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Query: UNIPROT:P23193 (transcription elongation factor)
 739 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

TFIIS is a transcription elongation factor that binds to RNA polymerase II and allows it to transcribe through a variety of transcriptional blockages by inducing cleavage near the 3' end of the nascent transcript. Although this cleavage reaction plays a key role in the process of reactivation of transcription by TFIIS, the exact mechanism by which TFIIS promotes readthrough by RNA polymerase II is not completely understood. We therefore undertook a systematic mutagenesis of the C-terminal half of TFIIS (delta TFIIS) to evaluate the contribution of charged residues in this region to induce transcript cleavage and promote readthrough in vitro. Twenty-two delta TFIIS alanine-scanning mutants were constructed by substitution of alanine for each amino acid in clusters of charged residues in the C-terminal half of HeLa TFIIS. The ability to induce transcript cleavage and readthrough of these mutants was tested in vitro using RNA polymerase II ternary elongation complexes arrested at a block to elongation. This alanine-scanning mutagenesis analysis allowed the identification of regions or residues important for the activity of TFIIS. Many of the mutants were reduced alike in both cleavage and readthrough activities. However, in several cases there was no simple correlation between these activity reductions.
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PMID:Alanine-scanning mutagenesis of human transcript elongation factor TFIIS. 757 53

Saccharomyces cerevisiae has a TFIIS-related transcription elongation factor, originally called P37 (Sawadogo, M., Sentenac, A., and Fromageot, P. (1979) J. Biol. Chem. 255, 12-15; Nakanishi, T., Nakano, A., Nomura, K., Sekimizu, K., and Natori, S. (1992) J. Biol. Chem. 267, 13200-13204), which binds directly to RNA polymerase II and stimulates read-through of intrinsic blocks to elongation. To elucidate functional features of this protein:protein interaction, we tested the ability of several forms of RNA polymerase II to respond to either full-length or an amino-terminal truncation of TFIIS. The variants of the polymerase differed in the structure of the carboxyl-terminal domain of the largest subunit or lacked two of the smaller subunits. No differences in ability to recognize intrinsic blocks to elongation or to read through them in response to either form of TFIIS were detected among these variants. Furthermore, ternary complexes containing each variant form of RNA polymerase cleave the 3' end of the nascent transcripts in response to TFIIS, a reaction previously reported for mammalian and Drosophila TFIIS (Kassavetis, G. A., and Geiduschek, E. P. (1993) Science 259, 944-945) and likely to be important in TFIIS function. Thus the carboxyl-terminal domain of the largest subunit and subunits four and seven of the polymerase, required in vivo, are not required in vitro for recognition of intrinsic blocks to elongation, read-through in response to TFIIS, or TFIIS-stimulated cleavage of the nascent transcript.
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PMID:Purified yeast RNA polymerase II reads through intrinsic blocks to elongation in response to the yeast TFIIS analogue, P37. 828 47

We have identified cDNAs encoding three related forms of transcription elongation factor TFIIS (S-II) in Xenopus laevis ovary. Comparison of Xenopus and mammalian sequences identifies likely diagnostic amino acids that distinguish classes of vertebrate TFIIS. The diversity of TFIIS polypeptides in Xenopus is due partly to the presence of two diverged genes in this tetraploid genome. We isolated genomic clones containing one of the genes, xTFIIS.oA, and, unlike a previously described vertebrate TFIIS gene, found that it contains introns. Alternative splicing at a CAG/CAG motif containing the 3' splice site of intron 4 produces the third form of xTFIIS, which differs from one of the others simply in lacking Ser109. Intron 6 of xTFIIS.oA contains splice and branch site consensus sequences conforming to those of the minor class of AT-AC introns and this was confirmed for the homeologous xTFIIS.oB gene by genomic PCR. Other unusual but functional variants of RNA processing signals were found in xTFIIS genes at the 5' splice site of intron 8 and the polyadenylation hexanucleotides. Utilization of multiple unusual processing signals may make the generation of mature xTFIIS.o mRNAs inefficient and the possible regulatory consequences of this are discussed.
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PMID:Genes encoding isoforms of transcription elongation factor TFIIS in Xenopus and the use of multiple unusual RNA processing signals. 883 76

