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Auxiliary Activity Family 14

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Auxiliary Activity Family AA14
Clan Structurally related to AA9
Mechanism lytic oxidase
Active site residues mononuclear copper ion
CAZy DB link

Substrate specificities

The gene encoding the first AA14 family member was identified by analysing transcriptomic and proteomic data from the white-rot basidiomycete Pycnoporus coccineus [1]. This gene was highly upregulated when the fungus was grown on pine or poplar. The corresponding protein (GenBank ID KY769370) was secreted only during growth on pine and poplar, suggesting a role in wood decay. AA14 modules never occur with CBMs, carbohydrate-binding modules which explains why the family could not be discovered by the module-walking approach, as were AA11 and AA13.

The only two AA14 characterized so far were tested for copper dependant oxidase activity on a range of polysaccharides. No activity could be detected on any substrate tested, including cellulose and xylans. However, addition of either of the AA14 enzymes to a Trichoderma reesei cocktail composed of mainly cellulases and xylanases led to a boost of glucose release from poplar and pine . This improvement in glucose release was dose dependent, yielding up to ~100% increase on pretreated softwood. AA14 enzymes also showed synergystic action on wood with AA9 LPMOs. Finally, activity was detected on xylan adsorbed onto cellulose chains, using solid state 13C CP/MAS NMR and mass spectrometry. The observed products were C1 oxidized species with an aldonic acid at the reducing end.

Kinetics and Mechanism

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Catalytic Residues

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Three-dimensional structures

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Family Firsts

First family member identified
AA14 from Pycnoporus coccineus [2].
First demonstration of oxidative cleavage
PcAA114A and PcAA114AB were shown to oxidatively cleave xylan chains bound to cellulose [2].
First 3-D structure
PcAA14B from P. coccineus 5NO7 [2]


  1. Couturier M, Navarro D, Chevret D, Henrissat B, Piumi F, Ruiz-Dueñas FJ, Martinez AT, Grigoriev IV, Riley R, Lipzen A, Berrin JG, Master ER, and Rosso MN. (2015) Enhanced degradation of softwood versus hardwood by the white-rot fungus Pycnoporus coccineus. Biotechnol Biofuels. 8, 216. DOI:10.1186/s13068-015-0407-8 | PubMed ID:26692083 | HubMed [Couturier2015]
  2. Couturier M, Ladevèze S, Sulzenbacher G, Ciano L, Fanuel M, Moreau C, Villares A, Cathala B, Chaspoul F, Frandsen KE, Labourel A, Herpoël-Gimbert I, Grisel S, Haon M, Lenfant N, Rogniaux H, Ropartz D, Davies GJ, Rosso MN, Walton PH, Henrissat B, and Berrin JG. (2018) Lytic xylan oxidases from wood-decay fungi unlock biomass degradation. Nat Chem Biol. 14, 306-310. DOI:10.1038/nchembio.2558 | PubMed ID:29377002 | HubMed [Couturier2018]
All Medline abstracts: PubMed | HubMed