Crystal structure of novel aryl-alcohol oxidase from thermophilic fungus Chaetomium thermophilum

L. Švecová^{1, 2}, T. Skálová¹, T. Kovaľ¹, L. H. Østergaard³, J. Dohnálek¹

¹Institute of Biotechnology of the Czech Academy of Sciences, v.v.i., Biocev center, Průmyslová 595, Vestec, 252 50, Czech Republic

²Faculty of Nuclear Sciences and Physical Engineering, Czech Technical University in Prague, Břehová 7,115 19, Praha 1, Czech Republic

³Novozymes A/S, Brudelysvej 26, DK-2880 Bagsværd, Denmark

leona.svecova@ibt.cas.cz

Cheatomium thermophilum var. thermophilum (Ct) is a cellulose–degrading thermophilic fungus living in soil, dung or compost heaps, which supply appropriate conditions (air access, heat and humidity) for its growth. The interest in Ct has increased in recent years, as a source of new thermostable proteins for industrial and biotechnological purposes, where the high temperatures are needed [1].

Here we present a novel aryl-alcohol oxidase (EC 1.1.3.7) from Chaetomium thermophilum (CtAAO), a monomeric extracellular oxidoreductase catalyzing FAD-dependent two-electron oxidation of aromatic alcohols to aldehydes during reductive half-reaction, accompanied by two-electron reduction of O₂ to H₂O₂ during oxidative half-reaction. H₂O₂ is further utilized by peroxidases during lignin degradation process [2]. CtAAO is a member of the glucose-methanol-choline oxidoreductase (GMC) family, whose members contain a highly conserved residue – the active-site histidine – in the C-terminal part. This residue plays the crucial role of a catalytic base activating electron-donating substrate for hydrogen transfer to the FAD isoalloxazine ring during the reductive half-reaction [3]. We determined the crystal structure of native CtAAO at 2 Å resolution. Compared to other members of the GMC family, the active site of CtAAO including the catalytic base His has a different arrangement of residues on the re-side of the isoalloxazine ring than has been observed previously.

1.         Li, A.-N. and Li, D.-C.,  J. Appl. Microbiol., 2009, 106, 369-380.

2.         Hernández-Ortega, A., Ferreira, P. and Martínez, A. T., Appl. Microbiol. Biotechnol., 2011, 93, 1395-1410.

3.         Dijkman, W. P., de Gonzalo, G., Mattevi, A. and Fraaije, M. W., Appl. Microbiol. Biotechnol., 2013, 97, 5177-5188.

This work is supported by the project BIOCEV (CZ.1.05/1.1.00/02.0109) and the project Structural dynamics of biomolecular systems (CZ.02.1.01/0.0/0.0/15_003/0000447) from the ERDF, institutional support of IBT CAS, v. v. i. RVO: 86652036) and by the Grant Agency of the Czech Technical University in Prague, grant No. SGS16/246/OHK4/3T/14.