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)

The nucleotide sequence of a 3180-base-pair segment of DNA, containing the sucA gene encoding the 2-oxoglutarate dehydrogenase component (E1o) of the 2-oxoglutarate dehydrogenase complex of Escherichia coli, has been determined by the dideoxy chain-termination method. The sucA structural gene contains 2796 base pairs (932 codons, excluding the initiation codon AUG) and encodes a polypeptide having a glutamine residue at the amino terminus, a glutamate residue at the carboxy-terminus and a calculated Mr = 104905. The predicted amino acid composition is in good agreement with published information obtained by hydrolysis of the purified enzyme. There is a striking lack of sequence homology between the 2-oxoglutarate dehydrogenase (E1o) and the corresponding pyruvate dehydrogenase (E1p), which suggests that the two components are not closely related in evolutionary terms. The location and polarity of the sucA gene, relative to the restriction map of the corresponding segment of DNA, are consistent with it being the proximal gene of the suc operon, as defined in previous genetic and post-infection labelling studies, but it could also form part of a more complex regulatory unit. The sucA gene is preceded by a segment of DNA that contains many substantial regions of hyphenated dyad symmetry including an IS-like sequence of the type that is thought to function as an intercistronic regulatory element. This segment also contains three putative RNA polymerase binding sites and a good ribosome binding site.
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PMID:Nucleotide sequence of the sucA gene encoding the 2-oxoglutarate dehydrogenase of Escherichia coli K12. 637 23

Transcription in vitro of two osmoregulated promoters, for the Escherichia coli osmB and osmY genes, was analysed using two species of RNA polymerase holoenzyme reconstituted from purified core enzyme and either sigma D (sigma 70, the major sigma in exponentially growing cells) or sigma S (sigma 38, the principal sigma at stationary growth phase). Under conditions of low ionic strength, the osmB and osmY promoters were transcribed by both E sigma D and E sigma S. Addition of up to 400 mM potassium glutamate (K glutamate), mimicking the intracellular ionic conditions under hyperosmotic stress, specifically enhanced transcription at these promoters by E sigma S but inhibited that by E sigma D. At similar high concentrations of potassium chloride (KCl), however, initiation at both these promoters was virtually undetectable. These data suggest that the RNA polymerase, E sigma S, itself can sense osmotic stress by responding to changes in intracellular K glutamate concentrations and altering its promoter selectivity in order to recognize certain osmoregulated promoters.
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PMID:Promoter selectivity control of Escherichia coli RNA polymerase by ionic strength: differential recognition of osmoregulated promoters by E sigma D and E sigma S holoenzymes. 747 60

The human beta-amyloid protein may play an important, possibly primary, role in the pathogenesis of Alzheimer's disease (AD), and it appears to potentiate the susceptibility of neurons to excitotoxicity. AD is associated with alterations in the N-methyl-D-aspartate (NMDA) and alpha-amino-3-hydroxy-5-methylisoxazole-4-propionic acid (AMPA) subtypes of glutamate receptors, and it has been suggested that excitotoxicity may play a role in neuronal damage in AD. In this study, we have used quantitative receptor autoradiography to examine NMDA and AMPA receptors in transgenic mice that contain the gene for the carboxyl-terminal 100 amino acids of the human amyloid precursor protein, beginning with the beta-amyloid region, which is under the control of the JC viral early region promoter. Reverse transcriptase-polymerase chain reaction confirmed that the brains of transgenic mice expressed beta-amyloid mRNA and that control mice did not. NMDA receptors, assessed with [3H]MK-801, were unchanged in the transgenic compared with the control mice. In the transgenic mice, there were no significant changes in [3H]AMPA receptor binding compared with controls. This study represents the first attempt to evaluate in transgenic mice the in vivo interaction between beta-amyloid expression and excitatory amino acid receptors.
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PMID:NMDA and AMPA receptors in transgenic mice expressing human beta-amyloid protein. 750 89

