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Nat Struct Mol Biol. 2011 Apr;18(4):478-85. doi: 10.1038/nsmb.2033. Epub 2011 Mar 13.

Rudimentary G-quadruplex-based telomere capping in Saccharomyces cerevisiae.

Author information

  • 1Department of Pathology and Laboratory Medicine, University of Pennsylvania School of Medicine, Philadelphia, Pennsylvania, USA.

Abstract

Telomere capping conceals chromosome ends from exonucleases and checkpoints, but the full range of capping mechanisms is not well defined. Telomeres have the potential to form G-quadruplex (G4) DNA, although evidence for telomere G4 DNA function in vivo is limited. In budding yeast, capping requires the Cdc13 protein and is lost at nonpermissive temperatures in cdc13-1 mutants. Here, we use several independent G4 DNA-stabilizing treatments to suppress cdc13-1 capping defects. These include overexpression of three different G4 DNA binding proteins, loss of the G4 DNA unwinding helicase Sgs1, or treatment with small molecule G4 DNA ligands. In vitro, we show that protein-bound G4 DNA at a 3' overhang inhibits 5'→3' resection of a paired strand by exonuclease I. These findings demonstrate that, at least in the absence of full natural capping, G4 DNA can play a positive role at telomeres in vivo.

PMID:
21399640
[PubMed - indexed for MEDLINE]
PMCID:
PMC3119813
Free PMC Article

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