Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:2.7.7.6 (RNA polymerase)
 34,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The C-terminal domain (CTD) of the largest subunit of yeast RNA polymerase II contains 26-27 tandem copies of a conserved heptapeptide of unknown function. Yeast strains whose CTD contains ten heptamers are viable but defective for transcription of the INO1 gene and cold sensitive for growth. Deletion of the SIN1 gene, which codes for a DNA-binding protein that negatively regulates HO transcription, restores INO1 transcription and reduces the cold sensitivity of such strains. A SIN1 deletion suppresses the lethality of a CTD with nine heptamer repeats but not with seven repeats. These observations indicate a functional relationship between SIN1 and the CTD: the CTD might remove SIN1 from DNA, or removal of SIN1 may be a prerequisite for function of the CTD. The SWI1, SWI2, and SWI3 genes, whose products activate HO transcription by antagonizing SIN1, are also required for INO1 transcription and may assist the CTD. In addition, an intact CTD binds nonspecifically to DNA in vitro.
 ...
PMID:A functional interaction between the C-terminal domain of RNA polymerase II and the negative regulator SIN1. 200 20

A mutagenic oligonucleotide cassette was used to introduce single and tandem amino acid substitutions into the proteinase 3C coding region of an infectious poliovirus type 1 cDNA. The sites targeted for mutagenesis, residues 60, 61, and 66, are located within a putative helical loop structure which may be involved in substrate recognition by the enzyme. Fourteen viable 3C proteinase mutants were isolated. A Lys----Arg substitution at position 60 resulted in cold sensitivity for growth at 33 degrees. Replacement of Lys 60 with Ile, either singly or in combination with substitutions at position 61, resulted in viruses that produced three- to fivefold more 3D RNA polymerase than wild-type poliovirus. 3C-mediated processing of the remaining sites within the polyprotein was not noticeably affected. The overproduction of 3D is a consequence of more efficient processing of the carboxy-terminal Gln-Gly amino acid pair of 3C. Together with a previous report in which substitution of Val 54 with an Ala residue results in a poliovirus that produces decreased levels of 3D, these observations provide evidence that the putative loop region (residues 51-66) may be a functional domain involved in recognition of the carboxy-terminal Gln-Gly cleavage site of 3C.
 ...
PMID:A genetic locus in mutant poliovirus genomes involved in overproduction of RNA polymerase and 3C proteinase. 215 85

The large subunit of RNA polymerase II contains a highly conserved and essential heptapeptide repeat (Pro-Thr-Ser-Pro-Ser-Tyr-Ser) at its carboxy terminus. Saccharomyces cerevisiae cells are inviable if their RNA polymerase II large subunit genes encode fewer than 10 complete heptapeptide repeats; if they encode 10 to 12 complete repeats cells are temperature-sensitive and cold-sensitive, but 13 or more complete repeats will allow wild-type growth at all temperatures. Cells containing C-terminal domains (CTDs) of 10 to 12 complete repeats are also inositol auxotrophs. The phenotypes associated with these CTD mutations are not a consequence of an instability of the large subunit; rather, they seem to reflect a functional deficiency of the mutant enzyme. We show here that partial deletion mutations in RNA polymerase II CTD affect the ability of the enzyme to respond to signals from upstream activating sequences in a subset of promoters in yeast. The number of heptapeptide repeats required for maximal response to signals from these sequences differs from one upstream activating sequence to another. One of the upstream elements that is sensitive to truncations of the CTD is the 17-base-pair site bound by the GAL4 transactivating factor.
 ...
PMID:RNA polymerase II C-terminal repeat influences response to transcriptional enhancer signals. 221 64

Conditional mutations in the Saccharomyces cerevisiae RNA polymerase II large subunit, RPB1, were obtained by introducing a mutagenized RPB1 plasmid into yeast cells, selecting for loss of the wild-type RPB1 gene, and screening the cells for heat or cold sensitivity. Sequence analysis of 10 conditional RPB1 mutations and 10 conditional RPB2 mutations revealed that the amino acid residues altered by these distinct mutations are nearly always invariant among eucaryotic RPB1 and RPB2 homologs. These results suggest that RNA polymerase mutants might be obtained in other eucaryotic organisms by alteration of these invariant residues.
 ...
PMID:Conditional mutations occur predominantly in highly conserved residues of RNA polymerase II subunits. 240 67

