Fig 3. Deletion of KEOPS subunit gene CGI121 compromises telomere recombination and inhibits cellular aging.

(A) Y’ recombination of cgi121Δ cells. The assay was performed as in Fig. 2C. (B) Telomere sequencing results of tlc1Δ and tlc1Δ cgi121Δ cells. Spores with genotype of tlc1Δ and tlc1Δ cgi121Δ were obtained from the same tetrad and grown for 50 generations before genomic DNA extraction. PCR of telomere IL was performed and the PCR products were ligated to pMD18-T vector and subjected to sequencing. Each column represents one sequenced telomere. The constant parts of the telomere sequences were indicated in blue and the divergent parts in pink (representing the recombined telomere sequences). About 100 clones of each strain were analyzed. (C) Lifespan assay of BY4742 cgi121Δ mutant strain. (D) Telomeric Southern blot and lifespan assay of tlc1Δ cgi121Δ pre-senescing cells. Spores with different genotypes and the same mating type α were grown for 50 generations and then subjected to telomere Southern blot (left) and lifespan analysis (right). (E) After super-elongation of telomeres, telomere length and lifespan of spores with different genotypes and mating type α were determined as in (D).