FIG. 4.

srs2Δ mutation suppresses ssDNA production in CLUV-exposed rad18Δ cells. (A and C) Asynchronous cultures of the indicated strains were treated with CLUV for 3 h and examined by fluorescence microscopy. The percentage of cells with RPA-YFP (A) or Ddc2-YFP (C) foci is shown. The results represent the means of three independent measurements. The error bars indicate the standard deviations. (B) Representative RPA-YFP foci are shown. (D) Asynchronous cultures were treated with CLUV for the indicated times or with 0.1% MMS for 30 min. Chromosomal DNA was separated by PFGE and detected by staining with SYBR gold. The percentage of cells with RPA-YFP foci is indicated at the bottom. (E) Cell viability was measured as described for Fig. 1A. The error bars indicate the standard deviations. All strains contain a deletion of SML1, which suppresses mec1Δ lethality without suppressing the checkpoint defect. (F) Deletion of SRS2 does not affect CLUV-induced RPA foci in rad18Δ cells when HR function is impaired. Cells grown to logarithmic phase were treated with CLUV and examined by fluorescence microscopy as with panel A. The results represent the means of at least three independent measurements. The error bars indicate the standard deviations.