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Biomedical subjects

L Rutberg

Publications and source records attributed to L Rutberg.

At least 55 records · Page 3Linked to original sources
PubMed1974

Glycerol metabolism in Bacillus subtilis: gene-enzyme relationships.

Bacillus subtilis mutants unable to catabolize glycerol (Glp mutants) were isolated and mapped. The location of the mutations on the chromosome was determined by a density transfer technique and confirmed by PBS1 transduction and transformation. The different mutations were ordered relative to each other. Mutations rendering the cells glycerol auxotrophic were also mapped and found not to be linked to the Glp mutations.

Bacillus subtilis↗
PubMed1974

Induction of prophage SPO2 in Bacillus subtilis by 6-(para)-hydroxyphenylazouracil.

DNA replication in Bacillus subtilis is reversibly inhibited by 6-(para)-hydroxyphenylazouracil (HpUra) (1971), whereas replication of temperature phage SPO2 is not affected by the drug. Experiments are presented which show that HpUra will induce bacteria lysogenic for SPO2. Also, prophage phi105, which is sensitive to the drug, is induced by HpUra. Induction of SPO2 lysogenics in the presence of HpUra gives selective synthesis of SPO2 DNA.

Azo Compounds↗
PubMed1974

Induction of prophage SPO2 in Bacillus subtilis: prophage excision in the absence of bacterial or bacteriophage DNA synthesis.

Bacillus subtilis lysogenic for SPO2 wild type was induced under conditions preventing synthesis of both bacterial and phage DNA. The infectivity of phage DNA in transfection is strongly decreased under these conditions, whereas the activity of single phage genes as measured by marker rescue with superinfecting phage is unaffected. DNA from induced cells was sedimented in neutral sucrose gradients. After induction, phage DNA was detected at a position in the gradients, which was different from the bulk of the bacterial DNA, corresponding to linear double-stranded DNA of about 25 x 10(6) daltons. Similar results were obtained with bacteria lysogenic for a SPO2 prophage carrying a DNA-negative mutation. No separation of phage and bacterial DNA activity was detected when chloramphenicol was present during the induction period. These experiments show that prophage SPO2 can excise from the bacterial chromosome without previous replication.

Azo Compounds↗
PubMed1973

Heat induction of prophage phi 105 in Bacillus subtilis: bacteriophage-induced bidirectional replication of the bacterial chromosome.

A mutant of Bacillus subtilis, dna-1, which cannot initiate new rounds of DNA replication (obtained from N. Sueoka) was lysogenized with wild-type phi 105 and with the heat-inducible mutant phi 105 cts23. Bacteria were incubated at the permissive temperature in the presence of chloramphenicol and then shifted to the nonpermissive temperature where induction of phi 105 cts23 occurs. DNA made after the shift was labeled with a density label, and the distribution of bacterial and phage markers in replicated and unreplicated DNA was determined. Similar experiments were performed with nonlysogenic dna-1 infected with phage phi 105 cts23 after the temperature shift. The results show that after induction of phi 105 cts23 prophage, bacterial markers on either side of the prophage replicate at an increased rate compared to more distant markers. No selective stimulation of bacterial DNA synthesis was observed on infection or after shifting bacteria lysogenic for noninducible phage to the higher temperature. Attempts to suppress the initiation mutation dna-1 by phage phi 105 were unsuccessful.

Bacillus subtilis↗
PubMed1972

Deoxyribonucleic acid polymerase activity in a deoxyribonucleic acid polymerase I-deficient mutant of Bacillus subtilis infected with temperature bacteriophage SPO2.

Increased deoxyribonucleic acid (DNA) polymerase activity is found in soluble extracts from a polymerase I-negative mutant of Bacillus subtilis after infection with temperate phage SPO2, or after induction of SPO2 prophage in lysogenic derivatives of this mutant. No increased enzyme activity is found after SPO2 infection in the presence of chloramphenicol. Infection of the polymerase-negative mutant with the DNA-negative sus mutant SPO2 L244 gives no increased enzyme activity, whereas infection with DNA-negative sus mutant SPO2 J385 gives enzyme activities comparable to those found in wild-type infected cells. These findings suggest that SPO2 determines a DNA polymerase activity essential for synthesis of phage DNA.

Bacillus subtilis↗
PubMed1972

Unrelatedness of temperate Bacillus subtilis bacteriophages SP02 and phi105.

