151
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Linder M, Salovuori I, Ruohonen L, Teeri TT. Characterization of a double cellulose-binding domain. Synergistic high affinity binding to crystalline cellulose. J Biol Chem 1996; 271:21268-72. [PMID: 8702902 DOI: 10.1074/jbc.271.35.21268] [Citation(s) in RCA: 102] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Most cellulose-degrading enzymes have a two-domain structure that consists of a catalytic and a cellulose-binding domain (CBD) connected by a linker region. The linkage and the interactions of the two domains represent one of the key questions for the understanding of the function of these enzymes. The CBDs of fungal cellulases are small peptides folding into a rigid, disulfide-stabilized structure that has a distinct cellulose binding face. Here we describe properties of a recombinant double CBD, constructed by fusing the CBDs of two Trichoderma reesei cellobiohydrolases via a linker peptide similar to the natural cellulase linkers. After expression in Escherichia coli, the protein was purified from the culture medium by reversed phase chromatography and the individual domains obtained by trypsin digestion. Binding of the double CBD and its single CBD components was investigated on different types of cellulose substrates as well as chitin. Under saturating conditions, nearly 20 micromol/g of the double CBD was bound onto microcrystalline cellulose. The double CBD exhibited much higher affinity on cellulose than either of the single CBDs, indicating an interplay between the two components. A two-step model is proposed to explain the binding behavior of the double CBD. A similar interplay between the domains in the native enzyme is suggested for its binding to cellulase.
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Affiliation(s)
- M Linder
- VTT, Biotechnology and Food Research, Box 1500, FIN-02044 VTT, Finland
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152
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Kleman-Leyer KM, Siika-Aho M, Teeri TT, Kirk TK. The Cellulases Endoglucanase I and Cellobiohydrolase II of Trichoderma reesei Act Synergistically To Solubilize Native Cotton Cellulose but Not To Decrease Its Molecular Size. Appl Environ Microbiol 1996; 62:2883-7. [PMID: 16535380 PMCID: PMC1388918 DOI: 10.1128/aem.62.8.2883-2887.1996] [Citation(s) in RCA: 94] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Degradation of cotton cellulose by Trichoderma reesei endoglucanase I (EGI) and cellobiohydrolase II (CBHII) was investigated by analyzing the insoluble cellulose fragments remaining after enzymatic hydrolysis. Changes in the molecular-size distribution of cellulose after attack by EGI, alone and in combination with CBHII, were determined by size exclusion chromatography of the tricarbanilate derivatives. Cotton cellulose incubated with EGI exhibited a single major peak, which with time shifted to progressively lower degrees of polymerization (DP; number of glucosyl residues per cellulose chain). In the later stages of degradation (8 days), this peak was eventually centered over a DP of 200 to 300 and was accompanied by a second peak (DP, (apprx=)15); a final weight loss of 34% was observed. Although CBHII solubilized approximately 40% of bacterial microcrystalline cellulose, the cellobiohydrolase did not depolymerize or significantly hydrolyze native cotton cellulose. Furthermore, molecular-size distributions of cellulose incubated with EGI together with CBHII did not differ from those attacked solely by EGI. However, a synergistic effect was observed in the reducing-sugar production by the cellulase mixture. From these results we conclude that EGI of T. reesei degrades cotton cellulose by selectively cleaving through the microfibrils at the amorphous sites, whereas CBHII releases soluble sugars from the EGI-degraded cotton cellulose and from the more crystalline bacterial microcrystalline cellulose.
