Asn145 and Ala161 appeared to be indispensable for KillerRed's phototoxic effect, although other substitutions are also important.
We characterized KillerRed phototoxic activity as a function of irradiation time. KillerRed kills 96% of E. coli cells after 10 min and almost all cells after 20 min of irradiation with white light (1 W/cm2). We also verified that cell killing depends on the wavelength of the incident light. KillerRed demonstrated a strong cell killing effect in green light (540–580 nm) and almost no effect upon irradiation with blue light (460–490 nm) of equal intensity (35 mW/cm2).