Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:2.7.7.7 (DNA polymerase)
 17,007 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The induction of prophage lambda by ultraviolet light has been measured in E. coli K12 lysogenic cells deficient in DNA polymerase I. The efficiency of the induction process was greater in polA1 polC(dnaE) double mutants incubated at the temperature that blocks DNA replication than in polA+ polC single mutants. Similarly, the polA1 mutation sensitized tif-promoted lysogenic induction in a polA1 tif strain at 42 degrees. In strains bearing the polA12 mutation, which growth normally at 30 degrees, induction of the prophage occurred after the shift to 42 degrees. It is concluded that dissapearance of the DNA polymerase I activity leads to changes in DNA replication that are able, per se, trigger the prophage induction process.
Mol Gen Genet 1977 Sep 09
PMID:Prophage induction in Escherichia coli K12 cells deficient in DNA polymerase I. 33 8

The influence of polyamines on the various activities of DNA polymerase I from Escherichia coli (EC 2.7.7.7) has been investigated. For all high molecular weight DNAs spermine and spermidine caused up to 80% inhibition when present in high concentrations, i.e. above 1 mM for spermine and 2 mM for spermidine. In the presence of low concentrations of polyamines a small activation was seen for some DNAs. The diamines cadaverine and putrescine had little influence on the rate of synthesis with natural occurring DNAs. In the case of d(A--T)n the activation/inhibition was found to be markedly dependent on the molecular weight of the samples used. With a low molecular weight DNA, 5.6 S, addition of spermidine resulted in up to 3-fold stimulation of activity. The activation was dependent on the concentration of MgCl2 and ionic strength; increasing concentration of these gave a decrease in the degree of activation. Polyamines also had a dramatic effect on the rate of synthesis using the homopolymers (dA)n . (dT)10 and (rA)n . (dT)10 . (20:1) as primers. Putrescine, in particular, increased the activity up to 10-fold with (rA)n . (dT)10 and somewhat less for (dA)n . (dT)10. The apparent Km for the primer (rA)n . (dT)10 decreased approx. 35-fold in the presence of 6.6 mM putrescine. There was no influence on the apparent Km for dTTP. The influence of polyamines on both the 5' leads to 3' and 3' leads to 5' nuclease activity was also investigated. Inhibition of nuclease activity was observed in the presence of polyamines, particularly with spermine. Thus with d(A--T)n and T7 DNA as substrates addition of 0.7 mM spermine resulted in almost complete inhibition of the activity. The dramatic inhibition observed with high concentrations of spermine (spermidine) both in the case of polymerizing and nuclease activity is thought to be due to polyamine-induced aggregation of DNA molecules.
Biochim Biophys Acta 1978 Sep 27
PMID:Influence of polyamines on the activity of DNA polymerase I from Escherichia coli. 36 Oct 88

The discovery of Australian antigen (HBsAg) has led to an increasing deal of knowledges about the virus of type B hepatitis (HBV); several markers of HBV have been detected and are becoming disposable for clinical and epidemiological purposes. The HBsAg is carried by 3 types of particulate structures discovered by electron microscopy as small spherical particles having diameter around 22 nm, long filaments and spherical particles having an overall diameter of the 42 nm (Dane-particle) with an electron-dense core. Dane-particle core contains circular double-stranded DNA molecules and an enzyme, the DNA polymerase. At present, Dane-particle is thought to represent the HBV, having properties consistent with those of a complete virus. Four antigen/antibody systems related to viral type B hepatitis have been discovered; they have been designated with the following nomenclature: HBsAg/anti-HBs, HBcAg/anti-HBc, HBeAg/anti-HBe, epilon antigen/anti epilson. The availability of the HBV markers for clinical purposes will permit a better understanding of the sequence of the biological reactions as well as of the clinical and epidemiological features concerning this viral infection: incubation period, acute disease, resolution, chronic carrier state, actively or passively immunized subject, persistent or subsided infectivity, prognosis.
Minerva Med 1979 Sep 26
PMID:[Markers of type B viral hepatitis]. 38 66

A sequence of 1019 nucleotides encompassing one of the 600 base inverted repeats and non-repeated flanking regions has been determined in the type A yeast 2 micrometers plasmid cloned in pMB9. Methods are described for applying the Maxam-Gilbert sequencing procedure to DNA fragments labelled at the 3'-end using a T4-polymerase exchange/repair reaction and for sequencing 5'-end labelled fragments using dideoxy-nucleotides as chain terminators in the presence of E. coli DNA polymerase (nach Klenow). A notable feature of the sequence is its unusual content of symmetry elements. In one region of 140 nucleotides, 137 are involved in a complex arrangement of direct and inverted repeats linked by palindromic sequences.
Nucleic Acids Res 1979 Sep 25
PMID:Sequence of 1019 nucleotides encompassing one of the inverted repeats from the yeast 2 micrometer plasmid. 38 82

Genetic recombination in Escherichia coli is a highly regulated process involving multiple gene products. We have investigated the role of DNA polymerase I in this process by studying the effect of the po1A1 mutation upon DNA transfer and conjugation in otherwise isogenic suppressor-free strains of E. coli K-12. It was found that the po1A1 mutation greatly reduces recombination in Hfr crosses (a factor of 20 in Pol+ x Po1A1 crosses and more than a factor of 100 in Po1A1 X Po1A1 crosses). However, since the po1A1 mutation reduces the strains capacity to act as a recipient for an F-prime and the analysis of recombination transfer gradients revealed no differences between Po1+ and Po1- strains, it is concluded that DNA polymerase I probably affects the transfer and/or stability of donor DNA rather than the recombinational process itself.
Can J Genet Cytol 1979 Sep
PMID:The influence of the PO1A1 mutation upon recombination in Escherichia coli K12. 39 70