The removal of introns from eukaryotic pre-mRNA occurs in a large ribonucleoprotein complex called the spliceosome. We have generated a monoclonal antibody (mAb 16H3) against four of the family of six SR proteins, known regulators of splice site selection and spliceosome assembly. In addition to the reactive SR proteins, SRp20, SRp40, SRp55, and SRp75, mAb 16H3 also binds approximately 20 distinct nuclear proteins in human, frog, and Drosophila extracts, whereas yeast do not detectably express the epitope. The antigens are shown to be nuclear, nonnucleolar, and concentrated at active sites of RNA polymerase II transcription which suggests their involvement in pre-mRNA processing. Indeed, most of the reactive proteins observed in nuclear extract are detected in spliceosomes (E and/or B complex) assembled in vitro, including the U1 70K component of the U1 small nuclear ribonucleoprotein particle and both subunits of U2AF. Interestingly, the 16H3 epitope was mapped to a 40-amino acid polypeptide composed almost exclusively of arginine alternating with glutamate and aspartate. All of the identified antigens, including the human homolog of yeast Prp22 (HRH1), contain a similar structural element characterized by arginine alternating with serine, glutamate, and/or aspartate. These results indicate that many more spliceosomal components contain such arginine-rich domains. Because it is conserved among metazoans, we propose that the "alternating arginine" domain recognized by mAb 16H3 may represent a common functional element of pre-mRNA splicing factors.
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PMID:A conserved epitope on a subset of SR proteins defines a larger family of Pre-mRNA splicing factors. 753 40

RNA polymerase from Bacillus subtilis is a complex mixture comprising a common core (beta beta' alpha 2), the 20.4 kDa delta (delta) protein, and of one of several sigma (sigma) specificity factors. The delta protein, together with several truncated variants, has been overproduced and purified from Escherichia coli. It is highly acidic (pI = 3.6) and contains two distinct regions, a 13 kDa amino-terminal domain with fairly uniform charge distribution and a glutamate and aspartate residue-rich carboxyl-terminal region. The purified amino-terminal domain (delta N) contains 32% alpha-helix and 16% beta-sheet, as judged by circular dichroism analysis. In contrast, an 8.5 kDa tryptic fragment containing the carboxyl-terminal region (delta C) is largely unstructured and highly charged (net charge of -47). RNA polymerase purified from a B. subtilis mutant with an insertion in the delta gene (rpoE::cat) contains a truncated delta protein, indicating that the amino-terminal domain is stable in vivo and contains a core-binding function. Addition of delta, but not sigma A or delta N, displaces RNA bound to RNA polymerase in a binary complex. The ability of delta to displace RNA efficiently requires the activities of both the amino-terminal core-binding domain and the polyanionic carboxyl-terminal region. Although delta C can also displace nucleic acids from RNA polymerase, this activity requires the addition of a large molar excess of protein and is relatively non specific in that both DNA and RNA are displaced. This suggests that the function of the amino-terminal domain is to bind and orient the carboxyl-terminal region on the surface of RNA polymerase.
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PMID:Structural analysis of the Bacillus subtilis delta factor: a protein polyanion which displaces RNA from RNA polymerase. 754 58

The activity of the proline catabolic enzyme pyrroline-5-carboxylate dehydrogenase (EC 1.5.1.12) was induced up to three-hundred-fold by the addition of three hundred proline to the growth medium of the Gram-positive bacterium Streptomyces coelicolor A3(2). Rifampicin, an inhibitor of RNA polymerase activity, abolished induction, implying that regulation was at the level of activation of gene transcription. The enzyme was purified and SDS-PAGE of the highly purified enzyme preparation revealed a single subunit with M(r) 68,000. A single band of protein, which also stained for enzyme activity, was observed after native gel electrophoresis. The M(r) of the enzyme was estimated to be approximately 265,000 by native gel electrophoresis and approximately 305,000 by gel filtration, which indicated that the enzyme had a tetrameric quaternary structure. The apparent Km for pyrroline-5-carboxylate was 109 +/- 7.3 microM, whilst that for NAD+ was 43.3 +/- 2.5 microM. Product inhibition by NADH (apparent Ki 0.6mM) was observed. The observed Vmax was 22.0 +/- 1 mol min-1 (mg protein)-1. Neither 1 nor 5 mM proline had any effect on enzyme activity, whilst glutamate was a very weak inhibitor.
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PMID:Interaction between primary and secondary metabolism in Streptomyces coelicolor A3(2): role of pyrroline-5-carboxylate dehydrogenase. 755 Oct 40

