Structural Features on the Substrate-Binding Surface of Fungal Lytic Polysaccharide Monooxygenases Determine Their Oxidative Regioselectivity

2018 ◽  
Vol 14 (3) ◽  
pp. 1800211 ◽  
Author(s):  
Barbara Danneels ◽  
Magali Tanghe ◽  
Tom Desmet
Keyword(s):  
Substrate Binding ◽  
Structural Features ◽  
Lytic Polysaccharide Monooxygenases ◽  
Binding Surface ◽  
Polysaccharide Monooxygenases

Recent insights into lytic polysaccharide monooxygenases (LPMOs)

2018 ◽  
Vol 46 (6) ◽  
pp. 1431-1447 ◽  
Author(s):  
Tobias Tandrup ◽  
Kristian E. H. Frandsen ◽  
Katja S. Johansen ◽  
Jean-Guy Berrin ◽  
Leila Lo Leggio
Keyword(s):  
Active Site ◽  
Room Temperature ◽  
Experimental Studies ◽  
Binding Mode ◽  
Structural Features ◽  
Oxygen Species ◽  
Animal Kingdom ◽  
X Ray ◽  
Lytic Polysaccharide Monooxygenases ◽  
Polysaccharide Monooxygenases

Lytic polysaccharide monooxygenases (LPMOs) are copper enzymes discovered within the last 10 years. By degrading recalcitrant substrates oxidatively, these enzymes are major contributors to the recycling of carbon in nature and are being used in the biorefinery industry. Recently, two new families of LPMOs have been defined and structurally characterized, AA14 and AA15, sharing many of previously found structural features. However, unlike most LPMOs to date, AA14 degrades xylan in the context of complex substrates, while AA15 is particularly interesting because they expand the presence of LPMOs from the predominantly microbial to the animal kingdom. The first two neutron crystallography structures have been determined, which, together with high-resolution room temperature X-ray structures, have putatively identified oxygen species at or near the active site of LPMOs. Many recent computational and experimental studies have also investigated the mechanism of action and substrate-binding mode of LPMOs. Perhaps, the most significant recent advance is the increasing structural and biochemical evidence, suggesting that LPMOs follow different mechanistic pathways with different substrates, co-substrates and reductants, by behaving as monooxygenases or peroxygenases with molecular oxygen or hydrogen peroxide as a co-substrate, respectively.

scholarly journals Identification of the molecular determinants driving the substrate specificity of fungal lytic polysaccharide monooxygenases (LPMOs)

2020 ◽  
pp. jbc.RA120.015545
Author(s):  
Kristian E. H. Frandsen ◽  
Mireille Haon ◽  
Sacha Grisel ◽  
Bernard Henrissat ◽  
Leila Lo Leggio ◽  
...  
Keyword(s):  
Substrate Specificity ◽  
Time Course ◽  
Plant Cell Wall ◽  
Plant Biomass ◽  
Substrate Binding ◽  
Glycoside Hydrolases ◽  
Sequence Alignments ◽  
Lytic Polysaccharide Monooxygenases ◽  
Molecular Determinants ◽  
Polysaccharide Monooxygenases

Understanding enzymatic breakdown of plant biomass is crucial to develop nature-inspired biotechnological processes. Lytic polysaccharide monooxygenases (LPMOs) are microbial enzymes secreted by fungal saprotrophs involved in carbon recycling. LPMOs modify biomass by oxidatively cleaving polysaccharides thereby enhancing the efficiency of glycoside hydrolases. Fungal AA9 LPMOs are active on cellulose but some members also display activity on hemicelluloses and/or oligosaccharides. Although the active site subsites are well defined for a few model LPMOs, the molecular determinants driving broad substrate specificity are still not easily predictable. Based on bioinformatic clustering and sequence alignments, we selected seven fungal AA9 LPMOs that differ in the amino-acid residues constituting their subsites. Investigation of their substrate specificities revealed that all these LPMOs are active on cellulose and cello-oligosaccharides, as well as plant cell wall-derived hemicellulosic polysaccharides and carry out C4 oxidative cleavage. The product profiles from cello-oligosaccharides degradation suggests that the subtle differences in amino acids sequence within the substrate-binding loop regions lead to different preferred binding modes. Our functional analyses allowed us to probe the molecular determinants of substrate binding within two AA9 LPMO sub-clusters. Many wood-degrading fungal species rich in AA9 genes have at least one AA9 enzyme with structural loop features that allow recognition of short β-(1,4)-linked glucan chains. Time-course monitoring of these AA9 LPMOs on cello-oligosaccharides also provides a useful model system for mechanistic studies of LPMO catalysis. These results are valuable for the understanding of LPMO contribution to wood decaying process in nature and for the development of sustainable biorefineries.