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153
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Tomme P, Kwan E, Gilkes NR, Kilburn DG, Warren RA. Characterization of CenC, an enzyme from Cellulomonas fimi with both endo- and exoglucanase activities. J Bacteriol 1996; 178:4216-23. [PMID: 8763951 PMCID: PMC178180 DOI: 10.1128/jb.178.14.4216-4223.1996] [Citation(s) in RCA: 53] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The cenC gene, encoding beta-1,4-glucanase C (CenC) from Cellulomonas fimi, was overexpressed in Escherichia coli with a tac-based expression vector. The resulting polypeptide, with an apparent molecular mass of 130 kDa, was purified from the cell extracts by affinity chromatography on cellulose followed by anion-exchange chromatography. N-terminal sequence analysis showed the enzyme to be properly processed. Mature CenC was optimally active at pH 5.0 and 45 degrees C. The enzyme was extremely active on soluble, fluorophoric, and chromophoric glycosides (4-methylumbelliferyl beta-glycosides, 2'-chloro-4'-nitrophenyl-beta-D-cellobioside, and 2'-chloro-4'-nitrophenyl-lactoside) and efficiently hydrolyzed carboxymethyl cellulose, barley beta-glucan, lichenan, and, to a lesser extent, glucomannan. CenC also hydrolyzed acid-swollen cellulose, Avicel, and bacterial microcrystalline cellulose. However, degradation of the latter was slow compared with its degradation by CenB, another C. fimi cellulose belonging to the same enzyme family. CenC acted with inversion of configuration at the anomeric carbon, in accordance with its classification as a family 9 member. The enzyme released mainly cellobiose from soluble cellodextrins and insoluble cellulose. Attack appeared to be from the reducing chain ends. Analysis of carboxymethyl cellulose hydrolysis suggests that CenC is semiprocessive enzyme with both endo- and exoglucanase activities.
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Affiliation(s)
- P Tomme
- Department of Microbiology, University of British Columbia, Vancouver, Canada
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154
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McGuire V, Alexander S. PsB multiprotein complex of Dictyostelium discoideum. Demonstration of cellulose binding activity and order of protein subunit assembly. J Biol Chem 1996; 271:14596-603. [PMID: 8662961 DOI: 10.1074/jbc.271.24.14596] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
The differentiated spores of Dictyostelium are surrounded by an extracellular matrix, the spore coat, which protects them from environmental factors allowing them to remain viable for extended periods of time. This presumably is a major evolutionary advantage. This unique extracellular matrix is composed of cellulose and glycoproteins. Previous work has shown that some of these spore coat glycoproteins exist as a preassembled multiprotein complex (the PsB multiprotein complex) which is stored in the prespore vesicles (Watson, N., McGuire, V., and Alexander, S (1994) J. Cell Sci. 107, 2567-2579). Later in development, the complex is synchronously secreted from the prespore vesicles and incorporated into the spore coat. We now have shown that the PsB complex has a specific in vitro cellulose binding activity. The analysis of mutants lacking individual subunits of the PsB complex revealed the relative order of assembly of the subunit proteins and demonstrated that the protein subunits must be assembled for cellulose binding activity. These results provide a biochemical explanation for the localization of this multiprotein complex in the spore coat.
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Affiliation(s)
- V McGuire
- Division of Biological Sciences, University of Missouri, Columbia, Missouri 65211, USA
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155
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Sakka K, Takada G, Karita S, Ohmiya K. Identification and characterization of cellulose-binding domains in xylanase A of Clostridium stercorarium. Ann N Y Acad Sci 1996; 782:241-51. [PMID: 8659900 DOI: 10.1111/j.1749-6632.1996.tb40565.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The xynA gene encoding a major xylanase of Clostridium stercorarium F-9 was sequenced. The structural gene consists of an open reading frame of 1533 bp encoding a protein of 511 amino acids with an M(r) of 56,519. XynA consists of a catalytic domain belonging to family G at the NH2-terminus and two direct repeats of about 90 amino acids with a short spacing at the COOH-terminus. The repeated sequences, CBDI and CBDII, were not homologous with amino acid sequences of the CBDs classified into families I to V. Nevertheless, XynA showed an affinity for insoluble cellulose such as Avicel. Binding of XynA to Avicel was strongly dependent on the concentration of the incubation buffer and was inhibited by Triton X-100. XynA bound to Avicel (2.4 nmol/g-cellulose) and acid-swollen cellulose (180 nmol/g-cellulose), suggesting that this enzyme has higher affinity for amorphous cellulose than for crystalline cellulose. Functions of CBDI and CBDII were investigated by constructing the mutant enzymes and evaluating the cellulose-binding ability of each of them. XynA4 lacking CBDI and XynA5 lacking CBDII bound to Avicel to a lesser extent than the parental enzyme XynA; but XynA6, devoid of both CBDs, did not bind at all, indicating that CBDI and CBDII each functioned independently as CBD in XynA and their binding capacity was additive. Although the Ruminococcus albus endoglucanase EgIV that was joined to CBDs of XynA acquired cellulose-binding ability, the substrate specificity of EgIV was not altered in the presence or absence of CBDs.
