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Zhang Y, Zhao Z, Liu H. Deriving Chemically Essential Interactions Based on Active Site Alignments and Quantum Chemical Calculations: A Case Study on Glycoside Hydrolases. ACS Catal 2015. [DOI: 10.1021/cs501709d] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Yinliang Zhang
- School
of Life Sciences, University of Science and Technology of China, 443 Huangshan Road, Hefei, Anhui 230027, China
| | - Zheng Zhao
- Hefei
Institutes of Physical Science, Chinese Academy of Sciences, Hefei, Anhui 230031, China
| | - Haiyan Liu
- School
of Life Sciences, University of Science and Technology of China, 443 Huangshan Road, Hefei, Anhui 230027, China
- Hefei National Laboratory for Physical Sciences at the Microscales, Hefei, Anhui 230027, China
- Hefei
Institutes of Physical Science, Chinese Academy of Sciences, Hefei, Anhui 230031, China
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2
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Nagao C, Nagano N, Mizuguchi K. Prediction of detailed enzyme functions and identification of specificity determining residues by random forests. PLoS One 2014; 9:e84623. [PMID: 24416252 PMCID: PMC3885575 DOI: 10.1371/journal.pone.0084623] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2013] [Accepted: 11/15/2013] [Indexed: 12/03/2022] Open
Abstract
Determining enzyme functions is essential for a thorough understanding of cellular processes. Although many prediction methods have been developed, it remains a significant challenge to predict enzyme functions at the fourth-digit level of the Enzyme Commission numbers. Functional specificity of enzymes often changes drastically by mutations of a small number of residues and therefore, information about these critical residues can potentially help discriminate detailed functions. However, because these residues must be identified by mutagenesis experiments, the available information is limited, and the lack of experimentally verified specificity determining residues (SDRs) has hindered the development of detailed function prediction methods and computational identification of SDRs. Here we present a novel method for predicting enzyme functions by random forests, EFPrf, along with a set of putative SDRs, the random forests derived SDRs (rf-SDRs). EFPrf consists of a set of binary predictors for enzymes in each CATH superfamily and the rf-SDRs are the residue positions corresponding to the most highly contributing attributes obtained from each predictor. EFPrf showed a precision of 0.98 and a recall of 0.89 in a cross-validated benchmark assessment. The rf-SDRs included many residues, whose importance for specificity had been validated experimentally. The analysis of the rf-SDRs revealed both a general tendency that functionally diverged superfamilies tend to include more active site residues in their rf-SDRs than in less diverged superfamilies, and superfamily-specific conservation patterns of each functional residue. EFPrf and the rf-SDRs will be an effective tool for annotating enzyme functions and for understanding how enzyme functions have diverged within each superfamily.
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Affiliation(s)
- Chioko Nagao
- National Institute of Biomedical Innovation, Ibaraki, Osaka, Japan
- * E-mail: (CN); (KM)
| | - Nozomi Nagano
- Computational Biology Research Center, AIST, Koto-ku, Tokyo, Japan
| | - Kenji Mizuguchi
- National Institute of Biomedical Innovation, Ibaraki, Osaka, Japan
- * E-mail: (CN); (KM)
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3
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Haq IU, Khan MA, Muneer B, Hussain Z, Afzal S, Majeed S, Rashid N, Javed MM, Ahmad I. Cloning, characterization and molecular docking of a highly thermostable β-1,4-glucosidase from Thermotoga petrophila. Biotechnol Lett 2012; 34:1703-9. [PMID: 22714267 DOI: 10.1007/s10529-012-0953-0] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2011] [Accepted: 04/30/2012] [Indexed: 11/27/2022]
Abstract
A genomic DNA fragment, encoding a thermotolerant β-glucosidase, of the obligate anaerobe Thermotoga petrophila RKU-1 was cloned after PCR amplification into Escherichia coli strain BL21 CodonPlus. The purified cloned enzyme was a monomeric, 51.5 kDa protein (by SDS-PAGE) encoded by 1.341 kb gene. The estimated K (m) and V (max) values against p-nitrophenyl-β-D-glucopyranoside were 2.8 mM and 42.7 mmol min(-1) mg(-1), respectively. The enzyme was also active against other p-nitrophenyl substrates. Possible catalytic sites involved in hydrolyzing different p-nitrophenyl substrates are proposed based on docking studies of enzyme with its substrates. Because of its unique characters, this enzyme is a potential candidate for industrial applications.
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Affiliation(s)
- Ikram Ul Haq
- Institute of Industrial Biotechnology, GC University, Lahore 54000, Pakistan.
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4
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Abstract
Industrial production of solvents such as EtOH and BuOH from cellulosic biomass has the potential to provide a sustainable energy source that is relatively cheap, abundant, and environmentally sound, but currently production costs are driven up by expensive enzymes, which are necessary to degrade cellulose into fermentable sugars. These costs could be significantly reduced if a microorganism could be engineered to efficiently and quickly convert cellulosic biomass directly to product in a one-step process. There is a large amount of biodiversity in the number of existing microorganisms that naturally possess the enzymes necessary to convert cellulose to usable sugars, and many of these microorganisms can directly ferment sugars to EtOH or other solvents. Currently, the vast majority of cellulolytic organisms are poorly understood and have complex metabolic networks. In this review, we survey the current state of knowledge on different cellulases and metabolic capabilities found in various cellulolytic microorganisms. We also propose that the use of large-scale metabolic models (and associated analyses) is potentially an ideal means for improving our understanding of basic metabolic network function and directing metabolic engineering efforts for cellulolytic microorganisms.
