1
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Jang WJ, Lee GH, Lee JM, Kim TY, Jeon MH, Kim YH, Lee EW. Improving enzyme activity, thermostability and storage stability of β-1,3-1,4-glucanase with poly-γ-glutamic acid produced by Bacillus sp. SJ-10. Enzyme Microb Technol 2020; 143:109703. [PMID: 33375971 DOI: 10.1016/j.enzmictec.2020.109703] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Revised: 11/02/2020] [Accepted: 11/05/2020] [Indexed: 10/23/2022]
Abstract
β-1,3-1,4-glucanase (BG) is an industrially important enzyme owing to its stringent specificity for β-glucan cleavage. In this study, poly-γ-glutamic acid (γ-PGA) was added to BG to investigate its effect on improving the activity and stability of the enzyme. The effect of γ-PGA was investigated by analyzing kinetic and thermodynamic parameters. Compared to control, significant differences (P < .05) in enzyme activity were observed when 1.0 %, 1.5 %, and 2.0 % γ-PGA was added, and the activities were increased 1.23 ± 0.05, 1.23 ± 0.07, and 1.31 ± 0.07-fold, respectively. Regarding thermostability, residual BG activity after a 1 h incubation at 60 °C was 12.53 ± 0.06 % without γ-PGA and 79.02 ± 5.76 % with 1% γ-PGA. The storage stability at 25 °C and 50 °C also increased when γ-PGA was present. The kinetics and thermodynamic investigations indicated that the increased activity and stability of BG when γ-PGA was added were due to increased values of the Vmax, Kcat, and activation energy for denaturation. The findings of this study suggest that adding γ-PGA to BG increases the application value of this enzyme in the food and feed industries.
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Affiliation(s)
- Won Je Jang
- Biopharmaceutical Engineering Major, Division of Applied Bioengineering, Dong-Eui University, Busan, 47340, Republic of Korea; Department of Biotechnology, Pukyong National University, Busan, 48513, Republic of Korea
| | - Ga Hye Lee
- Department of Biotechnology, Pukyong National University, Busan, 48513, Republic of Korea
| | - Jong Min Lee
- Industrial Bio-materials Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon, 34141, Republic of Korea
| | - Tae-Yong Kim
- Biopharmaceutical Engineering Major, Division of Applied Bioengineering, Dong-Eui University, Busan, 47340, Republic of Korea
| | - Mi-Hyun Jeon
- Biopharmaceutical Engineering Major, Division of Applied Bioengineering, Dong-Eui University, Busan, 47340, Republic of Korea
| | - Yang-Ho Kim
- Biopharmaceutical Engineering Major, Division of Applied Bioengineering, Dong-Eui University, Busan, 47340, Republic of Korea
| | - Eun-Woo Lee
- Biopharmaceutical Engineering Major, Division of Applied Bioengineering, Dong-Eui University, Busan, 47340, Republic of Korea.
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2
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Wei YD, Li Y, Deng C, Wu SH, Huang CJ, Yi Y. Expression and biochemical characterization of a multifunctional glycosidase from the thermophilic Bacillus licheniformis SR01. J GEN APPL MICROBIOL 2017; 63:259-265. [PMID: 28835594 DOI: 10.2323/jgam.2016.12.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
A gene (gkdA) (741 bp) encoding a putative protein of 247 amino acids was cloned from the Bacillus licheniformis SR01. The protein was expressed in Escherichia coli BL21 with a molecular mass estimated by SDS-PAGE of approximately 28.03 kDa and showed a calculating isoelectric point (pI) of 6.42. Structure analysis and function identification showed that the enzyme was a multifunctional glycosidase. Its specific activity was 0.013 U/μg. The recombinant glycosidase showed a maximum activity at 50°C and pH 7.0. It was very stable below 90°C and may have heat activation at higher temperatures. The relative residual activity was still more than 80% after 120 min at pH 5.0-10.0. The enzyme activity was inhibited by Cu2+, Fe2+, Ca2+, Mg2+, Co2+, Li+, SDS and EDTA, activated by Ca2+, and not affected by Mn2+ and K+. Under simulated stomach, and in vitro intestine, conditions, the enzyme retained 80%, and more than 100%, activity, respectively, after incubation for 90 min. The excellent properties of this enzyme, specifically its thermal stability and multifunctional abilities, give it potential application in the field of feed processing and other high-temperature processing industries.
