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Chen C, Yang H, Dong S, You C, Moraïs S, Bayer EA, Liu Y, Xuan J, Cui Q, Mizrahi I, Feng Y. A cellulosomal double-dockerin module from Clostridium thermocellum shows distinct structural and cohesin-binding features. Protein Sci 2024; 33:e4937. [PMID: 38501488 PMCID: PMC10949318 DOI: 10.1002/pro.4937] [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: 11/20/2023] [Revised: 02/05/2024] [Accepted: 02/07/2024] [Indexed: 03/20/2024]
Abstract
Cellulosomes are intricate cellulose-degrading multi-enzymatic complexes produced by anaerobic bacteria, which are valuable for bioenergy development and biotechnology. Cellulosome assembly relies on the selective interaction between cohesin modules in structural scaffolding proteins (scaffoldins) and dockerin modules in enzymes. Although the number of tandem cohesins in the scaffoldins is believed to determine the complexity of the cellulosomes, tandem dockerins also exist, albeit very rare, in some cellulosomal components whose assembly and functional roles are currently unclear. In this study, we characterized the structure and mode of assembly of a tandem bimodular double-dockerin, which is connected to a putative S8 protease in the cellulosome-producing bacterium, Clostridium thermocellum. Crystal and NMR structures of the double-dockerin revealed two typical type I dockerin folds with significant interactions between them. Interaction analysis by isothermal titration calorimetry and NMR titration experiments revealed that the double-dockerin displays a preference for binding to the cell-wall anchoring scaffoldin ScaD through the first dockerin with a canonical dual-binding mode, while the second dockerin module was unable to bind to any of the tested cohesins. Surprisingly, the double-dockerin showed a much higher affinity to a cohesin from the CipC scaffoldin of Clostridium cellulolyticum than to the resident cohesins from C. thermocellum. These results contribute valuable insights into the structure and assembly of the double-dockerin module, and provide the basis for further functional studies on multiple-dockerin modules and cellulosomal proteases, thus highlighting the complexity and diversity of cellulosomal components.
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Affiliation(s)
- Chao Chen
- CAS Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Synthetic BiologyQingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of SciencesQingdaoChina
- Shandong Energy InstituteQingdaoChina
- Qingdao New Energy Shandong LaboratoryQingdaoChina
- University of Chinese Academy of SciencesBeijingChina
| | - Hongwu Yang
- CAS Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Synthetic BiologyQingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of SciencesQingdaoChina
- Present address:
College of PharmacyNankai University, Tongyan Road 38, Haihe Education Park, Jinnan DistrictTianjin 300350China
| | - Sheng Dong
- CAS Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Synthetic BiologyQingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of SciencesQingdaoChina
- Shandong Energy InstituteQingdaoChina
- Qingdao New Energy Shandong LaboratoryQingdaoChina
- University of Chinese Academy of SciencesBeijingChina
| | - Cai You
- CAS Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Synthetic BiologyQingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of SciencesQingdaoChina
- Shandong Energy InstituteQingdaoChina
- Qingdao New Energy Shandong LaboratoryQingdaoChina
| | - Sarah Moraïs
- Department of Life Sciences and the National Institute for Biotechnology in the NegevBen‐Gurion University of the NegevBeer‐ShevaIsrael
| | - Edward A. Bayer
- Department of Life Sciences and the National Institute for Biotechnology in the NegevBen‐Gurion University of the NegevBeer‐ShevaIsrael
- Department of Biomolecular SciencesThe Weizmann Institute of ScienceRehovotIsrael
| | - Ya‐Jun Liu
- CAS Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Synthetic BiologyQingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of SciencesQingdaoChina
- Shandong Energy InstituteQingdaoChina
- Qingdao New Energy Shandong LaboratoryQingdaoChina
- University of Chinese Academy of SciencesBeijingChina
| | - Jinsong Xuan
- Department of Biological Science and Engineering, School of Chemical and Biological EngineeringUniversity of Science and Technology BeijingBeijingChina
| | - Qiu Cui
- CAS Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Synthetic BiologyQingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of SciencesQingdaoChina
- Shandong Energy InstituteQingdaoChina
- Qingdao New Energy Shandong LaboratoryQingdaoChina
- University of Chinese Academy of SciencesBeijingChina
- State Key Laboratory of Microbial TechnologyShandong UniversityQingdaoChina
| | - Itzhak Mizrahi
- Department of Life Sciences and the National Institute for Biotechnology in the NegevBen‐Gurion University of the NegevBeer‐ShevaIsrael
| | - Yingang Feng
- CAS Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Synthetic BiologyQingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of SciencesQingdaoChina
- Shandong Energy InstituteQingdaoChina
- Qingdao New Energy Shandong LaboratoryQingdaoChina
- University of Chinese Academy of SciencesBeijingChina
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Lamote B, da Fonseca MJM, Vanderstraeten J, Meert K, Elias M, Briers Y. Current challenges in designer cellulosome engineering. Appl Microbiol Biotechnol 2023; 107:2755-2770. [PMID: 36941434 DOI: 10.1007/s00253-023-12474-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Revised: 02/28/2023] [Accepted: 03/03/2023] [Indexed: 03/23/2023]