A gene designated tfs1 has been isolated from Schizosaccharomyces pombe based on its similarity to genes encoding transcription elongation factor TFIIS. The nucleotide sequence of the tfs1 gene predicts a polypeptide with similarity to mammalian. Drosophila and Saccharomyces cerevisiae TFIIS. A haploid Sz. pombe strain with tfs1 deleted from the genome is viable. Thus, tfs1 is not essential for viability. However, deletion of tfs1 results in slow growth and increased sensitivity to the drug 6-azauracil, a phenotype similar to that of a S. cerevisiae strain deleted for the gene encoding TFIIS. The DNA sequence of tfs1 has been deposited in GenBank under Accession Number U20526.
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PMID:Isolation and characterization of the Schizosaccharomyces pombe gene encoding transcript elongation factor TFIIS. 890 34

The products of the yeast CDC73 and PAF1 genes were originally identified as RNA polymerase II-associated proteins. Paf1p is a nuclear protein important for cell growth and transcriptional regulation of a subset of yeast genes. In this study we demonstrate that the product of CDC73 is a nuclear protein that interacts directly with purified RNA polymerase II in vitro. Deletion of CDC73 confers a temperature-sensitive phenotype. Combination of the cdc73 mutation with the more severe paf1 mutation does not result in an enhanced phenotype, indicating that the two proteins may function in the same cellular processes. To determine the relationship between Cdc73p and Paf1p and the recently described holoenzyme form of RNA polymerase II, we created yeast strains containing glutathione S-transferase (GST)-tagged forms of CDC73, PAF1, and TFG2 functionally replacing the chromosomal copies of the genes. Isolation of GST-tagged Cdc73p and Paf1p complexes has revealed a unique form of RNA polymerase II that contains both Cdc73p and Paf1p but lacks the Srbps found in the holoenzyme. The Cdc73p-Paf1p-RNA polymerase II-containing complex also includes Gal11p, and the general initiation factors TFIIB and TFIIF, but lacks TBP, TFIIH, and transcription elongation factor TFIIS as well as the Srbps. The Srbp-containing holoenzyme does not include either Paf1p or Cdc73p, demonstrating that these two forms of RNA polymerase II are distinct. In confirmation of the hypothesis that the two forms coexist in yeast cells, we found that a TFIIF-containing complex isolated via the GST-tagged Tfg2p construct contains both (i) the Srbps and (ii) Cdc73p and Paf1p. The Srbps and Cdc73p-Paf1p therefore appear to define two complexes with partially redundant, essential functions in the yeast cell. Using the technique of differential display, we have identified several genes whose transcripts require Cdc73p and/or Paf1p for normal levels of expression. Our analysis suggests that there are multiple RNA polymerase II-containing complexes involved in the expression of different classes of protein-coding genes.
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PMID:Cdc73p and Paf1p are found in a novel RNA polymerase II-containing complex distinct from the Srbp-containing holoenzyme. 903 43

There is a family of genes encoding TFIIS-related proteins in human cells. We have focused upon the genomic organization of one family member expressed primarily in the testis. This gene encodes a transcription elongation factor similar to but distinct from that encoded by a previously reported TFIIS gene. Also in contrast to the previously reported TFIIS gene, the testis gene contains introns. All exon-intron junction sequences match the consensus GT/AG rule. The gene consists of seven exons and six introns with a total size of approximately 7 kb. The nucleotide sequence of the 5 flanking region of the testis TFIIS gene contains several potential regulatory factor-binding sites, not all of which are present in the TFIIS gene, whose expression is nearly ubiquitous. Elucidation of the full structure of the testis TFIIS gene should be useful for determining its chromosomal localization and its potential role in the regulation of gene expression in human tissues.
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PMID:Genomic characterization of a testis-specific TFIIS (TCEA2) gene. 944 62

