201. Protection of DNA Ends by Telomeric 3' G-TaiI Sequences.
- Author
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Yuan-chin Tsai, Haiyan Qi, and Liu, Leroy F.
- Subjects
- *
DNA , *CHROMOSOMES , *TELOMERES , *CONFORMATIONAL analysis , *NUCLEOTIDE sequence - 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 end-protecting G-quadruplex conformation may be one of the reasons for the existence of the evolutionarily conserved G-stretch motifs in telomeric DNA sequences. [ABSTRACT FROM AUTHOR]
- Published
- 2007
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