Synergism of Cellulases from Trichoderma reesei in the Degradation of Cellulose

Henrissat, Bernard; Driguez, Hugues; Viet, C.; Schülein, M.

doi:10.1038/nbt0885-722

Cited by 467 publications

(306 citation statements)

References 22 publications

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“…In addition, the maximum DS is predicted to occur at a somewhat higher exo/ endo ratio as F a increases. Comparison of Figure 2A and B suggests that DP is a much more important substrate variable than F a in determining the DS, which is consistent with experimental results in which cellulose accessibility was changed with relatively little change in DP (Fan and Lee, 1983;Fan et al, 1980;Henrissat et al, 1985).…”

Section: Endoglucanase-exoglucanase Synergysupporting

confidence: 85%

A functionally based model for hydrolysis of cellulose by fungal cellulase

Zhang

Lynd

2006

Biotechnol. Bioeng.

204

158

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A new functionally based kinetic model for enzymatic hydrolysis of pure cellulose by the Trichoderma cellulase system is presented. The model represents the actions of cellobiohydrolases I, cellobiohydrolase II, and endoglucanase I; and incorporates two measurable and physically interpretable substrate parameters: the degree of polymerization (DP) and the fraction of b-glucosidic bonds accessible to cellulase, F a (Zhang and Lynd, 2004). Initial enzyme-limited reaction rates simulated by the model are consistent with several important behaviors reported in the literature, including the effects of substrate characteristics on exoglucanase and endoglucanase activities; the degree of endo/exoglucanase synergy; the endoglucanase partition coefficient on hydrolysis rates; and enzyme loading on relative reaction rates for different substrates. This is the first cellulase kinetic model involving a single set of kinetic parameters that is successfully applied to a variety of cellulosic substrates, and the first that describes more than one behavior associated with enzymatic hydrolysis. The model has potential utility for data accommodation and design of industrial processes, structuring, testing, and extending understanding of cellulase enzyme systems when experimental date are available, and providing guidance for functional design of cellulase systems at a molecular scale. Opportunities to further refine cellulase kinetic models are discussed, including parameters that would benefit from further study.

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Section: Endoglucanase-exoglucanase Synergysupporting

confidence: 85%

A functionally based model for hydrolysis of cellulose by fungal cellulase

Zhang

Lynd

2006

Biotechnol. Bioeng.

204

158

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“…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.…”

mentioning

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.

251

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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“…One of the main challenges to realizing this renewable energy source lies in mastering the process of producing fermentable sugars from the recalcitrant complex of cellulose, hemicellulose, and lignin that comprises lignocellulosic biomass. The fungus Trichoderma reesei (now classified as an anamorph of Hypocrea jecorina) breaks down biomass to meet its energy demands (1,2) and efficiently degrades biomass into sugars by producing several enzymes with complementary activities. Due to its high levels of enzyme production, T. reesei is the primary commercial source of cellulases.…”

mentioning

confidence: 99%

Small Angle Neutron Scattering Reveals pH-dependent Conformational Changes in Trichoderma reesei Cellobiohydrolase I

Pingali

O’Neill

McGaughey

et al. 2011

Journal of Biological Chemistry

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Cellobiohydrolase I (Cel7A) of the fungus Trichoderma reesei (now classified as an anamorph of Hypocrea jecorina) hydrolyzes crystalline cellulose to soluble sugars, making it of key interest for producing fermentable sugars from biomass for biofuel production. The activity of the enzyme is pH-dependent, with its highest activity occurring at pH 4 -5. To probe the response of the solution structure of Cel7A to changes in pH, we measured small angle neutron scattering of it in a series of solutions having pH values of 7.0, 6.0, 5.3, and 4.2. As the pH decreases from 7.0 to 5.3, the enzyme structure remains well defined, possessing a spatial differentiation between the cellulose binding domain and the catalytic core that only changes subtly. At pH 4.2, the solution conformation of the enzyme changes to a structure that is intermediate between a properly folded enzyme and a denatured, unfolded state, yet the secondary structure of the enzyme is essentially unaltered. The results indicate that at the pH of optimal activity, the catalytic core of the enzyme adopts a structure in which the compact packing typical of a fully folded polypeptide chain is disrupted and suggest that the increased range of structures afforded by this disordered state plays an important role in the increased activity of Cel7A through conformational selection.

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Synergism of Cellulases from Trichoderma reesei in the Degradation of Cellulose

Cited by 467 publications

References 22 publications

A functionally based model for hydrolysis of cellulose by fungal cellulase

A functionally based model for hydrolysis of cellulose by fungal cellulase

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

Small Angle Neutron Scattering Reveals pH-dependent Conformational Changes in Trichoderma reesei Cellobiohydrolase I

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