Fig. 1: Oriented triplex DNA (TD) as a synthetic receptor for transmembrane signal transduction.
From: Oriented triplex DNA as a synthetic receptor for transmembrane signal transduction
a Schematic illustration of TD assembly on a lipid bilayer membrane, showing the H+-induced conformational transition from duplex to triplex. Three cholesterols (khaki) conjugated to the stem of the TD hairpin anchor the TD across the bilayer membrane. An auxiliary sequence (Auxn, n = 11), complementary to the third strand, acts as a steric hindrance module to ensure the outward orientation of the TD on the membrane. Upon lowering the pH, the conformational change from duplex to triplex is coupled with the translocation of the signal tags from the exterior to the interior of the membrane, facilitating signal transduction and amplification across the membrane. Low pH triggers triplex formation and subsequent transmembrane signal transduction, observed as: (b) Fluorescence resonance energy transfer (FRET) occurrence, bringing Cy3 and Cy5 into proximity. c Photocleavage reactions accompanying signal module translocation into the membrane interior, leading to fluorescence emission within vesicles. d Catalytic conversion of the non-fluorescent ester substrate 8-acetoxypyrene-1,3,6-trisulfonatetrisodium salt (APTS) into the fluorescent product 8-hydroxypyrene-1,3,6-trisulfonatetrisodium salt (HPTS) upon internalization of the pro-catalyst dipyridylamine tagged to the 5'-terminus of TD.