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Affiliation(s)
- Christopher M Gowen
- Department of Chemical and Life Science Engineering, Virginia Commonwealth University, Richmond, VA 23284-3028, USA
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5
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Yang P, Li Y, Wang Y, Meng K, Luo H, Yuan T, Bai Y, Zhan Z, Yao B. A Novel β-mannanase with High Specific Activity from Bacillus circulans CGMCC1554: Gene Cloning, Expression and Enzymatic Characterization. Appl Biochem Biotechnol 2008; 159:85-94. [DOI: 10.1007/s12010-008-8364-3] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2008] [Accepted: 09/09/2008] [Indexed: 10/21/2022]
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6
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Tao H, Peralta-Yahya P, Decatur J, Cornish VW. Characterization of a new glycosynthase cloned by using chemical complementation. Chembiochem 2008; 9:681-4. [PMID: 18330853 DOI: 10.1002/cbic.200700545] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Haiyan Tao
- Department of Chemistry, Columbia University, New York, NY 10027, USA
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7
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Côté N, Fleury A, Dumont-Blanchette É, Fukamizo T, Mitsutomi M, Brzezinski R. Two exo-beta-D-glucosaminidases/exochitosanases from actinomycetes define a new subfamily within family 2 of glycoside hydrolases. Biochem J 2006; 394:675-86. [PMID: 16316314 PMCID: PMC1383717 DOI: 10.1042/bj20051436] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
A GlcNase (exo-beta-D-glucosaminidase) was purified from culture supernatant of Amycolatopsis orientalis subsp. orientalis grown in medium with chitosan. The enzyme hydrolysed the terminal GlcN (glucosamine) residues in oligomers of GlcN with transglycosylation observed at late reaction stages. 1H-NMR spectroscopy revealed that the enzyme is a retaining glycoside hydrolase. The GlcNase also behaved as an exochitosanase against high-molecular-mass chitosan with K(m) and kcat values of 0.16 mg/ml and 2832 min(-1). On the basis of partial amino acid sequences, PCR primers were designed and used to amplify a DNA fragment which then allowed the cloning of the GlcNase gene (csxA) associated with an open reading frame of 1032 residues. The GlcNase has been classified as a member of glycoside hydrolase family 2 (GH2). Sequence alignments identified a group of CsxA-related protein sequences forming a distinct GH2 subfamily. Most of them have been annotated in databases as putative beta-mannosidases. Among these, the SAV1223 protein from Streptomyces avermitilis has been purified following gene cloning and expression in a heterologous host and shown to be a GlcNase with no detectable beta-mannosidase activity. In CsxA and all relatives, a serine-aspartate doublet replaces an asparagine residue and a glutamate residue, which were strictly conserved in previously studied GH2 members with beta-galactosidase, beta-glucuronidase or beta-mannosidase activity and shown to be directly involved in various steps of the catalytic mechanism. Alignments of several other GH2 members allowed the identification of yet another putative subfamily, characterized by a novel, serine-glutamate doublet at these positions.
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Affiliation(s)
- Nathalie Côté
- *Centre d'Étude et de Valorisation de la Diversité Microbienne, Département de Biologie, Faculté des Sciences, Université de Sherbrooke, Sherbrooke, QC, Canada, J1K 2R1
| | - Alain Fleury
- *Centre d'Étude et de Valorisation de la Diversité Microbienne, Département de Biologie, Faculté des Sciences, Université de Sherbrooke, Sherbrooke, QC, Canada, J1K 2R1
| | - Émilie Dumont-Blanchette
- *Centre d'Étude et de Valorisation de la Diversité Microbienne, Département de Biologie, Faculté des Sciences, Université de Sherbrooke, Sherbrooke, QC, Canada, J1K 2R1
| | - Tamo Fukamizo
- †Department of Advanced Bioscience, Kinki University, 3327-204, Nakamachi, Nara 631-8505, Japan
| | - Masaru Mitsutomi
- ‡Department of Applied Biological Sciences, Saga University, Saga 840-8502, Japan
| | - Ryszard Brzezinski
- *Centre d'Étude et de Valorisation de la Diversité Microbienne, Département de Biologie, Faculté des Sciences, Université de Sherbrooke, Sherbrooke, QC, Canada, J1K 2R1
- To whom correspondence should be addressed (email )
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9
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Vocadlo DJ, Wicki J, Rupitz K, Withers SG. Mechanism of Thermoanaerobacterium saccharolyticum beta-xylosidase: kinetic studies. Biochemistry 2002; 41:9727-35. [PMID: 12146938 DOI: 10.1021/bi020077v] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The catalytic mechanism of Thermoanaerobacterium saccharolyticum beta-xylosidase (XynB) from family 39 of glycoside hydrolases has been subjected to a detailed kinetic investigation using a range of substrates. The enzyme exhibits a bell-shaped pH dependence of k(cat)/K(m), reflecting apparent pK(a) values of 4.1 and 6.8. The k(cat) and k(cat)/K(m) values for a series of aryl xylosides have been measured and used to construct two Brønsted plots. The plot of log(k(cat)/K(m)) against the pK(a) of the leaving group reveals a significant correlation (beta(lg) = -0.97, r(2) = 0.94, n = 8), indicating that fission of the glycosidic bond is significantly advanced in the transition state leading to the formation of the xylosyl-enzyme intermediate. The large negative value of the slope indicates that there is relatively little proton donation to the glycosidic oxygen in the transition state. A biphasic, concave-downward plot of log(k(cat)) against pK(a) provides good evidence for a two-step double-displacement mechanism involving a glycosyl-enzyme intermediate. For activated leaving groups (pK(a) < 9), the breakdown of the xylosyl-enzyme intermediate is the rate-determining step, as indicated by the absence of any effect of the pK(a) of the leaving group on log(k(cat)) (beta(lg) approximately 0). However, a strong dependence of the first-order rate constant on the pK(a) value of relatively poor leaving groups (pK(a) > 9) suggests that the xylosylation step is rate-determining for these substrates. Support for the dexylosylation chemical step being rate-determining for activated substrates comes from nucleophilic competition experiments in which addition of dithiothreitol results in an increase in turnover rates. Normal secondary alpha-deuterium kinetic isotope effects ((alpha-D)(V) or (alpha-D)(V/K) = 1.08-1.10) for three different substrates of widely varying pK(a) value (5.15-9.95) have been measured and these reveal that the transition states leading to the formation and breakdown of the intermediate are similar and both steps involve rehybridization of C1 from sp(3) to sp(2). These results are consistent only with "exploded" transition states, in which the saccharide moiety bears considerable positive charge, and the intermediate is a covalent acylal-ester where C1 is sp(3) hybridized.
