Combining pieces: a thorough analysis of light activation boosting power and co-substrate preferences for the catalytic efficiency of lytic polysaccharide monooxygenase MtLPMO9A

Abstract

Cost-efficient plant biomass conversion using biochemical and/or chemical routes is essential for transitioning to sustainable chemical technologies and renewable biofuels. Lytic polysaccharide monooxygenases (LPMOs) are copper-dependent enzymes that make part of modern hydrolytic cocktails destined for plant biomass degradation. Here, we characterized MtLPMO9A from Thermothelomyces thermophilus M77 (formerly Myceliophthora thermophila) and demonstrated that it could be efficiently driven by chlorophyllin excited by light in the presence of a reductant agent. However, in the absence of chemical reductant, chlorophyllin and light alone do not lead to a significant release of the reaction products by the LPMO, indicating a low capacity of MtLPMO9A reduction (either via direct electron transfer or via superoxide ion, O2•-). We showed that photocatalysis could significantly increase the LPMO activity against highly crystalline and recalcitrant cellulosic substrates, which are poorly degraded in the absence of chlorophyllin and light. We also evaluated the use of co-substrates by MtLPMO9A, revealing that the enzyme can use both hydrogen peroxide (H2O2) and molecular oxygen (O2) as co-substrates for cellulose catalytic oxidation.

Light Boosts the Activity of Novel LPMO from Aspergillus fumigatus Leading to Oxidative Cleavage of Cellulose and Hemicellulose

“…fumigatus and T. thermophilus. ,, The analysis of the products’ profile generated by Af AA9C allowed the classification of the enzyme as a type 3 LPMO since the enzyme was able to oxidize the substrate at C1 and C4, releasing cellodextrins (Glc 2 –Glc 6 ), aldonic acids (Glc 2 Glc1A–Glc 6 Glc1A), and ketoaldoses (C4-oxidized, GlcgemGlc n ) in the evaluated conditions (Figure ).…”

Evaluating the potential applications of brewers' spent grain in biogas generation, food and biotechnology industry: A review

“…Besides, chemical pretreatment include; acidic pretreatment, alkaline pretreatment, redox reactions and Fenton reactions, and ionic liquid but is environmentally unfriendly [ 60 ]. Biological pretreatment is another approach which include; ensiling, fungi, micro-aeration, microbial consortium [ 60 , 63 , 64 ] and enzymatic pretreatment. Hybrid pretreatment is another approach which include wet oxidation and ammonia freeze explosion [ 65 ].…”

Novel Aspergillus fumigatus recombinant LPMOs: biochemical characteristics, and their participation in saccharification and photobiocatalysis processes

“…The results of oxidative activity of AfAA9C (at pH 5.0 and 7.0) against Avicel PH-101, a model crystalline cellulose substrate, demonstrated a better performance at pH 7.0 since the enzyme was able to release large amounts of products in that condition compared to pH 5.0 (Figure 3.7 inset). Previous investigations showed the same behavior for other recombinant LPMOs from A. fumigatus and T. thermophilus (Higasi et al, 2021;Sepulchro et al, 2021;Velasco et al, 2021). The analysis of the products profile generated by AfAA9C allowed the classification of the enzyme as a type 3 LPMO since the enzyme was able to oxidize the substrate at C1 and C4, releasing cellodextrins (Glc2 -Glc6), aldonic acids (Glc2Glc1A -Glc6Glc1A) and ketoaldoses (C4-oxidized, GlcgemGlcn) in evaluated conditions (Figure 3.7).…”

“…The activity of the enzyme TtLPMO9E using only thylakoids/light or Chl/light without the addition of reducing agents was 10-fold lower compared to full lightinduced system including the reducing agent (Cannella et al, 2016). The low reducing power of pigment/light systems on LPMOs have been described for ScAA10C from Streptomyces coelicolor and MtLPMO9A from T. thermophilus (Bissaro et al, 2020;Sepulchro et al, 2021).…”