A DNA polymerase stop assay for G-quadruplex-interactive compounds

We have developed and characterized an assay for G-quadruplex-interactive c ompounds that makes use of the fact that G-rich DNA templates present obsta cles to DNA synthesis by DNA polymerases. Using Tao DNA polymerase and the G-quadruplex binding 2,6-diamidoanthraquinone BSU-1051, we find that BSU-10 51 leads to enhanced arrest of DNA synthesis in the presence of K+ by stabi lizing an intramolecular G-quadruplex structure formed by four repeats of e ither TTGGGG or TTAGGG in the template strand. The data provide additional evidence that BSU-1051 modulates telomerase activity by stabilization of te lomeric G-quadruplex DNA and point to a polymerase arrest assay as a sensit ive method for screening for G-quadruplex-interactive agents with potential clinical utility.