scholarly journals Structural analysis of the catalytic domain of Artemis endonuclease/SNM1C reveals distinct structural features

2020 ◽  
Vol 295 (35) ◽  
pp. 12368-12377 ◽  
Author(s):  
Md Fazlul Karim ◽  
Shanshan Liu ◽  
Adrian R. Laciak ◽  
Leah Volk ◽  
Mary Koszelak-Rosenblum ◽  
...  
Keyword(s):  
B Cell ◽  
Catalytic Domain ◽  
Substrate Binding ◽  
Binding Pocket ◽  
Structural Features ◽  
Zinc Ion ◽  
Dna Double Strand Breaks ◽  
Repair Gene ◽  
Dna Hairpins ◽  
Binding Surface

The endonuclease Artemis is responsible for opening DNA hairpins during V(D)J recombination and for processing a subset of pathological DNA double-strand breaks. Artemis is an attractive target for the development of therapeutics to manage various B cell and T cell tumors, because failure to open DNA hairpins and accumulation of chromosomal breaks may reduce the proliferation and viability of pre-T and pre-B cell derivatives. However, structure-based drug discovery of specific Artemis inhibitors has been hampered by a lack of crystal structures. Here, we report the structure of the catalytic domain of recombinant human Artemis. The catalytic domain displayed a polypeptide fold similar overall to those of other members in the DNA cross-link repair gene SNM1 family and in mRNA 3′-end-processing endonuclease CPSF-73, containing metallo-β-lactamase and β-CASP domains and a cluster of conserved histidine and aspartate residues capable of binding two metal atoms in the catalytic site. As in SNM1A, only one zinc ion was located in the Artemis active site. However, Artemis displayed several unique features. Unlike in other members of this enzyme class, a second zinc ion was present in the β-CASP domain that leads to structural reorientation of the putative DNA-binding surface and extends the substrate-binding pocket to a new pocket, pocket III. Moreover, the substrate-binding surface exhibited a dominant and extensive positive charge distribution compared with that in the structures of SNM1A and SNM1B, presumably because of the structurally distinct DNA substrate of Artemis. The structural features identified here may provide opportunities for designing selective Artemis inhibitors.

scholarly journals Sequence and Structural Analysis of AA9 and AA10 LPMOs: An Insight into the Basis of Substrate Specificity and Regioselectivity

2019 ◽  
Vol 20 (18) ◽  
pp. 4594 ◽  
Author(s):  
Xiaoli Zhou ◽  
Xiaohua Qi ◽  
Hongxia Huang ◽  
Honghui Zhu
Keyword(s):  
Structural Analysis ◽  
Substrate Specificity ◽  
Molecular Basis ◽  
Substrate Binding ◽  
Binding Modes ◽  
Substrate Specificities ◽  
Lytic Polysaccharide Monooxygenases ◽  
Polysaccharide Monooxygenases ◽  
Natural Carbon ◽  
Insight Into

Lytic polysaccharide monooxygenases (LPMOs) are key enzymes in both the natural carbon cycle and the biorefinery industry. Understanding the molecular basis of LPMOs acting on polysaccharide substrates is helpful for improving industrial cellulase cocktails. Here we analyzed the sequences, structures, and substrate binding modes of LPMOs to uncover the factors that influence substrate specificity and regioselectivity. Our results showed that the different compositions of a motif located on L2 affect the electrostatic potentials of substrate binding surfaces, which in turn affect substrate specificities of AA10 LPMOs. A conserved Asn at a distance of 7 Å from the active center Cu might, together with the conserved Ser immediately before the second catalytic His, determine the localization of LPMOs on substrate, and thus contribute to C4-oxidizing regioselectivity. The findings in this work provide an insight into the molecular basis of substrate specificity and regioselectivity of LPMOs.

