title: Protection of DNA ends by telomeric 3' G-tail sequences.
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.
authors.affiliation: Department of Pharmacology, University of Medicine and Dentistry of New Jersey (UMDNJ)-Robert Wood Johnson Medical School, Piscataway, New Jersey 08854, USA.
authors.forename: Yuan-Chin
authors.initials: YC
authors.lastname: Tsai
authors.forename: Haiyan
authors.initials: H
authors.lastname: Qi
authors.forename: Leroy F
authors.initials: LF
authors.lastname: Liu
mesh_terms: D024509:3' Flanking Region / Q000235:genetics; D002467:Cell Nucleus / Q000235:genetics; D017124:Conserved Sequence; D053903:DNA Breaks, Double-Stranded; D004249:DNA Damage / Q000235:genetics*; D004273:DNA, Neoplasm / Q000737:chemistry / Q000235:genetics*; D004277:DNA, Single-Stranded / Q000737:chemistry / Q000235:genetics*; D019143:Evolution, Molecular; D005816:Genetic Complementation Test; D006147:Guanine / Q000378:metabolism; D006367:HeLa Cells; D006801:Humans; D009690:Nucleic Acid Conformation; D016615:Telomere / Q000737:chemistry / Q000235:genetics*
chemical_list: D004273:DNA, Neoplasm; D004277:DNA, Single-Stranded; D006147:Guanine