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Affiliation(s)
- David J Vocadlo
- Protein Engineering Network of Centres of Excellence of Canada, Vancouver, British Columbia, Canada V6T 1Z1
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10
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Sunna A, Gibbs MD, Chin CW, Nelson PJ, Bergquist PL. A gene encoding a novel multidomain beta-1,4-mannanase from Caldibacillus cellulovorans and action of the recombinant enzyme on kraft pulp. Appl Environ Microbiol 2000; 66:664-70. [PMID: 10653733 PMCID: PMC91878 DOI: 10.1128/aem.66.2.664-670.2000] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Genomic walking PCR was used to obtained a 4,567-bp nucleotide sequence from Caldibacillus cellulovorans. Analysis of this sequence revealed that there were three open reading frames, designated ORF1, ORF2, and ORF3. Incomplete ORF1 encoded a putative C-terminal cellulose-binding domain (CBD) homologous to members of CBD family IIIb, while putative ORF3 encoded a protein of unknown function. The putative ManA protein encoded by complete manA ORF2 was an enzyme with a novel multidomain structure and was composed of four domains in the following order: a putative N-terminal domain (D1) of unknown function, an internal CBD (D2), a beta-mannanase catalytic domain (D3), and a C-terminal CBD (D4). All four domains were linked via proline-threonine-rich peptides. Both of the CBDs exhibited sequence similarity to family IIIb CBDs, while the mannanase catalytic domain exhibited homology to the family 5 glycosyl hydrolases. The purified recombinant enzyme ManAd3 expressed from the cloned catalytic domain (D3) exhibited optimum activity at 85 degrees C and pH 6.0 and was extremely thermostable at 70 degrees C. This enzyme exhibited high specificity with the substituted galactomannan locust bean gum, while more substituted galacto- and glucomannans were poorly hydrolyzed. Preliminary studies to determine the effect of the recombinant ManAd3 and a recombinant thermostable beta-xylanase on oxygen-delignified Pinus radiata kraft pulp revealed that there was an increase in the brightness of the bleached pulp.
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Affiliation(s)
- A Sunna
- Department of Biological Sciences, Macquarie University, Sydney, New South Wales 2109, Australia
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11
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Fierobe HP, Pagès S, Bélaïch A, Champ S, Lexa D, Bélaïch JP. Cellulosome from Clostridium cellulolyticum: molecular study of the Dockerin/Cohesin interaction. Biochemistry 1999; 38:12822-32. [PMID: 10504252 DOI: 10.1021/bi9911740] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Clostridium cellulolyticum produces cellulolytic complexes (cellulosomes) made of 10-13 cell wall degrading enzymes tightly bound to a scaffolding protein (CipC) by means of their dockerin domain. It has previously been shown that the receptor domains in CipC are the cohesin domains and that the cohesin/dockerin interaction is calcium-dependent. In the present study, surface plasmon resonance was used to demonstrate that the free cohesin1 from CipC and dockerin from CelA have the same K(D) (2.5 x 10(-)(10) M) as that of the entire CelA and a larger fragment of CipC, the latter of which contains, in addition to cohesin1, a cellulose binding domain and a hydrophilic domain of unknown function. This demonstrates that neither the catalytic domain of CelA nor the noncohesin domains of CipC have any influence on the interaction. Dockerin domains are composed of two conserved segments of 22 residues: removal of the second segment abolishes the affinity for cohesin1, whereas modified dockerins having twice the first segment, twice the second, or both segments but in a reverse order have K(D) values for cohesin1 in the same range as that observed for wild-type dockerin. These data indicate that if two segments are required for the complexation with the cohesin, segments 1 and 2 are similar enough to replace each other. Calcium overlay experiments revealed that the dockerin domain has one calcium binding site per conserved segment. Circular dichroism performed on wild-type and mutant dockerins indicates that this domain is well structured and that removal of calcium only weakly affects the secondary structure, which remains 40-45% helical.
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Affiliation(s)
- H P Fierobe
- Laboratoire de Bioénergétique et Ingénierie des Protéines, Centre National de la Recherche Scientifique, 31, Chemin Joseph-Aiguier, F-13402 Marseille, France.
