Figure 1.

(a) Schematic representation of the primary structure of recombinant latent MdPPO1 (56.4 kDa). The active domain of the enzyme is coloured red and the conserved regions (histidines) of the copper-coordinating motifs are presented in purple. The C-terminal domain is coloured green and the putative position of proteolytic activation between the active domain and the C-terminus is displayed in blue. (b) Structural representation of the active centre of the wild-type MdPPO1 from homology modelling shows the conserved histidines coordinating CuA (His86, His107 and His116) and CuB (His238, His242 and His272) and the positions of the mutated residues, namely the two activity controllers alanine (Ala239) and leucine (Leu243), both in purple, the water keeper glutamic acid (Glu234) in light green and the gatekeeper phenylalanine (Phe259) in red. The homology model of MdPPO1 was obtained in the same way as described in Kampatsikas et al. (2017 ▸).