SPO2 and phi105 are temperate Bacillus subtilis bacteriophages which have been suggested to belong to a cluster of related bacteriophages. In the present work, we show that SPO2 does not complement any of the 11 essential genes known in phi105 and that the phages do not recombine. Deoxyribonucleic acid (DNA)-DNA hybridization shows less than 10% homology between SPO2 and phi105 DNA. DNA synthesis in phi105 shows a greater dependence on host functions than does SPO2 DNA synthesis. Growth of phi105 but not of SPO2 is inhibited by the uracil analogue 6-(p-hydroxyphenylazo)-uracil. Infection of a DNA polymerase-deficient strain of B. subtilis with SPO2 leads to an increase in DNA polymerase activity in crude extracts, whereas no such increase is found after infection of this strain with phi105. It is concluded that SPO2 and phi105 are unrelated bacteriophages.

Azo Compounds↗
PubMed1971

Structure and biological activity of deoxyribonucleic acid from Bacillus bacteriophage phi 105: effects of Escherichia coli exonucleases.

The effects of Escherichia coli exonuclease I, exonuclease III, and deoxyribonucleic acid (DNA) polymerase on the biological activity of mature DNA from temperate Bacillus bacteriophage phi105 were investigated. Intact DNA loses infectivity rapidly upon exposure to exonuclease III. Although there is an overall decrease in marker rescue from exonuclease III-digested DNA, digestion preferentially affects markers at the end of the genetic map. This is taken to indicate a nonpermuted gene sequence in mature DNA. Incubation of mature DNA in the presence of exonuclease I or DNA polymerase has no effect on its biological activity. The possible structure of the ends of mature phi105 DNA is discussed. The rate of digestion of mature phi105 DNA by exonuclease III is only about 1/20 the rate of lambda DNA. Results of digestion of various DNA substrates by exonuclease III indicate that the enzyme distinguishes between different DNA terminal structures.

Bacillus subtilis↗
PubMed1971

Heat induction of prophage phi 105 in Bacillus subtilis: replication of the bacterial and bacteriophage genomes.

A temperature-inducible mutant of temperate Bacillus bacteriophage phi105 was isolated and used to lysogenize a thymine-requiring strain of Bacillus subtilis 168. Synthesis of phage and bacterial deoxyribonucleic acid (DNA) was studied by sucrose gradient centrifugation and density equilibrium centrifugation of DNA extracted from induced bacteria. The distribution of DNA in the gradients was measured by differential isotope and density labeling of DNA before and after induction and by measuring the biological activity of the DNA in genetic transformation, in rescue of phage markers, and in infectivity assays. At early times after induction, but after at least one round of replication, phage DNA remains associated with high-molecular-weight DNA, whereas, later in the infection, phage DNA is associated with material of decreasing molecular weight. Genetic linkage between phage and bacterial markers can be demonstrated in replicated DNA from induced cells. Prophage induction is shown to affect replication of the bacterial chromosome. The overall rate of replication of prelabeled bacterial DNA is identical in temperature-induced lysogenics and in "mock-induced" wild-type phi105 lysogenics. The rate of replication of the bacterial marker phe-1 (and also of nia-38), located close to the prophage in direction of the terminus of the bacterial chromosome, is increased in induced cells, however, relative to other bacterial markers tested. In temperature-inducible lysogenics, where the prophage also carries a ts mutation which blocks phage DNA synthesis, replication of both phage and bacterial DNA stops after about 50% of the phage DNA has replicated once. The results of these experiments suggest that the prophage is not initially excised in induced cells, but rather it is specifically replicated in situ together with adjacent parts of the bacterial chromosome.

Bacillus subtilis↗
PubMed1971

Growth of bacteriophage phi 105 and its deoxyribonucleic acid in radiation-sensitive mutants of Bacillus subtilis.

Growth of phage phi105 and its deoxyribonucleic acid (DNA) was studied in radiation-sensitive mutants of Bacillus subtilis. The recA gene is required for optimal prophage induction with mitomycin C and for infectivity of prophage DNA. rec B gene is required for marker rescue from mature DNA. The importance of bacterial genes for phage DNA activity seems to depend on phage DNA structure.

Bacillus subtilis↗
PubMed1970

Characterization of infectious deoxyribonucleic acid from temperature Bacillus subtilis bacteriophage phi105.

