Tsai Yuan-Chin, Qi Haiyan, Liu Leroy F
Department of Pharmacology, University of Medicine and Dentistry of New Jersey (UMDNJ)-Robert Wood Johnson Medical School, Piscataway, New Jersey 08854, USA.
J Biol Chem. 2007 Jun 29;282(26):18786-92. doi: 10.1074/jbc.M702171200. Epub 2007 May 4.
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.