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Affiliation(s)
- K Sakka
- Laboratory of Applied Microbiology, Faculty of Bioresources, Mie University, Tsu, Japan.
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156
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Sild V, Ståhlberg J, Pettersson G, Johansson G. Effect of potential binding site overlap to binding of cellulase to cellulose: a two-dimensional simulation. FEBS Lett 1996; 378:51-6. [PMID: 8549801 DOI: 10.1016/0014-5793(95)01420-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
A computer simulation model for the binding of ligands to a totally anisotropic surface (infinite two-dimensional square lattice) with overlapping binding sites has been developed. The validity of the simulation has been proven by comparison with cases where the correct results are known. The simulation of kinetics shows that when the lattice is close to saturation, the true equilibrium state is reached extremely slowly due to a lot of rearranging of the ligands on the lattice. Based on these findings, the terms 'apparent saturation' and 'apparent maximum coverage' have been introduced and defined. The largest discrepancies between 'apparent maximum coverage' and the theoretically predicted value were observed for ligands of large size and/or irregular shape. As an example, the model has been applied to describe the binding of cellobiohydrolase-I core to Avicel. A formula for calculation of the intrinsic binding constant, maximal binding capacity and specific surface of cellulose from real binding data has been derived.
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Affiliation(s)
- V Sild
- Institute of Molecular and Cell Biology, University of Tartu, Estonia
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157
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Tomme P, Driver DP, Amandoron EA, Miller RC, Antony R, Warren J, Kilburn DG. Comparison of a fungal (family I) and bacterial (family II) cellulose-binding domain. J Bacteriol 1995; 177:4356-63. [PMID: 7635821 PMCID: PMC177184 DOI: 10.1128/jb.177.15.4356-4363.1995] [Citation(s) in RCA: 72] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
A family II cellulose-binding domain (CBD) of an exoglucanase/xylanase (Cex) from the bacterium Cellulomonas fimi was replaced with the family I CBD of cellobiohydrolase I (CbhI) from the fungus Trichoderma reesei. Expression of the hybrid gene in Escherichia coli yielded up to 50 mg of the hybrid protein, CexCBDCbhI, per liter of culture supernatant. The hybrid was purified to homogeneity by affinity chromatography on cellulose. The relative association constants (Kr) for the binding of Cex, CexCBDCbhI, the catalytic domain of Cex (p33), and CbhI to bacterial microcrystalline cellulose (BMCC) were 14.9, 7.8, 0.8, and 10.6 liters g-1, respectively. Cex and CexCBDCbhI had similar substrate specificities and similar activities on crystalline and amorphous cellulose. Both released predominantly cellobiose and cellotriose from amorphous cellulose. CexCBDCbhI was two to three times less active than Cex on BMCC, but significantly more active than Cex on soluble cellulose and on xylan. Unlike Cex, the hybrid protein neither bound to alpha-chitin nor released small particles from dewaxed cotton fibers.
