Eukaryotic Rna Polymerases

Sentenac, André; Buhler, Jean‐Marie; Ruet, Anny; Huet, Janine; Iborra, François; Fromageot, P.

doi:10.1016/b978-0-08-022624-8.50025-9

Cited by 100 publications

(153 citation statements)

References 47 publications

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“…Taken together, our results imply the existence of a novel two-step mechanism in siRNA synthesis at highly methylated loci, with RNAPIVb being an essential component of a self-reinforcing loop coupling de novo DNA methylation to siRNA production. A major evolutionary distinction separating prokaryotes from eukaryotes is the passage from a unique multisubunit DNA-dependent RNA polymerase enzyme (RNAP) to three complexes (Roeder and Rutter 1969), each responsible for the transcription of a subclass of nuclear DNA sequences (Sentenac 1985). RNA polymerase I (RNAPI) transcribes the repeated genes encoding the large ribosomal RNAs, which represent up to four-fifths of total RNA.…”

mentioning

confidence: 99%

“…A major evolutionary distinction separating prokaryotes from eukaryotes is the passage from a unique multisubunit DNA-dependent RNA polymerase enzyme (RNAP) to three complexes (Roeder and Rutter 1969), each responsible for the transcription of a subclass of nuclear DNA sequences (Sentenac 1985). RNA polymerase I (RNAPI) transcribes the repeated genes encoding the large ribosomal RNAs, which represent up to four-fifths of total RNA.…”

mentioning

confidence: 99%

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Reinforcement of silencing at transposons and highly repeated sequences requires the concerted action of two distinct RNA polymerases IV in Arabidopsis

Pontier¹,

Yahubyan²,

Véga³

et al. 2005

Genes Dev.

357

441

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Recent genetic and biochemical studies have revealed the existence in plants of a fourth RNA polymerase, RNAPIV, which mediates siRNA accumulation and DNA methylation-dependent silencing of endogenous repeated sequences. Here, we show that Arabidopsis expresses, in fact, two evolutionarily related forms of RNAPIV, hereafter referred to as RNAPIVa and RNAPIVb. These two forms contain the same second-largest subunit (NRPD2), but differ at least by their largest subunit, termed NRPD1a and NRPD1b. Unlike NRPD1a, NRPD1b possesses a reiterated CTD, a feature that also characterizes the largest subunit of RNAPII. Our data indicate that RNAPIVb is the most abundant form of RNAPIV in Arabidopsis. Selective disruption of either form of RNAPIV indicates that RNAPIVa-dependent siRNA accumulation is not sufficient per se to drive robust silencing at endogenous loci and that high levels of DNA methylation and silencing depend on siRNA that are accumulated through a pathway involving the concerted action of both RNAPIV forms. Taken together, our results imply the existence of a novel two-step mechanism in siRNA synthesis at highly methylated loci, with RNAPIVb being an essential component of a self-reinforcing loop coupling de novo DNA methylation to siRNA production. A major evolutionary distinction separating prokaryotes from eukaryotes is the passage from a unique multisubunit DNA-dependent RNA polymerase enzyme (RNAP) to three complexes (Roeder and Rutter 1969), each responsible for the transcription of a subclass of nuclear DNA sequences (Sentenac 1985). RNA polymerase I (RNAPI) transcribes the repeated genes encoding the large ribosomal RNAs, which represent up to four-fifths of total RNA. RNA polymerase II (RNAPII) transcribes all of the cell protein-coding messenger RNAs (mRNAs) as well as some small nuclear RNAs (snRNAs). RNA polymerase III (RNAPIII) is dedicated to the transcription of a collection of genes whose main common feature is that they encode structural or catalytic RNAs (tRNAs, 5S RNA, snRNA) that are components of protein synthesis, splicing, and tRNA processing apparatuses. It is believed that this triplication event provided the eukaryotic cell with a greater flexibility toward energy-consuming cellular functions such as ribosome synthesis, as well as with more sophisticated means for the regulation of gene expression.Prokaryotic and eukaryotic RNA polymerases are multisubunit enzymes that are evolutionarily related to each other through their largest and second-largest subunits (Ebright 2000;Cramer 2002). The largest subunit (≈160 kDa: ␤Ј; A; RPA1; RPB1; RPC1) contains eight regions conserved in order and sequence (A to H), while the second-largest subunit (≈150 kDa: ␤; B; RPA2; RPB2; RPC2), contains nine such regions (A to I) (Allison et al. 1985;Sweetser et al. 1987). Although the role of these conserved domains is not yet fully understood, the structure determination of RNAPII suggests that they cooperate in the formation of a single fold cleft containing the active site of the enzyme (Cramer et al....

