Figure 1: Antibody-templated strand exchange allows translation from antibody to DNA.

(a) Principle of ATSE. In the absence of antibody (Ab) the strand exchange reaction is thermodynamically unfavourable and remains in the initial state with output strand (O) hybridized to the peptide-functionalized base strand (B). Scaffolding of the oligonucleotide reactants on the input antibody initiates intramolecular toehold-mediated strand exchange, forming a stable intramolecular bivalent complex (BI) and displacing O in solution. Activation of O is monitored by a downstream reporter duplex (Rep), resulting in a stoichiometric increase in fluorescence. (b) Monitoring the release of output strand O as a function of toehold length T in the absence (black) and presence of 5 nM of anti-HA antibody (red) or 5 nM anti-HIV1-p17 antibody (green). One normalized unit (n.u.) represents the fluorescence generated by the displacement of Rep by 1 nM O. (c) Apparent first-order rate constants (k_obs) obtained by fitting the kinetic traces shown in (b) using a single exponential. (d) Signal to background ratios as a function of T obtained by dividing the antibody-templated first-order rate constants by the background rate constants. All experiments were performed with [BO]=5.5 nM, [I]=5 nM, [Ab]=5 nM and [Rep]=10 nM at 28 °C in TE/Mg²⁺ buffer supplemented with 1 mg ml⁻¹ BSA. Error bars represent the standard error of estimated value of k_obs calculated from the Fisher information matrix.