Cdc13 and telomerase bind through different mechanisms at the lagging- and leading-strand telomeres.
Lagging-strand and leading-strand synthesis of chromosomes generates two structurally distinct ends at the telomeres. Based on sequence bias of yeast telomeres that contain a 250-300 bp array of C(1-3)A/ TG(1-3) repeats, we developed a method allowing us to distinguish which of the two daughter telomeres chromosome end-binding proteins bind to at the end of S phase. The single-stranded DNA-binding protein Cdc13 and the telomerase subunits Est1 and Est2 can bind to the two daughter telomeres, but only their binding to the leading-strand telomere depends on the Mre11/Rad50/Xrs2 (MRX) complex involved in both telomeric 5' nucleolytic resection and telomerase recruitment at short telomeres. Consistently, the MRX complex is mainly found to bind to the leading-strand telomere. Our results indicate that Cdc13 can bind to the telomeric template for lagging-strand replication. Since mre11-deficient strains have markedly short telomeres, telomere elongation by telomerase is likely to occur mainly at the leading-strand telomere.
Faure
Virginie
V
CNRS, UPR3081, Ifr88, Genome Instability and Carcinogenesis Conventionné par l'Université d'Aix-Marseille 2, 13402 Marseille Cedex 20, France.
Coulon
Stéphane
S
Hardy
Julien
J
Géli
Vincent
V
D004706:Endodeoxyribonucleases / Q000378:metabolism; D005090:Exodeoxyribonucleases / Q000378:metabolism; D011485:Protein Binding; D012441:Saccharomyces cerevisiae / Q000378:metabolism* / Q000648:ultrastructure; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D019098:Telomerase / Q000378:metabolism*; D016615:Telomere / Q000378:metabolism*; D034501:Telomere-Binding Proteins / Q000378:metabolism*
C452219:Cdc13 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D034501:Telomere-Binding Proteins; C099024:EST1 protein, S cerevisiae; C509185:EST2 protein, S cerevisiae; D019098:Telomerase; D004706:Endodeoxyribonucleases; D005090:Exodeoxyribonucleases; C094191:MRE11 protein, S cerevisiae