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

---

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

We have investigated the mechanism of transcription termination by T7 RNA polymerase using templates encoding variants of the transcription-termination structure (attenuator) of the regulatory region of the threonine (thr) operon of Escherichia coli. The thr attenuator comprises the following two distinct structural elements: a G + C-rich inverted repeat, which encodes an RNA hairpin structure, and A + T-rich regions, one of which contains a continuous sequence of template deoxyadenosine residues within which the transcription terminates. Fourteen attenuator variants were analyzed and we find that not only the hairpin structure itself but also its sequence influences termination. Furthermore, the formation of a hairpin in the RNA encoded by the A + T-rich regions of the attenuator is not mandatory for termination. A series of seven deletion variants that successively shorten the deoxyadenosine tract in the attenuator template were also analyzed. Results from these experiments indicate that complete readthrough occurs when there are four or fewer deoxyadenosine residues. With 5 template deoxyadenosine residues there is 5% termination increasing to 32% with 8 deoxyadenosines, the value produced by the wild-type attenuator. In addition, a comparison with E. coli RNA polymerase shows that T7 RNA polymerase requires a more perfect region of dyad symmetry and a longer deoxyadenosine tract than does the bacterial enzyme to terminate with maximum efficiency.
...
PMID:Transcription termination by bacteriophage T7 RNA polymerase at rho-independent terminators. 240 63

cAMP is an ubiquitous compound which is involved in the regulation of many biological processes. In bacteria such as E. coli, cAMP mediates the activation of catabolic operons via the CAP protein. The CAP-cAMP complex, whose tridimensional structure has recently been established, binds to the promoter regions of catabolic operons at a specific site, and activates their transcription by inducing RNA polymerase to bind and initiate transcription at the correct site. Various phenomenons including protein-protein interactions or CAP-induced DNA bending or kinking could be involved in the process of forming the open transcription complex. In eukaryotes, cAMP activates cAMP dependent protein kinases which covalently modify proteins by phosphorylation on serine or threonine residues. The catalytically inactive holoenzyme is generally a tetramer containing two regulatory subunits, each capable of binding two molecules of cAMP, and two catalytic subunits. In mammalian cells, two types of cAMP dependent protein kinases (I and II) can be distinguished on the basis of their regulatory subunits; their relative proportion varies from tissue to tissue. Binding of cAMP to the regulatory subunits induces the dissociation of the holoenzyme and releases the free and active catalytic subunits. Phosphorylation of proteins occurs at sequences containing two basic residues in the vicinity of the phosphorylated serine or threonine. A heat-stable protein, present in most eukaryotic cells, specifically interacts with the catalytic subunit and inhibits its activity. The amino-acid sequence of cAMP dependent protein kinases has recently been determined. It is interesting to note that the domains responsible for cAMP binding by the regulatory subunits of mammalian cAMP dependent protein kinases and CAP share important sequence homologies. The same phenomenon is observed concerning the domain responsible for ATP binding to the catalytic subunit of cAMP dependent protein kinases and that of tyrosine-specific protein kinases from oncoviruses. Other eukaryotic proteins such as S-adenosyl-L-homocysteine (SAH) hydrolase are also capable of binding cAMP. The latter is involved in the regulation of S-adenosyl-L-methionine dependent methylations, and its activity could be affected by cAMP. Besides its role as an effector of enzymatic activity via phosphorylation, such as in the regulation of glycogen metabolism, cAMP has recently been shown to activate the transcription of a number of eukaryotic genes. This process probably also involves protein phosphorylation, but its precise mechanism remains to be understood.
...
PMID:[Mode of action of cyclic amp in prokaryotes and eukaryotes, CAP and cAMP-dependent protein kinases]. 241 6

The complete nucleotide sequence of the asd gene of Streptococcus mutans encoding aspartate beta-semialdehyde dehydrogenase (EC 1.2.1.11), an enzyme comprised of 357 amino acids, having an Mr of 38,897 and active in the biosynthetic pathway of lysine, threonine, methionine, diaminopimelic acid, and isoleucine, has been determined. In addition we report the 276 nucleotides upstream of the structural gene which contain a highly efficient promoter identified by both RNA polymerase binding and in vitro transcription analysis. A leader transcript which terminates at a fixed point immediately preceding the asd promoter region was identified in the DNA sequence and confirmed by in vitro transcription analysis as well. The close proximity of this transcript and its p-independent transcriptional terminator to the asd coding sequence suggests involvement in a mechanism of regulation. Message stability experiments indicate the half-life of asd specific messages to be comparable to that of Escherichia coli messages. Conditions of varying concentrations of lysine, threonine, and methionine exert no apparent control over expression of the S. mutans asd gene in Escherichia coli suggesting the requirement of an accessory regulatory element specific for the S. mutans asd gene.
...
PMID:Nucleotide sequence of the asd gene of Streptococcus mutans. Identification of the promoter region and evidence for attenuator-like sequences preceding the structural gene. 243 99

