Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.1.21.1 (DNase)
 7,655 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

RNA polymerase was extracted from the Schmidt-Ruppin strain of Rous sarcoma virus (SR-RSV)-induced C3H/He mouse ascites sarcoma cells (SR-C3H). RNA polymerase was separated into RNA polymerases I and II by DEAE-Sephadex chromatography. RNA polymerase I was separated into Ia and Ib fractions by phospho-cellulose chromatography. In SR-C3H cells RNA polymerase Ib was the main component of RNA polymerase I. At 0.05--0.1 M ammonium sulphate RNA polymerase I transcribed native DNA most actively, and RNA polymerase II transcribed denatured DNA most actively. Partial digestion of DNA by DNAase I enhanced RNA synthesis by RNA polymerases I and II. At ionic strength over 0.2 M ammonium sulphate, the initiation reaction of RNA polymerases I and II was inhibited. The initiation complexes of RNA polymerases I and II with native DNA were more stable against high salt concentration than with denatured DNA.
 ...
PMID:Characterization of RNA polymerases from Rous sarcoma virus-induced mouse ascites sarcoma cells. 3 35

A factor stimulating RNA polymerase II from Ehrlich ascites tumor cells was purified. The final preparation appeared almost homogeneous on sodium dodecyl sulfate-polyacrylamide gel electrophoresis and had a molecular weight of 38 000. The endonuclease activity of about 10 mug of purified factor, if any was well below the 10(-5) mug equivalent of pancreatic deoxyribonuclease, indicating that the stimulation of RNA synthesis by this factor was not due to contaminating endonuclease. This factor specifically stimulated RNA polymerase II on native DNA as template and did not affect RNA polymerase I at all. The molecular size of RNA synthesized in the presence of this factor increased markedly compared with that synthetized by RNA polymerase II alone.
 ...
PMID:Purification of a factor from Ehrlich ascites tumor cells specifically stimulating RNA polymerase II. 99 Feb 65

Analysis by molecular hybridization of the RNAs transcribed by a cell-free fraction from avocado infected with avocado sunblotch viroid (ASBV) demonstrated the presence of newly synthesized viroid-specific sequences, most of which were of the same polarity as the mature infectious viroid RNA. Treatment of the cell-free fraction with DNase reduced the total synthesis of RNA considerably, but it did not influence that of the ASBV-specific RNAs, indicating that the latter were transcribed on an RNA template. Inhibition studies with alpha-amanitin showed that the synthesis of ASBV-specific RNAs was not affected by concentrations of 1 and 200 micrograms/ml of the drug, which typically inhibit RNA polymerase II and III, respectively, from most animal and plant systems. These results suggest that either RNA polymerase I or an unidentified RNA polymerase activity resistant to alpha-amanitin, acting on an RNA template, plays a role in the replication of ASBV, whereas for the rest of the viroids studied so far it appears that RNA polymerase II is involved. Analysis by polycrylamide gel electrophoresis under partially and fully denaturing conditions of the ASBV-specific RNAs synthesized in vitro showed that they contain unit and longer than unit length viroid strands, probably associated in complexes with single- and double-stranded regions. The structural properties of these complexes are similar to those of the RNAs accumulating in vivo in viroid-infected tissues, which are the postulated replicative intermediates of the rolling-circle mechanism proposed for viroid synthesis.
 ...
PMID:Characterization of RNAs specific to avocado sunblotch viroid synthesized in vitro by a cell-free system from infected avocado leaves. 173 98

We have prepared three types of RNA polymerase II transcription complexes: a preinitiation complex (complex 0), a complex which has synthesized two phosphodiester bonds (complex 2), and a complex which has synthesized 10-13 bonds (complex 10). We have studied the differential response of these complexes to a variety of disruptions: detergent (Sarkosyl), high levels of KCl, extended incubation at 25 degrees C, proteolysis, and digestion with DNase I. Complex 0 is extremely stable at 25 degrees C in the absence of ATP, but it is sensitive to the other treatments including 25 degrees C incubation in the presence of ATP. Once the complex has made two phosphodiester bonds, the properties almost reverse from those of complex 0; complex 2 remains unstable at 25 degrees C in the presence of ATP but is resistant to high levels of Sarkosyl and KCl, to extensive DNase I digestion, and to brief proteolysis. Addition of 10 or more bases to the growing RNA chain results in a complex completely resistant to all of the treatments used. When DNase I-trimmed complex 0 is allowed to initiate RNA synthesis, chains of about 33 bases are obtained. In contrast, DNase-trimmed complex 2 gives only about 23 base transcripts; DNase-treated complex 10 will elongate its nascent chains by about 21 bases as well (to give, on average, 34 base transcripts).
 ...
PMID:Transcription initiation by RNA polymerase II in vitro. Properties of preinitiation, initiation, and elongation complexes. 243 61

A native gel electrophoresis DNA binding assay was used to resolve complexes formed on the adenovirus Major Late Promoter by general transcription factors and RNA polymerase II. Five sets of complexes containing distinct components were identified. These complexes were generated by sequential binding of TFIID, TFIIA, TFIIB, RNA polymerase II, and TFIIE. The relative positions of each of the factors in the complexes were determined by DNAase I footprint analysis. TFIIA, derived from yeast or mammalian cells, formed a complex with yeast TFIID and the TATA element. TFIIB bound to this complex and probably acts as a "bridge" to the polymerase and the initiation site. The addition of ATP or dATP, necessary for "activation" of transcription, resulted in an alteration of the footprint in the +20 to +30 region, the same area protected upon addition of TFIIE to the initiation complex. Addition of ribonucleotide triphosphates generated new complexes that contained accurately initiated transcripts associated with the transcription machinery and the template DNA. A model for the interactions of components in initiation of transcription by RNA polymerase II is proposed.
 ...
PMID:Five intermediate complexes in transcription initiation by RNA polymerase II. 291 66

