Heterologous expression of trametes versicolor laccase in pichia pastoris and aspergillus niger

Abstract

Laccases are copper-containing phenol-oxidizing enzymes that are useful in many different applications, for example in lignocellulose processing and textile industry. Efficient and convenient systems for heterologous expression are needed for production and characterization of different laccases. The methylotrophic yeast Pichia pastoris has gained increasing attention as a host for fast and convenient expression of laccases under the control of the strong and methanol-inducible AOX1 promoter. In this study, the strong and constitutive glyceraldehyde-3-phosphate dehydrogenase (GAP) promoter was investigated as an alternative to the AOX1 system, which suffers from drawbacks such as the need for tight control of methanol levels. With filamentous fungi, such as Aspergillus niger, larger amounts of recombinant laccase can be produced, although the handling of the expression system is tedious in comparison with P. pastoris. Laccase cDNAs from the white-rot fungus Trametes versicolor were inserted between the glyceraldehyde 3-phosphate dehydrogenase (gpd) promoter and the glucoamylase (glaA) terminator and used for transformation of A. niger. The recombinant laccase was purified to homogeneity and its properties were compared with those of native T. versicolor laccase.