Extrachromosomal telomeric circles contribute to Rad52-, Rad50-, and polymerase delta-mediated telomere-telomere recombination in Saccharomyces cerevisiae.
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.
Lin
Chi-Ying
CY
Department of Microbiology, National Taiwan University College of Medicine,Taipei 10018, Taiwan.
Chang
Hsih-Hsuan
HH
Wu
Kou-Juey
KJ
Tseng
Shun-Fu
SF
Lin
Chuan-Chuan
CC
Lin
Chao-Po
CP
Teng
Shu-Chun
SC
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
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