BIOSYNTHETIC-PATHWAY FOR VERATRYL ALCOHOL IN THE LIGNINOLYTIC FUNGUS PHANEROCHAETE-CHRYSOSPORIUM

Veratryl alcohol (VA) is a secondary metabolite of white-rot fungi tha t produce the ligninolytic enzyme lignin peroxidase. VA stabilizes lig nin peroxidase, promotes the ability of this enzyme to oxidize a varie ty of physiological substrates, and is accordingly thought to play a s ignificant role in fungal ligninolysis. Pulse-labeling and isotope-tra pping experiments have now clarified the pathway for VA biosynthesis i n the white-rot basidiomycete Phanerochaete chrysosporium. The pulse-l abeling data, obtained with C-14-labeled phenylalanine, cinnamic acid, benzoic acid, and benzaldehyde, showed that radiocarbon labeling foll owed a reproducible sequence: it peaked first in cinnamate, then in be nzoate and benzaldehyde, and finally in VA. Phenylalanine, cinnamate, benzoate, and benzaldehyde were all efficient precursors of VA in vivo . The isotope-trapping experiments sho,ved that exogenous, unlabeled b enzoate and benzaldehyde were effective traps of phenylalanine-derived C-14. These results support a pathway in which VA biosynthesis procee ds as follows: phenylalanine --> cinnamate --> benzoate and/or benzald ehyde --> VA.