Characterization of basidiomycetes AA9 LPMOs and their potential application in cello oligosaccharides production

Abstract

The knowledge on the enzymatic degradation of polysaccharides advanced in the last decade mainly due to the identification of lytic polysaccharide monooxygenases (LPMOs), metalloenzymes that potentiate the enzymatic conversion of lignocellulose, breaking down the cellulose crystallinity throughout an oxidative mechanism. Recently, the application of these enzymes has been demonstrated to increase the yields of fermentable sugars and other products, such as cello oligosaccharides, during biomass saccharification. In nature, the fungal kingdom, especially basidiomycetes, displays a high number of genes encoding LPMOs from family AA9 (LPMO9s), however, enzymatic characteristics such as substrate specificity, kinetic parameters, and product profile are not fully understood. AA9 LPMOs were previously identified by proteomics approach in the secretome of white-rot basidiomycetes Pycnoporus coccineus and Trametes versicolor growing on lignocellulose and then selected as targets for heterologous expression. We present this project as a part of the requirements for Research Internship Abroad application in collaboration with Professor Paul H. Walton from the University of York. We aim to identify promising LPMOs to supplement the secretome of an Aspergillus niger engineered strain for cello-oligosaccharide production in the enzymatic saccharification micro assays of sugarcane straw. Selection will be based on in-depth comparisons between the biological and functional characteristics of at least three different LPMOs, focusing on structural and spectroscopic analyses. In addition, we expected to investigate the histidine brace motif from the active site of these enzymes and their role in the enzyme-substrate interactions, advancing on the studies with LPMOs. (AU)