Glutathione-dependent yield and repair of single-strand DNA breaks in irradiated cells.

The yield and rejoining of single-strand DNA breaks (ssb) was investigated after irradiation of cells which were deficient in glutathione (GSH) either due to a genetic defect of their GSH synthetase activity, or inhibition of gamma-glutamylcysteine synthetase activity by DL-buthionine-SR-sulfoximine (BSO). The results were concordant in indicating that decreased cellular GSH content is associated with an increased yield of ssb after anoxic, but not after aerobic radiation exposures. Rejoining of ssb was delayed and incomplete during a one hour's incubation period after oxic, but not after anoxic exposure of GSH-deficient cells. The defective rejoining capacity of these cells was restituted to nearly normal by the admixture of GSH-proficient cells in the incubation medium.