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Lyu Y, Luo H, Chai S, Zhang Y, Fan X, Wang S, Feng Z. Discovery and characterization of a novel PKD-Fn3 domains containing GH44 endoglucanase from a Tibetan metagenomic library. J Appl Microbiol 2023; 134:lxad187. [PMID: 37596069 DOI: 10.1093/jambio/lxad187] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Revised: 08/02/2023] [Accepted: 08/16/2023] [Indexed: 08/20/2023]
Abstract
AIMS To explore novel microbial endoglucanases with unique properties derived from extreme environments by using metagenomics approach. METHODS AND RESULTS A Tibetan soil metagenomic library was applied for screening cellulase-active clones by function-based metagenomics. The candidate genes in the active clones were identified through bioinformatic analyses and heterologously expressed using an Escherichia coli system. The recombinant endoglucanases were purified and characterized using enzyme assays to determine their bioactivities, stabilities, substrate specificities, and other enzymatic properties. A novel endoglucanase gene Zfeg1907 was identified, which consisted of a glycoside hydrolase family 44 (GH44) catalytic domain along with a polycystic kidney disease (PKD) domain and a fibronectin type Ⅲ (Fn3) domain at the C terminal. Recombinant enzyme ZFEG1907 and its truncated mutant ZFEG1907t (ΔPKDΔFn3) were successfully expressed and purified. The two recombinants exhibited catalytic activities toward carboxymethyl cellulose, konjac glucomannan (KGM), and lichenan. Both enzymes had an optimal temperature of 50°C and an optimal pH value of 5.0. The catalytic activities of both recombinant enzymes were promoted by adding Zn2+ and Ca2+ at the final concentration of 10 mM. The Km value of ZFEG1907 was lower, while the kcat/Km value of ZFEG1907 was higher than those of of ZFEG1907t when using carboxymethyl cellulose, KGM, and lichenan as substrates. Structure prediction of two recombinants revealed that PKD-Fn3 domains consisted of a flexible linker and formed a β-sandwich structure. CONCLUSIONS A novel endoglucanase ZFEG1907 contained a GH44 catalytic domain and a PKD-Fn3 domain was characterized. The PKD-Fn3 domains were not indispensable for the activity but contributed to the enzyme binding of the polysaccharide substrates as a carbohydrate-binding module (CBM).
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Affiliation(s)
- Yunbin Lyu
- College of Food Science and Technology, Nanjing Agricultural University, 1 Weigang, Nanjing 210095, China
| | - Hao Luo
- College of Food Science and Technology, Nanjing Agricultural University, 1 Weigang, Nanjing 210095, China
| | - Shumao Chai
- College of Food Science and Technology, Nanjing Agricultural University, 1 Weigang, Nanjing 210095, China
| | - Ying Zhang
- College of Food Science and Technology, Nanjing Agricultural University, 1 Weigang, Nanjing 210095, China
| | - Xinyu Fan
- College of Food Science and Technology, Nanjing Agricultural University, 1 Weigang, Nanjing 210095, China
| | - Shaochen Wang
- College of Food Science and Technology, Nanjing Agricultural University, 1 Weigang, Nanjing 210095, China
| | - Zhiyang Feng
- College of Food Science and Technology, Nanjing Agricultural University, 1 Weigang, Nanjing 210095, China
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Luís AS, Venditto I, Temple MJ, Rogowski A, Baslé A, Xue J, Knox JP, Prates JAM, Ferreira LMA, Fontes CMGA, Najmudin S, Gilbert HJ. Understanding how noncatalytic carbohydrate binding modules can display specificity for xyloglucan. J Biol Chem 2012; 288:4799-809. [PMID: 23229556 PMCID: PMC3576085 DOI: 10.1074/jbc.m112.432781] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Plant biomass is central to the carbon cycle and to environmentally sustainable industries exemplified by the biofuel sector. Plant cell wall degrading enzymes generally contain noncatalytic carbohydrate binding modules (CBMs) that fulfil a targeting function, which enhances catalysis. CBMs that bind β-glucan chains often display broad specificity recognizing β1,4-glucans (cellulose), β1,3-β1,4-mixed linked glucans and xyloglucan, a β1,4-glucan decorated with α1,6-xylose residues, by targeting structures common to the three polysaccharides. Thus, CBMs that recognize xyloglucan target the β1,4-glucan backbone and only accommodate the xylose decorations. Here we show that two closely related CBMs, CBM65A and CBM65B, derived from EcCel5A, a Eubacterium cellulosolvens endoglucanase, bind to a range of β-glucans but, uniquely, display significant preference for xyloglucan. The structures of the two CBMs reveal a β-sandwich fold. The ligand binding site comprises the β-sheet that forms the concave surface of the proteins. Binding to the backbone chains of β-glucans is mediated primarily by five aromatic residues that also make hydrophobic interactions with the xylose side chains of xyloglucan, conferring the distinctive specificity of the CBMs for the decorated polysaccharide. Significantly, and in contrast to other CBMs that recognize β-glucans, CBM65A utilizes different polar residues to bind cellulose and mixed linked glucans. Thus, Gln106 is central to cellulose recognition, but is not required for binding to mixed linked glucans. This report reveals the mechanism by which β-glucan-specific CBMs can distinguish between linear and mixed linked glucans, and show how these CBMs can exploit an extensive hydrophobic platform to target the side chains of decorated β-glucans.