TFIIS is a general transcription elongation factor that helps arrested RNA polymerase II elongation complexes resume transcription. We have previously shown that yeast TFIIS (yTFIIS) comprises three structural domains (I-III). The three-dimensional structures of domain II and part of domain III have been previously reported, but neither domain can autonomously stimulate transcription elongation. Here we report the NMR structural analysis of residues 131-309 of yTFIIS which retains full activity and contains all of domains II and III. We confirm that the structure of domain II in the context of fully active yTFIIS is the same as that determined previously for a shorter construct. We have determined the structure of the C-terminal zinc ribbon domain of active yTFIIS and shown that it is similar to that reported for a shorter construct of human TFIIS. The region linking domain II with the zinc ribbon of domain III appears to be conformationally flexible and does not adopt a single defined tertiary structure. NMR analysis of inactive mutants of yTFIIS support a role for the linker region in interactions with the transcription elongation complex.
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PMID:Yeast transcript elongation factor (TFIIS), structure and function. I: NMR structural analysis of the minimal transcriptionally active region. 971 87

The transcriptionally active fragment of the yeast RNA polymerase II transcription elongation factor, TFIIS, comprises a three-helix bundle and a zinc ribbon motif joined by a linker region. We have probed the function of this fragment of TFIIS using structure-guided mutagenesis. The helix bundle domain binds RNA polymerase II with the same affinity as does the full-length TFIIS, and this interaction is mediated by a basic patch on the outer face of the third helix. TFIIS mutants that were unable to bind RNA polymerase II were inactive for transcription activity, confirming the central role of polymerase binding in the TFIIS mechanism of action. The linker and zinc ribbon regions play roles in promoting cleavage of the nascent transcript and read-through past the block to elongation. Mutation of three aromatic residues in the zinc ribbon domain (Phe269, Phe296, and Phe308) impaired both transcript cleavage and read-through. Mutations introduced in the linker region between residues 240 and 245 and between 250 and 255 also severely impaired both transcript cleavage and read-through activities. Our analysis suggests that the linker region of TFIIS probably adopts a critical structure in the context of the elongation complex.
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PMID:Yeast transcript elongation factor (TFIIS), structure and function. II: RNA polymerase binding, transcript cleavage, and read-through. 971 88

We report the characterization of cDNA clones that define a new, third isoform of the transcription elongation factor TFIIS in Xenopus, mouse, and human. In Xenopus the mRNA of this isoform, termed TFIIS.h, shows tissue-restricted expression, frequently contains unspliced introns, and is characterized by three near-perfect 150-bp repeats at the 5'-terminus. Although we were unable to isolate full-length cDNAs, it is clear that these repeats contain an open reading frame encoding a region of TFIIS.h that is much more complex than in other isoforms. Identification of ESTs encoding TFIIS.h in mouse and human followed by the sequencing of cognate cDNA clones enabled the complete TFIIS.h coding region to be predicted. The conserved N- and C-terminal domains of mammalian TFIIS.h (TCEA3) are separated by a linker region that is more variable in sequence and that is also 50 amino acids longer than in other isoforms. The repetitive region of Xenopus TFIIS.h apparently corresponds to an even more extended linker. Phylogenetic analysis of TFIIS sequences demonstrates the ancient origins of the three vertebrate isoforms, although they appeared functionally equivalent in in vitro RNA cleavage assays.
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PMID:Identification of novel genes encoding transcription elongation factor TFIIS (TCEA) in vertebrates: conservation of three distinct TFIIS isoforms in frog, mouse, and human. 979 Jul 46

We have identified a novel pathway for protein import into the nucleus. We have shown that the previously identified but uncharacterized yeast protein Nmd5p functions as a karyopherin. It was therefore designated Kap119p (karyopherin with Mr of 119 kD). We localized Kap119p to both the nucleus and the cytoplasm. We identified the transcription elongation factor TFIIS as its major cognate import substrate. The cytoplasmic Kap119p exists as an approximately stoichiometric complex with TFIIS. RanGTP, not RanGDP, dissociated the isolated Kap119p/TFIIS complex and bound to Kap119p. Kap119p also bound directly to a number of peptide repeat containing nucleoporins in overlay assays. In wild-type cells, TFIIS was primarily localized to the nucleus. In a strain where KAP119 has been deleted, TFIIS was mislocalized to the cytoplasm indicating that TFIIS is imported into the nucleus by Kap119p. The transport of various substrates that use other karyopherin-mediated import or export pathways was not affected in a kap119Delta strain. Hence Kap119p is a novel karyopherin that is responsible for the import of the transcription elongation factor TFIIS.
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PMID:A novel nuclear import pathway for the transcription factor TFIIS. 985 43


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