Inhibition of therapeutically important polymerases with high affinity bis-intercalators

We have previously demonstrated that polymerases such as telomerase can be inhibited by molecules (e.g., intercalators) that target the key RNA/DNA duplex substrate. In this work we show that this also holds true for reverse transcriptase, and show that the lead intercalators can be modified to increase inhibition efficacy. Specifically, we use the strategy of multiple simultaneous intercalation, by linking two intercalators with a variable linker. The rationale behind this design is that a specific linker has the potential to increase affinity and specificity for the target duplex. We have synthesized a library of 45 ethidium bis-intercalators in which the distance between intercalators is systematically varied. We observe that members of the dimer library have improved telomerase and reverse transcriptase inhibition, relative to the monomeric leads. We show that this improvement in inhibition over mono-intercalators is most prominent when non-productive sites of inhibitor binding are limited in the assay mix. When this is done, a 400-fold increase in inhibition efficacy is observed.