Heat shock changes the response of the pso3 mutant of Saccharomyces cerevisiae to 8-methoxypsoralen photoaddition.
A putative tolerance, induced by heat shock (HS), to the lethal and mutagenic effects of 8-methoxypsoralen (8-MOP) photoaddition and hyperthermia was analyzed in Saccharomyces cerevisiae using the wild-type strain N123 and the isogenic DNA repair-deficient mutant pso3-1. In wild-type cells, the HS (38 degrees C for 1 h) did not modify either the survival or the mutation frequency observed after 8-MOP photoaddition, even though it conferred protection against the lethal effect of hyperthermia (50 degrees C). In the pso3-1 mutant, HS induced an increase of the survival, and a decrease of the mutation frequency, after 8-MOP photoaddition and it also protected against the lethal effect of hyperthermia. The responses induced by HS were specific for 8-MOP photoaddition, since they were not observed after 254 nm ultraviolet-light damage. These results indicate that the protection conferred by HS depends of the type of lesion, and operates through the induction of different repair processes. In the pso3-1 mutant, HS could channel the repair intermediates to and error-free repair pathway.
Keszenman
D J
DJ
Departamento de Biofísica, Facultad de Medicina, Universidad de la República, Montevideo, Uruguay.
Santos
J F
JF
Boeira
J M
JM
Saffi
J
J
Henriques
J A
JA
D004260:DNA Repair / Q000235:genetics; D004307:Dose-Response Relationship, Radiation; D005800:Genes, Fungal / Q000187:drug effects* / Q000528:radiation effects; D006358:Hot Temperature; D007700:Kinetics; D008730:Methoxsalen / Q000494:pharmacology*; D016296:Mutagenesis; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000254:growth & development* / Q000528:radiation effects; D014466:Ultraviolet Rays
D008730:Methoxsalen