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Query: EC:2.7.7.6 (RNA polymerase)
 34,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Yeast RNA polymerases A (I) and C (III) share a subunit called AC19. The gene encoding AC19 has been isolated from yeast genomic DNA using oligonucleotide probes deduced from peptide sequences of the isolated subunit. This gene (RPC19) contains an intron-free open reading frame of 143 amino acid residues. RPC19 is a single copy gene that maps on chromosome II and is essential for cell viability. The amino acid sequence contains a sequence motif common to the Escherichia coli RNA polymerase alpha subunit, the Saccharomyces cerevisiae AC40 and B44.5 subunits, the human hRPB33 product, and the CnjC conjugation-specific gene product of Tetrahymena. The 5'-upstream region contains a sequence element, the PAC box, that has been conserved in at least 10 genes encoding subunits of RNA polymerases A and C.
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PMID:RPC19, the gene for a subunit common to yeast RNA polymerases A (I) and C (III). 186 54

Antisera were raised against native RNA polymerases A or B, as well as against each individual subunit of RNA polymerase A from the yeast Saccharmoyces cerevisiae. The affinity spectrum of antibodies was evaluated by reacting electrophoretically separated enzyme subunits, transferred to a membrane, with 125I-labeled immunoglobulins. Alternatively, the subunit . immunoglobulin complex was revealed by 125I-labeled Protein A. Antibodies directed against native RNA polymerase A recognized the majority of the polypeptides forming the enzyme. When challenged with RNA polymerases B or C, this antibody preparation demonstrated the presence of polypeptides common to the three enzymes. A small cross-reaction was also found at the level of the large subunits of Enzyme B as well as some additional polypeptides of Enzyme C. Similar experiments with antibodies directed against native RNA polymerase B confirmed the presence of common subunits and also showed that the large polypeptides of the three enzymes share a few immunological determinants. Common subunits are AC40, ABC27, ABC23, AC19, and ABC14.5. Immunologically related sites were conserved in the large subunits of RNA polymerase A from remote yeast species. Similarly, yeast and wheat germ RNA polymerase B share immunological determinants on the large subunit as well as on a small peptide. On the other hand, there was no significant cross-reaction between yeast and mammalian Enzyme B or Escherichia coli RNA polymerase. Antibodies raised against the different polypeptide components of RNA polymerase A reacted specifically with the corresponding subunits. Inhibition studies with these subunit-specific antibodies showed that the common subunits are not always similarly exposed to antibody attack within the three enzymes. The data are discussed in terms of the structural similarity, organization and evolution of eukaryotic RNA polymerases.
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PMID:Immunological studies of yeast nuclear RNA polymerases at the subunit level. 700 Jul 67

We present homologies between archaeal and eucaryal DNA-dependent RNA polymerase (RNAP) subunits and transcription factors. The sequences of the Sulfolobus acidocaldarius subunits D, E, and N and alignments with eucaryal homologs are presented here. The similarities between archaeal transcription factors and their eucaryal homologs TFIIB and TBP have been established in other laboratories. The archaeal RNAP subunits H, K, and N, respectively, show high sequence similarity to ABC27, ABC23, and ABC10 beta (found in all three eucaryal RNAPs); subunit D, to AC40 (common to polymerase II and polymerase III) and B44 (polymerase II); and subunit L, to AC19 and B12.5. The similarity of subunit D and its eucaryal homologs to bacterial alpha is limited to the "alpha-motif," which is also present in subunit L and its eucaryal homologs. Genes encoding homologs of the related eucaryal RNAP subunits A12.2/B12.6 and also homologs of eucaryal transcription elongation factors of the TFIIS family have been detected in Sulfolobus acidocaldarius and Thermococcus celer. In archaea, the protein is not an RNAP subunit. Together with the sequence similarities between archaeal box A-containing and eucaryal TATA box-containing promoters, this shows that the archaeal and eucaryal transcription systems are truly homologous and that they differ structurally and functionally from the bacterial transcription machinery. In contrast, however, a number of genes for the archaeal transcription apparatus are organized in clusters resembling the clusters of transcription-associated genes in Bacteria.
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PMID:Transcription in archaea: similarity to that in eucarya. 759 27

