title: Extrachromosomal telomeric circles contribute to Rad52-, Rad50-, and polymerase delta-mediated telomere-telomere recombination in Saccharomyces cerevisiae.
abstract: Telomere maintenance is required for chromosome stability, and telomeres are typically replicated by the telomerase reverse transcriptase. In both tumor and yeast cells that lack telomerase, telomeres are maintained by an alternative recombination mechanism. By using an in vivo inducible Cre-loxP system to generate and trace the fate of marked telomeric DNA-containing rings, the efficiency of telomere-telomere recombination can be determined quantitatively. We show that the telomeric loci are the primary sites at which a marked telomeric ring-containing DNA is observed among wild-type and surviving cells lacking telomerase. Marked telomeric DNAs can be transferred to telomeres and form tandem arrays through Rad52-, Rad50-, and polymerase delta-mediated recombination. Moreover, increases of extrachromosomal telomeric and Y' rings were observed in telomerase-deficient cells. These results imply that telomeres can use looped-out telomeric rings to promote telomere-telomere recombination in telomerase-deficient Saccharomyces cerevisiae.
authors.affiliation: Department of Microbiology, National Taiwan University College of Medicine,Taipei 10018, Taiwan.
authors.forename: Chi-Ying
authors.initials: CY
authors.lastname: Lin
authors.forename: Hsih-Hsuan
authors.initials: HH
authors.lastname: Chang
authors.forename: Kou-Juey
authors.initials: KJ
authors.lastname: Wu
authors.forename: Shun-Fu
authors.initials: SF
authors.lastname: Tseng
authors.forename: Chuan-Chuan
authors.initials: CC
authors.lastname: Lin
authors.forename: Chao-Po
authors.initials: CP
authors.lastname: Lin
authors.forename: Shu-Chun
authors.initials: SC
authors.lastname: Teng
mesh_terms: D004258:DNA Polymerase III / Q000378:metabolism*; D004271:DNA, Fungal; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D005819:Genetic Markers; D016681:Genome, Fungal; D009690:Nucleic Acid Conformation; D051721:Rad52 DNA Repair and Recombination Protein; D011995:Recombination, Genetic; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D019098:Telomerase / Q000378:metabolism; D016615:Telomere / Q000235:genetics / Q000378:metabolism
chemical_list: D004271:DNA, Fungal; D004268:DNA-Binding Proteins; D005819:Genetic Markers; C086930:RAD50 protein, S cerevisiae; C497197:RAD52 protein, S cerevisiae; D051721:Rad52 DNA Repair and Recombination Protein; D029701:Saccharomyces cerevisiae Proteins; D019098:Telomerase; D004258:DNA Polymerase III