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Dissecting function and catalytic mechanism of fungal lytic polysaccharide monooxygenases

Liu, Bing (2019). Dissecting function and catalytic mechanism of fungal lytic polysaccharide monooxygenases. Diss. (sammanfattning/summary) Uppsala : Sveriges lantbruksuniv., Acta Universitatis Agriculturae Sueciae, 1652-6880 ; 2019:43
ISBN 978-91-7760-404-4
eISBN 978-91-7760-405-1
[Doctoral thesis]

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Abstract

Fungi use a complex and well-orchestrated enzyme machinery to degrade lignocellulose biomass, in which both hydrolytic and redox enzymes are involved. Lytic polysaccharide monoxygenases (LPMOs) are copper-dependent enzymes that cleave bonds in polysaccharides using oxidative mechanisms. LPMOs belonging to auxiliary activity family 9 (AA9) are widely distributed in the fungal kingdom. The aim of this study is to develop a better understanding of the roles of AA9 LPMOs in lignocellulose degradation with the focus on a white-rot softwood-decaying fungus Heterobasidion irregulare as well as to gain more insights into their catalytic mechanism by investigating the interaction of C1-specific AA9 LPMOs with substrate/co-substrate at molecular level. Two LPMOs from H. irregulare (HiLPMO9H and HiLPMO9I) were shown to have different substrate specificity against cellulose and glucomannan, indicating that AA9 LPMOs may be involved in degradation of different plant cell wall components during the decay of softwood by the H. irregulare (Paper I). Another H. irregulare LPMO (HiLPMO9B) was found to increase the substrate accessibility for a homologous cellobiohydrolase (HiCel7A) and the cooperation between these two enzymes were shown during crystalline cellulose degradation, indicating that AA9 LPMO may act in synergy with cellulases as importance members in the cellulose degradation system of H. irregulare (Paper II). Molecular dynamics showed that the C1-specific HiLPMO9B uses acidic residues to bind onto the cellulose surface in addition to hydrophobic residues (Paper III). Furthermore, it was shown that cyanide inhibits the activity of the C1-specific PcLPMO9D by competing with O2 binding to the enzyme. Cyanide was shown to bind to the axial position of copper coordinating sites, reflecting a possible scenario of the proposed Cu-superoxyl intermediate (Paper IV). The present study has increased our understanding of the functionalization of LPMO in basidiomycete fungi and has expanded the current view on possible substrate/co-substrate interaction at molecular level.

Authors/Creators:Liu, Bing
Title:Dissecting function and catalytic mechanism of fungal lytic polysaccharide monooxygenases
Series/Journal:Acta Universitatis Agriculturae Sueciae (1652-6880)
Year of publishing :2019
Number:2019:43
Number of Pages:72
Papers/manuscripts:
NumberReferences
ILiu, B., Olson, Å., Wu, M., Broberg, A. & Sandgren, M. (2017). Biochemical studies of two lytic polysaccharide monooxygenases from the white-rot fungus Heterobasidion irregulare and their roles in lignocellulose degradation. PLOS ONE, 12(12), p e0189479.
IILiu, B., Krishnaswamyreddy, S., Muraleedharan, M. N., Olson, Å., Broberg, A., Ståhlberg, J. & Sandgren, M. (2018). Side-by-side biochemical comparison of two lytic polysaccharide monooxygenases from the white-rot fungus Heterobasidion irregulare on their activity against crystalline cellulose and glucomannan. PLOS ONE, 13(9), p e0203430.
IIILiu, B., Kognole, A. A., Wu, M., Westereng, B., Crowley, M. F., Kim, S., Dimarogona, M., Payne, C. M. & Sandgren, M. (2018). Structural and molecular dynamics studies of a C1-oxidizing lytic polysaccharide monooxygenase from Heterobasidion irregulare reveal amino acids important for substrate recognition. The FEBS Journal, 285(12), pp 2225–2242.
IVForsberg, Z.*, Liu, B.*, Åsmund, K. R., Bissaro, B., Eijsink, V. G. H. Sandgren, M. Structural and biochemical study of the effects of cyanide on a fungal lytic polysaccharide monooxygenase (Manuscript). * First authorship shared
Place of Publication:Uppsala
Publisher:Department of Molecular Sciences , Swedish University of Agricultural Sciences
ISBN for printed version:978-91-7760-404-4
ISBN for electronic version:978-91-7760-405-1
ISSN:1652-6880
Language:English
Publication Type:Doctoral thesis
Article category:Other scientific
Full Text Status:Public
Agris subject categories.:X Agricola extesions > X30 Life sciences
Subjects:(A) Swedish standard research categories 2011 > 1 Natural sciences > 106 Biological Sciences (Medical to be 3 and Agricultural to be 4) > Structural Biology
(A) Swedish standard research categories 2011 > 1 Natural sciences > 106 Biological Sciences (Medical to be 3 and Agricultural to be 4) > Biochemistry and Molecular Biology
Keywords:lignocellulose, fungi, LPMO, biological role, catalytic mechanism
URN:NBN:urn:nbn:se:slu:epsilon-p-100744
Permanent URL:
http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-p-100744
ID Code:16247
Faculty:NJ - Fakulteten för naturresurser och jordbruksvetenskap
Department:(NL, NJ) > Department of Molecular Sciences
Deposited By: SLUpub Connector
Deposited On:30 Jul 2019 11:42
Metadata Last Modified:30 Jul 2019 11:42

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