scholarly journals Association of DNA topoisomerase I and RNA polymerase I: a possible role for topoisomerase I in ribosomal gene transcription

Chromosoma ◽  
1988 ◽  
Vol 96 (6) ◽  
pp. 411-416 ◽  
Author(s):  
Kathleen M. Rose ◽  
Jan Szopa ◽  
Fu-Sheng Han ◽  
Yung-Chi Cheng ◽  
Arndt Richter ◽  
...  
Keyword(s):  
Rna Polymerase ◽  
Gene Transcription ◽  
Topoisomerase I ◽  
Ribosomal Gene ◽  
Rna Polymerase I ◽  
Dna Topoisomerase I ◽  
Dna Topoisomerase ◽  
Polymerase I

scholarly journals A34.5, a nonessential component of yeast RNA polymerase I, cooperates with subunit A14 and DNA topoisomerase I to produce a functional rRNA synthesis machine.

1997 ◽  
Vol 17 (4) ◽  
pp. 1787-1795 ◽  
Author(s):  
O Gadal ◽  
S Mariotte-Labarre ◽  
S Chedin ◽  
E Quemeneur ◽  
C Carles ◽  
...  
Keyword(s):  
Rna Polymerase ◽  
Topoisomerase I ◽  
Synthetic Lethality ◽  
Rna Polymerase I ◽  
Rrna Synthesis ◽  
Dna Topoisomerase I ◽  
Dna Topoisomerase ◽  
Pol Ii ◽  
Pol I ◽  
Polymerase I

A34.5, a phosphoprotein copurifying with RNA polymerase I (Pol I), lacks homology to any component of the Pol II or Pol III transcription complexes. Cells devoid of A34.5 hardly affect growth and rRNA synthesis and generate a catalytically active but structurally modified enzyme also lacking subunit A49 upon in vitro purification. Other Pol I-specific subunits (A49, A14, and A12.2) are nonessential for growth at 30 degrees C but are essential (A49 and A12.2) or helpful (A14) at 25 or 37 degrees C. Triple mutants without A34.5, A49, and A12.2 are viable, but inactivating any of these subunits together with A14 is lethal. Lethality is rescued by expressing pre-rRNA from a Pol II-specific promoter, demonstrating that these subunits are collectively essential but individually dispensable for rRNA synthesis. A14 and A34.5 single deletions affect the subunit composition of the purified enzyme in pleiotropic but nonoverlapping ways which, if accumulated in the double mutants, provide a structural explanation for their strict synthetic lethality. A34.5 (but not A14) becomes quasi-essential in strains lacking DNA topoisomerase I, suggesting a specific role of this subunit in helping Pol I to overcome the topological constraints imposed on ribosomal DNA by transcription.

Identification of two steps during Xenopus ribosomal gene transcription that are sensitive to protein phosphorylation

1994 ◽  
Vol 14 (3) ◽  
pp. 2011-2020
Author(s):  
P Labhart
Keyword(s):  
Protein Kinase ◽  
Rna Polymerase ◽  
Protein Phosphorylation ◽  
Gene Transcription ◽  
Okadaic Acid ◽  
Protein Phosphatase ◽  
Transcription Initiation ◽  
Ribosomal Gene ◽  
Rna Polymerase I ◽  
Polymerase I

Protein kinase(s) and protein phosphatase(s) present in a Xenopus S-100 transcription extract strongly influence promoter-dependent transcription by RNA polymerase I. The protein kinase inhibitor 6-dimethyl-aminopurine causes transcription to increase, while the protein phosphatase inhibitor okadaic acid causes transcription to decrease. Repression is also observed with inhibitor 2, and the addition of extra protein phosphatase 1 stimulates transcription, indicating that the endogenous phosphatase is a type 1 enzyme. Partial fractionation of the system, single-round transcription reactions, and kinetic experiments show that two different steps during ribosomal gene transcription are sensitive to protein phosphorylation: okadaic acid affects a step before or during transcription initiation, while 6-dimethylaminopurine stimulates a process "late" in the reaction, possibly reinitiation. The present results are a clear demonstration that transcription by RNA polymerase I can be regulated by protein phosphorylation.

scholarly journals Identification of two steps during Xenopus ribosomal gene transcription that are sensitive to protein phosphorylation.

