The First Structure of a Glycoside Hydrolase Family 61 Member, Cel61B from Hypocrea jecorina, at 1.6 Å Resolution

Karkehabadi, Saeid; Hansson, Henrik; Kim, Steve; Piens, Kathleen; Mitchinson, Colin; Sandgren, Mats

doi:10.1016/j.jmb.2008.08.016

Cited by 196 publications

(206 citation statements)

References 50 publications

(44 reference statements)

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“…Another important issue for future studies is the role of the divalent metal ion which remains somewhat enigmatic for both CBM33 and GH61 enzymes. 11,17,18 We have used Mg 2þ in this study because an initial screening showed high activity when this metal was added. However, several metals worked well, confirming the apparent promiscuity that has been observed in other studies of both CBM33s 11 and GH61s.…”

Section: Resultsmentioning

confidence: 99%

“…Indeed, several bacteria that are able to degrade crystalline cellulose contain multiple CBM33 proteins 13,14 and some of these are known to be coregulated with cellulases. 15,16 Proteins classified as glycoside hydrolase family 61 (GH61) are structurally similar to CBM33 17,18 and are known to act synergistically with cellulases. However, the potentiating mechanism of these proteins remains enigmatic and activity has so far only been shown for rather complex substrates, that is, not for pure cellulose.…”

Section: Introductionmentioning

confidence: 99%

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Cleavage of cellulose by a CBM33 protein

et al. 2011

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Bacterial proteins categorized as family 33 carbohydrate-binding modules (CBM33) were recently shown to cleave crystalline chitin, using a mechanism that involves hydrolysis and oxidation. We show here that some members of the CBM33 family cleave crystalline cellulose as demonstrated by chromatographic and mass spectrometric analyses of soluble products released from Avicel or filter paper on incubation with CelS2, a CBM33-containing protein from Streptomyces coelicolor A3(2). These enzymes act synergistically with cellulases and may thus become important tools for efficient conversion of lignocellulosic biomass. Fungal proteins classified as glycoside hydrolase family 61 that are known to act synergistically with cellulases are likely to use a similar mechanism.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Cleavage of cellulose by a CBM33 protein

et al. 2011

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“…This could also explain the specificities displayed by CBM33 modules. The crystal structures of GH61s from Hypocrea jecorina (Karkehabadi et al, 2008) and Thielavia terrestris (Harris et al, 2010) reveal a similar surface to CBM33, again pointing to a disruptive function for these proteins. While the effects of noncatalytic proteins on cellulose hydrolysis, to date, have been disappointing, continued efforts at identifying the functional significance of these molecules is merited.…”

Section: How Do Cbms Potentiate Catalysis?mentioning

confidence: 89%

“…More modest potentiation of cellulases by "noncatalytic" bacterial CBMs has also been reported (Moser et al, 2008), while it has been suggested that several noncatalytic fungal proteins may play a role in plant cell wall disruption. It is believed that the primary function of GH61s (now established as fungal noncatalytic carbohydrate-binding proteins) is to disrupt plant cell wall structure and thus increase the access of degradative enzymes to their substrates (Rosgaard et al, 2006;Karkehabadi et al, 2008;Harris et al, 2010). Indeed, fungi often contain multiple copies of this protein, and they are coexpressed with a range of cellulases (Vanden Wymelenberg et al, 2009).…”

Section: How Do Cbms Potentiate Catalysis?mentioning

confidence: 99%

The Biochemistry and Structural Biology of Plant Cell Wall Deconstruction

2010

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“…In contrast to the classic hydrolytic enzymes that comprise many enzyme families, LPMOs only group into two distinct families (6): carbohydrate binding module family 33 (CBM33), with bacterial, viral, and some eukaryotic members, and glycoside hydrolase family 61 (GH61), with so far, only fungal members. The two LPMO families share a common fold, with a flat substrate binding surface that contains a metal binding site that includes two conserved histidines (5,7,8) (see below).…”

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confidence: 99%

NMR structure of a lytic polysaccharide monooxygenase provides insight into copper binding, protein dynamics, and substrate interactions

Aachmann

Sørlie

Skjåk‐Bræk

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

248

346

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Lytic polysaccharide monooxygenases currently classified as carbohydrate binding module family 33 (CBM33) and glycoside hydrolase family 61 (GH61) are likely to play important roles in future biorefining. However, the molecular basis of their unprecedented catalytic activity remains largely unknown. We have used NMR techniques and isothermal titration calorimetry to address structural and functional aspects of CBP21, a chitin-active CBM33. NMR structural and relaxation studies showed that CBP21 is a compact and rigid molecule, and the only exception is the catalytic metal binding site. NMR data further showed that His28 and His114 in the catalytic center bind a variety of divalent metal ions with a clear preference for Cu 2+ (K d = 55 nM; from isothermal titration calorimetry) and higher preference for Cu 1+ (K d ∼ 1 nM; from the experimentally determined redox potential for CBP21-Cu 2+ of 275 mV using a thermodynamic cycle). Strong binding of Cu 1+ was also reflected in a reduction in the pK a values of the histidines by 3.6 and 2.2 pH units, respectively. Cyanide, a mimic of molecular oxygen, was found to bind to the metal ion only. These data support a model where copper is reduced on the enzyme by an externally provided electron and followed by oxygen binding and activation by internal electron transfer. Interactions of CBP21 with a crystalline substrate were mapped in a 2 H/ 1 H exchange experiment, which showed that substrate binding involves an extended planar binding surface, including the metal binding site. Such a planar catalytic surface seems well-suited to interact with crystalline substrates.cellulose | biomass C hitin and cellulose represent some of nature's largest reservoirs of organic carbon in the form of monomeric hexose sugars (N-acetyl-glucosamine and glucose, respectively) linearly linked by β-1,4 glycosidic bonds. In their natural form, both polysaccharides are organized in crystalline arrangements that make up robust biological structures, like crustacean cuticles (chitin) or plant cell walls (cellulose). Although this crystalline nature is crucial for biological function, it provides a thorough challenge in industrial biorefining of biomass, where efficient enzymatic depolymerization of particularly cellulose is a critical step.Enzymatic degradation of recalcitrant polysaccharides has traditionally been thought to occur through the synergistic action of hydrolytic enzymes that have complementary activities (1, 2). Endo-acting hydrolases make random scissions on the polysaccharide chains, whereas exo-acting processive hydrolases mainly target chain ends. However, during the last 2 years, a new enzyme family targeting recalcitrant polysaccharides has been identified, namely the lytic polysaccharide monooxygenases [LPMOs; also referred to as lytic polysaccharide oxidases (3), polysaccharide monooxygenases (4), and oxidohydrolases (5)]. In contrast to the classic hydrolytic enzymes that comprise many enzyme families, LPMOs only group into two distinct families (6): carbohydrate binding modu...

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The First Structure of a Glycoside Hydrolase Family 61 Member, Cel61B from Hypocrea jecorina, at 1.6 Å Resolution

Cited by 196 publications

References 50 publications

Cleavage of cellulose by a CBM33 protein

Cleavage of cellulose by a CBM33 protein

The Biochemistry and Structural Biology of Plant Cell Wall Deconstruction

NMR structure of a lytic polysaccharide monooxygenase provides insight into copper binding, protein dynamics, and substrate interactions

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