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Publication Abstract from PubMed

Pyrrolo-quinoline quinone (PQQ) is an ortho-quinone cofactor of several prokaryotic oxidases. Widely available in diet and necessary for the correct growth of mice, PQQ has been suspected to be a vitamin for eukaryotes. However, no PQQ-dependent eukaryotic enzyme had been identified to use the PQQ until 2014, when a basidiomycete enzyme catalyzing saccharide dehydrogenation using PQQ as a cofactor was characterized and served to define Auxiliary Activity family 12 (AA12). Here we report the biochemical characterization of the AA12 enzyme encoded by the ascomycete Trichoderma reesei (TrAA12). Surprisingly, only weak activity against uncommon carbohydrates like L-fucose or D-arabinose was measured. The three-dimensional structure of TrAA12 reveals important similarities with bacterial glucose dehydrogenases (s-GDH). The enzymatic characterization and the structure solved in the presence of calcium confirms the importance of this ion in catalysis, as observed for s-GDH. The structural characterization of TrAA12 was completed by modeling PQQ and L-fucose in the enzyme active site. Based on these results, family AA12 enzymes are likely to have a catalytic mechanism close to that of bacterial s-GDH.Importance The Pyrrolo-quinoline quinone (PQQ) is an important co-factor synthesized by prokaryotes and involved in enzymatic alcohol and sugar oxidation. In eukaryotes, the benefit of PQQ as a vitamin has been suggested but never proved. Recently the first eukaryotic enzyme using PQQ was characterized in the basidiomycete Coprinopsis cinerea, demonstrating that fungi are able to use PQQ as an enzyme co-factor. This discovery led to the classification of the fungal PQQ-dependent enzymes in Auxiliary Activity family 12 (AA12) of the Carbohydrate Active Enzymes database (CAZy; http://www.cazy.org) classification. In the present paper, we report the characterization of ascomycete AA12 enzyme from Trichoderma reesei (TrAA12). Our enzymatic and phylogenetic results show divergence with the only other member of the family characterized, from the basidiomycete Coprinopsis cinerea The crystallographic structure of TrAA12 shows similarities to the global active site architecture of bacterial glucose dehydrogenases suggesting a common evolution between the both families.

The functional and structural characterization of Trichoderma reesei dehydrogenase belonging to the PQQ dependent family of Carbohydrate-Active Enzymes Family AA12.,Turbe-Doan A, Record E, Lombard V, Kumar R, Levasseur A, Henrissat B, Garron ML Appl Environ Microbiol. 2019 Oct 11. pii: AEM.00964-19. doi:, 10.1128/AEM.00964-19. PMID:31604773^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.