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Affiliation(s)
- Yang-Dao Wei
- College of Biological and Chemical Engineering, Guangxi University of Science and Technology.,Guangxi Key Laboratory of Green Processing of Sugar Resources, Guangxi University of Science and Technology.,Key Laboratory for Processing of Sugar Resources of Guangxi Higher Education Institutes, Guangxi University of Science and Technology
| | - Ya Li
- College of Biological and Chemical Engineering, Guangxi University of Science and Technology.,Guangxi Key Laboratory of Green Processing of Sugar Resources, Guangxi University of Science and Technology.,Key Laboratory for Processing of Sugar Resources of Guangxi Higher Education Institutes, Guangxi University of Science and Technology
| | - Chun Deng
- College of Biological and Chemical Engineering, Guangxi University of Science and Technology.,Guangxi Key Laboratory of Green Processing of Sugar Resources, Guangxi University of Science and Technology.,Key Laboratory for Processing of Sugar Resources of Guangxi Higher Education Institutes, Guangxi University of Science and Technology
| | - Shi-Hua Wu
- College of Biological and Chemical Engineering, Guangxi University of Science and Technology.,Guangxi Key Laboratory of Green Processing of Sugar Resources, Guangxi University of Science and Technology.,Key Laboratory for Processing of Sugar Resources of Guangxi Higher Education Institutes, Guangxi University of Science and Technology
| | - Cui-Ji Huang
- College of Biological and Chemical Engineering, Guangxi University of Science and Technology.,Guangxi Key Laboratory of Green Processing of Sugar Resources, Guangxi University of Science and Technology.,Key Laboratory for Processing of Sugar Resources of Guangxi Higher Education Institutes, Guangxi University of Science and Technology
| | - Yi Yi
- College of Biological and Chemical Engineering, Guangxi University of Science and Technology.,Guangxi Key Laboratory of Green Processing of Sugar Resources, Guangxi University of Science and Technology.,Key Laboratory for Processing of Sugar Resources of Guangxi Higher Education Institutes, Guangxi University of Science and Technology
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3
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Cano-Ramírez C, Santiago-Hernández A, Rivera-Orduña FN, García-Huante Y, Zúñiga G, Hidalgo-Lara ME. Expression, purification and characterization of an endoglucanase from Serratia proteamaculans CDBB-1961, isolated from the gut of Dendroctonus adjunctus (Coleoptera: Scolytinae). AMB Express 2016; 6:63. [PMID: 27576896 PMCID: PMC5005244 DOI: 10.1186/s13568-016-0233-9] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2016] [Accepted: 08/18/2016] [Indexed: 12/02/2022] Open
Abstract
Serratia proteamaculans CDBB-1961, a gut symbiont from the roundheaded pine beetle Dendroctonus adjunctus, displayed strong cellulolytic activity on agar-plates with carboxymethyl cellulose (CMC) as carbon source. Automatic genome annotation of S. proteamaculans made possible the identification of a single endoglucanase encoding gene, designated spr cel8A. The predicted protein, named Spr Cel8A shows high similarity (59–94 %) to endo-1,4-β-d-glucanases (EC 3.2.1.4) from the glycoside hydrolase family 8 (GH8). The gene spr cel8A has an ORF of 1113 bp, encoding a 371 amino acid residue protein (41.2 kDa) with a signal peptide of 23 amino acid residues. Expression of the gene spr cel8A in Escherichia coli yields a mature recombinant endoglucanase 39 kDa. Cel8A displayed optimal activity at pH 7.0 and 40 °C, with a specific activity of 0.85 U/mg. The enzyme was stable at pH from 4 to 8.5, retaining nearly 40–80 % of its original activity, and exhibited a half-life of 8 days at 40 °C. The Km and Vmax values for Spr Cel8A were 6.87 mg/ml and 3.5 μmol/min/mg of protein, respectively, using CMC as substrate. The final principle products of Spr Cel8A-mediated hydrolysis of CMC were cellobiose, cello oligosaccharides and a small amount of glucose, suggesting that Spr Cel8A is an endo-β-1,4-glucanase manifesting exo-activity. This is the first report regarding the functional biochemical and molecular characterization of an endoglucanase from S. proteamaculans, found in the gut-associated bacteria community of Dendroctonus bark beetles. These results contribute to improved understanding of the functional role played by this bacterium as a symbiont of bark beetles.
