The present invention relates to compositions and methods that allow the manipulation of the catalytic activity of multi-component nucleic acid complexes. Further, the invention provides methods which use these compositions and methods to create molecular sensors, molecular switches, and/or modulators or propagators of autocatalytic self-replicating cascades and other iterative processes. More particularly, the invention relates to compositions allowing self-assembly of active and inactive multicomponent nucleic acid complexes, methods of making such compositions, and methods for use.