Ligase-deficient yeast cells exhibit defective DNA rejoining and enhanced gamma ray sensitivity

Journal Article · Tue Jun 01 04:00:00 EDT 1982 · J. Bacteriol.; (United States)

OSTI ID:6578198

Moore, C W

Yeast cells deficient in DNA ligase were also deficient in their capacity to rejoin single-strand scissions in prelabeled nuclear DNA. After high-dose-rate gamma irradiation (10 and 25 krads), cdc9-9 mutant cells failed to rejoin single-strand scissions at the restrictive temperature of 37/sup 0/C. In contrast, parental (CDC9) cells (incubated with mutant cells both during and after irradiation) exhibited rapid medium-independent DNA rejoining after 10 min of post-irradiation incubation and slower rates of rejoining after longer incubation. Parental cells were also more resistant than mutant cells to killing by gamma irradiation. Approximately 2.5 +- 0.07 and 5.7 +- 0.6 single-strand breaks per 10/sup 8/ daltons were detected in DNAs from either CDC9 or cdc9-9 cells converted to spheroplasts immediately after 10 and 25 krads of irradiation, respectively. At the permissive temperature of 23/sup 0/C, the cdc9-9 cells contained 2 to 3 times the number of DNA single-strand breaks as parental cells after 10 min to 4 h of incubation after 10 krads of irradiation, and two- to eightfold more breaks after 10 min to 2.5 h of incubation after 25 krads of irradiation. Rejoining of single-strand scissions was faster in medium. After only 10 min in buffered growth medium after 10 krads of irradiation, the number of DNA single-strand breaks was reduced to 0.32 +- 0.3 (at 23/sup 0/C) or 0.21 +- 0.05 (at 37/sup 0/C) per 10/sup 8/ daltons in parental cells, but remained at 2.1 +- 0.06 (at 23/sup 0/C) or 2.3 +- 0.07 (at 37/sup 0/C) per 10/sup 8/ daltons in mutant cells. After 10 or 25 krads of irradiation plus 1 h of incubation in medium at 37/sup 0/C, only DNA from CDC9 cells was rejoined to the size of DNA from unirradiated cells, whereas at 23/sup 0/C, DNAs in both strains were completely rejoined.

• Research Organization: Univ. of Rochester, NY
• OSTI ID: 6578198
• Journal Information: J. Bacteriol.; (United States), Journal Name: J. Bacteriol.; (United States) Vol. 150:3; ISSN JOBAA
• Country of Publication: United States
• Language: English

Related Subjects

560131* -- Radiation Effects on Microorganisms-- Basic Studies-- (-1987)
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
BIOLOGICAL RECOVERY
BIOLOGICAL REPAIR
CARBON 14 COMPOUNDS
CELL KILLING
DNA
DOSE-RESPONSE RELATIONSHIPS
DOSES
ELECTROMAGNETIC RADIATION
ENZYME ACTIVITY
ENZYMES
FUNGI
GAMMA RADIATION
IONIZING RADIATIONS
ISOTOPE APPLICATIONS
LABELLED COMPOUNDS
LIGASES
MICROORGANISMS
NUCLEIC ACIDS
ORGANIC COMPOUNDS
PLANTS
RADIATION DOSES
RADIATIONS
RADIOINDUCTION
RADIOSENSITIVITY
RECOVERY
REPAIR
SACCHAROMYCES
SACCHAROMYCES CEREVISIAE
STRAND BREAKS
TRACER TECHNIQUES
TRITIUM COMPOUNDS
YEASTS