Figure 4: Antibody-Templated Strand Exchange allows antibodies to control DNAzyme and enzyme activity.

(a) Design and characterization of a DNAzyme-based actuator module. HA output O, generated by anti-HA antibody induced ATSE binds to a toehold on the inhibitor oligonucleotide (Inh) and displaces the DNAzyme (Dz), allowing it to adopt a catalytically active conformation while binding to substrate strand (S). After cleaving S, the product strands (P₁ and P₂) spontaneously dissociate from Dz to complete the catalytic cycle. Experiments were performed with [BO]=[I]=[Ab]=[DzInh]=5 nM, [S]=10 nM at 28 °C in TE/Mg²⁺ buffer containing 1 mg ml⁻¹ BSA. (b) Design and characterization of a DNA-directed reporter enzyme actuator module. A weak binding enzyme-inhibitor pair, TEM1-β-lactamase and its inhibitor protein BLIP (K_i=1.5 μM), are each conjugated to an oligonucleotide, inducing their interaction upon hybridization to a shared template strand. The output oligonucleotide O generated in the anti-HA antibody induced ATSE reaction binds to an internal toehold on the template oligonucleotide and displaces the enzyme from the template strand, resulting in enzyme activation. Experiments were performed with [BO]=[I]=[Ab]=5 nM, [Reporter Enzyme]=1 nM at 28 °C in TE/Mg²⁺ buffer containing 1 mg ml⁻¹ BSA. Error bars represent the s.d. of triplicate measurements.