Insights into an unusual auxiliary activity 9 family member lacking the histidine brace motif of lytic polysaccharide monooxygenases - Archive ouverte HAL
Journal Articles Journal of Biological Chemistry Year : 2019

Insights into an unusual auxiliary activity 9 family member lacking the histidine brace motif of lytic polysaccharide monooxygenases

Shingo Miyauchi
  • Function : Author
  • PersonId : 1017688
Jean-Guy Berrin
  • Function : Author
  • PersonId : 1133878
Leila Lo Leggio

Abstract

Lytic polysaccharide monooxygenases (LPMOs) are redox-enzymes involved in biomass degradation. All characterized LPMOs possess an active site of two highly conserved histidine residues coordinating a copper ion (the histidine brace), which are essential for LPMO activity. However, some protein sequences that belong to the AA9 LPMO family display a natural N-terminal His to Arg substitution (Arg-AA9). These are found almost entirely in the phylogenetic fungal class Agaricomycetes, associated with wood decay, but no function has been demonstrated for any Arg-AA9. Through bioinformatics, transcriptomic, and proteomic analyses we present data, which suggest that Arg-AA9 proteins could have a hitherto unidentified role in fungal degradation of lignocellulosic biomass in conjunction with other secreted fungal enzymes. We present the first structure of an Arg-AA9, LsAA9B, a naturally occurring protein from Lentinus similis. The LsAA9B structure reveals gross changes in the region equivalent to the canonical LPMO copper-binding site, whereas features implicated in carbohydrate binding in AA9 LPMOs have been maintained. We obtained a structure of LsAA9B with xylotetraose bound on the surface of the protein although with a considerably different binding mode compared with other AA9 complex structures. In addition, we have found indications of protein phosphorylation near the N-terminal Arg and the carbohydrate-binding site, for which the potential function is currently unknown. Our results are strong evidence that Arg-AA9s function markedly different from canonical AA9 LPMO, but nonetheless, may play a role in fungal conversion of lignocellulosic biomass.

Dates and versions

hal-02390181 , version 1 (02-12-2019)

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Kristian Frandsen, Morten Tovborg, Christian Jørgensen, Nikolaj Spodsberg, Marie-Noelle Rosso, et al.. Insights into an unusual auxiliary activity 9 family member lacking the histidine brace motif of lytic polysaccharide monooxygenases. Journal of Biological Chemistry, 2019, 294, pp.17117-17130. ⟨10.1074/jbc.RA119.009223⟩. ⟨hal-02390181⟩
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