MODIFYING FACTORS OF THE CELLULAR CONCENTRATION OF PHOTOLYASE MOLECULES IN Saccharomyces cerevisiae CELLS–I. EFFECTS OF TEMPERATURE AND LIGHT

Abstract

Abstract— The effects of temperature and light on the cellular concentration of photoreactivating enzyme (PRE) molecules in haploid Saccharomyces cerevisiae cells were investigated. (1) Temperature effect: The number of active PRE molecules per cell (NPRE) in cells grown at 37°C was about 13% of that grown at 23°C, although the amount of proteins per cell remained the same. (2) Light effect: NPRE in cells grown in light was about 2.8 times larger than that grown in the dark. The value of NPRE in cells grown in the light decreased more rapidly during holding in buffer in the dark than in the light. The NPRE decrease during holding in buffer in the dark was more rapid in cells grown in the light than grown in the dark. A comparable decrease was observed after holding in buffer in the presence of cycloheximide. (3) In cells harboring a plasmid containing the gene PHR1, NPRE was larger in cells grown at 23 than at 30°C.

MODIFYING FACTORS OF THE CELLULAR CONCENTRATION OF PHOTOLYASE MOLECULES IN Saccharomyces cerevisiae—II. EFFECTS OF PREILLUMINATION WITH LIGHT FLASHES

“…In the previous paper (Fukui and Laskowski, 1984) it has also been shown that &REact in stat-cells grown in the dark at 23, 30 or 37°C is 229, 92 and 31, respectively. This difference of NpREact in stat-cells grown a t various temperatures can hardly be explained solely by thermodynamic inactivation of active P R E molecules.…”

“…This preillumination effect agrees with the thermal stability-effect of preillumination on PR activity of active PRE molecules reported by Harm and Rupert (1976). In the previous paper the effect of continuous light-illumination on N p~E was investigated (Fukui, Laskowski, 1984). The N~R E~~~ of stat-cells grown in the dark at 30°C was about 90.…”

“…The time interval between the last preillumination flash and PR with 1 light flash after UV-irradiation was shorter than 1 h except in buffer holding experiments. The conditions of UVirradiation were described by Fukui and Laskowski (1984).…”

“…In a previous paper (Fukui and Laskowski, 1984), it was shown that NPREact was affected by lightillumination during cell culture and resuspension in buffer and also by temperature during cell culture. It was proposed that a portion of the variation of NpREact in cells illuminated with light was due to the activation of inactive PRE molecules by light illumination.…”

Repair of (6-4) Photoproducts in Cultured Goldfish Cells at Confluence or Treated with H2O2

“…Physiological changes are brought about by factors that are assumed not to damage DNA directly but to induce DNA repair ability, such as growth inhibition, temperature shift and depletion of nutrition (4,5). Regarding the SOS response and the adaptive responses in bacteria, there are many detailed reports on the molecular mechanisms for the induction of DNA repair ability (6)(7)(8)(9).…”