Abstract
Designer cellulosomes (DCs) are engineered multi-enzyme complexes, comprising carbohydrate-active enzymes attached to a common backbone, the scaffoldin, via high-affinity cohesin-dockerin interactions. The use of DCs in the degradation of renewable biomass polymers is a promising approach for biorefineries. Indeed, DCs have shown significant hydrolytic activities due to the enhanced enzyme-substrate proximity and inter-enzyme synergies, but technical hurdles in DC engineering have hindered further progress towards industrial application. The challenge in DC engineering lies in the large diversity of possible building blocks and architectures, resulting in a multivariate and immense design space. Simultaneously, the precise DC composition affects many relevant parameters such as activity, stability, and manufacturability. Since protein engineers face a lack of high-throughput approaches to explore this vast design space, DC engineering may result in an unsatisfying outcome. This review provides a roadmap to guide researchers through the process of DC engineering. Each step, starting from concept to evaluation, is described and provided with its challenges, along with possible solutions, both for DCs that are assembled in vitro or are displayed on the yeast cell surface. KEY POINTS: • Construction of designer cellulosomes is a multi-step process. • Designer cellulosome research deals with multivariate construction challenges. • Boosting designer cellulosome efficiency requires exploring a vast design space.
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Affiliation(s)
- Babette Lamote
- Laboratory of Applied Biotechnology, Department of Biotechnology, Ghent University, Ghent, Belgium
- Centre for Synthetic Biology, Department of Biotechnology, Ghent University, Ghent, Belgium
| | | | - Julie Vanderstraeten
- Laboratory of Applied Biotechnology, Department of Biotechnology, Ghent University, Ghent, Belgium
| | - Kenan Meert
- Laboratory of Applied Biotechnology, Department of Biotechnology, Ghent University, Ghent, Belgium
- Laboratory of Applied Mycology and Phenomics, Department of Plants and Crops, Ghent University, Ghent, Belgium
| | - Marte Elias
- Laboratory of Applied Biotechnology, Department of Biotechnology, Ghent University, Ghent, Belgium
- Centre for Synthetic Biology, Department of Biotechnology, Ghent University, Ghent, Belgium
| | - Yves Briers
- Laboratory of Applied Biotechnology, Department of Biotechnology, Ghent University, Ghent, Belgium.
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3
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Duarte M, Alves VD, Correia M, Caseiro C, Ferreira LM, Romão MJ, Carvalho AL, Najmudin S, Bayer EA, Fontes CM, Bule P. Structure-function studies can improve binding affinity of cohesin-dockerin interactions for multi-protein assemblies. Int J Biol Macromol 2022; 224:55-67. [DOI: 10.1016/j.ijbiomac.2022.10.102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Revised: 09/28/2022] [Accepted: 10/11/2022] [Indexed: 11/05/2022]
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4
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Conversion of the free Cellvibrio japonicus xyloglucan degradation system to the cellulosomal mode. Appl Microbiol Biotechnol 2022; 106:5495-5509. [DOI: 10.1007/s00253-022-12072-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 07/05/2022] [Accepted: 07/06/2022] [Indexed: 11/02/2022]
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5
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Chen C, Qi K, Chi F, Song X, Feng Y, Cui Q, Liu YJ. Dissolved xylan inhibits cellulosome-based saccharification by binding to the key cellulosomal component of Clostridium thermocellum. Int J Biol Macromol 2022; 207:784-790. [PMID: 35351552 DOI: 10.1016/j.ijbiomac.2022.03.158] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2022] [Revised: 03/01/2022] [Accepted: 03/24/2022] [Indexed: 12/16/2022]
Abstract
Polysaccharides derived from lignocellulose are promising sustainable carbon sources. Cellulosome is a supramolecular machine integrating multi-function enzymes for effective lignocellulose bio-saccharification. However, how various non-cellulose components of lignocellulose affect the cellulosomal saccharification is hitherto unclear. This study first investigated the stability and oxygen sensitivity of the cellulosome from Clostridium thermocellum during long-term saccharification process. Then, the differential inhibitory effects of non-cellulose components, including lignin, xylan, and arabinoxylan, on the cellulosome-based saccharification were determined. The results showed that lignin played inhibitory roles by non-productively adsorbing extracellular proteins of C. thermocellum. Differently, arabinoxylan preferred to bind with the cellulosomal components. Almost no adsorption of cellulosomal proteins on solid xylan was detected. Instead, xylan in water-dissolved form interacted with the cellulosomal proteins, especially the key exoglucanase Cel48S, leading to the xylan inhibitory effect. Compared to xylan, xylooligosaccharides influenced the cellulosome activity slightly. Hence, this work demonstrates that the timely hydrolysis or removal of dissolved xylan is important for cellulosome-based lignocellulose saccharification.
