae | ADP + phosphate | - |
? | |
| ATP + H2O | - |
Saccharomyces cerevisiae ATCC 204508 | ADP + phosphate | - |
? | |
| additional information | Saccharomyces cerevisiae Hrq1 and Pif1 DNA helicases synergistically modulate telomerase activity in vitro. The helicases alone have equal-but-opposite biphasic effects on telomerase, with Hrq1 stimulating activity at high concentrations. When the helicases are combined in reactions, they synergistically inhibit or stimulate telomerase activity depending on which helicase is catalytically active. Hrq1 affects telomerase activity by a different mechanism than Pif1. The in vitro helicase activity of Hrq1 is decreased about 4fold when unwinding a fork substrate with an RNA-DNA hybrid duplex region relative to a DNA-DNA duplex. Hrq1 has only subtle effects on telomerase activity on a 15-to-30-nt substrate, but on a long (50 nt) primer. Lower concentrations of Hrq1 slightly inhibit telomerase activity, but significant stimulation occurs at higher Hrq1 concentrations | Saccharomyces cerevisiae | ? | - |
- |
|
| additional information | Saccharomyces cerevisiae Hrq1 and Pif1 DNA helicases synergistically modulate telomerase activity in vitro. The helicases alone have equal-but-opposite biphasic effects on telomerase, with Hrq1 stimulating activity at high concentrations. When the helicases are combined in reactions, they synergistically inhibit or stimulate telomerase activity depending on which helicase is catalytically active. Hrq1 affects telomerase activity by a different mechanism than Pif1. The in vitro helicase activity of Hrq1 is decreased about 4fold when unwinding a fork substrate with an RNA-DNA hybrid duplex region relative to a DNA-DNA duplex. Hrq1 has only subtle effects on telomerase activity on a 15-to-30-nt substrate, but on a long (50 nt) primer. Lower concentrations of Hrq1 slightly inhibit telomerase activity, but significant stimulation occurs at higher Hrq1 concentrations | Saccharomyces cerevisiae ATCC 204508 | ? | - |
- |
|
Synonyms
| Synonyms | Comment | Organism |
|---|---|---|
| Hrq1 | - |
Saccharomyces cerevisiae |
General Information
| General Information | Comment | Organism |
|---|---|---|
| metabolism | Saccharomyces cerevisiae Hrq1 and Pif1 DNA helicases synergistically modulate telomerase activity in vitro. The helicases alone have equal-but-opposite biphasic effects on telomerase, with Hrq1 stimulating activity at high concentrations. When the helicases are combined in reactions, they synergistically inhibit or stimulate telomerase activity depending on which helicase is catalytically active. Hrq1 and Pif1 interact and their concerted activities ensure proper telomere length homeostasis in vivo. Modelling of Hrq1 and Pif1 cooperatively contributing to telomere length homeostasis in yeast, overview. Hrq1 affects telomerase activity by a different mechanism than Pif1 | Saccharomyces cerevisiae |
| physiological function | Saccharomyces cerevisiae Hrq1 DNA helicase synergistically modulates telomerase activity. Hrq1, the yeast homologue of the disease-linked human RecQ-like helicase 4 (RECQL4), is a catalytic inhibitor of telomerase. Hrq1 functions in telomere length homeostasis. The enzyme is involved in telomerase regulation together with DNA helicase Pif1. Hrq1 also promotes the formation of type I survivors in telomerase-null (tlc1DELTA) cells | Saccharomyces cerevisiae |
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