Isolation and characterization of a laccase gene from Podospora anserina

The genome of the filamentous ascomycete Podospora anserina contains at least four non-adjacent regions that are homologous to the laccase gene of Neurospora crassa. One of these regions contains a gene (lac2) encoding a protein that displays 62% identity with the N. crassa laccase. In shaken cultures, lac2 mRNA is present at low basal levels throughout the growth phase but increases at least 20-fold at the beginning of the autolytic phase and decreases again thereafter. Addition of aromatic xenobiotics (guaiacol, hydroquinone, benzoquinone) to the medium during the growth phase results in a rapid, drastic and temporary increase in the abundance of lac2 mRNA. The promoter region of lac2 contains two sequences which display complete homology with the eukaryotic Xenobiotic Responsive Element and two sequences homologous to the eukaryotic Antioxidant Responsive Element. The identity and function of the laccase encoded by lac2 are discussed.