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4
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Maktouf S, Moulis C, Miled N, Ellouz Chaabouni S, Remaud-Simeon M. A highly thermostable lichenase from Bacillus sp. UEB-S: Biochemical and molecular characterization. ACTA ACUST UNITED AC 2015. [DOI: 10.1016/j.molcatb.2015.01.016] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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5
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1,3-β-Glucanase from Vigna aconitifolia and its possible use in enzyme bioreactor fabrication. Int J Biol Macromol 2011; 49:894-9. [DOI: 10.1016/j.ijbiomac.2011.08.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2011] [Revised: 07/31/2011] [Accepted: 08/03/2011] [Indexed: 11/23/2022]
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6
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Jeng WY, Wang NC, Lin CT, Shyur LF, Wang AHJ. Crystal structures of the laminarinase catalytic domain from Thermotoga maritima MSB8 in complex with inhibitors: essential residues for β-1,3- and β-1,4-glucan selection. J Biol Chem 2011; 286:45030-40. [PMID: 22065588 DOI: 10.1074/jbc.m111.271213] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Laminarinases hydrolyzing the β-1,3-linkage of glucans play essential roles in microbial saccharide degradation. Here we report the crystal structures at 1.65-1.82 Å resolution of the catalytic domain of laminarinase from the thermophile Thermotoga maritima with various space groups in the ligand-free form or in the presence of inhibitors gluconolactone and cetyltrimethylammonium. Ligands were bound at the cleft of the active site near an enclosure formed by Trp-232 and a flexible GASIG loop. A closed configuration at the active site cleft was observed in some molecules. The loop flexibility in the enzyme may contribute to the regulation of endo- or exo-activity of the enzyme and a preference to release laminaritrioses in long chain carbohydrate hydrolysis. Glu-137 and Glu-132 are proposed to serve as the proton donor and nucleophile, respectively, in the retaining catalysis of hydrolyzation. Calcium ions in the crystallization media are found to accelerate crystal growth. Comparison of laminarinase and endoglucanase structures revealed the subtle difference of key residues in the active site for the selection of β-1,3-glucan and β-1,4-glucan substrates, respectively. Arg-85 may be pivotal to β-1,3-glucan substrate selection. The similarity of the structures between the laminarinase catalytic domain and its carbohydrate-binding modules may have evolutionary relevance because of the similarities in their folds.
