In vitro responses of nuclease sensors 1, 2, and 4 with a 3′-exonuclease (A), a 5′-exonuclease (B), and an endonuclease (C), respectively (red lines). Blue lines correspond to control experiments lacking enzyme. Insets show emission spectra over the time courses. Excitation 342 nm, emission 375 nm, [nuclease sensor] = 100 nM, 25 °C. [Exo T] = 25 U/mL, [RecJf] = 900 U/mL, [S1] = 100 U/mL. See SI for details.