(A) Illustration of FRET-sensitive RNA kissing complex formation enabled
by Cy3 (green) and Cy5 (red) labeled (SK2M)3 bPNA+ (blue
strands) that complex with RNA1 and RNA2 ColE1-derived hairpins containing
U6 domains (red lines). RNA1-U6:
5′-GGCAGCUUUUUUUUGGUAGUUUUUUGCUGCC-3′; RNA2-U6:
5′-GGCACCGUUUUUUCUACCAAUUUUUUCGGUGCC-3′. (B)
Polyacrylamide gel under kissing complex conditions with the following in each
lane from left to right: [RNA2-U6·Cy3-(SK2M)] alone; at 1:1
ratio, [RNA2-U6·Cy3-(SK2M)],
[RNA1-U6·Cy5-(SK2M)]; at 1:1:1 ratio
[RNA2-U6·Cy3-(SK2M)],
[RNA1-U6·Cy5-(SK2M)], Rop. As indicated, gel was imaged by Cy3
excitation and emission (Cy3), Cy5 excitation and emission (Cy5), Cy3 excitation
and Cy5 emission (FRET), and the merged channels (Merged). (C) With Cy3
excitation only, Cy3 fluorescence (570 nm, ■) from
[RNA2-U6·Cy3-(SK2M)] decreases upon addition of
[RNA1-U6·Cy5-(SK2M)] complex, while Cy5 emission (670 nm,
-●-) increases.