Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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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)

Rifampin-resistant (Rifr) mutants were isolated spontaneously from Bacillus subtilis strain 168. A fraction of the mutants did not grow on a minimal medium. A high concentration of one of the L-amino acids (glutamic acid, glutamine, arginine, proline, aspartic acid, or asparagine) was required to restore their growth on the medium. Further analysis of one of the mutants (strain RF 161) suggested that the mutant is unable to use ammonia as a nitrogen source and requires amino acids instead. Activity of glutamate synthase was not detected in the crude extract of the mutant. The Rifr mutation was closely located to cysA and the drug resistance was cotransformed with the property of amino acid requirement at 100% frequency. All revertants to prototrophy tested showed the rifampin-sensitive (Rifs) property. The activity of the DNA-dependent RNA polymerase of the mutant was resistant to rifampin. It is concluded that some alteration of RNA polymerase may cause absence of the activity of an enzyme involved in the nitrogen metabolism.
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PMID:Pleiotropic effect of a rifampin-resistant mutation in Bacillus subtilis. 9 17

Site-directed mutagenesis was performed to change the wild-type residue (asparagine) to aspartate, histidine, or tyrosine at amino acid 424 of the poliovirus RNA polymerase, 3Dpol. The mutations were introduced into plasmids containing full-length viral cDNA and plasmids which direct the expression of 3Dpol in Escherichia coli. Mutant viruses, recovered after transfection of HeLa cells with RNA transcripts of the full-length clones, produced small plaques at 32 degrees. In addition, the plaquing efficiency was decreased for all three mutants at 37 degrees, compared to 32 degrees. The polyprotein processing of all mutant viruses was normal at the temperatures tested, suggesting that the mutant plaque phenotypes were not due to incorrect processing of viral proteins. Analyses of viral RNA synthesis in infected cells and of the polymerase activities of mutant enzymes produced in E. coli suggested the following: (1) The his424 mutant enzyme appeared to be defective in the initiation of plus-strand RNA synthesis in HeLa cells. (2) The asp424 mutant enzyme appeared unable to assume proper conformation for active polymerase function when synthesized at 37 degrees. (3) The tyr424 mutant enzyme was totally inactive when synthesized in E. coli at 37 degrees.
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PMID:Temperature-sensitive polioviruses containing mutations in RNA polymerase. 132 90

In Saccharomyces cerevisiae, temperature-sensitive mutations in the genes RNA14 and RNA15 correlate with a reduction of mRNA stability and poly(A) tail length. Although mRNA transcription is not abolished in these mutants, the transcripts are rapidly deadenylated as in a strain carrying an RNA polymerase B(II) temperature-sensitive mutation. This suggests that the primary defect could be in the control of the poly(A) status of the mRNAs and that the fast decay rate may be due to the loss of this control. By complementation of their temperature-sensitive phenotype, we have cloned the wild-type genes. They are essential for cell viability and are unique in the haploid genome. The RNA14 gene, located on chromosome H, is transcribed as three mRNAs, one major and two minor, which are 2.2, 1.5, and 1.1 kb in length. The RNA15 gene gives rise to a single 1.2-kb transcript and maps to chromosome XVI. Sequence analysis indicates that RNA14 encodes a 636-amino-acid protein with a calculated molecular weight of 75,295. No homology was found between RNA14 and RNA15 or between RNA14 and other proteins contained in data banks. The RNA15 DNA sequence predicts a protein of 296 amino acids with a molecular weight of 32,770. Sequence comparison reveals an N-terminal putative RNA-binding domain in the RNA15-encoded protein, followed by a glutamine and asparagine stretch similar to the opa sequences. Both RNA14 and RNA15 wild-type genes, when cloned on a multicopy plasmid, are able to suppress the temperature-sensitive phenotype of strains bearing either the rna14 or the rna15 mutation, suggesting that the encoded proteins could interact with each other.
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PMID:Mutations in the yeast RNA14 and RNA15 genes result in an abnormal mRNA decay rate; sequence analysis reveals an RNA-binding domain in the RNA15 protein. 167 17

The gerD locus of Bacillus subtilis comprises a single gene whose function is essential for the germination of B. subtilis spores in media containing asparagine, glucose, and fructose. The expression of gerD has been characterized by using a chromosomal lacZ fusion to the gerD promoter. The promoter is switched on at the same time as the synthesis of glucose dehydrogenase, 2.5 h after sporulation has been initiated in the developing forespore. The gerD gene is not expressed in spoIIB or spoIIIA, -IIIB, -EIII, -FIII, or -IIIG mutants, but it is expressed in spoIIIC and -IIID and spoIVA mutant backgrounds. The in vivo transcriptional start point of the gene has been mapped by primer extension analysis, and sequences upstream from the start point show considerable homology with the promoter consensus sequences recognized by RNA polymerase containing the forespore-specific sigma factor sigma G (E sigma G). gerD is transcribed in vitro by E sigma G with a similar if not identical start point to that found in vivo, and expression of the gene can be rapidly induced in vegetative cells following the induction of sigma G synthesis. These results indicate that gerD is another member of the sigma G regulon, which includes a number of genes expressed only in the forespore compartment of sporulating cells of B. subtilis.
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PMID:Analysis of transcriptional control of the gerD spore germination gene of Bacillus subtilis 168. 190 67

The title compound 3, an amatoxin analogue containing L-alpha-aminobutyric acid instead of L-asparagine in position 1, as in natural toad stool peptides, has been synthesized. It does not inhibit the eukaryotic DNA-dependent RNA polymerase form II (or B) in concentrations up to 10(-4)M, whereas 50% inhibition is exerted in 10(-6)M solution by the corresponding Asn-analogue S-deoxo-Ile3-amaninamide 2. The striking difference seems to be due to a relatively small variation of the conformation recognized by sensitive NMR spectroscopic methods.
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PMID:S-deoxo-Abu1,Ile3-amaninamide, an inactive amatoxin analogue. 235 77

