The involvement of topoisomerases and DNA polymerase I in the mechanism of induced thermal and radiation resistance in yeast

Journal Article · Wed Aug 01 04:00:00 EDT 1990 · Radiation Research; (USA)

DOI:https://doi.org/10.2307/3577546· OSTI ID:6482669

Boreham, D R; Trivedi, A; Weinberger, P; Mitchel, R E ^[1]

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1. Atomic Energy of Canada Limited, Chalk River, Ontario (Canada)

Either an ionizing radiation exposure or a heat shock is capable of inducing both thermal tolerance and radiation resistance in yeast. Yeast mutants, deficient in topoisomerase I, in topoisomerase II, or in DNA polymerase I, were used to investigate the mechanism of these inducible resistances. The absence of either or both topoisomerase activities did not prevent induction of either heat or radiation resistance. However, if both topoisomerase I and II activities were absent, the sensitivity of yeast to become thermally tolerant (in response to a heat stress) was markedly increased. The absence of only topoisomerase I activity (top1) resulted in the constitutive expression of increased radiation resistance equivalent to that induced by a heat shock in wild-type cells, and the topoisomerase I-deficient cells were not further inducible by heat. This heat-inducible component of radiation resistance (or its equivalent constitutive expression in top1 cells) was, in turn, only a portion of the full response inducible by radiation. The absence of polymerase I activity had no detectable effect on either response. Our results indicate that the actual systems that confer resistance to heat or radiation are independent of either topoisomerase activity or DNA polymerase function, but suggest that topoisomerases may have a regulatory role during the signaling of these mechanisms. The results of our experiments imply that maintenance of correct DNA topology prevents induction of the heat-shock response, and that heat-shock induction of a component of the full radiation resistance in yeast may be the consequence of topoisomerase I inactivation.

• OSTI ID: 6482669
• Journal Information: Radiation Research; (USA), Journal Name: Radiation Research; (USA) Vol. 123:2; ISSN 0033-7587; ISSN RAREA
• Country of Publication: United States
• Language: English

Related Subjects

560130* -- Radiation Effects on Microorganisms
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
BIOLOGICAL FUNCTIONS
DNA POLYMERASES
ENZYME ACTIVITY
ENZYMES
EUMYCOTA
FUNCTIONS
FUNGI
ISOMERASES
MICROORGANISMS
NUCLEOTIDYLTRANSFERASES
PHOSPHORUS-GROUP TRANSFERASES
PLANTS
POLYMERASES
RADIOSENSITIVITY
RADIOSENSITIVITY EFFECTS
SACCHAROMYCES
SACCHAROMYCES CEREVISIAE
TRANSFERASES
YEASTS