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Affiliation(s)
- P Tomme
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, Canada
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158
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Reinikainen T, Teleman O, Teeri TT. Effects of pH and high ionic strength on the adsorption and activity of native and mutated cellobiohydrolase I from Trichoderma reesei. Proteins 1995; 22:392-403. [PMID: 7479712 DOI: 10.1002/prot.340220409] [Citation(s) in RCA: 106] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Cellobiohydrolase I (CBHI) is the major cellulase of Trichoderma reesei. The enzyme contains a discrete cellulose-binding domain (CBD), which increases its binding and activity on crystalline cellulose. We studied cellulase-cellulose interactions using site-directed mutagenesis on the basis of the three-dimensional structure of the CBD of CBHI. Three mutant proteins which have earlier been produced in Saccharomyces cerevisiae were expressed in the native host organism. The data presented here support the hypothesis that a conserved tyrosine (Y492) located on the flat and more hydrophilic surface of the CBD is essential for the functionality. The data also suggest that the more hydrophobic surface is not directly involved in the CBD function. The pH dependence of the adsorption revealed that electrostatic repulsion between the bound proteins may also control the adsorption. The binding of CBHI to cellulose was significantly affected by high ionic strength suggesting that the interaction with cellulose includes a hydrophobic effect. High ionic strength increased the activity of the isolated core and of mutant proteins on crystalline cellulose, indicating that once productively bound, the enzymes are capable of solubilizing cellulose even with a mutagenized or with no CBD.
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159
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Linder M, Mattinen ML, Kontteli M, Lindeberg G, Ståhlberg J, Drakenberg T, Reinikainen T, Pettersson G, Annila A. Identification of functionally important amino acids in the cellulose-binding domain of Trichoderma reesei cellobiohydrolase I. Protein Sci 1995; 4:1056-64. [PMID: 7549870 PMCID: PMC2143141 DOI: 10.1002/pro.5560040604] [Citation(s) in RCA: 158] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Cellobiohydrolase I (CBHI) of Trichoderma reesei has two functional domains, a catalytic core domain and a cellulose binding domain (CBD). The structure of the CBD reveals two distinct faces, one of which is flat and the other rough. Several other fungal cellulolytic enzymes have similar two-domain structures, in which the CBDs show a conserved primary structure. Here we have evaluated the contributions of conserved amino acids in CBHI CBD to its binding to cellulose. Binding isotherms were determined for a set of six synthetic analogues in which conserved amino acids were substituted. Two-dimensional NMR spectroscopy was used to assess the structural effects of the substitutions by comparing chemical shifts, coupling constants, and NOEs of the backbone protons between the wild-type CBD and the analogues. In general, the structural effects of the substitutions were minor, although in some cases decreased binding could clearly be ascribed to conformational perturbations. We found that at least two tyrosine residues and a glutamine residue on the flat face were essential for tight binding of the CBD to cellulose. A change on the rough face had only a small effect on the binding and it is unlikely that this face interacts with cellulose directly.
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Affiliation(s)
- M Linder
- Department of Biochemistry, University of Uppsala, Sweden
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160
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Din N, Coutinho J, Gilkes N, Jervis E, Kilburn D, Miller R, Ong E, Tomme P, Warren R. Interactions of cellulases from Cellulomonas fimi with cellulose. PROGRESS IN BIOTECHNOLOGY 1995. [DOI: 10.1016/s0921-0423(06)80109-7] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
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161
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Greenwood JM, Gilkes NR, Miller RC, Kilburn DG, Warren RAJ. Purification and processing of cellulose-binding domain-alkaline phosphatase fusion proteins. Biotechnol Bioeng 1994; 44:1295-305. [DOI: 10.1002/bit.260441105] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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162
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Goldstein MA, Doi RH. Mutation analysis of the cellulose-binding domain of the Clostridium cellulovorans cellulose-binding protein A. J Bacteriol 1994; 176:7328-34. [PMID: 7961505 PMCID: PMC197122 DOI: 10.1128/jb.176.23.7328-7334.1994] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Cellulose-binding protein A (CbpA) has been previously shown to mediate the interaction between crystalline cellulose substrates and the cellulase enzyme complex of Clostridium cellulovorans. CbpA contains a family III cellulose-binding domain (CBD) which, when expressed independently, binds specifically to crystalline cellulose. A series of N- and C-terminal deletions and a series of small internal deletions of the CBD were created to determine whether the entire region previously described as a CBD is required for the cellulose-binding function. The N- and C-terminal deletions reduced binding affinity by 10- to 100-fold. Small internal deletions of the CBD resulted in substantial reduction of CBD function. Some, but not all, point mutations throughout the sequence had significant disruptive effects on the binding ability of the CBD. Thus, mutations in any region of the CBD had effects on the binding of the fragment to cellulose. The results indicate that the entire 163-amino-acid region of the CBD is required for maximal binding to crystalline cellulose.