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12
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Ethier N, Talbot G, Sygusch J. Gene cloning, DNA sequencing, and expression of thermostable beta-mannanase from Bacillus stearothermophilus. Appl Environ Microbiol 1998; 64:4428-32. [PMID: 9797302 PMCID: PMC106664 DOI: 10.1128/aem.64.11.4428-4432.1998] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A DNA genomic library constructed from Bacillus stearothermophilus, a gram-positive, facultative thermophilic aerobe that secretes a thermostable beta-mannanase, was screened for mannan hydrolytic activity. Recombinant beta-mannanase activity was detected on the basis of the clearing of halos around Escherichia coli colonies grown on a dye-labelled substrate, Remazol brilliant blue-locust bean gum. The nucleotide sequence of the mannanase gene, manF, corresponded to an open reading frame of 2,085 bp that codes for a 32-amino-acid signal peptide and a mature protein with a molecular mass of 76,089 Da. From sequence analysis, ManF belongs to glycosyl hydrolase family 5 and exhibits higher similarity to eukaryotic than to bacterial mannanases. The manF coding sequence was subcloned into the pH6EX3 expression plasmid and expressed in E. coli as a recombinant fusion protein containing a hexahistidine N-terminal sequence. The fusion protein has thermostability similar to the native enzyme and was purified by Ni2+ affinity chromatography. The values for the kinetic parameters Vmax and Km were 384 U/mg and 2.4 mg/ml, respectively, for the recombinant mannanase and were comparable to those of the native enzyme.
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Affiliation(s)
- N Ethier
- Département de Biochimie, Faculté de Médecine, Université de Montréal, Montréal, Québec, Canada H3C 3J7
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13
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Abstract
Recent findings on the cellulolytic system of the mesophilic Clostridium cellulolyticum are reviewed. Six cellulases and the scaffolding protein, which are, at the present time, the known components of the cellulosome have been cloned. The catalytic and structural properties of the cloned enzymes CelA, CelC, CelD and CelF are described. It was shown that the grafting of the cellulases onto the scaffolding protein was performed using the dockerin-cohesin attachment device and was strictly dependent on the integrity of both components of the complex. The amino-acid sequences of dockerin and cohesin domains of C. cellulolyticum were compared to that of C. cellulovorans and C. thermocellum. This sequence analysis shows that domains belonging to the thermophilic or the mesophilic bacteria can be placed into two well defined groups. The genetic organization of the gene cluster of C. cellulolyticum is discussed.
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Affiliation(s)
- J P Bélaich
- Bioénergétique et Ingénierie des Proteines, IBSM, Centre National de la Recherche Scientifique, Marseille, France.
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14
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Margolles-clark E, Ihnen M, Penttilä M. Expression patterns of ten hemicellulase genes of the filamentous fungus Trichoderma reesei on various carbon sources. J Biotechnol 1997. [DOI: 10.1016/s0168-1656(97)00097-7] [Citation(s) in RCA: 121] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
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15
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Gal L, Pages S, Gaudin C, Belaich A, Reverbel-Leroy C, Tardif C, Belaich JP. Characterization of the cellulolytic complex (cellulosome) produced by Clostridium cellulolyticum. Appl Environ Microbiol 1997; 63:903-9. [PMID: 9055408 PMCID: PMC168382 DOI: 10.1128/aem.63.3.903-909.1997] [Citation(s) in RCA: 90] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The cellulolytic complex was isolated from Clostridium cellulolyticum grown on cellulose. Upon gel filtration, the complex was found to consist mainly of 600-kDa units, along with a 16-MDa aggregate. Its ability to degrade various substrates and its capacity to bind to the crystalline cellulose were measured. The results of sodium dodecyl sulfate-polyacrylamide gel electrophoresis, N-terminal sequencing, and blotting analysis showed that all of the known cellulases of this organism are present in this complex. Three major components were observed: the first component, a noncatalytic, large (160-kDa) protein, was identified based on its ability to bind to the dockerin-containing cellulases as scaffolding protein CipC. The other two components, which had molecular masses of 94 and 80.6 kDa, were identified as CelE and CelF, respectively. The identified cellulases and some other components of the cellulosome were able to bind to a miniCipC1 construct. In addition to providing an extensive description of the system, the results of the present study confirm that the dockerin-cohesin domain interaction plays an essential role in the constitution of the cellulosome.
