Fig. 1

Schematic presentation of the concerted action of polyphenol oxidases and LPMOs. Monophenols with a 1-hydroxy, 2-methoxy moiety are hydroxylated by MtPPO7 from M. thermophila C1. The resulting methoxylated catechols are excellent electron donors for MtLPMO9B activity. In comparison to MtPPO7, the mushroom tyrosinase AbPPO is able to convert non-methoxylated monophenols into compounds comprising a 1,2-benzenediol moiety. The released compounds comprising a 1,2-benzenediol moiety are able to donate electrons for MtLPMO9B activity. However, AbPPO exhibits a strong diphenolase activity which reduces the available amount of these compounds comprising a 1,2-benzenediol moiety for MtLPMO9B due to further oxidation of these compounds into ortho-quinones (indicated by dashed arrow)