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Affiliation(s)
- M A Goldstein
- Section of Molecular and Cellular Biology, University of California, Davis 95616
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163
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Kleman-Leyer KM, Kirk TK. Three Native Cellulose-Depolymerizing Endoglucanases from Solid-Substrate Cultures of the Brown Rot Fungus
Meruliporia (Serpula) incrassata. Appl Environ Microbiol 1994; 60:2839-45. [PMID: 16349351 PMCID: PMC201731 DOI: 10.1128/aem.60.8.2839-2845.1994] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Three extracellular cellulose-depolymerizing enzymes from cotton undergoing decay by the brown rot fungus
Meruliporia (Serpula) incrassata
were isolated by anion-exchange and hydrophobic interaction chromatographies. Depolymerization was detected by analyzing the changes in the molecular size distribution of cotton cellulose by high-performance size-exclusion chromatography. The average degree of polymerization (DP; number of glucosyl residues per cellulose chain) was calculated from the size-exclusion chromatography data. The very acidic purified endoglucanases, Cel 25, Cel 49, and Cel 57, were glycosylated and had molecular weights of 25,200, 48,500, and 57,100, respectively. Two, Cel 25 and Cel 49, depolymerized cotton cellulose and were also very active on carboxymethyl cellulose (CMC). Cel 57, by contrast, significantly depolymerized cotton cellulose but did not release reducing sugars from CMC and only very slightly reduced the viscosity of CMC solutions. Molecular size distributions of cotton cellulose attacked by the three endoglucanases revealed single major peaks that shifted to lower DP positions. A second smaller peak (DP, 10 to 20) was also observed in the size-exclusion chromatograms of cotton attacked by Cel 49 and Cel 57. Under the reaction conditions used, Cel 25, the most active of the cellulases, reduced the weight average DP from 3,438 to 315, solubilizing approximately 20% of the cellulose. The weight average DP values of cotton attacked under the same conditions by Cel 49 and Cel 57 were 814 and 534; weight losses were 9 and 11% respectively.
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Affiliation(s)
- K M Kleman-Leyer
- Department of Bacteriology, University of Wisconsin-Madison, Madison, Wisconsin 53706
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164
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Meinke A, Gilkes NR, Kwan E, Kilburn DG, Warren RA, Miller RC. Cellobiohydrolase A (CbhA) from the cellulolytic bacterium Cellulomonas fimi is a beta-1,4-exocellobiohydrolase analogous to Trichoderma reesei CBH II. Mol Microbiol 1994; 12:413-22. [PMID: 8065260 DOI: 10.1111/j.1365-2958.1994.tb01030.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The gene cbhA from the cellulolytic bacterium Cellulomonas fimi encodes a protein of 872 amino acids designated cellobiohydrolase A (CbhA). Mature CbhA contains 832 amino acid residues and has a predicted molecular mass of 85,349 Da. It is composed of five domains: an N-terminal catalytic domain, three repeated sequences of 95 amino acids, and a C-terminal cellulose-binding domain typical of other C. fimi glycanases. The structure and enzymatic activities of the CbhA catalytic domain are closely related to those of CBH II, an exocellobiohydrolase in the glycosyl hydrolase family B from the fungus Trichoderma reesei. CbhA is the first such enzyme to be characterized in bacteria. The data support the proposal that extended loops around the active site distinguish exohydrolases from endohydrolases in this enzyme family.