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confidence: 99%

mentioning

confidence: 99%

Reinforcement of silencing at transposons and highly repeated sequences requires the concerted action of two distinct RNA polymerases IV in Arabidopsis

Pontier¹,

Yahubyan²,

Véga³

et al. 2005

Genes Dev.

357

441

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“…Eukaryotic nuclear RNA polymerases are composed of 2 nonidentical large subunits with molecular weights between 120 and 240 kDa and about 9-13 smaller subunits (Sentenac, 1985;Young, 1991). The two large subunits of eukaryotic RNA polymerases are the structural and functional homologues of the P' and P subunit of the E. coli 223 RNA polymerase and form the major part of the catalytic site.…”

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confidence: 99%

Identification of a nucleic acid‐binding region within the largest subunit ofDrosophila melanogasterRNA polymerase II

1993

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The largest and the second-largest subunit of the multisubunit eukaryotic RNA polymerases are involved in interaction with the DNA template and the nascent RNA chain. Using Southwestern DNA-binding techniques and nitrocellulose filter binding assays of bacterially expressed fusion proteins, we have identified a region of the largest, 215-kDa, subunit of Drosophila RNA polymerase I1 that has the potential to bind nucleic acids nonspecifically. This nucleic acid-binding region is located between amino acid residues 309-384 and is highly conserved within the largest subunits of eukaryotic and bacterial RNA polymerases. A homology to a region of the DNAbinding cleft of Escherichia coli DNA polymerase I involved in binding of the newly synthesized DNA duplex provides indirect evidence that the nucleic acid-binding region of the largest subunit participates in interaction with double-stranded nucleic acids during transcription. The nonspecific DNA-binding behavior of the region is similar to that observed for the native enzyme in nitrocellulose filter binding assays and that of the separated largest subunit in Southwestern assays. A high content of basic amino acid residues is consistent with the electrostatic nature of nonspecific DNA binding by RNA polymerases.Keywords: fusion proteins; nucleic acid binding; RNA polymerase 11; Southwestern blotting Transcription of DNA into RNA is accomplished by DNA-dependent RNA polymerases. RNA synthesis involves recognition and binding of transcription factors and RNA polymerase to the promoter, initiation of RNA synthesis de novo, elongation of the RNA chain processively by movement of the enzyme along the DNA template, and finally termination and release of the nascent RNA chain. The first step in transcription initiation results in the formation of binary complexes. Two kinds of binary complexes can be observed for RNA polymerases. Nonspecific binary complexes are formed at all sites of the DNA template and are nonproductive. In contrast, specific complexes are formed at promoter sites leading to the initiation of RNA synthesis (Conaway & Conaway, 1991). In eukaryotes the formation of these specific preinitiation complexes involves the interaction of several general transcription initiation factors with promoter elements and the RNA polymerases (Sawadogo & Sentenac, ___.

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“…The 6 f small polypeptides, less than lOin number, have sizes ranging from lOto 40 kDa. The largest subunit of RNA polymerase II has been isolated and shown to exist in multiple subforms (Sentenac, 1985), resulting in RNA polymerase II heterogencity. These subforms, according to Kedinger et al (1974), are called 110, lIa and lIb.…”

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confidence: 99%

“…110 is a phosphorylated form of lia, and lib is an unphosphorylated cIeavage product of lIa generated by proteolysis that lacks the carboxyl terminal domain, with a reduced size of 180 kDa. The phosphorylated RNA polymerase 110 was found in yeast, plant and animal eclls (Dahmus, 1981;Sentenac, 1985). Phosphatase treatment of the (lIa) 240 kDa form of calf thymus RNA polymerase II phosphorylated in vitro results in a polypeptide of215 kDa.…”

mentioning

confidence: 99%

Expression of an EF-1α-like Rat cDNA, S1, in Escherichia coli and Production of a Rabbit Polyclonal Antiserum to the Recombinant Protein

Liu

Li²,

Wang³

1993

Biochemical and Biophysical Research Communications

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Eukaryotic Rna Polymerases

Cited by 100 publications

References 47 publications

Reinforcement of silencing at transposons and highly repeated sequences requires the concerted action of two distinct RNA polymerases IV in Arabidopsis

Reinforcement of silencing at transposons and highly repeated sequences requires the concerted action of two distinct RNA polymerases IV in Arabidopsis

Identification of a nucleic acid‐binding region within the largest subunit ofDrosophila melanogasterRNA polymerase II

Expression of an EF-1α-like Rat cDNA, S1, in Escherichia coli and Production of a Rabbit Polyclonal Antiserum to the Recombinant Protein

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