Inhibitors of protein synthesis identified by a high throughput multiplexed translation screen

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Abstract
The use of small molecule inhibitors of cellular processes is a powerful approach to understanding gene function that complements the genetic approach. We have designed a high throughput screen to identify new inhibitors of eukaryotic protein synthesis. We used a bicistronic mRNA reporter to multiplex our assay and simultaneously screen for inhibitors of cap‐dependent initiation, internal initiation and translation elongation/termination. Functional screening of >90 000 compounds in an in vitro translation reaction identified 36 inhibitors, 14 of which are known inhibitors of translation and 18 of which are nucleic acid‐binding ligands. Our results indicate that intercalators constitute a large class of protein synthesis inhibitors. Four non‐intercalating compounds were identified, three of which block elongation and one of which inhibits initiation. The novel inhibitor of initiation affects 5′ end‐mediated initiation, as well as translation initiated from picornaviral IRESs, but does not significantly affect internal initiation from the hepatitis C virus 5′‐untranslated region. This compound should be useful for delineating differences in mechanism of initiation among IRESs.