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Affiliation(s)
- A Meinke
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, Canada
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165
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Din N, Forsythe IJ, Burtnick LD, Gilkes NR, Miller RC, Warren RA, Kilburn DG. The cellulose-binding domain of endoglucanase A (CenA) from Cellulomonas fimi: evidence for the involvement of tryptophan residues in binding. Mol Microbiol 1994; 11:747-55. [PMID: 8196546 DOI: 10.1111/j.1365-2958.1994.tb00352.x] [Citation(s) in RCA: 95] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
Cellulomonas fimi endo-beta-1,4-glucanase A (CenA) contains a discrete N-terminal cellulose-binding domain (CBDCenA). Related CBDs occur in at least 16 bacterial glycanases and are characterized by four highly conserved Trp residues, two of which correspond to W14 and W68 of CBDCenA. The adsorption of CBDCenA to crystalline cellulose was compared with that of two Trp mutants (W14A and W68A). The affinities of the mutant CBDs for cellulose were reduced by approximately 50- and 30-fold, respectively, relative to the wild type. Physical measurements indicated that the mutant CBDs fold normally. Fluorescence data indicated that W14 and W68 were exposed on the CBD, consistent with their participation in binding to cellobiosyl residues on the cellulose surface.
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Affiliation(s)
- N Din
- Department of Microbiology, University of British Columbia, Vancouver, Canada
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166
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Ong E, Kilburn DG, Miller RC, Warren RA. Streptomyces lividans glycosylates the linker region of a beta-1,4-glycanase from Cellulomonas fimi. J Bacteriol 1994; 176:999-1008. [PMID: 8106343 PMCID: PMC205150 DOI: 10.1128/jb.176.4.999-1008.1994] [Citation(s) in RCA: 27] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
The beta-1,4-glycanase Cex of the gram-positive bacterium Cellulomonas fimi is a glycoprotein comprising a C-terminal cellulose-binding domain connected to an N-terminal catalytic domain by a linker containing only prolyl and threonyl (PT) residues. Cex is also glycosylated by Streptomyces lividans. The glycosylation of Cex produced in both C. fimi and S. lividans protects the enzyme from proteolysis. When the gene fragments encoding the cellulose-binding domain of Cex (CBDCex), the PT linker plus CBDCex (PT-CBDCex), and the catalytic domain plus CBDCex of Cex were expressed in S. lividans, only PT-CBDCex was glycosylated. Therefore, all the glycans must be O linked because only the PT linker was glycosylated. A glycosylated form and a nonglycosylated form of PT-CBDCex were produced by S. lividans. The glycosylated form of PT-CBDCex was heterogeneous; its average carbohydrate content was approximately 10 mol of D-mannose equivalents per mol of protein, but the glycans contained from 4 to 12 alpha-D-mannosyl and alpha-D-galactosyl residues. Glycosylated Cex from S. lividans was also heterogeneous. The presence of glycans on PT-CBDCex increased its affinity for bacterial microcrystalline cellulose. The location of glycosylation only on the linker region of Cex correlates with the properties conferred on the enzyme by the glycans.
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Affiliation(s)
- E Ong
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, Canada
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167
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Funane K, Shiraiwa M, Hashimoto K, Ichishima E, Kobayashi M. An active-site peptide containing the second essential carboxyl group of dextransucrase from Leuconostoc mesenteroides by chemical modifications. Biochemistry 1993; 32:13696-702. [PMID: 8257704 DOI: 10.1021/bi00212a039] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The treatment of Leuconostoc mesenteroides B-512F dextransucrase with 10 mM 1-ethyl-3-[3-(dimethylamino)propyl]carbodiimide (EDC) and glycine ethyl ester (GEE) inactivated the enzyme almost completely within 24 min where the modification of one carboxyl group/mol of the enzyme by EDC was attained. Though 30 mM diethyl pyrocarbonate (DEP) also inactivated the enzyme, about 35% of the activity remained during a 36-min incubation. When 10 mol of imidazole residues/mol of the enzyme was modified by DEP, 50% of the activity was still retained. The addition of the substrate sucrose greatly retarded the enzyme inactivation by EDC. However, the addition of dextran slightly protected the inactivation of the glucosyl-transferring activity and accelerated the inactivation of the sucrose-cleaving activity. In the case of DEP, the addition of sucrose or dextran gave no influence on the inactivation of the enzyme. Therefore, the carboxyl group seemed to play a more important role in the substrate binding and in the catalytic activity of the dextransucrase than the imidazolium group. Differential labeling of Leuconostoc dextransucrase by EDC was conducted in the presence of a sucrose analog, sucrose monocaprate. The fluorescent probe N-(1-naphthyl)ethylenediamine (EDAN) was used as the nucleophile instead of GEE. A fluorescent labeled peptide was isolated from a trypsin digest of the EDC-EDAN modified enzyme. The amino acid sequence of the isolated peptide was Leu-Gln-Glu-Asp-Asn-Ser-Asn-Val-Val-Val-Glu-Ala.(ABSTRACT TRUNCATED AT 250 WORDS)
