EXO1-dependent single-stranded DNA at telomeres activates subsets of DNA damage and spindle checkpoint pathways in budding yeast yku70Δ mutants (original) (raw)

  1. Laura Maringele and
  2. David Lydall1
  3. School of Biological Sciences, University of Manchester, Manchester M13 9PT, UK

Abstract

We have examined the role of checkpoint pathways in responding to a_yku70_Δ defect in budding yeast. We show that_CHK1_, MEC1, and RAD9 checkpoint genes are required for efficient cell cycle arrest of _yku70_Δ mutants cultured at 37°C, whereas RAD17,RAD24, MEC3, DDC1, and _DUN1_play insignificant roles. We establish that cell cycle arrest of_yku70_Δ mutants is associated with increasing levels of single-stranded DNA in subtelomeric Y‘ regions, and find that the mismatch repair-associated EXO1 gene is required for both ssDNA generation and cell cycle arrest of _yku70_Δ mutants. In contrast, MRE11 is not required for ssDNA generation. The behavior of _yku70_Δ _exo1_Δ double mutants strongly indicates that ssDNA is an important component of the arrest signal in_yku70_Δ mutants and demonstrates a link between damaged telomeres and mismatch repair-associated exonucleases. This link is confirmed by our demonstration that EXO1 also plays a role in ssDNA generation in cdc13-1 mutants. We have also found that the MAD2 but not the BUB2 spindle checkpoint gene is required for efficient arrest of _yku70_Δ mutants. Therefore, subsets of both DNA-damage and spindle checkpoint pathways cooperate to regulate cell division of _yku70_Δ mutants.

Footnotes