Characterization of Novel PQQ-Dependent Enzyme in Coprinopsis cinerea

What is it about?

In this study, researchers characterized CcPDH, a quinohemoprotein enzyme found in Coprinopsis cinerea. CcPDH is a new type of pyrroloquinoline-quinone (PQQ)-dependent pyranose dehydrogenase, the first found among all eukaryotes. The enzyme contains a three-domain structure, with a cytochrome domain homologous to cellobiose dehydrogenase from Phanerochaete chrysosporium, a C-terminal family 1-type carbohydrate-binding module, and a novel central catalytic domain containing PQQ as a cofactor. The study focused on the biochemical and electrochemical characterization of CcPDH, including UV-vis and resonance Raman spectroscopic studies, which reveal characteristics of a 6-coordinated low-spin heme b in both the ferric and ferrous states, as well as intramolecular electron transfer from the PQQ to heme b. The formal potential of the heme was evaluated to be 130 mV vs. NHE by cyclic voltammetry. The researchers also determined the substrate specificity of CcPDH, which prefers monosaccharides with equatorial C-2, C-3 hydroxyl groups and an axial C-4 hydroxyl group in the 1 C 4 chair conformation. Furthermore, a binding study shows a high binding affinity of CcPDH for cellulose, suggesting that CcPDH function is related to the enzymatic degradation of plant cell wall. Overall, the study provides new insights into the structure and function of CcPDH, a PQQ-dependent enzyme, and its potential applications in biodegradation and biomass conversion or as an anode catalyst for bioelectrochemical applications.

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Why is it important?

The research is important because it helps to better understand the structure and function of CcPDH, a novel quinohemoprotein enzyme discovered in the basidiomycete Coprinopsis cinerea. This knowledge can contribute to the development of new biotechnological applications, such as enzymatic degradation of plant cell walls or bioelectronic devices. Key Takeaways: 1. CcPDH is a novel quinohemoprotein enzyme with a three-domain structure, including a cytochrome domain, a carbohydrate-binding module, and a central catalytic domain containing PQQ as a cofactor. 2. The cytochrome domain of CcPDH shares significant homology with that of CDH from the wood-rotting basidiomycete Phanerochaete chrysosporium, indicating a potential role in extracellular oxidative degradation. 3. CcPDH exhibits dehydrogenase activity towards monosaccharides in a 1 C 4 chair conformation, indicating a preference for specific sugar configurations. 4. CcPDH has a high binding affinity for cellulose, suggesting a potential role in the degradation of plant cell walls. 5. The research contributes to a better understanding of PQQ-dependent enzymes and their potential applications in biotechnology, such as bioelectronics and biomass conversion.