title: Activities of Secreted Aryl Alcohol Quinone Oxidoreductases from Pycnoporus cinnabarinus Provide Insights into Fungal Degradation of Plant Biomass.
abstract: Auxiliary activities family 3 subfamily 2 (AA3_2) from the CAZy database comprises various functions related to ligninolytic enzymes, such as fungal aryl alcohol oxidases (AAO) and glucose oxidases, both of which are flavoenzymes. The recent study of the Pycnoporus cinnabarinus CIRM BRFM 137 genome combined with its secretome revealed that four AA3_2 enzymes are secreted during biomass degradation. One of these AA3_2 enzymes, scf184803.g17, has recently been produced heterologously in Aspergillus niger Based on the enzyme's activity and specificity, it was assigned to the glucose dehydrogenases (PcinnabarinusGDH [PcGDH]). Here, we analyze the distribution of the other three AA3_2 enzymes (scf185002.g8, scf184611.g7, and scf184746.g13) to assess their putative functions. These proteins showed the highest homology with aryl alcohol oxidase from Pleurotus eryngii Biochemical characterization demonstrated that they were also flavoenzymes harboring flavin adenine dinucleotide (FAD) as a cofactor and able to oxidize a wide variety of phenolic and nonphenolic aryl alcohols and one aliphatic polyunsaturated primary alcohol. Though presenting homology with fungal AAOs, these enzymes exhibited greater efficiency in reducing electron acceptors (quinones and one artificial acceptor) than molecular oxygen and so were defined as aryl-alcohol:quinone oxidoreductases (AAQOs) with two enzymes possessing residual oxidase activity (PcAAQO2 and PcAAQO3). Structural comparison of PcAAQO homology models with P. eryngii AAO demonstrated a wider substrate access channel connecting the active-site cavity to the solvent, explaining the absence of activity with molecular oxygen. Finally, the ability of PcAAQOs to reduce radical intermediates generated by laccase from P. cinnabarinus was demonstrated, shedding light on the ligninolytic system of this fungus.
authors.affiliation: INRA, UMR 1163 Biotechnologie des Champignons Filamenteux, Polytech Marseille, Marseille, France yann.mathieu@univ-amu.fr.|Aix Marseille Université, UMR 1163 Biotechnologie des Champignons Filamenteux, Polytech Marseille, Marseille, France.
authors.forename: Yann
authors.initials: Y
authors.lastname: Mathieu
authors.affiliation: INRA, UMR 1163 Biotechnologie des Champignons Filamenteux, Polytech Marseille, Marseille, France.|Aix Marseille Université, UMR 1163 Biotechnologie des Champignons Filamenteux, Polytech Marseille, Marseille, France.
authors.forename: Francois
authors.initials: F
authors.lastname: Piumi
authors.affiliation: INRA, UMR 1163 Biotechnologie des Champignons Filamenteux, Polytech Marseille, Marseille, France.|Aix Marseille Université, UMR 1163 Biotechnologie des Champignons Filamenteux, Polytech Marseille, Marseille, France.
authors.forename: Richard
authors.initials: R
authors.lastname: Valli
authors.affiliation: Biotechnology for Lignocellulosic Biomass Lab, Centro de Investigaciones Biológicas, Madrid, Spain.
authors.forename: Juan Carro
authors.initials: JC
authors.lastname: Aramburu
authors.affiliation: Departamento de Bioquímica y Biología Molecular y Celular, Instituto de Biocomputación y Física de Sistemas Complejos, Universidad de Zaragoza, Zaragoza, Spain.
authors.forename: Patricia
authors.initials: P
authors.lastname: Ferreira
authors.affiliation: INRA, UMR 1163 Biotechnologie des Champignons Filamenteux, Polytech Marseille, Marseille, France.|Aix Marseille Université, UMR 1163 Biotechnologie des Champignons Filamenteux, Polytech Marseille, Marseille, France.
authors.forename: Craig B
authors.initials: CB
authors.lastname: Faulds
authors.affiliation: INRA, UMR 1163 Biotechnologie des Champignons Filamenteux, Polytech Marseille, Marseille, France.|Aix Marseille Université, UMR 1163 Biotechnologie des Champignons Filamenteux, Polytech Marseille, Marseille, France.
authors.forename: Eric
authors.initials: E
authors.lastname: Record
mesh_terms: D000429:Alcohol Oxidoreductases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018533:Biomass; D001711:Biotransformation; D003067:Coenzymes / Q000378:metabolism; D005182:Flavin-Adenine Dinucleotide / Q000378:metabolism; D005420:Flavoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D008031:Lignin / Q000378:metabolism*; D008958:Models, Molecular; D011487:Protein Conformation; D055494:Pycnoporus / Q000201:enzymology*; D011809:Quinones / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity
chemical_list: D003067:Coenzymes; D005420:Flavoproteins; D011809:Quinones; C036909:lignocellulose; D005182:Flavin-Adenine Dinucleotide; D008031:Lignin; D000429:Alcohol Oxidoreductases; C077759:aryl-alcohol oxidase