The characterization of RNA polymerase subunit genes has revealed that some subunits are shared by the three nuclear enzymes, some are homologous, and some are unique to RNA polymerases I, II, or III. We report here the isolation and characterization of the yeast RNA polymerase II subunit RPB11, which is encoded by a single copy RPB11 gene located directly upstream of the topoisomerase I gene, TOPI, on chromosome XV. The sequence of the gene predicts an RPB11 subunit of 120 amino acids (13,600 daltons), only two amino acids shorter than the RPB9 polypeptide, that co-migrates with RPB11 under most SDS-PAGE conditions, RPB11 was found to be an essential gene that encodes a protein closely related to an essential subunit shared by RNA polymerases I and III, AC19. RPB11 contains a 19 amino acid segment found in three other yeast RNA polymerase subunits and the bacterial RNA polymerase subunit alpha. Some mutations that affect RNA polymerase assembly map within this segment, suggesting that this region may play a role in subunit interactions. As the isolation of RPB11 completes the isolation of known yeast RNA polymerase II subunit genes, we briefly summarize the salient features of these twelve genes and the polypeptides that they encode.
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PMID:Yeast RNA polymerase II subunit RPB11 is related to a subunit shared by RNA polymerase I and III. 850 29

The AC40 and AC19 subunits (encoded by RPC40 and RPC19) are shared by yeast RNA polymerases I and III and have a local sequence similarity to prokaryotic alpha subunits. Mutational analysis of the corresponding "alpha motif" indicated that its integrity is essential on AC40 subunit but is not essential on AC19 subunit. By applying the two-hybrid method, these two polypeptides were shown to associate in vivo. Extragenic suppression of rpc19 and rpc40 mutations confirmed that AC19 and AC40 subunits interact with each other in vivo and revealed an interaction with ABC10 beta subunit [encoded by RPB10; Woychick, N. A. & Young, R.A. (1990) J. Biol. Chem. 265, 17816-17819], one of the five polypeptides common to all three nuclear RNA polymerases. A correction of the RPB10 sequence showed that ABC10 beta subunit is a 70-amino acid polypeptide, as confirmed by peptide microsequencing. These results suggest that the assembly of RNA polymerase I and III requires the association of ABC10 beta subunit with an AC19/AC40 heterodimer.
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PMID:Interactions between three common subunits of yeast RNA polymerases I and III. 851 95

Two subunits in RNA polymerase II (e.g. RPB3 and RPB11 in yeast) and two subunits common to RNA polymerases I and III (e.g. AC40 and AC19 in yeast) contain one or two motifs related to the alpha subunit in prokaryotic RNA polymerases. We have sequenced two different cDNAs (AtRPB36a and AtRPB36b), the two corresponding genes from Arabidopsis thaliana that are homologs of yeast RPB3, and an Arabidopsis cDNA (AtRPB13.6) that is a homolog of yeast RPB11. The B36a subunit is the predominant B36 subunit associated with RNA polymerase II purified from Arabidopsis suspension culture cells, and this subunit has a stoichiometry of about 1. Results from protein association assays showed that the B36a and B36b subunits did not associate, but each of these subunits did associate with the B13.6 subunit in vivo and in vitro. Two motifs in the B36b subunit related to the prokaryotic alpha subunit were shown to be required for the in vitro interactions with the B13.6 subunit. Our results suggest that the B36 and B13.6 subunits associate to form heterodimers in Arabidopsis RNA polymerase II like the AC40 and AC19 heterodimers reported for yeast RNA polymerases I and III but unlike the B44 homodimers reported for yeast RNA polymerase II.
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PMID:Association between 36- and 13.6-kDa alpha-like subunits of Arabidopsis thaliana RNA polymerase II. 861 87

Immunoelectron microscopy was used to determine the spatial organization of the yeast RNA polymerase I core subunits on a three-dimensional model of the enzyme. Images of antibody-labeled enzymes were compared with the native enzyme to determine the localization of the antibody binding site on the surface of the model. Monoclonal antibodies were used as probes to identify the two largest subunits homologous to the bacterial beta and beta' subunits. The epitopes for the two monoclonal antibodies were mapped using subunit-specific phage display libraries, thus allowing a direct correlation of the structural data with functional information on conserved sequence elements. An epitope close to conserved region C of the beta-like subunit is located at the base of the finger-like domain, whereas a sequence between conserved regions C and D of the beta'-like subunit is located in the apical region of the enzyme. Polyclonal antibodies outlined the alpha-like subunit AC40 and subunit AC19 which were found co-localized also in the apical region of the enzyme. The spatial location of the subunits is correlated with their biological activity and the inhibitory effect of the antibodies.
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PMID:Localization of yeast RNA polymerase I core subunits by immunoelectron microscopy. 888 55

