6RS7

X-ray crystal structure of LsAA9B (deglycosylated form)

Summary for 6RS7

• Entry DOI: 10.2210/pdb6rs7/pdb
• Descriptor: AA9, 2-acetamido-2-deoxy-beta-D-glucopyranose-(1-4)-2-acetamido-2-deoxy-beta-D-glucopyranose, alpha-D-mannopyranose, ... (8 entities in total)
• Functional Keywords: fungal, family aa9, unknown function
• Biological source: Lentinus similis
• Total number of polymer chains: 1
• Total formula weight: 24755.96

Authors

Frandsen, K.E.H.,Tovborg, M.,Poulsen, J.C.N.,Johansen, K.S.,Lo Leggio, L. (deposition date: 2019-05-21, release date: 2019-09-11, Last modification date: 2024-10-09)

Primary citation

Frandsen, K.E.H.,Tovborg, M.,Jorgensen, C.I.,Spodsberg, N.,Rosso, M.N.,Hemsworth, G.R.,Garman, E.F.,Grime, G.W.,Poulsen, J.N.,Batth, T.S.,Miyauchi, S.,Lipzen, A.,Daum, C.,Grigoriev, I.V.,Johansen, K.S.,Henrissat, B.,Berrin, J.G.,Lo Leggio, L.
Insights into an unusual Auxiliary Activity 9 family member lacking the histidine brace motif of lytic polysaccharide monooxygenases.
J.Biol.Chem., 294:17117-17130, 2019

PubMed 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 , 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, AA9B, a naturally occurring protein from The AA9B 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 AA9B 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.

PubMed: 31471321
DOI: 10.1074/jbc.RA119.009223

Experimental method

X-RAY DIFFRACTION (1.6 Å)