We have examined in isolated liver mitochondria the effect of cold exposure on DNA, RNA and protein synthesis in normal, hypothyroid and mildly hyperthyroid rats. In normal rats DNA polymerase activity increased from the first day of cold exposure remaining high up to the fifteenth day. RNA polymerase and protein synthesis were stimulated from the fifth day of cold exposure, maintaining a high level up to the fifteenth day. These activities were related to serum triiodothyronine (T3) levels. Indeed propylthiouracil (PTU) administration to cold-exposed rats drastically depressed the above activities, whereas T3 administration to PTU-treated cold-exposed rats restored them to about the values prevalent in normal cold-exposed rats. The translation products analyzed by gel electrophoresis showed that different effects may be exerted by T3 depending on whether its circulating levels are physiologically or pharmacologically modified. These findings suggest that T3 may be involved in the regulation of the acclimation process by acting, presumably with a permissive role, on those activities which determine a modification of the mitochondrial morphometric features and an increase in mitochondria number and turnover.
 ...
PMID:Mitochondrial DNA, RNA and protein synthesis in normal, hypothyroid and mildly hyperthyroid rat liver during cold exposure. 245 25

Suppressors of a temperature-sensitive RNA polymerase II mutation were isolated to identify proteins that interact with RNA polymerase II in yeast cells. Ten independently isolated extragenic mutations that suppressed the temperature-sensitive mutation rpb1-1 and produced a cold-sensitive phenotype were all found to be alleles of a single gene, SRB1. An SRB1 partial deletion mutant was further investigated and found to exhibit several pleiotropic phenotypes. These included suppression of numerous temperature-sensitive RNA polymerase II mutations, alteration of the temperature growth range of cells containing wild-type RNA polymerase, and sterility of cells of alpha mating type. The ability of SRB1 mutations to suppress the temperature-sensitive phenotype of RNA polymerase II mutants did not extend to other temperature-sensitive mutants investigated. Isolation of the SRB1 gene revealed that SRB1 is KEX2. These results indicate that the KEX2 protease, whose only known substrates are hormone precursors, can have an important influence on RNA polymerase II and the temperature-dependent growth properties of yeast cells.
 ...
PMID:KEX2 mutations suppress RNA polymerase II mutants and alter the temperature range of yeast cell growth. 266 32

RPB4 encodes the fourth-largest RNA polymerase II subunit in Saccharomyces cerevisiae. The RPB4 gene was cloned and sequenced, and its identity was confirmed by amino acid sequence analysis of tryptic peptides from the purified subunit. The RPB4 DNA sequence predicted a protein of 221 amino acids with a molecular mass of 25,414 daltons. The central 100 amino acids of the RPB4 protein were found to be similar to a segment of the major sigma subunit in Escherichia coli RNA polymerase. Deletion of RPB4 produced cells that were heat and cold sensitive but could grow, albeit slowly, at intermediate temperatures. RNA polymerase II lacking the RPB4 subunit exhibited markedly reduced activity in crude extracts in vitro. The RPB4 subunit, although not essential for mRNA synthesis or enzyme assembly, was essential for normal levels of RNA polymerase II activity and indispensable for cell viability over a wide temperature range.
 ...
PMID:RNA polymerase II subunit RPB4 is essential for high- and low-temperature yeast cell growth. 267 72

