Formation of the G-quadruplex and i-motif structures in retinoblastoma susceptibility genes (Rb).

ABSTRACT: The formation of G-quadruplex and i-motif structures in the 5' end of the retinoblastoma (Rb) gene was examined using chemical modifications, circular dichroism (CD) and fluorescence spectroscopy. It was found that substitutions of 8-methylguanine at positions that show syn conformations in antiparallel G-quadruplexes stabilize the structure in the G-rich strand. The complementary C-rich 18mer forms an i-motif structure, as suggested by CD spectroscopy. Based on the C to T mutation experiments, C bases participated in the C-C+ base pair of the i-motif structure were determined. Experiments of 2-aminopurine (2-AP) substitution reveal that an increase of fluorescence in the G-quadruplex relative to duplex is attributed to unstacked 2-AP within the loop of G-quadruplex. The fluorescence exper

SUBMITTER: Xu Y 

PROVIDER: S-EPMC1361614 | biostudies-literature | 2006

REPOSITORIES: biostudies-literature