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Affiliation(s)
- Wen-Yih Jeng
- Institute of Biological Chemistry, Core Facility for Protein Production and X-ray Structural Analysis, Academia Sinica, Taipei 115, Taiwan
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7
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Rubini M, Dillon A, Kyaw C, Faria F, Poças-Fonseca M, Silva-Pereira I. Cloning, characterization and heterologous expression of the firstPenicillium echinulatumcellulase gene. J Appl Microbiol 2010; 108:1187-98. [DOI: 10.1111/j.1365-2672.2009.04528.x] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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8
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Hong F, Qiu K. An alternative carbon source from konjac powder for enhancing production of bacterial cellulose in static cultures by a model strain Acetobacter aceti subsp. xylinus ATCC 23770. Carbohydr Polym 2008. [DOI: 10.1016/j.carbpol.2007.09.015] [Citation(s) in RCA: 131] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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9
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Characterization of an endo-1,4-β-glucanase from Lilium longiflorum that functioned in pollen germination and pollen tube growth. ACTA ACUST UNITED AC 2008. [DOI: 10.1007/s11434-008-0143-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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10
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Gargallo R, Cedano J, Mozo-Villarias A, Querol E, Oliva B. Study of the influence of temperature on the dynamics of the catalytic cleft in 1,3-1,4-β-glucanase by molecular dynamics simulations. J Mol Model 2006; 12:835-45. [PMID: 16525847 DOI: 10.1007/s00894-006-0110-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2005] [Accepted: 01/10/2006] [Indexed: 10/24/2022]
Abstract
The dependence of some molecular motions in the enzyme 1,3-1,4-beta-glucanase from Bacillus licheniformis on temperature changes and the role of the calcium ion in them were explored. For this purpose, two molecular dynamics simulated trajectories along 4 ns at low (300 K) and high (325 K) temperatures were generated by the GROMOS96 package. Several structural and thermodynamic parameters were calculated, including entropy values, solvation energies, and essential dynamics (ED). In addition, thermoinactivation experiments to study the influence of the calcium ion and some residues on the activity were conducted. The results showed the release of the calcium ion, which, in turn, significantly affected the movements of loops 1, 2, and 3, as shown by essential dynamics. These movements differ at low and high temperatures and affect dramatically the activity of the enzyme, as observed by thermoinactivation studies.
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Affiliation(s)
- Raimundo Gargallo
- Department of Analytical Chemistry, Universitat de Barcelona, Martí i Franquès 1-11, Barcelona, 08028, Spain
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11
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Abou-Hachem M, Karlsson EN, Simpson PJ, Linse S, Sellers P, Williamson MP, Jamieson SJ, Gilbert HJ, Bolam DN, Holst O. Calcium binding and thermostability of carbohydrate binding module CBM4-2 of Xyn10A from Rhodothermus marinus. Biochemistry 2002; 41:5720-9. [PMID: 11980476 DOI: 10.1021/bi012094a] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Calcium binding to carbohydrate binding module CBM4-2 of xylanase 10A (Xyn10A) from Rhodothermus marinus was explored using calorimetry, NMR, fluorescence, and absorbance spectroscopy. CBM4-2 binds two calcium ions, one with moderate affinity and one with extremely high affinity. The moderate-affinity site has an association constant of (1.3 +/- 0.3) x 10(5) M(-1) and a binding enthalpy DeltaH(a) of -9.3 +/- 0.4 kJ x mol(-1), while the high-affinity site has an association constant of approximately 10(10) M(-1) and a binding enthalpy DeltaH(a) of -40.5 +/- 0.5 kJ x mol(-1). The locations of the binding sites have been identified by NMR and structural homology, and were verified by site-directed mutagenesis. The high-affinity site consists of the side chains of E11 and D160 and backbone carbonyls of E52 and K55, while the moderate-affinity site comprises the side chain of D29 and backbone carbonyls of L21, A22, V25, and W28. The high-affinity site is in a position analogous to the calcium site in CBM4 structures and in a recent CBM22 structure. Binding of calcium increases the unfolding temperature of the protein (T(m)) by approximately 23 degrees C at pH 7.5. No correlation between binding affinity and T(m) change was noted, as each of the two calcium ions contributes almost equally to the increase in unfolding temperature.
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Affiliation(s)
- Maher Abou-Hachem
- Department of Biotechnology, Center for Chemistry and Chemical Engineering, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden.
