Kinetochores Prevent Repair of UV Damage in Saccharomyces cerevisiae Centromeres

AUTOR(ES)

Capiaghi, Christoph

FONTE

American Society for Microbiology

RESUMO

Centromeres form specialized chromatin structures termed kinetochores which are required for accurate segregation of chromosomes. DNA lesions might disrupt protein-DNA interactions, thereby compromising segregation and genome stability. We show that yeast centromeres are heavily resistant to removal of UV-induced DNA lesions by two different repair systems, photolyase and nucleotide excision repair. Repair resistance persists in G1- and G2/M-arrested cells. Efficient repair was obtained only by disruption of the kinetochore structure in a ndc10-1 mutant, but not in cse4-1 and cbf1Δ mutants. Moreover, UV photofootprinting and DNA repair footprinting showed that centromere proteins cover about 120 bp of the centromere elements CDEII and CDEIII, including 20 bp of flanking CDEIII. Thus, DNA lesions do not appear to disrupt protein-DNA interactions in the centromere. Maintaining a stable kinetochore structure seems to be more important for the cell than immediate removal of DNA lesions. It is conceivable that centromeres are repaired by postreplication repair pathways.

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