We have isolated the murine cDNA homologue of the human protein tyrosine phosphatase PTP-PEST (MPTP-PEST) from an 18.5-day mouse embryonic kidney library. The cDNA isolated has a single open reading frame predicting a protein of 775 amino acids. When expressed in vitro as a glutathione S-transferase fusion protein, the catalytic domain (residues 1-453) shows intrinsic phosphatase activity. Reverse transcriptase PCR and Northern-blot analysis show that MPTP-PEST mRNA is expressed throughout murine development. Indirect immunofluorescence in COS-1 cells against a heterologous epitope tag attached to the N-terminus of MPTP-PEST, together with cellular fractionation and Western-blot experiments from different murine cell lines, indicate that MPTP-PEST is a free cytosolic protein of 112 kDa. Finally, sequence analysis indicates that the C-terminal portion of the protein contains four regions rich in proline, glutamate, serine and threonine, otherwise known as PEST sequences. These are characteristic of proteins that display very short intracellular half-lives. Despite the presence of these motifs, pulse-chase labelling experiments demonstrate that MPTP-PEST has a half-life of more than 4 h.
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PMID:Murine protein tyrosine phosphatase-PEST, a stable cytosolic protein tyrosine phosphatase. 777 23

Bacteriophage T4 middle promoters, which are transcribed using phage-modified host RNA polymerase and the T4 transcriptional activator, MotA, match the host sigma 70 consensus sequence at -10, but they have a different consensus ((t/a)(t/a)TGCTT(t/c)A) (a MotA box) at -30. While the T4 middle promoter PuvsX has these -10 and -30 motifs, it also has matches to the MotA box at -35, -51, -70, and -87. We show that MotA binds to PuvsX DNA, footprinting a region that includes the MotA boxes at -30, -35, and -51. Very high levels of MotA are required for footprinting and gel-shift experiments, and protein-DNA complexes formed in the presence of both phage-modified polymerase and MotA are more resistant to HindIII cleavage than those formed with either protein alone. These results suggest that MotA-DNA interactions may be stabilized by phage-modified polymerase. Sequences between -18 and -38 are absolutely required for MotA activation of transcription, but sequences upstream of -38 are stimulatory, particularly when chloride instead of glutamate is the major anion. Our results dissect PuvsX into a core promoter, downstream of -38, which is required for MotA activation, and an upstream region that enhances transcription especially under conditions less favourable for protein-DNA interactions.
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PMID:The bacteriophage T4 middle promoter PuvsX: analysis of regions important for binding of the T4 transcriptional activator MotA and for activation of transcription. 778 37

The transcription of sigma 54 RNA polymerase-dependent nitrogen-regulated genes is activated by nitrogen regulator I (NRI)-phosphate. The kinase NRII is responsible for the phosphorylation of NRI. It has been shown that NRII also has the ability to dephosphorylate NRI-phosphate but only when PII is present at a concentration greatly in excess of that of NRII. We have now shown that glutamate enables PII to stimulate the dephosphorylation of NRI-phosphate when present in equimolar concentration with NRII. This effect of glutamate appears to be a backup control that becomes effective when the normal regulation of PII activity is disabled.
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PMID:Activation of the dephosphorylation of nitrogen regulator I-phosphate of Escherichia coli. 786 Jun 2

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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