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Affiliation(s)
- L Gal
- Laboratoire de Bioénergétique et Ingéniérie des Protéines, IFR C1, Centre National de la Recherche Scientifique, Marseille, France
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Bauer MW, Bylina EJ, Swanson RV, Kelly RM. Comparison of a beta-glucosidase and a beta-mannosidase from the hyperthermophilic archaeon Pyrococcus furiosus. Purification, characterization, gene cloning, and sequence analysis. J Biol Chem 1996; 271:23749-55. [PMID: 8798600 DOI: 10.1074/jbc.271.39.23749] [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: 02/02/2023] Open
Abstract
Two distinct exo-acting, beta-specific glycosyl hydrolases were purified to homogeneity from crude cell extracts of the hyperthermophilic archaeon Pyrococcus furiosus: a beta-glucosidase, corresponding to the one previously purified by Kengen et al. (Kengen, S. W. M., Luesink, E. J., Stams, A. J. M., and Zehnder, A. J. B. (1993) Eur. J. Biochem. 213, 305-312), and a beta-mannosidase. The beta-mannosidase and beta-glucosidase genes were isolated from a genomic library by expression screening. The nucleotide sequences predicted polypeptides with 510 and 472 amino acids corresponding to calculated molecular masses of 59.0 and 54.6 kDa for the beta-mannosidase and the beta-glucosidase, respectively. The beta-glucosidase gene was identical to that reported by Voorhorst et al. (Voorhorst, W. G. B., Eggen, R. I. L., Luesink, E. J., and deVos, W. M. (1995) J. Bacteriol. 177, 7105-7111; GenBank accession no. U37557U37557). The deduced amino acid sequences showed homology both with each other (46.5% identical) and with several other glycosyl hydrolases, including the beta-glycosidases from Sulfolobus solfataricus, Thermotoga maritima, and Caldocellum saccharolyticum. Based on these sequence similarities, the beta-mannosidase and the beta-glucosidase can both be classified as family 1 glycosyl hydrolases. In addition, the beta-mannosidase and beta-glucosidase from P. furiosus both contained the conserved active site residues found in all family 1 enzymes. The beta-mannosidase showed optimal activity at pH 7.4 and 105 degrees C. Although the enzyme had a half-life of greater than 60 h at 90 degrees C, it is much less thermostable than the beta-glucosidase, which had a reported half-life of 85 h at 100 degrees C. Km and Vmax values for the beta-mannosidase were determined to be 0.79 mM and 31.1 micromol para-nitrophenol released/min/mg with p-nitrophenyl-beta-D-mannopyranoside as substrate. The catalytic efficiency of the beta-mannosidase was significantly lower than that reported for the P. furiosus beta-glucosidase (5.3 versus 4, 500 s-1 mM-1 with p-nitrophenyl-beta-D-glucopyranoside as substrate). The kinetic differences between the two enzymes suggest that, unlike the beta-glucosidase, the primary role of the beta-mannosidase may not be disaccharide hydrolysis. Other possible roles for this enzyme are discussed.
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Affiliation(s)
- M W Bauer
- Department of Chemical Engineering, North Carolina State University, Raleigh, North Carolina 27695-7905, USA
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17
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Reverbel-Leroy C, Belaich A, Bernadac A, Gaudin C, Belaich JP, Tardif C. Molecular study and overexpression of the Clostridium cellulolyticum celF cellulase gene in Escherichia coli. MICROBIOLOGY (READING, ENGLAND) 1996; 142 ( Pt 4):1013-1023. [PMID: 8936327 DOI: 10.1099/00221287-142-4-1013] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
The CelF-encoding sequence was isolated from Clostridium cellulolyticum genomic DNA using the inverse PCR technique. The gene lies between cipC (the gene encoding the cellulosome scaffolding protein) and celC (coding for the endoglucanase C) in the large cel cluster of this mesophilic cellulolytic Clostridium species. Comparisons between the deduced amino acid sequence of the mature CelF (693 amino acids, molecular mass 77626) and those of other beta-glycanases showed that this enzyme belongs to the recently proposed family L of cellulases (family 48 of glycosyl hydrolases). The protein was overproduced in Escherichia coli using the T7 expression system. It formed both cytoplasmic and periplasmic inclusion bodies when induction was performed at 37 degrees C. Surprisingly, the protein synthesized from the cytoplasmic production vector was degraded in the Ion protease-deficient strain BL21(DE3). The induction conditions were optimized with regard to the concentration of inductor, cell density, and temperature and time of induction in order to overproduce an active periplasmic protein (CelFp) which was both soluble and stable. It was collected using the osmotic shock method. The enzymic degradation of various cellulosic substrates by CelFp was studied. CelFp degraded swollen Avicel more efficiently than substituted soluble CM-cellulose or crystalline Avicel and was not active on xylan. Its activity is therefore quite different from that of endoglucanases, which are most active on CM-cellulose.
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Affiliation(s)
- Corinne Reverbel-Leroy
- Bioénergétique et Ingéniérie des protéines, Centre National de la Recherche Scientifique, 31 chemin Joseph Aiguier, BP71, 13402 Marseille Cedex 20, France
| | - Anne Belaich
- Bioénergétique et Ingéniérie des protéines, Centre National de la Recherche Scientifique, 31 chemin Joseph Aiguier, BP71, 13402 Marseille Cedex 20, France
| | - Alain Bernadac
- Laboratoire d'lngéniérie et Dynamique des Systèmes Membranaires, Centre National de la Recherche Scientifique, 31 chemin Joseph Aiguier, BP71, 13402 Marseille Cedex 20, France
| | - Christian Gaudin
- Bioénergétique et Ingéniérie des protéines, Centre National de la Recherche Scientifique, 31 chemin Joseph Aiguier, BP71, 13402 Marseille Cedex 20, France
| | - Jean-Pierre Belaich
- Université de Provence, Marseille, France 3
- Bioénergétique et Ingéniérie des protéines, Centre National de la Recherche Scientifique, 31 chemin Joseph Aiguier, BP71, 13402 Marseille Cedex 20, France
| | - Chantal Tardif
- Université de Provence, Marseille, France 3
- Bioénergétique et Ingéniérie des protéines, Centre National de la Recherche Scientifique, 31 chemin Joseph Aiguier, BP71, 13402 Marseille Cedex 20, France
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18
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Attwood GT, Herrera F, Weissenstein LA, White BA. An endo-beta-1,4-glucanase gene (celA) from the rumen anaerobe Ruminococcus albus 8: cloning, sequencing, and transcriptional analysis. Can J Microbiol 1996; 42:267-78. [PMID: 8868234 DOI: 10.1139/m96-039] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
A genomic library of Ruminococcus albus 8 DNA was constructed in Escherichia coli using bacteriophage lambda ZapII. This library was screened for cellulase components and several Ostazin brilliant red/carboxymethyl cellulose positive clones were isolated. All of these clones contained a common 3.4-kb insert, which was recovered as a plasmid by helper phage excision. The carboxymethyl cellulase coding region was localized to a 1.4-kb region of DNA by nested deletions, and a clone containing the entire celA gene was sequenced. Analysis of the sequence revealed a 1231-bp open reading frame, coding for a protein of 411 amino acids with a predicted molecular weight of 45 747. This protein, designated CelA, showed extensive homology with family 5 endoglucanases by both primary amino acid sequence alignment and hydrophobic cluster analysis. Cell-free extracts of E. coli containing the celA clone demonstrated activity against carboxymethyl cellulose and acid swollen cellulose but not against any of the p-nitrophenol glycosides tested, indicating an endo-beta-1,4-glucanase type of activity. In vitro transcription-translation experiments showed that three proteins of 48,000, 44,000, and 23,000 molecular weight were produced by clones containing the celA gene. Northern analysis of RNA extracted from R. albus 8 grown on cellulose indicated a celA transcript of approximately 2700 bases, whereas when R. albus 8 was grown on cellobiose, celA transcripts of approximately 3000 and 600 bases were detected. Primer extension analysis of these RNAs revealed different transcription initiation sites for the celA gene when cells were grown with cellulose or cellobiose as the carbon source. These two sites differed by 370 bases in distance. A model, based on transcription and sequence data, is proposed for celA regulation.