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Affiliation(s)
- K Funane
- Molecular Engineering Laboratory, National Food Research Institute, Ministry of Agriculture, Forestry and Fisheries, Ibaraki, Japan
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168
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Gilkes NR, Kilburn DG, Miller RC, Warren RA, Sugiyama J, Chanzy H, Henrissat B. Visualization of the adsorption of a bacterial endo-beta-1,4-glucanase and its isolated cellulose-binding domain to crystalline cellulose. Int J Biol Macromol 1993; 15:347-51. [PMID: 8110656 DOI: 10.1016/0141-8130(93)90052-n] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Endo-beta-1,4-glucanase A (CenA), a cellulase from the bacterium Cellulomonas fimi, is composed of two domains: a catalytic domain and a cellulose-binding domain. Adsorption of CenA and its isolated cellulose-binding domain (CBD.PTCenA) to Valonia cellulose microcrystals was examined by transmission electron microscopy using an antibody sandwich technique (CenA/CBD.PTCenA-alpha CenA IgG-protein A-gold conjugate). Adsorption of both CenA and CBD.PTCenA occurred along the lengths of the microcrystals, with an apparent preference for certain crystal faces or edges. CenA or CBD.PTCenA, but not the isolated catalytic domain, were shown to prevent the flocculation of microcrystalline bacterial cellulose. The cellulose-binding domain may assist crystalline cellulose hydrolysis in vitro by promoting substrate dispersion.
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Affiliation(s)
- N R Gilkes
- Department of Microbiology, University of British Columbia, Vancouver, Canada
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169
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Coutinho J, Gilkes N, Kilburn D, Warren R, Miller R. The nature of the cellulose-binding domain effects the activities of a bacterial endoglucanase on different forms of cellulose. FEMS Microbiol Lett 1993. [DOI: 10.1111/j.1574-6968.1993.tb06516.x] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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170
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Srisodsuk M, Reinikainen T, Penttilä M, Teeri T. Role of the interdomain linker peptide of Trichoderma reesei cellobiohydrolase I in its interaction with crystalline cellulose. J Biol Chem 1993. [DOI: 10.1016/s0021-9258(19)36847-4] [Citation(s) in RCA: 54] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022] Open
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171
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Ramos L, Nazhad M, Saddler J. Effect of enzymatic hydrolysis on the morphology and fine structure of pretreated cellulosic residues. Enzyme Microb Technol 1993. [DOI: 10.1016/0141-0229(93)90093-h] [Citation(s) in RCA: 84] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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172
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Goldstein MA, Takagi M, Hashida S, Shoseyov O, Doi RH, Segel IH. Characterization of the cellulose-binding domain of the Clostridium cellulovorans cellulose-binding protein A. J Bacteriol 1993; 175:5762-8. [PMID: 8376323 PMCID: PMC206653 DOI: 10.1128/jb.175.18.5762-5768.1993] [Citation(s) in RCA: 131] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Cellulose-binding protein A (CbpA), a component of the cellulase complex of Clostridium cellulovorans, contains a unique sequence which has been demonstrated to be a cellulose-binding domain (CBD). The DNA coding for this putative CBD was subcloned into pET-8c, an Escherichia coli expression vector. The protein produced under the direction of the recombinant plasmid, pET-CBD, had a high affinity for crystalline cellulose. Affinity-purified CBD protein was used in equilibrium binding experiments to characterize the interaction of the protein with various polysaccharides. It was found that the binding capacity of highly crystalline cellulose samples (e.g., cotton) was greater than that of samples of low crystallinity (e.g., fibrous cellulose). At saturating CBD concentration, about 6.4 mumol of protein was bound by 1 g of cotton. Under the same conditions, fibrous cellulose bound only 0.2 mumol of CBD per g. The measured dissociation constant was in the 1 microM range for all cellulose samples. The results suggest that the CBD binds specifically to crystalline cellulose. Chitin, which has a crystal structure similar to that of cellulose, also was bound by the CBD. The presence of high levels of cellobiose or carboxymethyl cellulose in the assay mixture had no effect on the binding of CBD protein to crystalline cellulose. This result suggests that the CBD recognition site is larger than a simple cellobiose unit or more complex than a repeating cellobiose moiety. This CBD is of particular interest because it is the first CBD from a completely sequenced nonenzymatic protein shown to be an independently functional domain.