Phenol-extracted, infectious deoxyribonucleic acid (DNA) species from phi105 phage particles, from phi105 lysogenic bacteria, and from induced phi105 lysogenic bacteria were sedimented in sucrose gradients. Infectious DNA from phi105 particles sedimented like the bulk of mature phage DNA in neutral sucrose. Infectivity of prophage DNA was associated with fast-sedimenting material of heterogenous size. Infectious vegetative phage DNA sedimented somewhat faster than mature phage DNA; it was rapidly converted to a poorly infectious form during the infection.

Bacillus subtilis↗
PubMed1970

Mapping of prophage and mature deoxyribonucleic acid from temperate Bacillus bacteriophage phi 105 by marker rescue.

By using temperature-sensitive (ts) and suppressor-sensitive (sus) mutants, 11 essential genes have been identified in phage phi105. The order of the genes has been established in two- and three-factor crosses. The genes can be arranged in a linear order; this order is identical in the vegetative phage and in the prophage. One gene essential for phage deoxyribonucleic acid (DNA) synthesis has been found. Marker rescue from prophage and mature DNA, taken up by competent bacteria, was studied by superinfection with phage carrying one sus and one ts mutation. In prophage DNA, all single markers studied are rescued at similar frequencies. The frequency of co-rescue of two markers is proportional to the recombinational distance between the markers. Thus, colinearity between the genetic map and the position on the DNA molecule of those mutations used to establish the map is demonstrated. The results indicate that the recombination frequencies observed in vegetative crosses are a relative measure of the physical distance between markers. All single markers are not rescued at equal frequencies from mature DNA. The frequency of co-rescue of two markers is related to the recombinational distance only over a distance about one-fourth or less of the genetic map. Markers separated by 10% recombination, or more, are co-rescued at 5 to 10% of the frequency of rescue of single markers. Shearing of mature DNA into half-sized molecules reduces the efficiency by which single markers are rescued by a factor of 5 to 10. The results of experiments on co-rescue of two markers from half-sized mature DNA indicate a preferred break-point near the middle of the genetic map; the results are compatible with a nonpermuted sequence in mature DNA. It is pointed out and discussed that mature DNA exhibits several anomalies in marker rescue experiments.

Bacillus↗
PubMed1970

Low-frequency rescue of a genetic marker in deoxyribonucleic acid from Bacillus bacteriophage phi 105 by superinfecting bacteriophage.

Markers in gene L, which maps at the right end of the vegetative and prophage maps, are rescued at a strongly reduced frequency from mature phi105 deoxyribonucleic acid (DNA) by superinfecting phage but at high frequency from vegetative and prophage DNA. It is suggested that the ends of mature DNA are degraded when DNA is taken up by competent cells.

Bacillus↗
PubMed1969

Linked transformation of bacterial and prophage markers in Bacillus subtilis 168 lysogenic for bacteriophage phi 105.

Level of competence reached by Bacillus subtilis 168 lysogenic for temperate phage phi 105 was reduced compared to that reached by nonlysogenic cells. This effect was probably related to an alteration of the bacterial surface. Deoxyribonucleic acid extracted from phi 105 lysogenic bacteria was used to transform other lysogenic bacteria. About 25% linkage was found between the bacterial phe-1 marker and prophage marker ts N15. The order of a few prophage markers relative to phe-1 was established in three-factor crosses. The usefulness of this system for a study of the linkage between an integrated prophage genome and that of its host was discussed.

Bacillus subtilis↗
PubMed1969

Mapping of a temperate bacteriophage active on Bacillus subtilis.

Bacteriophage phi105 is a temperate bacteriophage for Bacillus subtilis 168. Temperature-sensitive and plaque mutants of phi105 were isolated. The results of two- and three-factor crosses with these mutants suggest the vegetative map of phi105 to be circular. The location of prophage phi105 between bacterial markers phe-1 and ilvA1 was shown by means of PBS1 transduction. Five markers in the prophage were linearly ordered with respect to the bacterial markers. Linkage between bacterial and prophage markers was demonstrated in transformation experiments with deoxyribonucleic acid extracted from lysogenic bacteria. The data demonstrate that prophage phi105 is linearly inserted into the bacterial chromosome.

Bacillus subtilis↗