Functional characterization of a lytic polysaccharide monooxygenase from the thermophilic fungus Myceliophthora thermophila

Author(s)

Kadowaki, Marco A. S. ^[1] ; Varnai, Aniko ^[2] ; Jameson, John-Kristian ^[2] ; Leite, Ana E. T. ^[1] ; Costa-Filho, Antonio J. ^[3] ; Kumagai, Patricia S. ^[1] ; Prade, Rolf A. ^{[4, 5]} ; Polikarpov, Igor ^[1] ; Eijsink, Vincent G. H. ^[2]

Affiliation

^[1] Univ Sao Paulo, Dept Phys & Interdisciplinary Sci, Sao Carlos Inst Phys, Sao Carlos, SP - Brazil

^[2] Norwegian Univ Life Sci NMBU, Fac Chem Biotechnol & Food Sci, As - Norway

^[3] Univ Sao Paulo, Dept Phys, Fac Filosofia Ciencias & Letras Ribeirao Preto, Sao Paulo - Brazil

^[4] Oklahoma State Univ, Dept Microbiol & Mol Genet, Stillwater, OK 74078 - USA

^[5] Oklahoma State Univ, Dept Biochem & Mol Biol, Stillwater, OK 74078 - USA

• Document type: Journal article
• Source: PLoS One; v. 13, n. 8 AUG 20 2018.
• Web of Science Citations: 5

Abstract

Thermophilic fungi are a promising source of thermostable enzymes able to hydrolytically or oxidatively degrade plant cell wall components. Among these enzymes are lytic polysaccharide monooxygenases (LPMOs), enzymes capable of enhancing biomass hydrolysis through an oxidative mechanism. Myceliophthora thermophila (synonym Sporotrichum thermophile), an Ascomycete fungus, expresses and secretes over a dozen different LPMOs. In this study, we report the overexpression and biochemical study of a previously uncharacterized LPMO (MtLPMO9J) from M. thermophila M77 in Aspergillus nidulans. MtLPMO9J is a single-domain LPMO and has 63% sequence similarity with the catalytic domain of NcLPMO9C from Neurospora crassa. Biochemical characterization of MtLPMO9J revealed that it performs C4-oxidation and is active against cellulose, soluble cello-oligosaccharides and xyloglucan. Moreover, biophysical studies showed that MtLPMO9J is structurally stable at pH above 5 and at temperatures up to 50 degrees C. Importantly, LC-MS analysis of the peptides after tryptic digestion of the recombinantly produced protein revealed not only the correct processing of the signal peptide and methylation of the N-terminal histidine, but also partial autoxidation of the catalytic center. This shows that redox conditions need to be controlled, not only during LPMO reactions but also during protein production, to protect LPMOs from oxidative damage. (AU)

• FAPESP's process: 11/20505-4 - Two important classes of glycosyl hydrolases: functional studies and structural analysis
• Grantee: Marco Antonio Seiki Kadowaki
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• FAPESP's process: 15/13684-0 - Structural and functional studies of enzymes that participate in complex carbohydrates synthesis and degradation
• Grantee: Igor Polikarpov
• Support Opportunities: Research Projects - Thematic Grants