Figure 1.

MRN is required for NHEJ repair of unprotected taz1Δ telomeres. (A) Scheme of telomeric NotI restriction fragments. Chromosomes I and II each release two telomeric restriction fragments (C, I, L and M). Chromosome III lacks NotI restriction sites. (B) Disruption of the MRN complex prevents taz1Δ NHEJ-mediated telomeric fusions. NotI digests of genomic DNA of the indicated strains were separated by PFGE and chromosomal end-to-end fusions were detected by Southern blot using a telomere probe (arrows indicate the positions of the resolved telomere fusions). C* indicates a C restriction fragment migrating alongside the unresolved C+I, L and M fusion bands. Please note that lanes come from the same Southern blot and that only irrelevant lanes have been removed in the interest of clarity. Full-sized source images of the original scans can be found as an online supplement to this paper. (C) Nitrogen starvation-induced lethality of taz1Δ cells is rescued by deletion of mrn⁺. Logarithmically growing and nitrogen-starved cells were plated on rich medium, and their ability to form colonies was scored after a 5-day incubation at 32°C. A minimum of three independent experiments was performed. Error bars represent 2 × s.e.m.