scholarly journals Interactions of a fungal lytic polysaccharide monooxygenase with β-glucan substrates and cellobiose dehydrogenase

2016 ◽  
Vol 113 (21) ◽  
pp. 5922-5927 ◽  
Author(s):  
Gaston Courtade ◽  
Reinhard Wimmer ◽  
Åsmund K. Røhr ◽  
Marita Preims ◽  
Alfons K. G. Felice ◽  
...  
Keyword(s):  
Substrate Binding ◽  
Copper Ion ◽  
Cellobiose Dehydrogenase ◽  
Titration Calorimetry ◽  
Nmr Studies ◽  
Lytic Polysaccharide Monooxygenase ◽  
Enzyme Substrate ◽  
Binding Surface ◽  
Copper Site ◽  
Polysaccharide Monooxygenases

Lytic polysaccharide monooxygenases (LPMOs) are copper-dependent enzymes that catalyze oxidative cleavage of glycosidic bonds using molecular oxygen and an external electron donor. We have used NMR and isothermal titration calorimetry (ITC) to study the interactions of a broad-specificity fungal LPMO, NcLPMO9C, with various substrates and with cellobiose dehydrogenase (CDH), a known natural supplier of electrons. The NMR studies revealed interactions with cellohexaose that center around the copper site. NMR studies with xyloglucans, i.e., branched β-glucans, showed an extended binding surface compared with cellohexaose, whereas ITC experiments showed slightly higher affinity and a different thermodynamic signature of binding. The ITC data also showed that although the copper ion alone hardly contributes to affinity, substrate binding is enhanced for metal-loaded enzymes that are supplied with cyanide, a mimic of O2−. Studies with CDH and its isolated heme b cytochrome domain unambiguously showed that the cytochrome domain of CDH interacts with the copper site of the LPMO and that substrate binding precludes interaction with CDH. Apart from providing insights into enzyme–substrate interactions in LPMOs, the present observations shed new light on possible mechanisms for electron supply during LPMO action.

scholarly journals Quantifying oxidation of cellulose-associated glucuronoxylan by two lytic polysaccharide monooxygenases from Neurospora crassa

2021 ◽  
Author(s):  
Olav A. Hegnar ◽  
Heidi Østby ◽  
Dejan M. Petrović ◽  
Lisbeth Olsson ◽  
Anikó Várnai ◽  
...  
Keyword(s):  
Neurospora Crassa ◽  
Plant Cell Wall ◽  
Plant Biomass ◽  
Hydrolytic Enzymes ◽  
Structural Features ◽  
Cell Wall Polysaccharides ◽  
Functional Variation ◽  
Lytic Polysaccharide Monooxygenases ◽  
Polysaccharide Monooxygenases ◽  
Oxidized Products

Family AA9 lytic polysaccharide monooxygenases (LPMOs) are abundant in fungi where they catalyze oxidative depolymerization of recalcitrant plant biomass. These AA9 LPMOs cleave cellulose, and some also act on hemicelluloses, primarily other (substituted) β-(1→4)-glucans. Oxidative cleavage of xylan has been shown for only a handful AA9 LPMOs, and it remains unclear whether this activity is a minor side reaction or primary function. Here, we show that Nc LPMO9F and the phylogenetically related, hitherto uncharacterized Nc LPMO9L from Neurospora crassa are active on both cellulose and cellulose-associated glucuronoxylan, but not on glucuronoxylan alone. A newly developed method for simultaneous quantification of xylan-derived and cellulose-derived oxidized products showed that Nc LPMO9F preferentially cleaves xylan when acting on a cellulose–beechwood glucuronoxylan mixture, yielding about three times more xylan-derived than cellulose-derived oxidized products. Interestingly, under similar conditions, Nc LPMO9L and previously characterized Mc LPMO9H from Malbranchea cinnamomea showed different xylan-to-cellulose preferences, giving oxidized product ratios of about 0.5:1 and 1:1, respectively, indicative of functional variation among xylan-active LPMOs. Phylogenetic and structural analysis of xylan-active AA9 LPMOs led to the identification of characteristic structural features, including unique features that do not occur in phylogenetically remote AA9 LPMOs, such as four AA9 LPMOs whose lack of activity towards glucuronoxylan was demonstrated in the present study. Taken together, the results provide a path towards discovery of additional xylan-active LPMOs and show that the huge family of AA9 LPMOs has members that preferentially act on xylan. These findings shed new light on the biological role and industrial potential of these fascinating enzymes. Importance Plant cell wall polysaccharides are highly resilient to depolymerization by hydrolytic enzymes, partly due to cellulose chains being tightly packed in microfibrils that are covered by hemicelluloses. Lytic polysaccharide monooxygenases (LPMOs) seem well suited to attack these resilient co-polymeric structures, but the occurrence and importance of hemicellulolytic activity among LPMOs remains unclear. Here we show that certain AA9 LPMOs preferentially cleave xylan when acting on a cellulose–glucuronoxylan mixture, and that this ability is the result of protein evolution that has resulted in a clade of AA9 LPMOs with specific structural features. Our findings strengthen the notion that the vast arsenal of AA9 LPMOs in certain fungal species provides functional versatility, and that AA9 LPMOs may have evolved to promote oxidative depolymerization of a wide variety of recalcitrant, co-polymeric plant polysaccharide structures. These findings have implications for understanding the biological roles and industrial potential of LPMOs.

