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Utilization of laccases in biotechnology and bioremediation has created a strong demand for the characterization of new enzymes and an increase in production of known laccases. Thus, additional research into these enzymes is critically needed. In this study, we report a comparative study of the biochemical and transcriptional properties of two different laccase isozymes from Trametes hirsuta 072 – the constitutive and inducible forms. A recombinant LacC enzyme was expressed in Penicillium canescens to characterize its properties. LacC is single-purpose enzyme, unlike LacA, which can operate efficiently under a wide range of temperatures and pHs (55–70 °C and pH 3–5, respectively). LacC has a lower RedOx potential than LacA and does not oxidize substrates containing amine groups. Expression of the lacC gene was selective compared to that of the lacA gene and increased significantly in the presence of complex synthetic compounds such as dyes and xenobiotics. This study shows that laccases from the multigene families of basidiomycetes differ significantly in their properties, thus providing a complementary effect during lignin degradation.

Laccases, blue copper-containing oxidases, ≿an play an important role in a variety of natural processes. The majority of fungal laccases are encoded by multigene families that express closely related proteins with distinct functions. Currently, only the properties of major gene products of the fungal laccase families have been described. Our study is focused on identification and characterization of laccase genes, which are transcribed in basidiomycete Trametes hirsuta 072, an efficient lignin degrader, in a liquid medium, both without and with induction of laccase transcription by copper ions. We carried out production of cDNA libraries from total fungal RNA, followed by suppression subtractive hybridization and mirror orientation selection procedures, and then used Next Generation Sequencing to identify low abundance and differentially expressed laccase transcripts. This approach resulted in description of five laccase genes of the fungal family, which, according to the phylogenetic analysis, belong to distinct clusters within the Trametes genus. Further analysis established similarity of physical, chemical, and catalytic properties between laccases inside each cluster. Structural modeling suggested importance of the sequence differences in the clusters for laccase substrate specificity and catalytic efficiency. The implications of the laccase variations for the fungal physiology are discussed.