Abstract
The extreme ends of eukaryotic chromosomes contain 3' extensions in the form of single-stranded G-rich repeats, referred to as telomeric 3' G-tails or overhangs. Increasing evidence has suggested that telomeric 3' G-tails can adopt a G-quadruplex conformation both in vitro and in vivo. However, the role of G-quadruplexes on the structure and function of telomeric 3' G-tails remains unclear. In the current study, we showed that the human telomeric 3' G-tail sequence protected the duplex DNA ends in cis from being recognized as double strand breaks. This protection is dependent on the G-quadruplex conformation of the 3' G-tail sequence. These results suggest that the ability of telomeric 3' G-tails to adopt the endprotecting G-quadruplex conformation may be one of the reasons for the existence of the evolutionarily conserved G-stretch motifs in telomeric DNA sequences.
Highlights
Telomeres are special protein-DNA complexes at the ends of linear chromosomes in most eukaryotic cells
We have investigated the possible role of the G-quadruplex conformation of the telomeric 3Ј G-tails in protecting telomeric DNA ends from being recognized as DNA double strand breaks
Compared with the IC50 value, our results showed that Arylmorpholine analog 37 (AMA-37) effectively reduced the phosphorylation signal of p53 (Ser-15) to 50% at 10 M in 0.5 mM ATP (Fig. 1B, top panel, lane 5) and to less than 10% at 1 M in 0.1 mM ATP
Summary
Telomeres are special protein-DNA complexes at the ends of linear chromosomes in most eukaryotic cells. We showed that the human telomeric 3 G-tail sequence protected the duplex DNA ends in cis from being recognized as double strand breaks.
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