Aspergillus fumigatus alb1 encodes naphthopyrone synthase when expressed in Aspergillus oryzae

Conidial pigment biosynthesis is an important virulence factor in Aspergill us fumigatus, a human fungal pathogen. Involvement of DHN-melanin pathway i n the biosynthesis of A. fumigatus conidial pigment implies that the Alb1p polyketide synthase (PKS) is a 1,3,6,8-tetrahydroxynaphthalene (T4HN) synth ase. The Alb1p, however, shows higher sequence similarity to a naphthopyron e synthase than to a T4HN synthase. To clarify the function of Alb1p, the a lb1 gene was overexpressed in a heterologous host Aspergillus oryzae. The A lb1p PKS product in this heterologous expression system was identified as h eptaketide naphthopyrone instead of pentaketide T4HN. The data suggest that Alb1p is a naphthopyrone synthase. (C) 2000 Federation of European Microbi ological Societies. Published by Elsevier Science B.V. All rights reserved.