Telomeres are conserved DNA sequences that cap the ends of chromosomes. The human telomere sequence contains a 3' overhang of single stranded DNA of tandem repeats of TTAGGG, short fragments of which form various G-quadruplex structures in vitro. Our group has recently discovered that irradiation of the sequence d[AGGG(TTAGGG)3], Tel22, with biologically relevant light results in the formation of a significant amount of a number of anti thymine dimers between the loops of the G-quadruplex structure. Irradiation of d[AAA(GGG(TTAGGG)3AA], however, produced mainly one product that was most consistent with the involvement of a form 3 G-quartet structure. The current study focuses on elucidating the structural features of G-quadruplexes that facilitate formation of the anti thymine dimers by making a series of substitutions and insertions in the sequence to stabilize specific structures. The results with a number of sequence variants are most consistent with the involvement of the form 3 structure.  

Structure-activity relationships of photocrosslinking of G-quadruplex loops by anti cyclobutane thymine dimer formation

242nd National Meeting (2011)

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