scholarly journals Novel molecular biological tools for the efficient expression of fungal lytic polysaccharide monooxygenases in Pichia pastoris

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Lukas Rieder ◽  
Katharina Ebner ◽  
Anton Glieder ◽  
Morten Sørlie
Keyword(s):  
Pichia Pastoris ◽  
Biomass Conversion ◽  
Single Step ◽  
Additional Advantage ◽  
Lytic Polysaccharide Monooxygenases ◽  
Expression Host ◽  
Shake Flask Cultivation ◽  
Polysaccharide Monooxygenases ◽  
Efficient Expression ◽  
High Yields

Abstract Background Lytic polysaccharide monooxygenases (LPMOs) are attracting large attention due their ability to degrade recalcitrant polysaccharides in biomass conversion and to perform powerful redox chemistry. Results We have established a universal Pichia pastoris platform for the expression of fungal LPMOs using state-of-the-art recombination cloning and modern molecular biological tools to achieve high yields from shake-flask cultivation and simple tag-less single-step purification. Yields are very favorable with up to 42 mg per liter medium for four different LPMOs spanning three different families. Moreover, we report for the first time of a yeast-originating signal peptide from the dolichyl-diphosphooligosaccharide-protein glycosyltransferase subunit 1 (OST1) form S. cerevisiae efficiently secreting and successfully processes the N-terminus of LPMOs yielding in fully functional enzymes. Conclusion The work demonstrates that the industrially most relevant expression host P. pastoris can be used to express fungal LPMOs from different families in high yields and inherent purity. The presented protocols are standardized and require little equipment with an additional advantage with short cultivation periods.

scholarly journals Oxidative Power: Tools for Assessing LPMO Activity on Cellulose

Biomolecules ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 1098
Author(s):  
Federica Calderaro ◽  
Loes E. Bevers ◽  
Marco A. van den Berg
Keyword(s):  
Experimental Design ◽  
Mode Of Action ◽  
Data Interpretation ◽  
Electron Donors ◽  
Cellulolytic Enzymes ◽  
Inhibiting Factors ◽  
Lytic Polysaccharide Monooxygenases ◽  
Polysaccharide Monooxygenases ◽  
Power Tools ◽  
Reliable Methods

Lytic polysaccharide monooxygenases (LPMOs) have sparked a lot of research regarding their fascinating mode-of-action. Particularly, their boosting effect on top of the well-known cellulolytic enzymes in lignocellulosic hydrolysis makes them industrially relevant targets. As more characteristics of LPMO and its key role have been elucidated, the need for fast and reliable methods to assess its activity have become clear. Several aspects such as its co-substrates, electron donors, inhibiting factors, and the inhomogeneity of lignocellulose had to be considered during experimental design and data interpretation, as they can impact and often hamper outcomes. This review provides an overview of the currently available methods to measure LPMO activity, including their potential and limitations, and it is illustrated with practical examples.

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