scholarly journals Transcriptionally active RNA polymerases from Morris hepatomas and rat liver. Elucidation of the mechanism for the preferential increase in the tumour RNA polymerase I

1980 ◽  
Vol 190 (3) ◽  
pp. 781-789 ◽  
Author(s):  
B W Duceman ◽  
S T Jacob
Keyword(s):  
Rna Polymerase ◽  
Tumour Growth ◽  
Rna Polymerases ◽  
Rna Polymerase I ◽  
Product Analysis ◽  
Sephadex Column ◽  
Tissue Homogenates ◽  
Enzyme Pattern ◽  
Polymerase I

The amount and/or activity of DNA-dependent RNA polymerase I, Ii and III from resting liver, regenerating liver and a series of Morris hepatomas (5123D, 7800, 7777, 3924A) were determined after extraction of the enzymes from whole tissue homogenates and subsequent fractionation by DEAE-Sephadex column chromatography. When compared with resting liver, the tumours exhibited a characteristic enzyme pattern in which polymerase I, but not II, was increased. The increase in RNA polymerase I was proportional to the tumour growth rates. Alterations in polymerase III were confined to the most rapidly proliferating hepatomas. By contrast, all classes of RNA polymerase were found to be increased during liver regeneration. Relative to resting liver, the fastest growing tumour, 3924A, exhibited the highest activities and/or amounts of RNA polymerase I (8-fold) and III (5-fold) per g of tissue. These alterations in the tumour RNA polymerases were reflected in corresponding increases in the transcriptionally active (bound or chromatin-associated) enzyme population. The mechanisms underlying the augmented synthesis of RNA in vitro by bound polymerase I from hepatoma 3924A were elucidated by product analysis. The results indicated that, relative to liver RNA polymerase I, the tumour enzyme produced more nascent RNA chains and elongated these chains at a faster rate. The number of 3'-termini, as measured by incorporation into uridine, was higher in the hepatoma even under conditions which prevented re-initiation. suggesting increased amount of transcriptionally active RNA polymerase I in the tumour.

Phosphorylation of RNA polymerases: specific association of protein kinase NIl with RNA polymerase I

1983 ◽  
Vol 302 (1108) ◽  
pp. 135-142 ◽  
Keyword(s):  
Protein Kinase ◽  
Rna Polymerase ◽  
Rna Synthesis ◽  
Rna Polymerase Iii ◽  
Rna Polymerases ◽  
Rna Polymerase I ◽  
Liver Protein ◽  
Protein Kinase N ◽  
Polymerase I

The activities of the three DNA-dependent RNA polymerases from a rapidly growing rat tumour, Morris hepatoma 3924 A, and from rat liver were examined. The activity of RNA polymerase I was higher in the tumour than in the liver. The enhanced capacity for RNA synthesis was a result of a higher concentration of polymerase I in the tumour as well as of an activation of this enzyme vivo. The possibility that the high specific activity of the hepatoma polymerase I resulted from phosphorylation was investigated. Two major cyclic-AMP-independent nuclear casein kinases (NI and N il) were identified; the activity of protein kinase N il in the tumour was ten times that in liver. Protein kinase N il was capable of activating and phosphorylating RNA polymerase I in vitro . This kinase could also stimulate RNA polymerase II activity, although to a lesser extent than RNA polymerase I. RNA polymerase III was not affected by protein kinase NIL Protein kinase N il was tightly associated with polymerase I and was found even in purified preparations of the polymerase. Antibodies against both RNA polymerase I and protein kinase N il were present in sera of patients with certain rheumatic autoimmune diseases. These results imply that RNA polymerase I and protein kinase NIl are in close association in vivo as well as in vitro and that polymerase phosphorylation may regulate the rate of ribosomal RNA synthesis in the cell.

Events during eucaryotic rRNA transcription initiation and elongation: conversion from the closed to the open promoter complex requires nucleotide substrates

1988 ◽  
Vol 8 (5) ◽  
pp. 1940-1946
Author(s):  
E Bateman ◽  
M R Paule
Keyword(s):  
Rna Polymerase ◽  
Transcription Initiation ◽  
Topological Analysis ◽  
Acanthamoeba Castellanii ◽  
Rna Polymerase I ◽  
Initiation Factor ◽  
Rrna Transcription ◽  
Promoter Complex ◽  
Polymerase I

Chemical footprinting and topological analysis were carried out on the Acanthamoeba castellanii rRNA transcription initiation factor (TIF) and RNA polymerase I complexes with DNA during transcription initiation and elongation. The results show that the binding of TIF and polymerase to the promoter does not alter the supercoiling of the DNA template and the template does not become sensitive to modification by diethylpyrocarbonate, which can identify melted DNA regions. Thus, in contrast to bacterial RNA polymerase, the eucaryotic RNA polymerase I-promoter complex is in a closed configuration preceding addition of nucleotides in vitro. Initiation and 3'-O-methyl CTP-limited translocation by RNA polymerase I results in separation of the polymerase-TIF footprints, leaving the TIF footprint unaltered. In contrast, initiation and translocation result in a significant change in the conformation of the polymerase-DNA complex, culminating in an unwound DNA region of at least 10 base pairs.

scholarly journals RNA polymerase I (Pol I) passage through nucleosomes depends on Pol I subunits binding its lobe structure

