A, UV-Vis spectra of the photosensory domain of A. nidulans FphA (PGP) after co-expression together with bacterial HO (BphO) or A. alternata HoxA, HoxB or HoxA plus HoxB overnight at 20°C in the dark. PGP was purified via the Strep-tag system and concentrated before recording the spectra. Inset, left lane: Molecular mass markers stained with Coomassie Blue. Middle lanes: Zinc-induced red fluorescence (labeled zinc, Zn2+) of equal amounts of PGP expressed in E. coli along with bacterial BphO (O) or A. alternata HoxA plus HoxB (A+B). right lanes: Coomassie Blue staining (C.B.) of the polyacrylamide gel used for the Zn2+ fluorescence. 