We have previously isolated a mouse RPA40 (mRPA40) cDNA encoding the 40-kDa subunit of mouse RNA polymerase I and demonstrated that mRPA40 is a mouse homolog of the yeast subunit AC40, which is a subunit of RNA polymerases I and III, having a limited homology to bacterial RNA polymerase subunit alpha (Song, C. Z., Hanada, K., Yano, K., Maeda, Y., Yamamoto, K., and Muramatsu, M. (1994) J. Biol. Chem. 269, 26976-26981). In an extension of the study we have now cloned mouse RPA16 (mRPA16) cDNA encoding the 16-kDa subunit of mouse RNA polymerase I by a yeast two-hybrid system using mRPA40 as a bait. The deduced amino acid sequence shows 45% identity to the yeast subunit AC19 of RNA polymerases I and III, known to associate with AC40, and a local similarity to bacterial alpha subunit. We have shown that mRPA40 mutants failed to interact with mRPA16 and that neither mRPA16 nor mRPA40 can interact by itself in the yeast two-hybrid system. These results suggest that higher eukaryotic RNA polymerase I conserves two distinct alpha-related subunits that function to associate with each other in an early stage of RNA polymerase I assembly.
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PMID:Mouse RNA polymerase I 16-kDa subunit able to associate with 40-kDa subunit is a homolog of yeast AC19 subunit of RNA polymerases I and III. 895 28

Archaeal RNA polymerases (RNAPs) resemble the eukaryotic nuclear RNAPs in complexity, and many of their subunits display a high degree of sequence similarity to their eukaryotic counterparts. Here we describe specific protein-protein contacts present between individual recombinant RNAP subunits from the archaeon Methanococcus jannaschii. Subunits D and L interact specifically with each other in two-hybrid assays. D also interacts under the same conditions with the RPB11 and AC19 subunits from the yeast Saccharomyces cerevisiae, suggesting that essential elements of the binding surface between these proteins have been conserved across the archaeal/eukaryotic evolutionary domain boundary. Interactions between L and RPB3 or AC40 were, however, not detectable. Recombinant D and L subunits associate under in vitro conditions and copurify with each other during size-exclusion chromatography. Addition of an another recombinant subunit (N) to the D-L complex results in the formation of a triple complex. This D-L-N complex resembles the RPB3-RPB11-RPB10 or AC40-AC19-RPB10 complexes in eukaryotic RNAPIIand RNAPI/RNAPIII, respectively. Our data provide evidence for a close similarity in the quaternary arrangement of a subset of archaeal and eukaryotic RNA polymerase subunits and the conservation of the protein-protein contacts formed between them.
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PMID:In vitro assembly of an archaeal D-L-N RNA polymerase subunit complex reveals a eukaryote-like structural arrangement. 983 83

Eukaryotic RNA polymerases I and III consist of multiple subunits. Each of these enzymes includes two distinct and evolutionarily conserved subunits called alpha-related subunits which are shared only by polymerases I and III. The alpha-related subunits show limited homology with the alpha-subunit of prokaryotic RNA polymerase. To gain further insight into the structure and function of alpha-related subunits, we cloned and characterized a gene from Schizosaccharomyces pombe that encodes a protein of 17 kDa which can functionally replace AC19 - an alpha-related subunit of RNA polymerases I and III of Saccharomyces cerevisiae - and was thus named rpa17+. RPA17 has 125 amino acids and shows 63% identity to AC19 over a 108-residue stretch, whereas the N-terminal regions of the two proteins are highly divergent. Disruption of rpa17+ shows that the gene is essential for cell growth. Sequence comparison with other alpha-related subunits from different species showed that RPA17 contains an 81-amino acid block that is evolutionarily conserved. Deletion analysis of the N- and C-terminal regions of RPA17 and AC19 confirms that the 81-amino acid block is important for the function of the alpha-related subunits.
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PMID:The fission yeast rpa17+ gene encodes a functional homolog of AC19, a subunit of RNA polymerases I and III of Saccharomyces cerevisiae. 1010 72


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