A survey of substrate specificity among Auxiliary Activity Family 5 copper radical oxidases

• Published in: Cellular and molecular life sciences : CMLS Vol. 78; no. 24; pp. 8187 - 8208
• Main Authors: Cleveland, Maria E., Mathieu, Yann, Ribeaucourt, David, Haon, Mireille, Mulyk, Paul, Hein, Jason E., Lafond, Mickael, Berrin, Jean-Guy, Brumer, Harry
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01.12.2021; Springer Nature B.V; Springer Verlag
• Subjects: Alcohol; Alcohol oxidase; Alcohol Oxidoreductases - chemistry; Alcohol Oxidoreductases - metabolism; Alcohols; Aldehydes; Biocatalysts; Biochemistry; Biodiesel fuels; Biofuels; Biomedical and Life Sciences; Biomedicine; Bioplastics; Biotechnology; Carbohydrates; Catalysts; Cell Biology; Copper; Copper - chemistry; Copper - metabolism; Dicarboxylic acids; Enzymes; Free Radicals - chemistry; Free Radicals - metabolism; Fungal Proteins - chemistry; Fungal Proteins - metabolism; Fusarium - enzymology; Fusarium graminearum; Galactose; Glyceraldehyde; Glycerol; Homology; Hydroxymethylfurfural; Life Sciences; Metalloproteins - chemistry; Metalloproteins - metabolism; Original; Original Article; Oxidation; Oxidation-Reduction; Oxidoreductases - chemistry; Oxidoreductases - metabolism; Phylogeny; Protein Conformation; Raffinose; Reagents; Substrate Specificity; Substrates; Galactose oxidase; Alcohol oxidase; Biocatalysis; Copper radical oxidase; Auxiliary Activity Family 5; Copper radical oxidaseAlcohol oxidaseGalactose oxidaseBiocatalysisAuxiliary Activity Family 5
• ISSN: 1420-682X; 1420-9071
• DOI: 10.1007/s00018-021-03981-w

There is significant contemporary interest in the application of enzymes to replace or augment chemical reagents toward the development of more environmentally sound and sustainable processes. In particular, copper radical oxidases (CRO) from Auxiliary Activity Family 5 Subfamily 2 (AA5_2) are attractive, organic cofactor-free catalysts for the chemoselective oxidation of alcohols to the corresponding aldehydes. These enzymes were first defined by the archetypal galactose-6-oxidase (GalOx, EC 1.1.3.13) from the fungus Fusarium graminearum . The recent discovery of specific alcohol oxidases (EC 1.1.3.7) and aryl alcohol oxidases (EC 1.1.3.47) within AA5_2 has indicated a potentially broad substrate scope among fungal CROs. However, only relatively few AA5_2 members have been characterized to date. Guided by sequence similarity network and phylogenetic analysis, twelve AA5_2 homologs have been recombinantly produced and biochemically characterized in the present study. As defined by their predominant activities, these comprise four galactose 6-oxidases, two raffinose oxidases, four broad-specificity primary alcohol oxidases, and two non-carbohydrate alcohol oxidases. Of particular relevance to applications in biomass valorization, detailed product analysis revealed that two CROs produce the bioplastics monomer furan-2,5-dicarboxylic acid (FDCA) directly from 5-hydroxymethylfurfural (HMF). Furthermore, several CROs could desymmetrize glycerol (a by-product of the biodiesel industry) to d - or l -glyceraldehyde. This study furthers our understanding of CROs by doubling the number of characterized AA5_2 members, which may find future applications as biocatalysts in diverse processes.