1994 ◽  
Vol 14 (3) ◽  
pp. 2011-2020 ◽  
Author(s):  
P Labhart
Keyword(s):  
Protein Kinase ◽  
Rna Polymerase ◽  
Protein Phosphorylation ◽  
Gene Transcription ◽  
Okadaic Acid ◽  
Protein Phosphatase ◽  
Transcription Initiation ◽  
Ribosomal Gene ◽  
Rna Polymerase I ◽  
Polymerase I

Protein kinase(s) and protein phosphatase(s) present in a Xenopus S-100 transcription extract strongly influence promoter-dependent transcription by RNA polymerase I. The protein kinase inhibitor 6-dimethyl-aminopurine causes transcription to increase, while the protein phosphatase inhibitor okadaic acid causes transcription to decrease. Repression is also observed with inhibitor 2, and the addition of extra protein phosphatase 1 stimulates transcription, indicating that the endogenous phosphatase is a type 1 enzyme. Partial fractionation of the system, single-round transcription reactions, and kinetic experiments show that two different steps during ribosomal gene transcription are sensitive to protein phosphorylation: okadaic acid affects a step before or during transcription initiation, while 6-dimethylaminopurine stimulates a process "late" in the reaction, possibly reinitiation. The present results are a clear demonstration that transcription by RNA polymerase I can be regulated by protein phosphorylation.

scholarly journals Feedback regulation of vitamin D metabolism by 1,25-dihydroxycholecalciferol

1977 ◽  
Vol 164 (1) ◽  
pp. 83-89 ◽  
Author(s):  
K W Colston ◽  
I M A Evans ◽  
T C Spelsberg ◽  
I MacIntyre
Keyword(s):  
Vitamin D ◽  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Gene Transcription ◽  
Subcutaneous Administration ◽  
Feedback Regulation ◽  
Rna Polymerase I ◽  
Hydroxylase Activity ◽  
Vitamin D Metabolism ◽  
Polymerase I

Many factors influence the production of 1,25(OH)2D3 (1,25-dihydroxycholecalciferol) by the kidney. One important factor seems to be feedback regulation by 1,25(OH)2D3 itself. Administration of 1,25(OH)2D3 to vitamin D-deficient chicks abolishes renal 25(OH)D3(25-hydroxycholecalciferol)1-hydroxylase activity and induces the appearance of 25(OH)D3 24-hydroxylase activity. It is likely that these effects are mediated via a nuclear effect, as they are prevented by pretreatment with actinomycin D and alpha-amanitin. Further, 1,25(OH)2D3 has a marked effect on gene transcription in the kidney cell, as assessed by measurement of RNA polymerase activities. RNA polymerase I and II activities are 80-90% inhibited by 12.5nmol of 1,25(OH)2D3 within 30min of subcutaneous administration, indicating an immediate and massive decrease in total gene transcription. By 4h RNA polymerase II activity has returned to control values, but RNA polymerase I activity is markedly enhanced. These results are consistent with the view that regulation of cholecalciferol metabolism in the kidney is associated with an effect of the active metabolite on the kidney nucleus.

The effects of camptothecin on RNA polymerase II transcription: Roles of DNA topoisomerase I

Biochimie ◽  
2007 ◽  
Vol 89 (4) ◽  
pp. 482-489 ◽  
Author(s):  
Giovanni Capranico ◽  
Francesca Ferri ◽  
Maria Vittoria Fogli ◽  
Alessandra Russo ◽  
Luca Lotito ◽  
...  
Keyword(s):  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Topoisomerase I ◽  
Dna Topoisomerase I ◽  
Dna Topoisomerase ◽  
Rna Polymerase Ii Transcription
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