Binding of a designed anti-cancer drug to the central cavity of an RNA three-way junction.

Getting to the heart of it: Co-crystallization of an RNA three-way junction with a cylindrical di-iron(II)-based anti-cancer drug (green) results in π-stacking interactions between the cylinder and the central base pairs of the RNA structure. The shape, size, and cationic nature of the cylinder were found to be responsible for this perfect fit. Native gel electrophoresis studies confirmed stabilization of the RNA three-way junction by the iron(II) cylinder.