Human erythrocytes contain a membrane protein, MACIF, which inhibits the formation of a membrane attack complex (MAC) of complement. We have cloned and sequenced the complementary DNA of MACIF messenger RNA. The amino acid sequence predicted from its nucleotide sequence consists of 128 amino acids. The amino-terminal 25 residues may correspond to a signal peptide. The carboxy-terminal sequence confirmed that MACIF is a glycosylphosphatidylinositol (GPI)-anchored protein. The amino acid sequence of MACIF was partially determined by established techniques for protein chemistry and the resultant sequence was consistent with that predicted from the nucleotide sequence. The results of sequence analyses also suggested that asparagine at the 18th position was N-glycosylated. When mRNA obtained from the MACIF cDNA clone with SP6 RNA polymerase was microinjected into Xenopus oocytes, the oocytes synthesized a product which exhibited MACIF activity and reacted with anti-MACIF antibody. Comparison of the predicted sequence revealed significant homology with mouse Ly-6 antigens.
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PMID:Molecular cloning and characterization of MACIF, an inhibitor of membrane channel formation of complement. 260 9

RNA polymerase II is inhibited by the mushroom toxin alpha-amanitin. A mouse BALB/c 3T3 cell line was selected for resistance to alpha-amanitin and characterized in detail. This cell line, designated A21, was heterozygous, possessing both amanitin-sensitive and -resistant forms of RNA polymerase II; the mutant form was 500 times more resistant to alpha-amanitin than the sensitive form. By using the wild-type mouse RNA polymerase II largest subunit (RPII215) gene (J.A. Ahearn, M.S. Bartolomei, M. L. West, and J. L. Corden, submitted for publication) as the probe, RPII215 genes were isolated from an A21 genomic DNA library. The mutant allele was identified by its ability to transfer amanitin resistance in a transfection assay. Genomic reconstructions between mutant and wild-type alleles localized the mutation to a 450-base-pair fragment that included parts of exons 14 and 15. This fragment was sequenced and compared with the wild-type sequence; a single AT-to-GC transition was detected at nucleotide 6819, corresponding to an asparagine-to-aspartate substitution at amino acid 793 of the predicted protein sequence. Knowledge of the position of the A21 mutation should facilitate the study of the mechanism of alpha-amanitin resistance. Furthermore, the A21 gene will be useful for studying the phenotype of site-directed mutations in the RPII215 gene.
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PMID:Localization of an alpha-amanitin resistance mutation in the gene encoding the largest subunit of mouse RNA polymerase II. 382 24

Earlier, we reported a 30-200-fold reduction in the yield of infectious vesicular stomatitis virus (VSV) released from L cells treated with 10-30 reference units ml-1 of interferon (IFN); however, in these cultures virus particle production, as measured by VSV particle-associated viral RNA, virus nucleocapsid protein and viral transcriptase, was inhibited less than 10-fold. There was biochemical and morphological evidence of a significant reduction in glycoprotein (G) and membrane protein (M) of VSV particles released from IFN-treated cells. We compare here the effects of tunicamycin (TM) and IFN in L cells. Treatment with TM or IFN reduced the production of infectious VSV particles, decreased the amount of G and M proteins in VSV released from treated cells, and inhibited an early step in the formation of asparagine-linked oligosaccharide chains, the incorporation by membrane preparations from treated cells of N-acetylglucosamine into glycolipids with the properties of dolichol derivatives.
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PMID:Interferon treatment inhibits glycosylation of a viral protein. 615 39

We report the identification of three new alpha-amanitin resistance mutations in the gene encoding the largest subunit of mouse RNA polymerase II (RPII215). These mutations are clustered in a region of the largest subunit that is important for transcription elongation. This same domain has been identified as the site of alpha-amanitin resistance mutations in both Drosophila and Caenarhabditis elegans. The sequences encompassing this cluster of mutations are highly conserved among RNA polymerase II genes from a number of species, including those that are naturally more resistant to alpha-amanitin suggesting that this region of the largest subunit is critical for a conserved catalytic function. The mutations reported here change leucine 745 to phenylalanine, arginine 749 to proline, or isoleucine 779 to phenylalanine. Together with the previously reported asparagine 792 to aspartate substitution these mutations define a potential alpha-amanitin binding pocket in a region of the mouse subunit that could be involved in translocation of polymerase during elongation.
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PMID:Clustered alpha-amanitin resistance mutations in mouse. 789 49

High affinity sodium- and potassium-coupled L-glutamate transport into presynaptic nerve terminals and fine glial processes removes the neurotransmitter from the synaptic cleft, thereby terminating glutamergic transmission. This report describes that the purified L-glutamate transporter from pig brain is phosphorylated by protein kinase C, predominantly at serine residues. Upon exposure of C6 cells, a cell line of glial origin, to 12-O-tetradecanoylphorbol-13-acetate, about a 2-fold stimulation of L-glutamate transport is observed within 30 min. Concomitantly, the level of phosphorylation increases with similar kinetics. The phorbol ester also stimulates L-glutamate transport in HeLa cells infected with a recombinant vaccinia virus expressing T7 RNA polymerase and transfected with pT7-GLT-1. The latter is a recently cloned rat brain glutamate transporter of glial origin. Mutation of serine 113 to asparagine does not affect the levels of expressed transport but abolishes its stimulation by the phorbol ester. To our knowledge, this is the first direct demonstration of the regulation of a neurotransmitter transporter by phosphorylation.
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PMID:Phosphorylation and modulation of brain glutamate transporters by protein kinase C. 790 7


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