Desorption of <i>Trichoderma reesei</i> cellulase from cellulose by a range of desorbents

Otter, Don; Munro, Peter A.; Scott, G. K.; Geddes, Robert

doi:10.1002/bit.260340303

Cited by 66 publications

(51 citation statements)

References 23 publications

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“…To further probe what determinants exist beyond the cellulolytic GH family containing enzymes in the genus Caldicellulosiruptor, Avicel-induced proteins were identified via bottom-up proteomics. Avicel was used as a model plant biomass substrate due to the large proportion of cellulose in plant cell walls and previous studies on T. reesei cellulase systems demonstrating strong affinity of cellulases for Avicel (38,62). A strong, potentially irreversible interaction between Caldicellulosiruptor proteins and Avicel would be ideal for proteomic screening to identify substrate-bound proteins, since their affinity for Avicel would have to withstand washing steps to remove cells.…”

Section: Fig S2 Andmentioning

confidence: 99%

Caldicellulosiruptor Core and Pangenomes Reveal Determinants for Noncellulosomal Thermophilic Deconstruction of Plant Biomass

et al. 2012

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Extremely thermophilic bacteria of the genus Caldicellulosiruptor utilize carbohydrate components of plant cell walls, including cellulose and hemicellulose, facilitated by a diverse set of glycoside hydrolases (GHs). From a biofuel perspective, this capability is crucial for deconstruction of plant biomass into fermentable sugars. While all species from the genus grow on xylan and acidpretreated switchgrass, growth on crystalline cellulose is variable. The basis for this variability was examined using microbiological, genomic, and proteomic analyses of eight globally diverse Caldicellulosiruptor species. The open Caldicellulosiruptor pangenome (4,009 open reading frames [ORFs]) encodes 106 GHs, representing 43 GH families, but only 26 GHs from 17 families are included in the core (noncellulosic) genome (1,543 ORFs). Differentiating the strongly cellulolytic Caldicellulosiruptor species from the others is a specific genomic locus that encodes multidomain cellulases from GH families 9 and 48, which are associated with cellulose-binding modules. This locus also encodes a novel adhesin associated with type IV pili, which was identified in the exoproteome bound to crystalline cellulose. Taking into account the core genomes, pangenomes, and individual genomes, the ancestral Caldicellulosiruptor was likely cellulolytic and evolved, in some cases, into species that lost the ability to degrade crystalline cellulose while maintaining the capacity to hydrolyze amorphous cellulose and hemicellulose. Interest in cellulosic biofuels (29) has sparked efforts to isolate microorganisms capable of both hydrolysis and fermentation of plant biomass, a process referred to as consolidated bioprocessing (CBP) (49, 50). Since plant biomass deconstruction could be accelerated at elevated temperatures, thermophilic microorganisms have been considered catalysts for CBP (8). Of particular note in this regard are members of the extremely thermophilic genus Caldicellulosiruptor that inhabit globally diverse, terrestrial hot springs (12,27,56,57,61,69,80,98) and thermally heated mud flats (31). Caldicellulosiruptor species are Gram-positive bacteria and typically associate with plant debris; consequently, all isolates characterized to date hydrolyze certain complex carbohydrates characteristic of plant cell walls (8, 97). As such, members of the genus Caldicellulosiruptor are excellent genetic reservoirs of enzymes for plant biomass degradation and, pending the development of functional genetics systems, are potential metabolic hosts for CBP (9).Currently, there are two main paradigms described for microbial degradation of crystalline cellulose: cellulosomal (3) and noncellulosomal (48, 54). Enzymatically, both systems require the concerted efforts of cellobiohydrolases, endocellulases, and ␤-glucosidases (49). Crystalline cellulose deconstruction via cell membrane-bound cellulosomes was first described in the thermophile Clostridium thermocellum and has since been described in other mesophilic Firmicutes, such as Clostridium cellulolyticum,...

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Section: Fig S2 Andmentioning

confidence: 99%

Caldicellulosiruptor Core and Pangenomes Reveal Determinants for Noncellulosomal Thermophilic Deconstruction of Plant Biomass

et al. 2012

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“…To exclude the effect of cellulase adsorbed on the residue fibers on the capacity for its re-adsorption, a desorption experiment was performed as a control experiment. The residue cotton fibers were washed with Triton X-100 (0.01%) and glycerol (10 %) in NaAc buffer pH 4.8 at 408C for 10 min to remove any adsorbed cellulase (Otter et al, 1988), and the desorbed cotton fibers were then re-suspended in a buffer containing fresh crude cellulase for all adsorption tests as described above.…”

Section: Changes In the Adsorption Capacity Of Cellulase After Re-hydmentioning

confidence: 99%

Changes in the structural properties and rate of hydrolysis of cotton fibers during extended enzymatic hydrolysis

