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)

Blood samples containing antibodies to DNA were obtained from patients with systemic lupus erythematosus (SLE) and rabbits immunized with denatured DNA complexed to methylated bovine serum albumin. The immunoglobulin fractions from these sources did not decrease the over-all template activity of singlestranded DNA with DNA polymerase or DNA-dependent RNA polymerase. In competition studies, both DNA polymerase and DNA-dependent RNA polymerase inhibited the binding of DNA antibodies to single-stranded DNA, as evidenced by inhibition of micro-complement fixation. These findings suggest that antibodies to DNA fail to decrease denatured DNA template activity because the enzymes which use a single-stranded DNA template can displace or block the antibodies from the denatured DNA as a result of greater binding affinity to the denatured DNA. The anti-DNA antibodies associated with SLE, therefore, may not be involved in the pathogenesis of the intracellular abnormalities associated with the disease.
 ...
PMID:In vitro effect of antibodies to DNA on the template activity of DNA. 417 49

Two of the adenovirus capsid proteins, the fiber and the hexon, complexed with either KB cell or type 5 adenovirus deoxyribonucleic acid (DNA). Maximal binding occurred at 0.01 m NaCl; increasing the ionic strength of the reaction mixture to 0.2 m NaCl resulted in a decrease in the association of either antigen to DNA. Variations of pH between 6.3 and 8.4 did not affect the binding of fiber antigen to DNA. Below pH 7.5, however, there was a small decrease in the ability of the hexon to bind nucleic acid. The association between the adenovirus structural proteins and DNA was reversible and was independent of whether the DNA was native or denatured. The fiber or hexon protein inhibited the DNA-dependent ribonucleic acid (RNA) polymerase and the DNA polymerase from KB cells. On a weight basis, the fiber protein inhibited enzymatic activity to a greater extent than the hexon. Increasing the template DNA concentration decreased this inhibition. The inhibition of the DNA-dependent RNA polymerase activity by either antigen could be reversed by increasing the ionic strength of the reaction mixture. After infection of KB cells with type 5 adenovirus, the levels of DNA and RNA polymerases remained unchanged for 15 to 20 hr. Thereafter, the specific activity of both enzymes decreased. By 30 hr postinfection, the polymerase activities were only about 30% of the enzyme activities in uninfected cells.
 ...
PMID:Role of adenovirus structural proteins in the cessation of host-cell biosynthetic functions. 430 13

The effect of histones on accessibility of DNA to DNase in chromatin of thymus nuclei has been studied by selective extraction of either lysine-rich or arginine-rich histones. It was found that all histones block accessibility but that, weight for weight, lysine-rich histones block much more effectively than do arginine-rich histones. We point to the contrast between accessibility of DNA to DNase and of DNA to RNA polymerase, and to what may be the similarity between accessibility to DNase and DNA polymerase.
 ...
PMID:Blocking by histones of accessibility to DNA in chromatin. 450 81

Highly purified DNA polymerase of chicken embryo was used to investigate the mechanism of DNA replication. The templates used included synthetic homopolymer pairs, as well as DNA of bacteriophage f1 and DNA-RNA hybrids prepared by partial or complete transcription of f1 DNA. The evidence suggests that the DNA synthesized is complementary either to the DNA or the RNA strand of the hybrid, depending on the relative lengths of the two strands, with the longer serving as the template and the shorter as the primer. While f1 DNA itself lacks template properties, the f1 DNA-RNA hybrids are efficient templates; and composition studies show the DNA synthesized to be complementary to the DNA strand of the hybrid. These observations suggest a mechanism of DNA replication in which the initial synthesis of a stable primer by RNA polymerase plays a pivotal role.
 ...
PMID:Mechanism of DNA replication by highly purified DNA polymerase of chicken embryo. 450 82

Soluble enzyme fractions from uninfected Escherichia coli convert M13 and varphiX174 viral single strands to their double-stranded replicative forms. Rifampicin, an inhibitor of RNA polymerase, blocks conversion of M13 single strands to the replicative forms in vivo and in vitro. However, rifampicin does not block synthesis of the replicative forms of varphiX174 either in vivo or in soluble extracts. The replicative form of M13 synthesized in vitro consists of a full-length, linear, complementary strand annealed to a viral strand. The conversion of single strands of M13 to the replicative form proceeds in two separate stages. The first stage requires enzymes, ribonucleoside triphosphates, and single-stranded DNA; the reaction is inhibited by rifampicin. The macromolecular product separated at this stage supports DNA synthesis with deoxyribonucleoside triphosphates and a fresh addition of enzymes; ribonucleoside triphosphates are not required in this second stage nor does rifampicin inhibit the reaction. We presume that in the first stage there is synthesis of a short RNA chain, which then primes the synthesis of a replicative form by a DNA polymerase.
 ...
PMID:RNA synthesis initiates in vitro conversion of M13 DNA to its replicative form. 455 37