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Affiliation(s)
- G T Attwood
- Department of Animal Sciences, University of Illinois at Urbana-Champaign, 61801, USA
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19
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Macarrón R, Henrissat B, Claeyssens M. Family A cellulases: two essential tryptophan residues in endoglucanase III from Trichoderma reesei. BIOCHIMICA ET BIOPHYSICA ACTA 1995; 1245:187-90. [PMID: 7492576 DOI: 10.1016/0304-4165(95)00091-o] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
Three tryptophan residues are readily oxidised by N-bromosuccinimide in endoglucanase III from Trichoderma reesei. Evidence was obtained that the residue first modified is situated in the cellulose-binding domain and the second in the enzyme's catalytic site. The latter influences the binding and hydrolysis of soluble substrates. The modification of a third residue does not further affect the catalytic properties. The present results complement published data concerning other identified catalytic residues, and help to clarify the active site structure of family A cellulases.
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Affiliation(s)
- R Macarrón
- Departamento de Bioquímica Biología Molecular I, Facultad de Ciencias Químicas, Universidad Complutense, Madrid, Spain
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20
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Ducros V, Czjzek M, Belaich A, Gaudin C, Fierobe HP, Belaich JP, Davies GJ, Haser R. Crystal structure of the catalytic domain of a bacterial cellulase belonging to family 5. Structure 1995; 3:939-49. [PMID: 8535787 DOI: 10.1016/s0969-2126(01)00228-3] [Citation(s) in RCA: 112] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
BACKGROUND Cellulases are glycosyl hydrolases--enzymes that hydrolyze glycosidic bonds. They have been widely studied using biochemical and microbiological techniques and have attracted industrial interest because of their potential in biomass conversion and in the paper and textile industries. Glycosyl hydrolases have lately been assigned to specific families on the basis of similarities in their amino acid sequences. The cellulase endoglucanase A produced by Clostridium cellulolyticum (CelCCA) belongs to family 5. RESULTS We have determined the crystal structure of the catalytic domain of CelCCA at a resolution of 2.4 A and refined it to 1.6 A. The structure was solved by the multiple isomorphous replacement method. The overall structural fold, (alpha/beta)8, belongs to the TIM barrel motif superfamily. The catalytic centre is located at the C-terminal ends of the beta strands; the aromatic residues, forming the substrate-binding site, are arranged along a long cleft on the surface of the globular enzyme. CONCLUSIONS Strictly conserved residues within family 5 are described with respect to their catalytic function. The proton donor, Glu170, and the nucleophile, Glu307, are localized on beta strands IV and VII, respectively, and are separated by 5.5 A, as expected for enzymes which retain the configuration of the substrate's anomeric carbon. Structure determination of the catalytic domain of CelCCA allows a comparison with related enzymes belonging to glycosyl hydrolase families 2, 10 and 17, which also display an (alpha/beta)8 fold.
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Affiliation(s)
- V Ducros
- Institut de Biologie Structurale et Microbiologie, URA 1296, CNRS, Marseille, France
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21
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Saxena S, Fierobe HP, Gaudin C, Guerlesquin F, Belaich JP. Biochemical properties of a beta-xylosidase from Clostridium cellulolyticum. Appl Environ Microbiol 1995; 61:3509-12. [PMID: 7574661 PMCID: PMC167631 DOI: 10.1128/aem.61.9.3509-3512.1995] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
A 43-kDa beta-xylosidase from Clostridium cellulolyticum was purified to homogeneity. The enzyme releases xylose from p-nitrophenylxylose and xylodextrins with a degree of polymerization ranging between 2 and 5. The N-terminal amino acid sequence of the enzyme showed homologies with three other bacterial beta-xylosidases. By proton nuclear magnetic resonance spectroscopy, the enzyme was found to act by inverting the beta-anomeric configuration.
