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Biomedical subjects

A R Price

Publications and source records attributed to A R Price.

At least 37 records · Page 2Linked to original sources
PubMed1976

Bacteriophage PBS2-induced inhibition of uracil-containing DNA degradation.

Degradation of uracil-containing DNA by Bacillus subtilis extracts and its inhibition after infection by the uracil-containing DNA phage PBS2 have been investigated to resolve differences between the published reports of Tomita and Takahashi (1975) and Friedberg et al. (1975, 1976). The product of hydrolysis of PBS2 DNA, tritium labeled in its uracil and cytosine residues, is solely uracil and not deoxyuridine. The degrading activity is completely inhibited within 7 min after PBS2 infection, before any other known PBS2-induced protein is detectable. The production of the PBS2 inhibitor (a small, heat-stable protein) continues until 10 to 20 min postinfection.

Bacillus subtilis↗
PubMed1975

Bacillus subtilis deoxyuridinetriphosphatase and its bacteriophage PBS2-induced inhibitor.

Extracts of Bacillus subtilis contain a deoxyuridinetriphosphatase (dUTPase) activity with a molecular weight of approximately 48,000. The enzyme is maximally active at pH 8.5, being stimulated by Mg2+ and inhibited by EDTA. The enzyme is specific for dUTP among all the natural nucleotides tested, with an apparent Km for dUTP of 2 muM. Bacteriophage PBS2, whose DNA contains uracil instead of thymine, induces upon infection of B. subtilis a new 83,000-dalton protein which inhibits the host's dUTPase. The inhibitor acts immediately and reversibly in vitro to inhibit dUMP production from dUTP. The inhibitor's action is maximal in dUTPase assays performed at pH 6 to 7, and is minimal at pH 9.7. The inhibitor seems to form a higher molecular weight complex with the B. subtilis dUTPase. Increasing the pH of the medium for PBS2 infection from pH 7 to pH 8.85 caused a dramatic decrease in the synthesis of phage DNA and progeny phage. The newly synthesized DNA had an altered thymine/uracil ratio, being increased from less than 0.03 to greater than 1.0. We propose that infection at high pH prevents the PBS2-induced dUTPase inhibitor from blocking the B. subtilis dUTPase activity, thereby allowing the degradation of dUTP and the synthesis of dTTP (both of which are DNA polymerase substrates), so that thymine replaces some of the uracil normally found in PBS2 DNA.

Bacillus subtilis↗
PubMed1975

Inhibition of bacteriophage PBS2 replication in Bacillus subtilis by phleomycin.

Phleomycin is an effective inhibitor of the replication of Bacillus subtilis bacteriophage PBS2, whose DNA contains uracil instead of thymine. Phleomycin does not affect the induction of the known phage enzymes involved in deoxyribonucleotide metabolism. But phage DNA synthesis is severely inhibited by phleomycin, and late virion protein synthesis is eliminated. These effects appear to result from a phleomycin-induced degradation of the parental phage DNA. Similar inhibitory and degradative effects on DNA are seen in phleomyinc-treated, uninfected cells. This system is unaffected by the related antibiotic, bleomycin.

Adenine↗
PubMed1974

Rifampicin-resistant bacteriophage PBS2 infection and RNA polymerase in Bacillus subtilis.

Bacteriophage PBS2 replication is unaffected by rifampicin and other rifamycin derivatives, which are potent inhibitors of Bacillus subtilis RNA synthesis. Extracts of gently-lysed infected cells contain a DNA-dependent RNA polymerase activity which is specific for uracil-containing PBS2 DNA. The PBS2-induced RNA polymerase is insensitive to rifamycin derivatives which inhibit the host's RNA polymerase.

Aminoglycosides↗
PubMed1974

Mutants of Bacillus subtilis bacteriophage phi e defective in dTTP-dUTP nucleotidohydrolase.

Mutants of bacteriophage phie inducing only 1 to 5% of wild-type levels of dTTP-dUTP nucleotidohydrolase give normal bursts of viable progeny phage whose DNA contains 5 to 10% thymine (but no uracil) in place of 5-hydroxymethyluracil. The relative heat lability of one phage mutant enzyme solubilized from the membrane fraction of infected cells suggests that a phie gene codes for the induced dTTPase-dUTPase.

Bacillus subtilis↗
PubMed1974

Bacteriophage PBS2-induced deoxycytidine triphosphate deaminase in Bacillus subtilis.

The dCTP deaminase induced by Bacillus subtilis bacteriophage PBS2, whose DNA contains uracil instead of thymine, requires metal ion and thiol activators and has a molecular weight of 125,000. The enzyme displays sigmoidal substrate saturation kinetics and inhibition by dUTP, consistent with the deaminase's proposed role of providing balanced levels of dUTP and dCTP for PBS2 uracil-DNA synthesis.

Aminohydrolases↗
PubMed1973

Resistance of bacteriophage PBS2 infection to 6-(p-hydroxyphenylazo)-uracil, an inhibitor of Bacillus subtilis deoxyribonucleic acid synthesis.

6-(p-Hydroxyphenylazo)-uracil (HPUra), an inhibitor of semiconservative deoxyribonucleic acid (DNA) synthesis in Bacillus subtilis, does not prevent (but slightly reduces the rate of) replication of the uracil-containing DNA phage PBS2. Our observations are consistent with the hypothesis that all B. subtilis phages which are resistant to HPUra are able to induce a new DNA polymerase activity.

Azo Compounds↗
PubMed1973

Effect of nalidixic acid on PBS2 bacteriophage infection of Bacillus subtilis.

Infection of Bacillus subtilis by PBS2 phage, whose DNA contains uracil instead of thymine, is relatively unaffected by low concentrations of nalidixic acid which severely inhibit B. subtilis DNA synthesis. High concentrations of nalidixic acid do inhibit PBS2 DNA synthesis, but more severely reduce the burst size of PBS2 infections. Hydroxyurea blocks PBS2 DNA synthesis, preventing progeny phage production.

Bacillus subtilis↗
PubMed1972

New deoxyribonucleic acid polymerase induced by Bacillus subtilis bacteriophage PBS2.

The deoxyribonucleic acid (DNA) of Bacillus subtilis phage PBS2 has been confirmed to contain uracil instead of thymine. PBS2 phage infection of wild-type cells or DNA polymerase-deficient cells results in an increase in the specific activity of DNA polymerase. This induction of DNA polymerase activity is prevented by actinomycin D and chloramphenicol. In contrast to the major B. subtilis DNA polymerase, which prefers deoxythymidine triphosphate (dTTP) to deoxyuridine triphosphate (dUTP), the DNA polymerase in crude extracts of PBS2-infected cells is equally active whether dTTP or dUTP is employed. This phage-induced polymerase may be responsible for the synthesis of uracil-containing DNA during PBS2 phage infection.

Bacillus subtilis↗