Fig. 1.

Tetrahymena telomerase RNA pseudoknot. (A) Telomerase RNA contains a potential pseudoknot consisting of stems A and B, located downstream from the template. The TBE, template recognition element (TRE), and stemloop IV (IV) constitute TERT binding sites and are shown in gray. Stem I (I) and proximal stem IV bind p65 and are shown in beige. (B) Labeling and mutation schemes used to test the formation of the pseudoknot. Two sets of labeling sites, A sites (U63 and U92) and B sites (U73 and U99), were designed to flank stems A and B, respectively. Each set includes a FRET donor (Cy3) and acceptor (Cy5) sites marked by the colored stars. Nucleotide substitutions designed to either disrupt or recover base-pairing potential of the two stems are marked in red. Stems targeted by the mutations are highlighted in gray.