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Affiliation(s)
- S Saxena
- Laboratoire de Biochimie et Génétique Moléculaire des Anaérobies, IFRC1, Centre National de la Recherche Scientifique, Marseille, France
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22
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Dominguez R, Souchon H, Spinelli S, Dauter Z, Wilson KS, Chauvaux S, Béguin P, Alzari PM. A common protein fold and similar active site in two distinct families of beta-glycanases. NATURE STRUCTURAL BIOLOGY 1995; 2:569-76. [PMID: 7664125 DOI: 10.1038/nsb0795-569] [Citation(s) in RCA: 133] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The structure of Clostridium thermocellum endoglucanase CelC, a member of the largest cellulase family (family A), has been determined at 2.15 A resolution. The protein folds into an (alpha/beta)8 barrel, with a deep active-site cleft generated by the insertion of a helical subdomain. The structure of the catalytic core of xylanase XynZ, which belongs to xylanase family F, has been determined at 1.4 A resolution. In spite of significant differences in substrate specificity and structure (including the absence of the helical subdomain), the general polypeptide folding pattern, architecture of the active site and catalytic mechanism of XynZ and CelC are similar, suggesting a common evolutionary origin.
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Affiliation(s)
- R Dominguez
- Unité d'Immunologie Structurale, URA 1961 CNRS, Institute Pasteur, Paris, France
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23
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Lin C, Stahl DA. Comparative analyses reveal a highly conserved endoglucanase in the cellulolytic genus Fibrobacter. J Bacteriol 1995; 177:2543-9. [PMID: 7730288 PMCID: PMC176915 DOI: 10.1128/jb.177.9.2543-2549.1995] [Citation(s) in RCA: 26] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
An RNA probe complementary to the endoglucanase 3 gene (cel-3) of Fibrobacter succinogenes S85 hybridized to chromosomal DNAs from isolates representing the genetic diversity of the genus. The probe was subsequently used to identify putative cel-3-containing clones from genomic libraries of representative Fibrobacter isolates. Comparative sequence analyses of the cloned cel-3 genes confirmed that cel-3 is conserved among Fibrobacter isolates and that the ancestral cel-3 gene appears to have coevolved with the genus, since the same genealogy was inferred from sequence comparisons of 16S rRNAs and cel-3 genes. Hybridization comparisons using a xylanase gene probe suggested similar conservation of this gene. Together the data indicate that the cellulolytic apparatus is conserved among Fibrobacter isolates and that comparative analyses of homologous elements of the apparatus from different members, in relationship to the now established phylogeny of the genus, could serve to better define the enzymatic basis of fiber digestion in this genus.
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Affiliation(s)
- C Lin
- Department of Veterinary Pathobiology, University of Illinois at Urbana-Champaign 61801, USA
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24
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Jenkins J, Lo Leggio L, Harris G, Pickersgill R. Beta-glucosidase, beta-galactosidase, family A cellulases, family F xylanases and two barley glycanases form a superfamily of enzymes with 8-fold beta/alpha architecture and with two conserved glutamates near the carboxy-terminal ends of beta-strands four and seven. FEBS Lett 1995; 362:281-5. [PMID: 7729513 DOI: 10.1016/0014-5793(95)00252-5] [Citation(s) in RCA: 194] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Comparison of the recently determined crystal structures Pseudomonas fluorescens subsp. cellulosa family F xylanase, (1-3)-beta-glucanase and (1-3,1-4)-beta-glucanase and the catalytic domain of E. coli beta-galactosidase reveals that they belong to a superfamily of 8-fold beta/alpha-barrels with similar amino acid residues at their active sites. In the three families that these enzymes represent, the nucleophile is a glutamate, which is located close to the carboxy-terminus of beta-strand seven. In addition all three enzymes have the sequence asparagine-glutamate close to the carboxy-terminus of beta-strand four. This glutamate has been identified as the acid/base in the family F xylanases and is essential for catalysis in beta-galactosidase. We suggest that the equivalent residue in the barley glucanases is the acid/base. Analysis of the sequences of family 1 beta-glucosidases and family 5 cellulases shows that these enzymes also belong to this superfamily which we call the 4/7 superfamily.
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Affiliation(s)
- J Jenkins
- Department of Protein Engineering, Reading Laboratory, UK
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25
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The catalytic domain of endoglucanase A from Clostridium cellulolyticum belonging to family 5: an α/β-barrel enzyme. ACTA ACUST UNITED AC 1995. [DOI: 10.1016/s0921-0423(06)80107-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register]
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26
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Affiliation(s)
- P Tomme
- Department of Microbiology and Immunology, University of British Columbia, Vancouver, Canada
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27
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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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28
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Kawaminami S, Ozaki K, Sumitomo N, Hayashi Y, Ito S, Shimada I, Arata Y. A stable isotope-aided NMR study of the active site of an endoglucanase from a strain of Bacillus. J Biol Chem 1994. [DOI: 10.1016/s0021-9258(19)61969-1] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
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29
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Ozaki K, Sumitomo N, Hayashi Y, Kawai S, Ito S. Site-directed mutagenesis of the putative active site of endoglucanase K from Bacillus sp. KSM-330. BIOCHIMICA ET BIOPHYSICA ACTA 1994; 1207:159-64. [PMID: 8075149 DOI: 10.1016/0167-4838(94)00060-3] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The roles of one Glu and four Asp residues of endoglucanase K from Bacillus sp. KSM-330, which are conserved in all the endo-beta-glucanases in the family D, were analyzed by site-directed mutagenesis. The gene for endoglucanase K was mutated to replace Asp-154, Asp-191, Asp-193 or Asp-300 by Asn, or to replace Glu-130 by Gln in the encoded enzyme. Mutant and wild-type genes were separately expressed in Bacillus subtilis and the resultant enzymes were purified from the culture broth. All mutant enzymes exhibited the same mobility on SDS-polyacrylamide gel electrophoresis as the wild-type enzyme and gave similar circular dichroism spectra to that of the wild-type enzyme. Substitution of Glu-130, Asp-191, Asp-193 or Asp-300 significantly decreased the specific activity of the enzyme toward CM-cellulose. Kinetic analysis of the abilities of these mutant enzymes to liberate p-nitrophenol from p-nitrophenylcellotrioside revealed that all the mutant enzymes had very much lower kcat values than that of the wild-type enzyme, while the Km values of these mutant enzymes were almost the same as that of the wild-type enzyme. Of these Glu and Asp residues, Glu-130 and Asp-191 seem to be most likely to be catalytic residues because substitutions of these residues resulted in the lowest kcat values of the mutant enzymes.