Wang

Zhang

Gao

et al. 2006

Biotech & Bioengineering

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An extended enzymatic hydrolysis of cotton fibers by crude cellulase from Trichoderma pseudokoningii S-38 is described with characterization of both the enzyme changes of activities and cellulose structure. The hydrolysis rates declined drastically during the early stage and then slowly and steadily throughout the whole hydrolysis process the same trend could be seen during the following re-hydrolysis process. Morphological and structural changes to the fibers, such as swelling, frequent surface erosion, and variation in the packing and orientation of microfibrils, were investigated by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Observation of X-ray diffraction and IR spectra suggests that the hydrolysis process results in a gradual increase in the relative intensity of the hydrogen bond network, and a gradual decrease in the apparent crystal size of cellulose. The I(alpha) crystal phase was hydrolyzed more easily than was the I(beta) crystal phase. Apart from the inactivation of CBHs activity, changes in the packing and arrangement of microfibrils and the structural heterogeneity of cellulose during hydrolysis could be responsible for the reduction in the rate of reaction, especially in its later stages. The results indicate that the enzymatic hydrolysis of cellulose occurs on the outer layer of the fiber surface and that, following this, the process continues in a sub-layer manner.

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“…Many studies directly correlate the efficiency of crystalline cellulose degradation to the binding efficiency of the enzyme (11) and the removal of a CBD typically results in a decrease of about 50-80% of the activity of a given cellulase on solid but not on soluble substrates (12,13). Studies carried out mainly with fungal cellulases indicate that once adsorbed, harsh conditions are required for their desorption (14)(15)(16). This has led to the suggestion that the binding is irreversible (17)(18)(19).…”

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confidence: 99%

The cellulose-binding domain of the major cellobiohydrolase of Trichoderma reesei exhibits true reversibility and a high exchange rate on crystalline cellulose.

Linder

Teeri

1996

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

165

126

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Cellulose-binding domains (CBDs) bind specifically to cellulose, and form distinct domains of most cellulose degrading enzymes. The CBD-mediated binding of the enzyme has a fundamental role in the hydrolysis of the solid cellulose substrate. In this work we have investigated the reversibility and kinetics of the binding of the CBD from Trichoderma reesei cellobiohydrolase I on microcrystalline cellulose. The CBD was produced in Escherichia coli, purified, and radioactively labeled by reductive alkylation with 3H.Sensitive detection of the labeled CBD allowed more detailed analysis of its behavior than has been possible before, and important novel features were resolved. Binding of the CBD was found to be temperature sensitive, with an increased affinity at lower temperatures. The interaction of the CBD with cellulose was shown to be fully reversible and the CBD could be eluted from cellulose by simple dilution. The rate of exchange measured for the CBD-cellulose interaction compares well with the hydrolysis rate of cellobiohydrolase I, which is consistent with its proposed mode of action as a processive exoglucanase.Cellulose is a polymer composed of D-glucose units linked by 13-1,4-glycosidic bonds. The cellulose chains can pack together to form fibers, which are crystalline in nature (1). This solid and ordered substrate poses some special requirements on the enzymes hydrolyzing it. Most cellulose degrading enzymes have a bifunctional organization composed of Iwo domains connected by a linker region. One of the domaind is dedicated for binding to the solid cellulose and is called a cellulosebinding domain (CBD). The other domain contains the catalytic machinery. These catalytic domains have been grouped into several families sharing the same basic structure and the same chemical reaction mechanism (2). Trichoderma reesei cellobiohydrolase I (CBHI) is an exoglucanase with a long tunnel-shaped active site (3). CBHI and other exoglucanases initiate the hydrolysis at the chain ends, and do not produce significant amounts of new chain ends on the cellulose surface (4). They seem to act by a processive mechanism hydrolyzing consecutive bonds along the same chain without dissociating (2, 3). The endoglucanases cleave internal bonds along the cellulose chains probably by cycles of adsorption and desorption.Based on sequence comparisons the CBDs have been grouped into several families (5). To date, the threedimensional structures of two CBDs have been published. One is from T. reesei CBHI (6) and the other from Cellulomonas fimi xylanase/cellobiohydrolase Cex (7). Both the fold and the size of these CBDs are different, but a common pattern of aromatic residues and amides is found at the surface of both proteins. Many experiments have shown that this surface is the primary interaction site between a CBD and cellulose (7-10). Many studies directly correlate the efficiency of crystalline cellulose degradation to the binding efficiency of the enzyme (11) and the removal of a CBD typically results in a decrease of a...

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Desorption of Trichoderma reesei cellulase from cellulose by a range of desorbents

Cited by 66 publications

References 23 publications

Caldicellulosiruptor Core and Pangenomes Reveal Determinants for Noncellulosomal Thermophilic Deconstruction of Plant Biomass

Caldicellulosiruptor Core and Pangenomes Reveal Determinants for Noncellulosomal Thermophilic Deconstruction of Plant Biomass

Changes in the structural properties and rate of hydrolysis of cotton fibers during extended enzymatic hydrolysis

The cellulose-binding domain of the major cellobiohydrolase of Trichoderma reesei exhibits true reversibility and a high exchange rate on crystalline cellulose.

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