Use of RNA-bound Tb3+ as a FRET donor

Lanthanide ions such as Tb(3+) and Eu(3+) have long been used to probe RNA and protein structures due to their luminescence properties and their steric and chemical similarities to biological metal ions such as Mg(2+) and Ca(2+). In this article, we introduce a method that utilizes the enhanced Tb(3+) luminescence upon site-binding to RNA molecules as a FRET donor. Using this method, it is possible to identify specific metal ion-binding locations within a folded RNA molecule. Applications of this method include introducing FRET donors into molecules of interest by engineering RNA loops or bulges as Tb(3+)-binding pockets.