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Affiliation(s)
- K Ozaki
- Tochigi Research Laboratories, Kao Corporation, Tochigi, Japan
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30
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Abstract
Cellulolytic microorganisms play an important role in the biosphere by recycling cellulose, the most abundant carbohydrate produced by plants. Cellulose is a simple polymer, but it forms insoluble, crystalline microfibrils, which are highly resistant to enzymatic hydrolysis. All organisms known to degrade cellulose efficiently produce a battery of enzymes with different specificities, which act together in synergism. The study of cellulolytic enzymes at the molecular level has revealed some of the features that contribute to their activity. In spite of a considerable diversity, sequence comparisons show that the catalytic cores of cellulases belong to a restricted number of families. Within each family, available data suggest that the various enzymes share a common folding pattern, the same catalytic residues, and the same reaction mechanism, i.e. either single substitution with inversion of configuration or double substitution resulting in retention of the beta-configuration at the anomeric carbon. An increasing number of three-dimensional structures is becoming available for cellulases and xylanases belonging to different families, which will provide paradigms for molecular modeling of related enzymes. In addition to catalytic domains, many cellulolytic enzymes contain domains not involved in catalysis, but participating in substrate binding, multi-enzyme complex formation, or possibly attachment to the cell surface. Presumably, these domains assist in the degradation of crystalline cellulose by preventing the enzymes from being washed off from the surface of the substrate, by focusing hydrolysis on restricted areas in which the substrate is synergistically destabilized by multiple cutting events, and by facilitating recovery of the soluble degradation products by the cellulolytic organism. In most cellulolytic organisms, cellulase synthesis is repressed in the presence of easily metabolized, soluble carbon sources and induced in the presence of cellulose. Induction of cellulases appears to be effected by soluble products generated from cellulose by cellulolytic enzymes synthesized constitutively at a low level. These products are presumably converted into true inducers by transglycosylation reactions. Several applications of cellulases or hemicellulases are being developed for textile, food, and paper pulp processing. These applications are based on the modification of cellulose and hemicellulose by partial hydrolysis. Total hydrolysis of cellulose into glucose, which could be fermented into ethanol, isopropanol or butanol, is not yet economically feasible. However, the need to reduce emissions of greenhouse gases provides an added incentive for the development of processes generating fuels from cellulose, a major renewable carbon source.
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Affiliation(s)
- P Béguin
- Unité de Physiologie Cellulaire, Département des Biotechnologies, Institut Pasteur, Paris, France
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31
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32
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Macarron R, van Beeumen J, Henrissat B, de la Mata I, Claeyssens M. Identification of an essential glutamate residue in the active site of endoglucanase III from Trichoderma reesei. FEBS Lett 1993; 316:137-40. [PMID: 8093602 DOI: 10.1016/0014-5793(93)81202-b] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
n-Propyl, n-butyl and n-pentyl beta-cellobiosides with a reactive omega-epoxide in their aglycon completely and irreversibly inactivate endoglucanase III from Trichoderma reesei. The pentyl derivative was found to be most effective. From these affinity labeling experiments evidence was found for the implication of Glu329 in the reaction mechanism. This is discussed in relation to other structural/functional data known for endoglucanase III and several other family A glycanases.
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Affiliation(s)
- R Macarron
- Departamento de Bioquimica, Facultad de Ciencias Biologicas, Universidad Complutense, Madrid, Spain
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33
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Navas J, Béguin P. Site-induced mutagenesis of conserved residues of Clostridium Thermocellum endoglucanase celc. Biochem Biophys Res Commun 1992; 189:807-12. [PMID: 1361730 DOI: 10.1016/0006-291x(92)92274-2] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Four conserved residues of Clostridium thermocellum endoglucanase CelC were replaced by site-directed mutagenesis. Proteins mutated in His-90, Asn-139 and Glu-140 showed strongly reduced activity, in agreement with predictions of sequence alignments. Mutations in Glu-140 did not result in any detectable change in Km, or apparent size, suggesting that Glu-140 is directly involved in catalysis. The pH optimum of the proteins carrying the Glu-140/Ala and Glu140/Gln mutations was lower than that of the wild type, whereas the activity vs. pH profile of Glu-140/Asp CelC was similar to that of the wild type, suggesting that Glu-140 may act as a proton donor.
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Affiliation(s)
- J Navas
- Département des Biotechnologies, Institut Pasteur, Paris, France
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