The effect of infusion of a methionine-free total parenteral nutrition solution for 7 d on ribonucleic acids in liver of rats were investigated. The control solution contained leucine, valine, isoleucine, lysine, phenylalanine, threonine, tryptophan, arginine, histidine, glycine, methionine, glucose and vitamins and minerals. Deprivation of a methionine is known to increase the activity of RNA polymerase I. Infusing the methionine-free solution resulted in the accumulation of RNA molecules larger than 28S in the liver nuclei and resulted in a higher rate of rRNA synthesis than in rats infused with the control solution. A methionine deficiency did not impede either the processing of 45S pre-rRNA or transport of 28S and 18S rRNA into cytoplasm. When rats were infused with the methionine-free solution for 7 d followed by the control solution for 2 d, the level of RNA in the nucleus as well as the rate of RNA polymerase I were similar to the levels in rats receiving the control solution for 9 d. There were no significant changes in the rate of DNA synthesis due to nutritional manipulations.
...
PMID:Alteration in the ribonucleic acids in rat liver induced by a methionine-free total parenteral nutrition solution. 243 90

We describe a mutation that changes the fine specificity of promoter selection by a secondary form of RNA polymerase holoenzyme in Bacillus subtilis. The product of regulatory gene spo0H is an RNA polymerase sigma factor called sigma H, which directs transcription of a sporulation gene known as spoVG. We show that the spo0H mutation spo0H81, which blocks transcription from the wild-type spoVG promoter, enhances transcription from a mutant form of the spoVG promoter (spoVG249) bearing a severe down-mutation (a G.C to A.T transition) at position -13 in the "-10 region." Suppression of the spoVG249 mutation is specific in the sense that the transcription from several other spoVG mutant promoters was not restored by the mutant sigma. Evidently, spo0H81 is a change-of-specificity mutation that alters sigma H-RNA polymerase in a way that decreases its capacity to use the wild-type spoVG promoter, while increasing its capacity to use the mutant promoter. Transcription experiments in vitro using RNA polymerase containing the wild-type or mutant sigma support this interpretation. The spo0H81 mutation causes a threonine (Thr100) to isoleucine substitution in a region of sigma H that is highly homologous among sigma factors of diverse origins. We discuss the possibility that Thr100 is an amino acid-base-pair contact site and that sigma factors contact the -10 region of their cognate promoters by means of amino acid residues in this highly conserved region.
...
PMID:Mutation changing the specificity of an RNA polymerase sigma factor. 250 May 29

The unique C-terminal repeat domain (CTD) of the largest subunit (IIa) of eukaryotic RNA polymerase II consists of multiple repeats of the heptapeptide consensus sequence Tyr-Ser-Pro-Thr-Ser-Pro-Ser. The number of repeats ranges from 26 in yeast to 42 in Drosophila to 52 in mouse. The CTD is essential in vivo, but its structure and function are not yet understood. The CTD can be phosphorylated at multiple serine and threonine residues, generating a form of the largest subunit (II0) with markedly reduced mobility in NaDodSO4/polyacrylamide gels. To investigate this extensive phosphorylation, which presumably modulates functional properties of RNA polymerase II, we began efforts to purify a specific CTD kinase. Using CTD-containing fusion proteins as substrates, we have purified a CTD kinase from the yeast Saccharomyces cerevisiae. The enzyme extensively phosphorylates the CTD portion of both the fusion proteins and intact subunit IIa, producing products with reduced electrophoretic mobilities. The properties of the CTD kinase suggest that it is distinct from previously described protein kinases. Analogous activities were also detected in Drosophila and HeLa cell extracts.
...
PMID:A protein kinase that phosphorylates the C-terminal repeat domain of the largest subunit of RNA polymerase II. 265 24