In a coupled system consisting of RNA polymerase and DNA polymerase I of Escherichia coli, the four deoxyribo- and the four ribonucleoside triphosphates, and DNA of bacteriophage f1 as template, DNA synthesis depends on the concomitant synthesis of RNA. Over a wide range of concentrations of the two polymerases, RNA synthesis was unaffected by the simultaneous synthesis of DNA, whereas the rate of DNA synthesis depended on the level of RNA synthesis. In the coupled reaction, RNA synthesis starts immediately at a high rate, which subsequently decreases, whereas DNA synthesis starts after a lag and its rate increases as the reaction proceeds. Upon addition of rifampicin, the rate of RNA synthesis falls abruptly, while that of DNA declines only gradually. The base composition of the DNA synthesized in the coupled reaction is complementary to that of f1 DNA template. It is suggested that the RNA synthesized by the RNA polymerase serves as a primer rather than as a template for the DNA polymerase.
 ...
PMID:Coupling of replication to transcription in vitro. 455

Conversion of single-stranded DNA of phage varphiX174 to the double-stranded replicative form in Escherichia coli uses enzymes essential for initiation and replication of the host chromosome. These enzymes can now be purified by the assay that this phage system provides. The varphiX174 conversion is distinct from that of M13. The reaction requires different host enzymes and is resistant to rifampicin and streptolydigin, inhibitors of RNA polymerase. However, RNA synthesis is essential for varphiX174 DNA synthesis: the reaction is inhibited by low concentrations of actinomycin D, all four ribonucleoside triphosphates are required, and an average of one phosphodiester bond links DNA to RNA in the isolated double-stranded circles. Thus, we presume that, as in the case of M13, synthesis of a short RNA chain primes the synthesis of a replicative form by DNA polymerase. Initiation of DNA synthesis by RNA priming is a mechanism of wide significance.
 ...
PMID:Initiation of DNA synthesis: synthesis of phiX174 replicative form requires RNA synthesis resistant to rifampicin. 456 Jun 96

During nonpermissive infection by a T7 amber mutant in gene 1 (phage RNA polymerase-deficient), synthesis of the products of the phage genes 3 (endonuclease), 3, 5 (lysozyme), 5 (DNA polymerase), and 17 (serum blocking power) was shown to occur at about half the rate as during wild-type infection. This relatively high rate of expression of "late" genes (transcribed normally by the phage RNA polymerase) seems to be a general feature of all T7 mutants in gene 1 from our collection. In contrast, T3 gene 1 mutants and a T7 gene 1 mutant from another collection showed late protein synthesis at very reduced rates. Synthesis of the gene 3 endonuclease by T7 gene 1 mutants was very sensitive to the addition of rifampin 2 min after infection, conditions under which there was very little inhibition during wild-type infection. This supports the notion that late gene expression during nonpermissive infection by gene 1 mutants is dependent on the transcription of the T7 genome by the host RNA polymerase. In contrast to T3 gene 1 mutants, the T7 gene 1 mutants of our collection directed the synthesis of phage DNA during nonpermissive infection. This DNA accumulated as a material sedimenting faster than mature T7 DNA.
 ...
PMID:Synthesis of bacteriophage-coded gene products during infection of Escherichia coli with amber mutants of T3 and T7 defective in gene 1. 457 63

The accessibility of DNA in chromatin to both exogenous DNA polymerase and RNA polymerase is slight when compared to isolated DNA. DNA in extracted chromatin is somewhat more accessible to these enzymes than is DNA in the chromatin of isolated nuclei; and the DNA template of chromatin is more accessible to DNA polymerase than to RNA polymerase. In these experiments we have given much attention to the technique of scintillation counting, since artifacts arising in this procedure can lead to erroneous conclusions.
 ...
PMID:Accessibility of DNA in chromatin to DNA polymerase and RNA polymerase. 457 15

Exogenous DNA and RNA polymerases were used to measure the template activity of DNA in chromatin in isolated thymus nuclei from which lysinerich or arginine-rich histones were selectively extracted. Measurements were on nuclei containing 20-1200 mug of DNA per ml, the distinctions becoming clear at the higher concentrations. Experiments with RNA polymerase showed only moderate increases in template activity upon extraction of histone, although the removal of lysinerich histone had a greater effect than that of arginine-rich histone. DNA polymerase action on nuclei minus lysinerich histone achieved high results, exceeding even those on DNA itself.
 ...
PMID:Effects of selective extraction of histones on template activities of chromatin by use of exogenous DNA and RNA polymerases. 457 8


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