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Eukaryot Cell. 2011 Aug;10(8):1131-42. doi: 10.1128/EC.05079-11. Epub 2011 Jun 10.

Recombination can either help maintain very short telomeres or generate longer telomeres in yeast cells with weak telomerase activity.

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1
Department of Genetics, Fred Davison Life Science Complex, University of Georgia, Athens, GA 30602-7223, USA.

Abstract

Yeast mutants lacking telomerase are able to elongate their telomeres through processes involving homologous recombination. In this study, we investigated telomeric recombination in several mutants that normally maintain very short telomeres due to the presence of a partially functional telomerase. The abnormal colony morphology present in some mutants was correlated with especially short average telomere length and with a requirement for RAD52 for indefinite growth. Better-growing derivatives of some of the mutants were occasionally observed and were found to have substantially elongated telomeres. These telomeres were composed of alternating patterns of mutationally tagged telomeric repeats and wild-type repeats, an outcome consistent with amplification occurring via recombination rather than telomerase. Our results suggest that recombination at telomeres can produce two distinct outcomes in the mutants we studied. In occasional cells, recombination generates substantially longer telomeres, apparently through the roll-and-spread mechanism. However, in most cells, recombination appears limited to helping to maintain very short telomeres. The latter outcome likely represents a simplified form of recombinational telomere maintenance that is independent of the generation and copying of telomeric circles.

PMID:
21666075
PMCID:
PMC3165439
DOI:
10.1128/EC.05079-11
[Indexed for MEDLINE]
Free PMC Article
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