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Affiliation(s)
- Ana S Luís
- CIISA, Faculdade de Medicina Veterinária, Universidade Técnica de Lisboa, Avenida da Universidade Técnica, 1300-477 Lisboa, Portugal
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Moraïs S, Barak Y, Lamed R, Wilson DB, Xu Q, Himmel ME, Bayer EA. Paradigmatic status of an endo- and exoglucanase and its effect on crystalline cellulose degradation. BIOTECHNOLOGY FOR BIOFUELS 2012; 5:78. [PMID: 23095278 PMCID: PMC3502487 DOI: 10.1186/1754-6834-5-78] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2012] [Accepted: 10/19/2012] [Indexed: 05/07/2023]
Abstract
BACKGROUND Microorganisms employ a multiplicity of enzymes to efficiently degrade the composite structure of plant cell wall cellulosic polysaccharides. These remarkable enzyme systems include glycoside hydrolases (cellulases, hemicellulases), polysaccharide lyases, and the carbohydrate esterases. To accomplish this challenging task, several strategies are commonly observed either separately or in combination. These include free enzyme systems, multifunctional enzymes, and multi-enzyme self-assembled designer cellulosome complexes. RESULTS In order to compare these different paradigms, we employed a synthetic biology approach to convert two different cellulases from the free enzymatic system of the well-studied bacterium, Thermobifida fusca, into bifunctional enzymes with different modular architectures. We then examined their performance compared to those of the combined parental free-enzyme and equivalent designer-cellulosome systems. The results showed that the cellulolytic activity displayed by the different architectures of the bifunctional enzymes was somewhat inferior to that of the wild-type free enzyme system. CONCLUSIONS The activity exhibited by the designer cellulosome system was equal or superior to that of the free system, presumably reflecting the combined proximity of the enzymes and high flexibility of the designer cellulosome components, thus enabling efficient enzymatic activity of the catalytic modules.
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Affiliation(s)
- Sarah Moraïs
- Department of Biological Chemistry, The Weizmann Institute of Science, Rehovot, Israel
- Faculty of Agricultural, Food and Environmental Quality Sciences, The Hebrew University of Jerusalem, P.O. Box 12, Rehovot, 76100, Israel
| | - Yoav Barak
- Department of Biological Chemistry, The Weizmann Institute of Science, Rehovot, Israel
- Chemical Research Support, The Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Raphael Lamed
- Department of Molecular Microbiology and Biotechnology, Tel Aviv University, Ramat Aviv, 69978, Israel
| | - David B Wilson
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, 14853, USA
| | - Qi Xu
- Biosciences Center, National Renewable Energy Laboratory (NREL) and BioEnergy Science Center (BESC), Golden, CO, USA
| | - Michael E Himmel
- Biosciences Center, National Renewable Energy Laboratory (NREL) and BioEnergy Science Center (BESC), Golden, CO, USA
| | - Edward A Bayer
- Department of Biological Chemistry, The Weizmann Institute of Science, Rehovot, Israel
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Brás JLA, Correia MAS, Romão MJ, Prates JAM, Fontes CMGA, Najmudin S. Purification, crystallization and preliminary X-ray characterization of the pentamodular arabinoxylanase CtXyl5A from Clostridium thermocellum. Acta Crystallogr Sect F Struct Biol Cryst Commun 2011; 67:833-6. [PMID: 21795807 PMCID: PMC3144809 DOI: 10.1107/s1744309111020823] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2011] [Accepted: 05/30/2011] [Indexed: 11/10/2022]
Abstract
The cellulosome, a highly elaborate extracellular multi-enzyme complex of cellulases and hemicellulases, is responsible for the degradation of plant cell walls. The xylanase CtXyl5A (Cthe_2193) is a multimodular arabinoxylanase which is one of the largest components of the Clostridium thermocellum cellulosome. The N-terminal catalytic domain of CtXyl5A, which is a member of glycoside hydrolase family 5 (GH5), is responsible for the hydrolysis of arabinoxylans. Appended after it are three noncatalytic carbohydrate-binding modules (CBMs), which belong to families 6 (CBM6), 13 (CBM13) and 62 (CBM62). In addition, CtXyl5A has a fibronectin type III-like (Fn3) module preceding the CBM62 and a type I dockerin (DOK) module following it which allows the enzyme to be integrated into the cellulosome through binding to a cohesin module of the protein scaffold CipA. Crystals of the pentamodular enzyme without the DOK module at the C-terminus, with the domain architecture CtGH5-CBM6-CBM13-Fn3-CBM62, have been obtained. The structure of this pentamodular xylanase has been determined by molecular replacement to a resolution of 2.64 Å using coordinates of CtGH5-CBM6, Fn3 and CBM62 from the PDB as search models.
