Fig. 1: Structures of the Rev response element (RRE).

A Secondary structure of the predicted four-stem RRE RNA. Stem-loop II (SLII) is boxed in black, and the high-affinity Rev-binding site is indicated with red dashed lines. B Design of SLII–tRNA. The SLII sequence is inserted into the anticodon stem of tRNA. Stem IIA is fused to the tRNA scaffold. The high-affinity Rev-binding site is indicated with red dashed lines. An additional guanine nucleotide (G53) was incorporated into stem IIB to engineer a tetraloop. C Structure of the SLII–tRNA in the closed conformation. The secondary structure (left) and the crystal structure (right) are shown. SLII consists of stems IIA (red), IIB (blue), and IIC (green). The high-affinity Rev-binding site (the triple guanine motif and junction nucleotides between IIB and IIC) is shown in orange. The tRNA scaffold is shown in purple. D Structure of the SLII–tRNA in the open conformation. The secondary structure (left) and the crystal structure (right) are shown. The SLII stems and the high-affinity Rev-binding site are colored as in (C).