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12
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Mølhøj M, Ulvskov P, Dal Degan F. Characterization of a functional soluble form of a Brassica napus membrane-anchored endo-1,4-beta-glucanase heterologously expressed in Pichia pastoris. PLANT PHYSIOLOGY 2001; 127:674-84. [PMID: 11598241 PMCID: PMC125102 DOI: 10.1104/pp.010269] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/19/2001] [Revised: 05/16/2001] [Accepted: 07/06/2001] [Indexed: 05/18/2023]
Abstract
The Brassica napus gene, Cel16, encodes a membrane-anchored endo-1,4-beta-glucanase with a deduced molecular mass of 69 kD. As for other membrane-anchored endo-1,4-beta-glucanases, Cel16 consists of a predicted intracellular, charged N terminus (methionine(1)-lysine(70)), a hydrophobic transmembrane domain (isoleucine(71)-valine(93)), and a periplasmic catalytic core (lysine(94)-proline(621)). Here, we report the functional analysis of Delta(1-90)Cel16, the N terminally truncated Cel16, missing residues 1 through 90 and comprising the catalytic domain of Cel16 expressed recombinantly in the methylotrophic yeast Pichia pastoris as a soluble protein. A two-step purification protocol yielded Delta(1-90)Cel16 in a pure form. The molecular mass of Delta(1-90)Cel16, when determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis, was about 130 kD and about 60 kD after enzymatic removal of N-glycans, fitting the expected molecular mass of 59 kD. Delta(1-90)Cel16 was highly N glycosylated as compared with the native B. napus Cel16 protein. Delta(1-90)Cel16 had a pH optimum of 6.0. The activity of Delta(1-90)Cel16 was inhibited by EDTA and exhibited a strong dependence on calcium. Delta(1-90)Cel16 showed substrate specificity for low substituted carboxymethyl-cellulose and amorphous cellulose. It did not hydrolyze crystalline cellulose, xyloglycan, xylan, (1-->3),(1-->4)-beta-D-glucan, the highly substituted hydroxyethylcellulose, or the oligosaccharides cellotriose, cellotetraose, cellopentaose, or xylopentaose. Size exclusion analysis of Delta(1-90)Cel16-hydrolyzed carboxymethylcellulose showed that Delta(1-90)Cel16 is a true endo-acting glucanase.
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Affiliation(s)
- M Mølhøj
- Biotechnology Group and Center for Molecular Plant Physiology (PlaCe), Danish Institute of Agricultural Sciences, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Denmark
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13
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Planas A. Bacterial 1,3-1,4-beta-glucanases: structure, function and protein engineering. BIOCHIMICA ET BIOPHYSICA ACTA 2000; 1543:361-382. [PMID: 11150614 DOI: 10.1016/s0167-4838(00)00231-4] [Citation(s) in RCA: 197] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
1,3-1,4-beta-Glucanases (or lichenases, EC 3.2.1.73) hydrolyse linear beta-glucans containing beta-1,3 and beta-1,4 linkages such as cereal beta-glucans and lichenan, with a strict cleavage specificity for beta-1,4 glycosidic bonds on 3-O-substituted glucosyl residues. The bacterial enzymes are retaining glycosyl hydrolases of family 16 with a jellyroll beta-sandwich fold and a substrate binding cleft composed of six subsites. The present paper reviews the structure-function aspects of the enzymatic action including mechanistic enzymology, protein engineering and X-ray crystallographic studies.
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Affiliation(s)
- A Planas
- Laboratory of Biochemistry, Institut Químic de Sarrià, Universitat Ramon Llull, Via Augusta, 390, 08017, Barcelona, Spain.