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Affiliation(s)
- Joana L. A. Brás
- CIISA – Faculdade de Medicina Veterinária, Universidade Técnica de Lisboa, Avenida da Universidade Técnica, 1300-477 Lisboa, Portugal
| | - Márcia A. S. Correia
- CIISA – Faculdade de Medicina Veterinária, Universidade Técnica de Lisboa, Avenida da Universidade Técnica, 1300-477 Lisboa, Portugal
- REQUIMTE, Departamento de Química, FCT-UNL, 2829-516 Caparica, Portugal
| | - Maria J. Romão
- REQUIMTE, Departamento de Química, FCT-UNL, 2829-516 Caparica, Portugal
| | - José A. M. Prates
- CIISA – Faculdade de Medicina Veterinária, Universidade Técnica de Lisboa, Avenida da Universidade Técnica, 1300-477 Lisboa, Portugal
| | - Carlos M. G. A. Fontes
- CIISA – Faculdade de Medicina Veterinária, Universidade Técnica de Lisboa, Avenida da Universidade Técnica, 1300-477 Lisboa, Portugal
| | - Shabir Najmudin
- CIISA – Faculdade de Medicina Veterinária, Universidade Técnica de Lisboa, Avenida da Universidade Técnica, 1300-477 Lisboa, Portugal
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Luís AS, Alves VD, Romão MJ, Prates JAM, Fontes CMGA, Najmudin S. Overproduction, purification, crystallization and preliminary X-ray characterization of a novel carbohydrate-binding module of endoglucanase Cel5A from Eubacterium cellulosolvens. Acta Crystallogr Sect F Struct Biol Cryst Commun 2011; 67:491-3. [PMID: 21505249 PMCID: PMC3080158 DOI: 10.1107/s1744309111004246] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2010] [Accepted: 02/03/2011] [Indexed: 05/30/2023]
Abstract
The anaerobic cellulolytic rumen bacterium Eubacterium cellulosolvens produces a large array of cellulases and hemicellulases that are responsible for the hydrolysis of plant cell-wall polysaccharides. One of these enzymes, endoglucanase Cel5A, comprises two tandemly repeated novel carbohydrate-binding modules (CBMs) and two catalytic domains belonging to glycoside hydrolase family 5 joined by flexible linker sequences. The novel CBM located at the N-terminus of the endoglucanase has been crystallized. The crystals belonged to the hexagonal space group P6(1)22 and contained a single molecule in the asymmetric unit. The structure of the L-selenomethionine derivative has been solved by a MAD experiment on crystals that diffracted to 1.75 Å resolution.
