Specific xylan activity revealed for AA9 Lytic Polysaccharide Monooxygenases of the thermophilic fungus Malbranchea cinnamomea by functional characterization
Journal article, 2019

The thermophilic biomass-degrader Malbranchea cinnamomea exhibits poor growth on cellulose but excellent growth on hemicelluloses as the sole carbon source. This is surprising considering that its genome encodes eight lytic polysaccharide monooxygenases (LPMOs) from auxiliary activity family 9 (AA9), enzymes known for their high potential in accelerating cellulose depolymerization. We characterized four of the eight (M. cinnamomea AA9s) McAA9s, namely, McAA9A, McAA9B, McAA9F, and McAA9H, to gain a deeper understanding about their roles in the fungus. The characterized McAA9s were active on hemicelluloses, including xylan, glucomannan, and xyloglucan, and furthermore, in accordance with transcriptomics data, differed in substrate specificity. Of the McAA9s, McAA9H is unique, as it preferentially cleaves residual xylan in phosphoric acid-swollen cellulose (PASC). Moreover, when exposed to cellulose-xylan blends, McAA9H shows a preference for xylan and for releasing (oxidized) xylooligosaccharides. The cellulose dependence of the xylan activity suggests that a flat conformation, with rigidity similar to that of cellulose microfibrils, is a prerequisite for productive interaction between xylan and the catalytic surface of the LPMO. McAA9H showed a similar trend on xyloglucan, underpinning the suggestion that LPMO activity on hemicelluloses strongly depends on the polymers’ physicochemical context and conformation. Our results support the notion that LPMO multiplicity in fungal genomes relates to the large variety of copolymeric polysaccharide arrangements occurring in the plant cell wall.



biomass degradation



Silvia Hüttner

Chalmers, Biology and Biological Engineering, Industrial Biotechnology

Anikó Varnai

Norwegian University of Life Sciences

Dejan Petrović

Norwegian University of Life Sciences

Cao Xuan Bach

Chalmers, Biology and Biological Engineering

Kim Anh Dang Thi

Chalmers, Biology and Biological Engineering, Industrial Biotechnology

Vu Nguyen Thanh

Food Industries Research Institute

Vincent G.H. Eijsink

Norwegian University of Life Sciences

Johan Larsbrink

Chalmers, Biology and Biological Engineering, Industrial Biotechnology

Lisbeth Olsson

Chalmers, Biology and Biological Engineering, Industrial Biotechnology

Applied and Environmental Microbiology

0099-2240 (ISSN) 1098-5336 (eISSN)

Vol. 85 23

Enzymes discovery and production in Vietnam for the production of sustainable biofuels and biochemicals

Swedish Research Council (VR), 2014-12-01 -- 2016-12-31.

Driving Forces

Sustainable development

Subject Categories

Industrial Biotechnology

Biochemistry and Molecular Biology


Areas of Advance


Life Science Engineering (2010-2018)


Basic sciences





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