To determine whether chloroplast RNA polymerase will accurately terminate transcription in vitro, we have fused the spinach chloroplast rbcL promoter to the 3' end of the rbcL gene as well as to various factor independent transcription terminators from E. coli. Transcription of the rbcL minigene did not result in production of the expected 265 nucleotide RNA. However, the spinach chloroplast RNA polymerase did terminate transcription with varying efficiency at the thra, rrnB, rrnC and gene 32 terminators. The most efficient transcription termination was observed for the threonine attenuator. For each of the prokaryotic terminators, the chloroplast enzyme ceased transcription at essentially the same position as the E. coli RNA polymerase. These data indicate that the transcription termination process in chloroplasts has some features in common with the mechanism used in prokaryotes.
...
PMID:Recognition of prokaryotic transcription terminators by spinach chloroplast RNA polymerase. 284 17

Antisera were raised in rabbits against fusion proteins consisting of beta-galactosidase and partial amino acid sequences of Semliki Forest virus (SFV)-specific non-structural proteins nsP1, nsP2, nsP3 and nsP4. The antisera were specific since each of them precipitated only one labelled protein of a size expected for nsP1, nsP2, nsP3 or nsP4 from lysates of [35S]methionine-labelled SFV-infected BHK-21 cells. The specific antisera also precipitated p220 (with sequences of nsP1, nsP2 and nsP3), p155 (nsP1 and nsP2) and p135 (nsP3 and nsP4) which have been previously shown to be cleavage products of the polyprotein precursor of the non-structural proteins. nsP1, nsP4 and most of nsP3, together with the virus-specific RNA polymerase activity, were in the mitochondrial pellet (P15) fraction of infected BHK-21 cells whereas nsP2 was evenly distributed between P15 and the supernatant fraction (S15). Only antisera directed against nsP3 sequences precipitated a labelled protein from cells incubated with [32P]orthophosphate during SFV infection. Treatment of the immunoprecipitate with calf alkaline intestinal phosphatase reduced the amount of labelled nsP3 considerably. Immunoprecipitated 32P-labelled nsP3, isolated by SDS-PAGE, was subjected to acid hydrolysis. Both phosphoserine and phosphothreonine but not phosphotyrosine could be identified in the hydrolysate. Approximately twice as much [32P]serine as [32P]threonine was detected in nsP3. P15 and S15 fractions were prepared from [35S]methionine- and 32P-labelled SFV-infected cells and the 35S/32P ratio of nsP3 was determined after immunoprecipitation and SDS-PAGE. The nsP3 in S15 was less heavily phosphorylated (about 50%) than P15-associated nsP3. Anti-nsP3 serum revealed large cytoplasmic vesicles in SFV-infected cells in indirect immunofluorescence microscopy.
...
PMID:Semliki Forest virus-specific non-structural protein nsP3 is a phosphoprotein. 297 May 23

Purified eukaryotic nuclear RNA polymerase II consists of three subspecies that differ in the apparent molecular masses of their largest subunit, designated IIo, IIa, and IIb for polymerase species IIO, IIA, and IIB, respectively. Subunits IIo, IIa, and IIb are the products of a single gene. We present here the amino acid composition of calf thymus subunits IIa and IIb and the C-terminal amino acid sequence of subunit IIa (IIo) inferred from the nucleotide sequence of part of the mouse gene encoding this RNA polymerase subunit. The calculated amino acid composition of the peptide unique to subunit IIa indicates that subunit IIa contains a domain rich in serine, proline, threonine, and tyrosine. The sequence at the 3' end of the mouse RNA polymerase II largest subunit gene reveals that the C-terminal domain consists of 52 repeats of a seven amino acid block with the consensus sequence Tyr-Ser-Pro-Thr-Ser-Pro-Ser. This sequence is also unusual in that it contains a high percentage of potential phosphorylation sites.
...
PMID:A unique structure at the carboxyl terminus of the largest subunit of eukaryotic RNA polymerase II. 299 85

Purified RNA polymerase II from chicken leukemia cells was found to be an effective substrate for protein kinase C but not cAMP-dependent protein kinase. Protein kinase C catalyzed the incorporation of 1-2 mol of phosphate per mol of polymerase II and the reaction was totally calcium and lipid dependent. Electrophoresis studies revealed a time-dependent increase of phosphate incorporation into RNA polymerase II subunits of 220 KDa, 180 KDa and 150 KDa, with a preferential phosphorylation of the 180 KDa polypeptide. The phosphorylated enzyme has a preference for using single-stranded DNA as the template for transcription, including transcription of the single-stranded myb oncogene sequence. Phosphoamino acid analysis indicated that both serine and threonine residues were phosphorylated at equal amounts. Phosphorylation by protein kinase C increased the affinity of substrate-polymerase binding and the initial rate of RNA synthesis, suggesting a mechanism by which gene expression can be activated by protein kinase C.
...
PMID:Protein kinase C phosphorylates leukemia RNA polymerase II. 347 67


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

---