The largest subunit of RNA polymerase II contains a repeated heptapeptide sequence at its carboxy terminus. Yeast mutants with certain partial deletions of the carboxy-terminal repeat (CTR) domain are temperature-sensitive, cold-sensitive and are inositol auxotrophs. Intragenic and extragenic suppressors of the cold-sensitive phenotype of CTR domain deletion mutants were isolated and studied to investigate the function of this domain. Two types of intragenic suppressing mutations suppress the temperature-sensitivity, cold-sensitivity and inositol auxotrophy of CTR domain deletion mutants. Most intragenic mutations enlarge the repeat domain by duplicating various portions of the repeat coding sequence. Other intragenic suppressing mutations are point mutations in a conserved segment of the large subunit. An extragenic suppressing mutation (SRB2-1) was isolated that strongly suppresses the conditional and auxotrophic phenotypes of CTR domain mutations. The SRB2 gene was isolated and mapped, and an SRB2 partial deletion mutation (srb2 delta 10) was constructed. The srb2 delta 10 mutants are temperature-sensitive, cold-sensitive and are inositol auxotrophs. These phenotypes are characteristic of mutations in genes encoding components of the transcription apparatus. We propose that the SRB2 gene encodes a factor that is involved in RNA synthesis and may interact with the CTR domain of the large subunit of RNA polymerase II.
 ...
PMID:Intragenic and extragenic suppressors of mutations in the heptapeptide repeat domain of Saccharomyces cerevisiae RNA polymerase II. 269 7

Coliphage lambda gene expression is regulated temporally by systems of termination and antitermination of transcription. The lambda-encoded N protein (pN) acting with host factors (Nus) at sites (nut) located downstream from early promoters is the first of these systems to operate during phage development. We report observations on some of the components of this complex system that, in part, address the way in which these elements interact to render RNA polymerase termination-resistant. (1) The isolation of a conditionally lethal cold-sensitive nusA mutation demonstrates that NusA is essential for bacterial growth. (2) The effect on lambda growth in a host in which the Salmonella NusA protein is overproduced suggests that NusA is essential for N-mediated antitermination in phage lambda. (3) A truncated NusA product, representing only the amino two-thirds of the native protein, is active for both bacterial growth and pN action, indicating that the carboxy end of the molecule may not be a functionally important region. (4) lambda pN can function with the heterologous nut region from Salmonella typhimurium phage P22 when lambda pN is overproduced, demonstrating that lambda pN can function with the nut regions of other lambdoid phages. (5) A single base-pair change in the lambda nutR boxA sequence that was selected to permit a lambda derivative to utilize the Salmonella NusA protein restores lambda growth in the Escherichia coli nusA1 host.
 ...
PMID:lambda N antitermination system: functional analysis of phage interactions with the host NusA protein. 282 Dec 65

The specific transcription of a cloned Drosophila melanogaster tRNAVal4 gene and a tRNASer7 gene by extracts from a homologous embryonic cell line showed lag periods of about 30 min before maximum rates were reached. This lag appeared to represent the time to form an active transcription complex. Thus, when extracts were incubated with template DNA for 30 min at 22 degrees C and stored in the cold, the subsequent transcription rate was linear with time and without a lag. After ultracentrifugation of a preincubated reaction mixture on a sucrose step gradient consisting of 20, 30, 40, and 60% shelves, about 40% of the transcription activity in the extract was found in the 40% shelf. This fraction formed almost exclusively RNA I, the unprocessed tRNA gene transcript, and transcription required only addition of ribonucleoside triphosphates. The rate of formation of RNA by the 40% sucrose fraction was linear against time, with no lag, and linear with the quantity of fraction. The yield of activity isolated on the gradient was directly proportional to the quantity of cloned gene in the preincubation mixture. At a limiting concentration of the gene in the preincubation mixture, the turnover number of the isolated complex was approximately 50 transcripts/gene/h. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis of fractions containing the complex still showed many bands, although the complex activity was greatly purified compared to the extract. From the sedimentation behavior of the isolated active transcription complex and from its stability and transcriptional properties, we conclude that the 40% sucrose fraction contains an active transcription complex containing a cloned tRNA gene, RNA polymerase III, and the accessory protein factors required for transcription.
 ...
PMID:Partial purification of stable transcription complexes with cloned tRNA genes of Drosophila melanogaster. 392 73


<< Previous 1 2 3 4 5 6 7 8 9 10 Next >>