Deoxyribonucleic acid (DNA) polymerase III is not detectable in Bacillus subtilis spores; the enzyme activity appears 20 to 30 min after spore activation and rapidly increases just before the onset of the first round of DNA replication (30 min later); the level of polymerase III further increases and reaches its maximum (on a per-genome basis) when the cells enter the vegetative phase of growth; this level is six- to eightfold higher than the one observed during germination. In the stationary phase, the polymerase III drops to levels comparable to those found in germinating spores at the first round of replication. On the contrary, DNA polymerase I is present at appreciable levels in the dormant spore; it increases during vegetative growth by a factor of three and, during the stationary phase, reaches its maximum level which is sixfold higher than that observed in the spores. The block of protein synthesis during vegetative growth does not cause an appreciable reduction of the two enzymes (in absolute terms), showing that the regulation of their levels is probably not due to a balance between synthesis and breakdown. These results indicate that polymerase III is probably one of the factors controlling the initiation of DNA synthesis during spore germination.
J Bacteriol 1977 Sep
PMID:Modulation of deoxyribonucleic acid polymerase III level during the life cycle of Bacillus subtilis. 40 27

An enzyme which enhances the priming activity of gamma-irradiated DNA for type I DNA polymerase (EC 2.7.7.7) was identified and partially purified from extracts of Bacillus subtilis cells. The enzyme preferentially degraded gamma-irradiated DNA into acid-soluble materials. DNA preparations treated with heat, ultraviolet light, pancreatic DNAase (EC 3.1.4.5) or micrococcal DNAase (EC 3.1.4.7) were not susceptible to the enzyme. However, sonication rendered DNA susceptible to the enzyme to some extent. From these results, it is supposed that this enzyme may function by 'cleaning' damaged terminals produced by gamma-irradiation to serve as effective priming sites for repair synthesis by the type I DNA polymerase.
Biochim Biophys Acta 1977 Sep 20
PMID:Studies on DNA repair in Bacillus subtilis. III. Identification of an exonuclease which enhances the priming activity of gamma-irradiated dna by "cleaning' damaged ends. 40 35

Idoxuridine which was first used in 1960 (Kaufman et al., 1962), has been for many years the only antiviral agent available in the treatment of herpetic keratitis. It is however no more successful than is mechanical removal of diseased epithelium (Patterson & Jones, 1967), and furthermore it may give rise to serious toxic side effects. The search for an alternative medication is therefore a pressing one. Trifluorothymidine (F3T) has, in recent years, been shown to be more effective than IDU and to be free from significant toxicity. Both of these drugs are pyrimidine nucleosides. Adenine Arabinoside or Arabinoside-A (Ara-A) is, by contrast, a purine nucleoside. It is thought to exert its antiviral effect by blocking DNA polymerase and ribonucleotide reductase.
Doc Ophthalmol 1977 Sep 30
PMID:Treatment of herpetic keratitis. 41 44

6-(Phenylhydrazino)uracils inhibit the replication-specific enzyme DNA polymerase III of Bacillus subtilis by forming a strong, reversible complex with template-primer DNA and enzyme. The phenyl ring interacts with a hydrophobic enzyme site which, on the basis of structure-activity relationships of substituted analogues, appears to possess the following characteristics: (1) planarity or near-planarity; (2) a finite capacity to accommodate bulky substituents; and (3) location near the domain of the enzyme active site. A mutant DNA polymerase III, derived from a mutant strain of B. subtilis selected for resistance to 6-(p-hydroxyphenylazo)pyrimidines, is resistant only to inhibitors bearing p-hydroxy or amino groups and is hypersensitive to inhibitors containing nonpolar substituents; these results suggest the existence of mutable, secondary regions of the binding site which interact with para substituents and, thus, influence the strength of the primary phenyl-enzyme interaction.
J Med Chem 1977 Sep
PMID:Inhibitors of Bacillus subtilis DNA polymerase III. Structure-activity relationships of 6-(phenylhydrazino)uracils. 41 33

6-(Benzylamino)uracils and substituted 6-anilinouracils have been found to be potent inhibitors of Bacillus subtilis DNA polymerase III by a mechanism identical with that of 6-(phenylhydrazino)uracils. Higher phenylalkylamino homologues are progressively weaker inhibitors of the enzyme. Examination of the effects of substituents on the activity of 6-(benzylamino)uracils against wild-type and mutant enzymes and preliminary results for 6-anilinouracils have permitted further dissection of the mechanism of inhibition. The experimental results indicate that (1) the polymerase inhibitor binding site is compact, accommodating only small alterations in the distance between the uracil and phenyl rings, (2) the phenyl ring, which provides the major contribution to inhibitor-enzyme binding, adopts a specific active conformation, and (3) an enzyme site which interacts with substituents in the phenyl ring forms a part of the active site of DNA polymerase III.
J Med Chem 1977 Sep
PMID:Inhibitors of Bacillus subtilis DNA polymerase III. 6-(arylalkylamino)uracils and 6-anilinouracils. 41 34


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