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14
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Johnson PE, Creagh AL, Brun E, Joe K, Tomme P, Haynes CA, McIntosh LP. Calcium binding by the N-terminal cellulose-binding domain from Cellulomonas fimi beta-1,4-glucanase CenC. Biochemistry 1998; 37:12772-81. [PMID: 9737854 DOI: 10.1021/bi980978x] [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: 02/08/2023]
Abstract
The interaction of the N-terminal cellulose-binding domain, CBDN1, from Cellulomonas fimi beta-1,4-glucanase CenC with calcium was investigated using NMR spectroscopy and calorimetry. CBDN1 binds a single calcium ion with an equilibrium association constant of approximately 10(5) M-1 at 35 degreesC and pH 6.0. Binding is exothermic (-42 +/- 2 kJ mol-1) under these conditions and is accompanied by a small negative change in heat capacity (DeltaCp = -0.41 +/- 0.16 kJ mol-1 K-1). From an NMR line shape analysis, the rate constants for calcium association and dissociation were found to be (5 +/- 2) x 10(7) s-1 M-1 and (4.5 +/- 0.6) x 10(2) s-1, respectively. The rapid association kinetics indicate that the calcium-binding site on CBDN1 is accessible and, to the first approximation, preformed. Based on patterns of chemical shift perturbations, and structural comparisons with the Bacillus sp. 1, 3-1,4-beta-glucanases, the backbone carbonyl oxygens of Thr8, Gly30, and Asp142 and a side chain carboxyl oxygen of Asp142 are postulated to form the calcium-binding site of CBDN1. Consistent with the calcium-independent affinity of CBDN1 for cellopentaose, this exposed site is located on the face of CBDN1 opposite to that forming the oligosaccharide-binding cleft. The midpoint denaturation temperature of CBDN1 is increased by approximately 8 degreesC at pH 6.0 in the presence of saturating amounts of calcium, confirming that metal ion binding is thermodynamically linked to native-state stability.
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Affiliation(s)
- P E Johnson
- Protein Engineering Network of Centres of Excellence, The University of British Columbia, Vancouver, Canada
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15
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Gueguen Y, Voorhorst WG, van der Oost J, de Vos WM. Molecular and biochemical characterization of an endo-beta-1,3- glucanase of the hyperthermophilic archaeon Pyrococcus furiosus. J Biol Chem 1997; 272:31258-64. [PMID: 9395451 DOI: 10.1074/jbc.272.50.31258] [Citation(s) in RCA: 112] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
We report here the first molecular characterization of an endo-beta-1,3-glucanase from an archaeon. Pyrococcus furiosus is a hyperthermophilic archaeon that is capable of saccharolytic growth. The isolated lamA gene encodes an extracellular enzyme that shares homology with both endo-beta-1,3- and endo-beta-1,3-1,4-glucanases of the glycosyl hydrolase family 16. After deletion of the N-terminal leader sequence, a lamA fragment encoding an active endo-beta-1,3-glucanase was overexpressed in Escherichia coli using the T7-expression system. The purified P. furiosus endoglucanase has highest hydrolytic activity on the beta-1,3-glucose polymer laminarin and has some hydrolytic activity on the beta-1,3-1,4 glucose polymers lichenan and barley beta-glucan. The enzyme is the most thermostable endo-beta-1,3-glucanase described up to now; it has optimal activity at 100-105 degrees C. In the predicted active site of glycosyl hydrolases of family 16 that show predominantly endo-beta-1,3-glucanase activity, an additional methionine residue is present. Deletion of this methionine did not change the substrate specificity of the endoglucanase, but it did cause a severe reduction in its catalytic activity, suggesting a structural role of this residue in constituting the active site. High performance liquid chromatography analysis showed in vitro hydrolysis of laminarin by the endo-beta-1,3-glucanase proceeds more efficiently in combination with an exo-beta-glycosidase from P. furiosus (CelB). This most probably reflects the physiological role of these enzymes: cooperation during growth of P. furiosus on beta-glucans.
