DARK REACTIVATION OF ULTRAVIOLET IRRADIATED BACTERIOPHAGE DEOXYRIBONUCLEIC ACID IN VITRO

Journal Article · Mon Feb 17 04:00:00 EST 1964 · Biochimica et Biophysica Acta (Netherlands)

DOI:https://doi.org/10.1016/0926-6550(64)90108-2· OSTI ID:4078478

Roersch, A; van der Kamp, C; Adema, J

Preincubation of irradiated RF-DNA with an enzyme preparation from Micrococcus lysodeikticus led to a marked increase of the biological activity of the DNA in hcr/sup -/ spheroplasts. A cell-free extract of M. lysodeikticus was brought to 55% saturation with ammonium sulfate, the precipitate was collected and redissolved in 0.01 M phosphate buffer (pH 7.0). 0.1 ml of these preparations (1 mgprotein/ml) were incubated for 30 min at 37 deg with 0.1 ml uv- irradiated and nonirradiated solutions of RF-DNA (1 mu g DNA/ml). After incubation the mixtures were diluted one in ten in phosphate buffer; 0.l ml of these dilutions were added to spheroplast suspensions of wild type E. coli K l2 S hcr/sup +/ and of its hcr/sup -/ mutant. The results of a number of representative experiments are summarized. The preincubation with the enzyme preparation had a negligible effect on the activity of nonirradiated DNA; the biological activity of irradiated DNA was strongly enhanced only when its activity was estimated in hcr- spheroplasts (dose reduction 2.6) and not in hcr/ sup +/ spheroplasts. This indicates that the reaction in vitro replaces to a certain extent the genetically determined dark-reactivation capacity of the wild type. The thermolability of the active component suggests that the reaction is of enzymic nature. The reactivated DNA fraction increased with the length of the preincubation period which indicates that the reaction occurs in vitro and that the effect is not due to an activation of the spheroplast system. The residual reactivation observed when an undiluted enzyme preparation was added at zero time was due to the proceeding of the reactivation process during the l0-min absorption period of the DNA to the spheroplasts. Extensive dialysis did not reduce the activity of the enzyme preparation nor did the addition of Mg/sup 2+/ stimulate it. (C.H.)

• Research Organization: National Defense Research Organization TNO, Rijswijk, Netherlands
• Sponsoring Organization: USDOE
• NSA Number: NSA-18-015832
• OSTI ID: 4078478
• Journal Information: Biochimica et Biophysica Acta (Netherlands), Journal Name: Biochimica et Biophysica Acta (Netherlands) Vol. Vol: 80; ISSN BBACA
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

ACIDITY
AMMONIUM COMPOUNDS
BACTERIA
BACTERIOPHAGES
BIOLOGY AND MEDICINE
DIALYSIS
DNA
ENZYMES
ESCHERICHIA COLI
IONS
IRRADIATION
MAGNESIUM
MEMBRANES
METABOLISM
MICROCOCCUS LYSODEIKTICUS
NUCLEIC ACIDS
PHOSPHATES
PRECIPITATION
SEPARATION PROCESSES
SOLUTIONS
SULFATES
TEMPERATURE
ULTRAVIOLET RADIATION