2020 ◽  
Vol 295 (15) ◽  
pp. 4782-4795 ◽  
Author(s):  
Philipp E. Merkl ◽  
Michael Pilsl ◽  
Tobias Fremter ◽  
Katrin Schwank ◽  
Christoph Engel ◽  
...  
Keyword(s):  
Rna Polymerase ◽  
Rna Polymerase I ◽  
Dna Templates ◽  
Pol Ii ◽  
Naked Dna ◽  
Pol I ◽  
Intrinsic Capacity ◽  
Pol Iii ◽  
Polymerase I

RNA polymerase I (Pol I) is a highly efficient enzyme specialized in synthesizing most ribosomal RNAs. After nucleosome deposition at each round of rDNA replication, the Pol I transcription machinery has to deal with nucleosomal barriers. It has been suggested that Pol I–associated factors facilitate chromatin transcription, but it is unknown whether Pol I has an intrinsic capacity to transcribe through nucleosomes. Here, we used in vitro transcription assays to study purified WT and mutant Pol I variants from the yeast Saccharomyces cerevisiae and compare their abilities to pass a nucleosomal barrier with those of yeast Pol II and Pol III. Under identical conditions, purified Pol I and Pol III, but not Pol II, could transcribe nucleosomal templates. Pol I mutants lacking either the heterodimeric subunit Rpa34.5/Rpa49 or the C-terminal part of the specific subunit Rpa12.2 showed a lower processivity on naked DNA templates, which was even more reduced in the presence of a nucleosome. Our findings suggest that the lobe-binding subunits Rpa34.5/Rpa49 and Rpa12.2 facilitate passage through nucleosomes, suggesting possible cooperation among these subunits. We discuss the contribution of Pol I–specific subunit domains to efficient Pol I passage through nucleosomes in the context of transcription rate and processivity.

Inactivation of rat liver RNA polymerases I and II and yeast RNA polymerase I by pyridoxal 5'-phosphate. Evidence for the participation of lysyl residues at the active site

Biochemistry ◽  
1975 ◽  
Vol 14 (22) ◽  
pp. 4907-4911 ◽  
Author(s):  
Joseph Martial ◽  
Josefina Zaldivar ◽  
Paulina Bull ◽  
Alejandro Venegas ◽  
Pablo Valenzuela
Keyword(s):  
Rna Polymerase ◽  
Rat Liver ◽  
Active Site ◽  
Rna Polymerases ◽  
Rna Polymerase I ◽  
Polymerase I

scholarly journals Nucleolin Is Required for RNA Polymerase I Transcription In Vivo

2006 ◽  
Vol 27 (3) ◽  
pp. 937-948 ◽  
Author(s):  
Brenden Rickards ◽  
S. J. Flint ◽  
Michael D. Cole ◽  
Gary LeRoy
Keyword(s):  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Rna Polymerase I ◽  
Rrna Genes ◽  
Accessory Proteins ◽  
Naked Dna ◽  
Nucleolar Chromatin ◽  
Polymerase I

ABSTRACT Eukaryotic genomes are packaged with histones and accessory proteins in the form of chromatin. RNA polymerases and their accessory proteins are sufficient for transcription of naked DNA, but not of chromatin, templates in vitro. In this study, we purified and identified nucleolin as a protein that allows RNA polymerase II to transcribe nucleosomal templates in vitro. As immunofluorescence confirmed that nucleolin localizes primarily to nucleoli with RNA polymerase I, we demonstrated that nucleolin allows RNA polymerase I transcription of chromatin templates in vitro. The results of chromatin immunoprecipitation experiments established that nucleolin is associated with chromatin containing rRNA genes transcribed by RNA polymerase I but not with genes transcribed by RNA polymerase II or III. Knockdown of nucleolin by RNA interference resulted in specific inhibition of RNA polymerase I transcription. We therefore propose that an important function of nucleolin is to permit RNA polymerase I to transcribe nucleolar chromatin.

scholarly journals Modifications of both selectivity factor and upstream binding factor contribute to poliovirus-mediated inhibition of RNA polymerase I transcription

2005 ◽  
Vol 86 (8) ◽  
pp. 2315-2322 ◽  
Author(s):  
Rajeev Banerjee ◽  
Mary K. Weidman ◽  
Sonia Navarro ◽  
Lucio Comai ◽  
Asim Dasgupta
Keyword(s):  
Rna Polymerase ◽  
Rna Polymerase I ◽  
Rrna Synthesis ◽  
Selectivity Factor ◽  
Pol I ◽  
Binding Factor ◽  
Infected Cells ◽  
Upstream Binding Factor ◽  
Polymerase I

Soon after infection, poliovirus (PV) shuts off host-cell transcription, which is catalysed by all three cellular RNA polymerases. rRNA constitutes more than 50 % of all cellular RNA and is transcribed from rDNA by RNA polymerase I (pol I). Here, evidence has been provided suggesting that both pol I transcription factors, SL-1 (selectivity factor) and UBF (upstream binding factor), are modified and inactivated in PV-infected cells. The viral protease 3Cpro appeared to cleave the TATA-binding protein-associated factor 110 (TAF110), a subunit of the SL-1 complex, into four fragments in vitro. In vitro protease-cleavage assays using various mutants of TAF110 and purified 3Cpro indicated that the Q265G266 and Q805G806 sites were cleaved by 3Cpro. Both SL-1 and UBF were depleted in PV-infected cells and their disappearance correlated with pol I transcription inhibition. rRNA synthesis from a template containing a human pol I promoter demonstrated that both SL-1 and UBF were necessary to restore pol I transcription fully in PV-infected cell extracts. These results suggested that both SL-1 and UBF are transcriptionally inactivated in PV-infected HeLa cells.

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