Characterization and synergistic action of a tetra‐modular lytic polysaccharide monooxygenase from Bacillus cereus

Abstract

Lytic polysaccharide monooxygenases (LPMOs) contribute to enzymatic conversion of recalcitrant polysaccharides such as chitin and cellulose and may also play a role in bacterial infections. Some LPMOs are multimodular, the implications of which remain only partly understood. We have studied the properties of a tetra‐modular LPMO from the food poisoning bacterium Bacillus cereus (named BcLPMO10A). We show that BcLPMO10A, comprising an LPMO domain, two fibronectin‐type III (FnIII)‐like domains, and a carbohydrate‐binding module (CBM5), is a powerful chitin‐active LPMO. While the role of the FnIII domains remains unclear, we show that enzyme functionality strongly depends on the CBM5, which, by promoting substrate binding, protects the enzyme from inactivation. BcLPMO10A enhances the activity of chitinases during the degradation of α‐chitin.

Controlled depolymerization of cellulose by light-driven lytic polysaccharide oxygenases

“…6c). Similar amounts of H 2 O 2 were measured when Avicel was replaced by ScAA10C-Cu(II), where the latter is known to produce H 2 O 2 when incubated with reductant and O 2 in the absence of substrate 45 . These results indicate that in these AscA-driven reactions, the substrate contributes to the generation of H 2 O 2 , possibly because of the pro-oxidant properties of AscA that become apparent in the presence of free metals (see ref.…”

“…Oxidized dimers and trimers were quantified using GlcGlc1A and (Glc) 2 Glc1A standards obtained by incubating (40°C, 1000 rpm) cellobiose (2 mM) or cellotriose (2 mM) with the cellobiose dehydrogenase from Myriococcum thermophilum (MtCDH, 62 2 μM, 3 successive additions every 24 h to obtain maximum conversion of 95%). Chito-oligosaccharides resulting from the action of SmAA10A on β-chitin were analyzed using a Dionex Ultimate 3000 UHPLC system equipped with a Rezex RFQ-Fast acid H + (8%) 7.8 × 100 mm column as previously described 45 . The elution of chitooligosaccharides was monitored using a UV detector (194 nm).…”

Substrate selectivity in starch polysaccharide monooxygenases

“…Substrate occupancy at the active site is an important criterion to minimize off-pathway oxidations that lead to enzyme inactivation (36,37). In line with this, the observed loss in activity with 25 mg/ml amylose may have been a result of a subsaturating amylose concentration.…”

Enzymatic Modifications of Chitin, Chitosan, and Chitooligosaccharides

“…Chitin-active LPMO was first demonstrated in 2010 for the Serratia marcescens AA10 (CBP21) (Vaaje-Kolstad et al, 2010). In contrast to glycoside hydrolases (GHs), such as chitinases and chitosanases, LPMOs are capable of directly cleaving glycolic bonds in highly crystallized chitin (Mutahir et al, 2018). To date, LPMOs with chitinolytic activities have been identified in carbohydrate auxiliary activity families AA10, AA11, and AA15 (Hemsworth et al, 2015).…”