Structural dynamics of lytic polysaccharide monooxygenase during catalysis

Frantisek Filandr, Daniel Kavan, Daniel Kracher, Christophe V.F.P. Laurent, Roland Ludwig, Petr Man*, Petr Halada

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Lytic polysaccharide monooxygenases (LPMOs) are industrially important oxidoreductases employed in lignocellulose saccharification. Using advanced time-resolved mass spectrometric techniques, we elucidated the structural determinants for substrate-mediated stabilization of the fungal LPMO9C from Neurospora crassa during catalysis. LPMOs require a reduction in the active-site copper for catalytic activity. We show that copper reduction in NcLPMO9C leads to structural rearrangements and compaction around the active site. However, longer exposure to the reducing agent ascorbic acid also initiated an uncoupling reaction of the bound oxygen species, leading to oxidative damage, partial unfolding, and even fragmentation of NcLPMO9C. Interestingly, no changes in the hydrogen/deuterium exchange rate were detected upon incubation of oxidized or reduced LPMO with crystalline cellulose, indicating that the LPMO-substrate interactions are mainly side-chain mediated and neither affect intraprotein hydrogen bonding nor induce significant shielding of the protein surface. On the other hand, we observed a protective effect of the substrate, which slowed down the autooxidative damage induced by the uncoupling reaction. These observations further complement the picture of structural changes during LPMO catalysis.

Original languageEnglish
Article number242
JournalBiomolecules
Volume10
Issue number2
DOIs
Publication statusPublished - Feb 2020
Externally publishedYes

Keywords

  • Hydrogen/deuterium exchange mass spectrometry
  • Lignocellulose degradation
  • Lytic polysaccharide monooxygenase
  • Oxidative amino acid modification
  • Peptide bond cleavage
  • Reactive oxygen species

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology

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