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Affiliation(s)
- Ana S. Luís
- CIISA – Faculdade de Medicina Veterinária, Universidade Técnica de Lisboa, Avenida da Universidade Técnica, 1300-477 Lisboa, Portugal
| | - Victor D. Alves
- CIISA – Faculdade de Medicina Veterinária, Universidade Técnica de Lisboa, Avenida da Universidade Técnica, 1300-477 Lisboa, Portugal
| | - Maria J. Romão
- REQUIMTE, Departamento de Química, FCT–UNL, 2829-516 Caparica, Portugal
| | - José A. M. Prates
- CIISA – Faculdade de Medicina Veterinária, Universidade Técnica de Lisboa, Avenida da Universidade Técnica, 1300-477 Lisboa, Portugal
| | - Carlos M. G. A. Fontes
- CIISA – Faculdade de Medicina Veterinária, Universidade Técnica de Lisboa, Avenida da Universidade Técnica, 1300-477 Lisboa, Portugal
| | - Shabir Najmudin
- CIISA – Faculdade de Medicina Veterinária, Universidade Técnica de Lisboa, Avenida da Universidade Técnica, 1300-477 Lisboa, Portugal
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Dori-Bachash M, Dassa B, Peleg O, Pineiro SA, Jurkevitch E, Pietrokovski S. Bacterial intein-like domains of predatory bacteria: a new domain type characterized in Bdellovibrio bacteriovorus. Funct Integr Genomics 2009; 9:153-66. [PMID: 19153786 DOI: 10.1007/s10142-008-0106-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2008] [Revised: 12/08/2008] [Accepted: 12/20/2008] [Indexed: 10/21/2022]
Abstract
We report a new family of bacterial intein-like domains (BILs) identified in ten proteins of four diverse predatory bacteria. BILs belong to the HINT (Hedgehog/Intein) superfamily of domains that post-translationally self-process their protein molecules by protein splicing and self-cleavage. The new, C-type, BILs appear with other domains, including putative predator-specific domain 1 (PPS-1), a new domain typically appearing immediately upstream of C-type BILs. The Bd2400 protein of the obligate predator Bdellovibrio bacteriovorus includes a C-type BIL and a PPS-1 domains at its C-terminal part, and a signal peptide and two polycystic kidney disease domains at its N-terminal part. We demonstrate the in vivo transcription, translation, secretion, and processing of the B. bacteriovorus protein, and the in vitro autocatalytic N-terminal cleavage activity of its C-type BIL. Interestingly, whereas the Bd2400 gene is constitutively expressed, its protein product is differentially processed throughout the dimorphic life cycle of the B. bacteriovorus predator. The modular structure of the protein, its localization, and complex processing suggest that it may be involved in the interaction between the predator and its prey.
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Affiliation(s)
- Mally Dori-Bachash
- Department of Plant Pathology and Microbiology, Faculty of Agriculture, Food and Environment, The Hebrew University, Rehovot, Israel
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Najmudin S, Guerreiro CIPD, Carvalho AL, Prates JAM, Correia MAS, Alves VD, Ferreira LMA, Romão MJ, Gilbert HJ, Bolam DN, Fontes CMGA. Xyloglucan is recognized by carbohydrate-binding modules that interact with beta-glucan chains. J Biol Chem 2005; 281:8815-28. [PMID: 16314409 DOI: 10.1074/jbc.m510559200] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Enzyme systems that attack the plant cell wall contain noncatalytic carbohydrate-binding modules (CBMs) that mediate attachment to this composite structure and play a pivotal role in maximizing the hydrolytic process. Although xyloglucan, which includes a backbone of beta-1,4-glucan decorated primarily with xylose residues, is a key component of the plant cell wall, CBMs that bind to this polymer have not been identified. Here we showed that the C-terminal domain of the modular Clostridium thermocellum enzyme CtCel9D-Cel44A (formerly known as CelJ) comprises a novel CBM (designated CBM44) that binds with equal affinity to cellulose and xyloglucan. We also showed that accommodation of xyloglucan side chains is a general feature of CBMs that bind to single cellulose chains. The crystal structures of CBM44 and the other CBM (CBM30) in CtCel9D-Cel44A display a beta-sandwich fold. The concave face of both CBMs contains a hydrophobic platform comprising three tryptophan residues that can accommodate up to five glucose residues. The orientation of these aromatic residues is such that the bound ligand would adopt the twisted conformation displayed by cello-oligosaccharides in solution. Mutagenesis studies confirmed that the hydrophobic platform located on the concave face of both CBMs mediates ligand recognition. In contrast to other CBMs that bind to single polysaccharide chains, the polar residues in the binding cleft of CBM44 play only a minor role in ligand recognition. The mechanism by which these proteins are able to recognize linear and decorated beta-1,4-glucans is discussed based on the structures of CBM44 and the other CBMs that bind single cellulose chains.
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Affiliation(s)
- Shabir Najmudin
- Requimte, Departamento de Química, FCT-UNL, 2829-516 Caparica, Portugal, CIISA-Faculdade de Medicina Veterinária, Universidade Técnica de Lisboa, Avenida da Universidade Técnica, 1300-477 Lisboa, Portugal
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