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Affiliation(s)
- M A Goldstein
- Department of Biochemistry and Biophysics, University of California Davis 95616
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173
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174
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Meinke A, Gilkes NR, Kilburn DG, Miller RC, Warren RA. Cellulose-binding polypeptides from Cellulomonas fimi: endoglucanase D (CenD), a family A beta-1,4-glucanase. J Bacteriol 1993; 175:1910-8. [PMID: 8458833 PMCID: PMC204259 DOI: 10.1128/jb.175.7.1910-1918.1993] [Citation(s) in RCA: 52] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Five cellulose-binding polypeptides were detected in Cellulomonas fimi culture supernatants. Two of them are CenA and CenB, endo-beta-1,4-glucanases which have been characterized previously; the other three were previously uncharacterized polypeptides with apparent molecular masses of 120, 95, and 75 kDa. The 75-kDa cellulose-binding protein was designated endoglucanase D (CenD). The cenD gene was cloned and sequenced. It encodes a polypeptide of 747 amino acids. Mature CenD is 708 amino acids long and has a predicted molecular mass of 74,982 Da. Analysis of the predicted amino acid sequence of CenD shows that the enzyme comprises four domains which are separated by short linker polypeptides: an N-terminal catalytic domain of 405 amino acids, two repeated sequences of 95 amino acids each, and a C-terminal domain of 105 amino acids which is > 50% identical to the sequences of cellulose-binding domains in Cex, CenA, and CenB from C. fimi. Amino acid sequence comparison placed the catalytic domain of CenD in family A, subtype 1, of beta-1,4-glycanases. The repeated sequences are more than 40% identical to the sequences of three repeats in CenB and are related to the repeats of fibronectin type III. CenD hydrolyzed the beta-1,4-glucosidic bond with retention of anomeric configuration. The activities of CenD towards various cellulosic substrates were quite different from those of CenA and CenB.
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Affiliation(s)
- A Meinke
- Department of Microbiology, University of British Columbia, Vancouver, Canada
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175
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Poole DM, Hazlewood GP, Huskisson NS, Virden R, Gilbert HJ. The role of conserved tryptophan residues in the interaction of a bacterial cellulose binding domain with its ligand. FEMS Microbiol Lett 1993; 106:77-83. [PMID: 8440467 DOI: 10.1111/j.1574-6968.1993.tb05938.x] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
The five conserved tryptophan residues in the cellulose binding domain of xylanase A from Pseudomonas fluorescens subsp. cellulosa were replaced with alanine and phenylalanine. The mutated domains were fused to mature alkaline phosphatase, and the capacity of the hybrid proteins to bind cellulose was assessed. Alanine substitution of the tryptophan residues, in general, resulted in a significant decrease in the capacity of the cellulose binding domains to bind cellulose. Mutant domains containing phenylalanine substitution retained some affinity for cellulose. The C-terminal proximal tryptophan did not play an important role in ligand binding, while Trp13, Trp34 and Trp38 were essential for the cellulose binding domain to retain cellulose binding capacity. Data presented in this study suggest major differences in the mechanism of cellulose attachment between Pseudomonas and Cellulomonas cellulose binding domains.
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Affiliation(s)
- D M Poole
- Department of Biological and Nutritional Sciences, University of Newcastle upon Tyne, UK
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