Characterization of two family AA9 LPMOs from Aspergillus tamarii with distinct activities on xyloglucan reveals structural differences linked to cleavage specificity.

Autor: Monclaro AV; Laboratory of Enzymology, University of Brasília, Campus Universitário Darcy Ribeiro, Brasília, Brazil.; Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences (NMBU), Ås, Norway., Petrović DM; Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences (NMBU), Ås, Norway., Alves GSC; Laboratory of Microbiology, University of Brasília, Campus Universitário Darcy Ribeiro, Brasília, Brazil., Costa MMC; Brazilian Agricultural Research Corporation, Embrapa CENARGEN, Brasília, Brazil., Midorikawa GEO; Laboratory of Microbiology, University of Brasília, Campus Universitário Darcy Ribeiro, Brasília, Brazil., Miller RNG; Laboratory of Microbiology, University of Brasília, Campus Universitário Darcy Ribeiro, Brasília, Brazil., Filho EXF; Laboratory of Enzymology, University of Brasília, Campus Universitário Darcy Ribeiro, Brasília, Brazil., Eijsink VGH; Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences (NMBU), Ås, Norway., Várnai A; Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences (NMBU), Ås, Norway.
Jazyk: angličtina
Zdroj: PloS one [PLoS One] 2020 Jul 08; Vol. 15 (7), pp. e0235642. Date of Electronic Publication: 2020 Jul 08 (Print Publication: 2020).
DOI: 10.1371/journal.pone.0235642
Abstrakt: Aspergillus tamarii grows abundantly in naturally composting waste fibers of the textile industry and has a great potential in biomass decomposition. Amongst the key (hemi)cellulose-active enzymes in the secretomes of biomass-degrading fungi are the lytic polysaccharide monooxygenases (LPMOs). By catalyzing oxidative cleavage of glycoside bonds, LPMOs promote the activity of other lignocellulose-degrading enzymes. Here, we analyzed the catalytic potential of two of the seven AA9-type LPMOs that were detected in recently published transcriptome data for A. tamarii, namely AtAA9A and AtAA9B. Analysis of products generated from cellulose revealed that AtAA9A is a C4-oxidizing enzyme, whereas AtAA9B yielded a mixture of C1- and C4-oxidized products. AtAA9A was also active on cellopentaose and cellohexaose. Both enzymes also cleaved the β-(1→4)-glucan backbone of tamarind xyloglucan, but with different cleavage patterns. AtAA9A cleaved the xyloglucan backbone only next to unsubstituted glucosyl units, whereas AtAA9B yielded product profiles indicating that it can cleave the xyloglucan backbone irrespective of substitutions. Building on these new results and on the expanding catalog of xyloglucan- and oligosaccharide-active AA9 LPMOs, we discuss possible structural properties that could underlie the observed functional differences. The results corroborate evidence that filamentous fungi have evolved AA9 LPMOs with distinct substrate specificities and regioselectivities, which likely have complementary functions during biomass degradation.
Competing Interests: The authors declare that no competing interests exist. Embrapa, the employer of MMCC, is a not-for-profit, state-funded research organization. This does not alter our adherence to PLOS ONE policies on sharing data and materials.
Databáze: MEDLINE
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