The lytic polysaccharide monooxygenase LPMO9H catalyzes oxidative cleavage of diverse plant cell wall matrix glycans.
Mathieu Fanuel, Sona Garajova, David Ropartz, Nicholas McGregor, Harry Brumer, Hélène Rogniaux, Jean-Guy Berrin
Author Information
Mathieu Fanuel: Unité de Recherche Biopolymères, Interactions, Assemblages, INRA, 44316 Nantes, France.
Sona Garajova: Polytech Marseille, UMR1163 Biodiversité et Biotechnologie Fongiques, INRA, Aix-Marseille Université, Avenue de Luminy, 13288 Marseille, France.
David Ropartz: Unité de Recherche Biopolymères, Interactions, Assemblages, INRA, 44316 Nantes, France.
Nicholas McGregor: Michael Smith Laboratories, University of British Columbia, 2185 East Mall, Vancouver, BC V6T 1Z4 Canada.
Harry Brumer: Michael Smith Laboratories, University of British Columbia, 2185 East Mall, Vancouver, BC V6T 1Z4 Canada.
Hélène Rogniaux: Unité de Recherche Biopolymères, Interactions, Assemblages, INRA, 44316 Nantes, France.
Jean-Guy Berrin: Polytech Marseille, UMR1163 Biodiversité et Biotechnologie Fongiques, INRA, Aix-Marseille Université, Avenue de Luminy, 13288 Marseille, France. ORCID
BACKGROUND: The enzymatic conversion of plant biomass has been recently revolutionized by the discovery of lytic polysaccharide monooxygenases (LPMO) that catalyze oxidative cleavage of polysaccharides. These powerful enzymes are secreted by a large number of fungal saprotrophs and are important components of commercial enzyme cocktails used for industrial biomass conversion. Among the 33 AA9 LPMOs encoded by the genome of , the LPMO9H enzyme catalyzes mixed C1/C4 oxidative cleavage of cellulose and cello-oligosaccharides. Activity of LPMO9H on several hemicelluloses has been suggested, but the regioselectivity of the cleavage remained to be determined. RESULTS: In this study, we investigated the activity of LPMO9H on mixed-linkage glucans, xyloglucan and glucomannan using tandem mass spectrometry and ion mobility-mass spectrometry. Structural analysis of the released products revealed that LPMO9H catalyzes C4 oxidative cleavage of mixed-linkage glucans and mixed C1/C4 oxidative cleavage of glucomannan and xyloglucan. Gem-diols and ketones were produced at the non-reducing end, while aldonic acids were produced at the reducing extremity of the products. CONCLUSION: The ability of LPMO9H to target polysaccharides, differing from cellulose by their linkages, glycosidic composition and/or presence of sidechains, could be advantageous for this coprophilous fungus when catabolizing highly variable polysaccharides and for the development of optimized enzyme cocktails in biorefineries.
