Figure 2.

The targeted disassembly of a kissing complex is triggered by the invasion of a capping oligonucleotide complementary to the loop sequence. (A) The kissing complex and the constituting tetrahedrons were incubated for 25 min with a 2-fold excess of capping oligonucleotide with complementarity to loop sequence hairpin 1. In the case of pre-incubation, the respective molecules are indicated by a box. Schematic drawings of the structures visible after native gel electrophoresis on 4% polyacrylamide gels (with 11.5 mM Mg2+) are indicated on the right. The experiment was performed at two different temperatures: on ice (lanes 7 and 9) or at 25°C (lanes 8 and 10). Tetrahedrons with empty circles indicate the position of monomeric tetrahedrons, irrespective of the nature of the loop sequence (1 or 2). (B) In an extended experiment at 25°C, it was possible to show the disintegration of the kissing complex (lane 2) as a slow one-way reaction over 48 h (0–48, lanes 3–16) by formation of a complex of tetrahedron hairpin 1 and capping strand (lane 1). The reaction starts at time point 0 h by addition of the capping oligonucleotide whereas a control sample without capping oligonucleotide was analyzed for each time point, too. Due to the slow kinetics the major fraction of kissing complex was only disassembled after more than 24 h.