Transcription analysis of pyranose dehydrogenase from the basidiomycete Agaricus bisporus and characterization of the recombinantly expressed enzyme.

Agaricus bisporus is a litter degrading basidiomycete commonly found in humic-rich environments. It is used as model organism and cultivated in large scale for food industry. Due to its ecological niche it produces a variety of enzymes for detoxification and degradation of humified plant litter. One of these, pyranose dehydrogenase, is thought to play a role in detoxification and lignocellulose degradation. It is a member of the glucose-methanol-choline family of flavin-dependent enzymes and oxidizes a wide range of sugars with concomitant reduction of electron acceptors like quinones. In this work, transcription of pdh in A. bisporus was investigated with real-time PCR revealing influence of the carbon source on pdh expression levels. The gene was isolated and heterologously expressed in Pichia pastoris . Characterization of the recombinant enzyme showed a higher affinity towards disaccharides compared to other tested pyranose dehydrogenases from related Agariceae . Homology modeling and sequence alignments indicated that two loops of high sequence variability at substrate access site could play an important role in modulating these substrate specificities. [ABSTRACT FROM AUTHOR]