Discovery of Ligands for a Novel Target, the Human Telomerase RNA, Based on Flexible-Target Virtual Screening and NMR
Irene Gómez Pinto†‡, Christophe Guilbert†, Nikolai B. Ulyanov†, Jay Stearns§ and Thomas L. James*†
The human ribonucleoprotein telomerase is a validated anticancer drug target, and hTR-P2b is a part of the human telomerase RNA (hTR) essential for its activity. Interesting ligands that bind hTR-P2b were identified by iteratively using a tandem structure-based approach: docking of potential ligands from small databases to hTR-P2b via the program MORDOR, which permits flexibility in both ligand and target, with subsequent NMR screening of high-ranking compounds. A high percentage of the compounds tested experimentally were found via NMR to bind to the U-rich region of hTR-P2b; most have MW < 500 Da and are from different compound classes, and several possess a charge of 0 or +1. Of the 48 ligands identified, 24 exhibit a decided preference to bind hTR-P2b RNA rather than A-site rRNA and 10 do not bind A-site rRNA at all. Binding affinity was measured by monitoring RNA imino proton resonances for some of the compounds that showed hTR binding preference.