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Affiliation(s)
- Y Gueguen
- Bacterial Genetics Group, Department of Microbiology, Wageningen Agricultural University, Hesselink van Suchtelenweg 4, NL-6703 CT Wageningen, The Netherlands
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16
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Spurway TD, Morland C, Cooper A, Sumner I, Hazlewood GP, O'Donnell AG, Pickersgill RW, Gilbert HJ. Calcium protects a mesophilic xylanase from proteinase inactivation and thermal unfolding. J Biol Chem 1997; 272:17523-30. [PMID: 9211898 DOI: 10.1074/jbc.272.28.17523] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Crystal structure analysis of Pseudomonas fluorescens subsp. cellulosa xylanase A (XYLA) indicated that the enzyme contained a single calcium binding site that did not exhibit structural features typical of the EF-hand motif. Isothermal titration calorimetry revealed that XYLA binds calcium with a Ka of 4.9 x 10(4) M-1 and a stoichiometry consistent with one calcium binding site per molecule of enzyme. Occupancy of the calcium binding domain with its ligand protected XYLA from proteinase and thermal inactivation and increased the melting temperature of the enzyme from 60.8 to 66.5 degrees C. However, the addition of calcium or EDTA did not influence the catalytic activity of the xylanase. Replacement of the calcium binding domain, which is located within loop 7 of XYLA, with the corresponding short loop from Cex (a Cellulomonas fimi xylanase/exoglucanase), did not significantly alter the biochemical properties of the enzyme. These data suggest that the primary function of the calcium binding domain is to increase the stability of the enzyme against thermal unfolding and proteolytic attack. To understand further the nature of the calcium binding domain of XYLA, four variants of the xylanase, D256A, N261A, D262A, and XYLA"', in which Asp-256, Asn-261, and Asp-262 had all been changed to alanine, were constructed. These mutated enzymes did not show any significant binding to Ca2+, indicating that Asp-256, Asn-261, and Asp-262 play a pivotal role in the affinity of XYLA for the divalent cation. In the presence or absence of calcium, XYLA"' exhibited thermal stability similar to that of the native enzyme bound to Ca2+ ions, although the variant was sensitive to proteinase inactivation. The role of the calcium binding domain in vivo and the possible mechanism by which the domain evolved are discussed.
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Affiliation(s)
- T D Spurway
- Department of Biological and Nutritional Sciences, University of Newcastel upon Tyne, Newcastle upon Tyne NE1 7RU, United Kingdom
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17
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Welfle K, Misselwitz R, Politz O, Borriss R, Welfle H. Individual amino acids in the N-terminal loop region determine the thermostability and unfolding characteristics of bacterial glucanases. Protein Sci 1996; 5:2255-65. [PMID: 8931144 PMCID: PMC2143288 DOI: 10.1002/pro.5560051112] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Thermostability and unfolding behavior of the wild-type (1,3-1,4)-beta-glucanases from Bacillus macerans (MAC) and Bacillus amyloliquefaciens (AMY) and of two hybrid enzymes H(A12-M) delta F14 and H(A12-M) delta Y13F14A were studied by spectroscopic and microcalorimetric measurements. H(A12-M) delta F14 is constructed by the fusion of 12 N-terminal amino acids of AMY with amino acids 13-214 of MAC, and by deletion of F14. In H(A12-M) delta Y13F14A, the N-terminal region of MAC is exchanged against the AMY sequence, Y13 is deleted, and Phe 14 is exchanged against Ala. The sequence of the N-terminal loop region from Pro 9 to amino acid 16 (or 17) is very important for the properties of the enzymes and influences the effects of Ca2+ ions on the thermostability and unfolding behavior of the enzymes. The half transition temperatures T(m) are higher in the presence of Ca2+ than in Ca2+ free buffer. Furthermore, the unfolding mechanism is influenced by Ca2+. In Ca(2+)-free buffer, MAC, H(A12-M) delta F14 and H(A12-M) delta Y13F14A unfold in a single cooperative transition from the folded state to the unfolded state, whereas for AMY, a two-step unfolding was found. In the presence of Ca2+, the two-step unfolding of AMY is strengthened. Furthermore, for H(A12-M) delta F14, a two-step unfolding is induced by Ca2+. These data indicate a two-domain structure of AMY and H(A12-M) delta F14, in the presence of Ca2+. Thus, point mutations in a peripheral loop region are decisive for thermal stabilities and unfolding mechanisms of the studied glucanases in the presence of Ca2+.
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Affiliation(s)
- K Welfle
- Institute of Biology, Faculty I for Mathematical and Natural Sciences, Humboldt-University, Berlin, Germany.
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