Previously, we have shown that DNA in a small fraction (2-5%) of SV40 minichromosomes was torsionally strained and could be relaxed by treating minichromosomes with topoisomerase I. This fraction was enriched with endogeneous RNA polymerase II (Luchnik et al., 1982, EMBO J., 1, 1353). Here we show that one and the same fraction of SV40 minichromosomes is hypersensitive to DNAase I and is relaxable by topoisomerase I. Moreover, this fraction completely loses its hypersensitivity to DNAase I upon relaxation. The possibility that this fraction of minichromosomes can be represented by naked DNA is ruled out by the results of studying the kinetics of minichromosome digestion by DNAase I in comparison to digestion of pure SV40 DNA and by measuring the buoyant density of SV40 chromatin in equilibrium CsCl gradient. Our data obtained with SV40 minichromosomes may be relevant to the mechanism responsible for DNAase I hypersensitivity in the loops or domains of cellular chromatin.
 ...
PMID:DNAaseI-hypersensitive minichromosomes of SV40 possess an elastic torsional strain in DNA. 298 17

A phosphocellulose flowthrough fraction required for accurate transcription in vitro by RNA polymerase II was found to contain a DNase inhibitor which was necessary to maintain template integrity (Price D.H., Sluder A.E. & Greenleaf A.L. (1987) J. Biol. Chem. 262, 3244-3255). Starting with a Drosophila Kc cell nuclear extract, the DNase inhibitory activity has been purified 19,000-fold. In combination with the other necessary fractions, the highly purified inhibitor continues to support reconstruction of transcription. It thus appears to be the only required activity in the original phosphocellulose flowthrough fraction. The inhibitor is a protein which does not bind to DNA or inhibit DNase I, so that it has also been useful in assays for DNA binding proteins in crude, DNase-contaminated fractions.
 ...
PMID:An activity necessary for in vitro transcription is a DNase inhibitor. 312 25

The mammalian activator protein ATF stimulates transcription from the adenovirus E4 promoter by binding to multiple upstream promoter and enhancer elements. DNAase footprint analyses have revealed that there are cooperative interactions between ATF and TFIID (the mammalian TATA factor) when both are bound simultaneously to the promoter and that these interactions in turn facilitate promoter recognition by RNA polymerase II and the general initiation factors TFIIB and TFIIE. However, the complex of TFIID and the other general factors is stable following oligonucleotide-mediated dissociation of ATF from the complete preinitiation complex. These results indicate that TFIID is a direct target for ATF, that these interactions facilitate assembly of a complete preinitiation complex, and that the role of ATF might be transient.
 ...
PMID:Transcription factor ATF interacts with the TATA factor to facilitate establishment of a preinitiation complex. 341 54

In the accompanying paper (Horikoshi et al., 1988) the interaction between ATF and the general transcription initiation factors was analyzed by DNAase I footprinting experiments. Here, we use transcription assays to investigate the role of ATF in the assembly of a functional preinitiation complex. Addition of an oligonucleotide containing an ATF binding site inhibits E4 transcription by sequestering ATF. However, following preincubation of the E4 promoter in the nuclear extract, transcription is refractory to inhibition by the ATF oligonucleotide. Formation of this oligonucleotide-refractory complex occurs at an early stage in the overall transcription initiation reaction and is dependent upon ATF and the general transcription factors RNA polymerase II, TFIIB, and TFIID. This latter result suggests that the assembly and maintenance of a functional preinitiation complex involves cooperative interactions among the various transcription factors. The general transcription factor TFIIE, although required for transcriptional activity, is not involved in the assembly of an ATF oligonucleotide-refractory complex. Our results support the possibility that ATF may be required only transiently for assembly of a functional preinitiation complex.
 ...
PMID:Analysis of the role of the transcription factor ATF in the assembly of a functional preinitiation complex. 341 55

Drosophila Kc cells were utilized to prepare nuclear extracts in which promoter-containing DNA templates were efficiently transcribed by RNA polymerase II. A combination of fractionation schemes was used to identify and partially purify seven activities (factors) which affected the transcription of four different genes in vitro. Reconstructing specific transcription required exogenous RNA polymerase II in addition to these factors. Moreover, the high efficiency of transcription characteristic of the crude extract was preserved in reconstruction reactions. The methods used are presented in detail. Functions were assigned to several of the factors. One essential factor appeared to affect initiation and displayed chromatographic properties unlike any other Drosophila transcription factor previously described. Two factors specifically affected RNA chain elongation. Another activity was a DNase inhibitor required to preserve template integrity in the fractionated system. The remaining three factors were not absolutely essential but affected the specific in vitro transcription either qualitatively or quantitatively. A comparison of these transcription factors with other Drosophila and mammalian transcription factors is made.
 ...
PMID:Fractionation of transcription factors for RNA polymerase II from Drosophila Kc cell nuclear extracts. 381 40


1 2 3 4 Next >>