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Affiliation(s)
- Chao Chen
- CAS Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Synthetic Biology, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, PR China; Shandong Energy Institute, Qingdao 266101, PR China; Qingdao New Energy Shandong Laboratory; Dalian National Laboratory for Clean Energy, Qingdao 266101, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China
| | - Kuan Qi
- CAS Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Synthetic Biology, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, PR China; Shandong Energy Institute, Qingdao 266101, PR China; Qingdao New Energy Shandong Laboratory; Dalian National Laboratory for Clean Energy, Qingdao 266101, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China
| | - Fang Chi
- CAS Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Synthetic Biology, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, PR China; Shandong Energy Institute, Qingdao 266101, PR China; Qingdao New Energy Shandong Laboratory; Dalian National Laboratory for Clean Energy, Qingdao 266101, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China
| | - Xiaojin Song
- CAS Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Synthetic Biology, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, PR China; Shandong Energy Institute, Qingdao 266101, PR China; Qingdao New Energy Shandong Laboratory; Dalian National Laboratory for Clean Energy, Qingdao 266101, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China
| | - Yingang Feng
- CAS Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Synthetic Biology, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, PR China; Shandong Energy Institute, Qingdao 266101, PR China; Qingdao New Energy Shandong Laboratory; Dalian National Laboratory for Clean Energy, Qingdao 266101, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China
| | - Qiu Cui
- CAS Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Synthetic Biology, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, PR China; Shandong Energy Institute, Qingdao 266101, PR China; Qingdao New Energy Shandong Laboratory; Dalian National Laboratory for Clean Energy, Qingdao 266101, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China
| | - Ya-Jun Liu
- CAS Key Laboratory of Biofuels, Shandong Provincial Key Laboratory of Synthetic Biology, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, PR China; Shandong Energy Institute, Qingdao 266101, PR China; Qingdao New Energy Shandong Laboratory; Dalian National Laboratory for Clean Energy, Qingdao 266101, PR China; University of Chinese Academy of Sciences, Beijing 100049, PR China.
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6
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de Sandozequi A, Salazar-Cortés JJ, Tapia-Vázquez I, Martínez-Anaya C. Prevalent association with the bacterial cell envelope of prokaryotic expansins revealed by bioinformatics analysis. Protein Sci 2022; 31:e4315. [PMID: 35481628 PMCID: PMC9045087 DOI: 10.1002/pro.4315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2021] [Revised: 04/05/2022] [Accepted: 04/06/2022] [Indexed: 11/10/2022]
Abstract
Expansins are a group of proteins from diverse organisms from bacteria to plants. Although expansins show structural conservation, their biological roles seem to differ among kingdoms. In plants, these proteins remodel the cell wall during plant growth and other processes. Contrarily, determination of bacterial expansin activity has proven difficult, although genetic evidence of bacterial mutants indicates that expansins participate in bacteria-plant interactions. Nevertheless, a large proportion of expansin genes are found in the genomes of free-living bacteria, suggesting roles that are independent of the interaction with living plants. Here, we analyzed all available sequences of prokaryotic expansins for correlations between surface electric charge, extra protein modules, and sequence motifs for association with the bacteria exterior after export. Additionally, information on the fate of protein after translocation across the membrane also points to bacterial cell association of expansins through six different mechanisms, such as attachment of a lipid molecule for membrane anchoring in diderm species or covalent linking to the peptidoglycan layer in monoderms such as the Bacilliales. Our results have implications for expansin function in the context of bacteria-plant interactions and also for free-living species in which expansins might affect cell-cell or cell-substrate interaction properties and indicate the need to re-examine the roles currently considered for these proteins.
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Affiliation(s)
- Andrés de Sandozequi
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, UNAM, Av. Universidad 2001, Chamilpa, Cuernavaca, Morelos, Mexico
| | - Juan José Salazar-Cortés
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, UNAM, Av. Universidad 2001, Chamilpa, Cuernavaca, Morelos, Mexico
| | - Irán Tapia-Vázquez
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, UNAM, Av. Universidad 2001, Chamilpa, Cuernavaca, Morelos, Mexico
| | - Claudia Martínez-Anaya
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, UNAM, Av. Universidad 2001, Chamilpa, Cuernavaca, Morelos, Mexico
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7
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Li J, Chen C, Liu YJ, Cui Q, Bayer EA, Feng Y. NMR chemical shift assignments of a module of unknown function in the cellulosomal secondary scaffoldin ScaF from Clostridium thermocellum. BIOMOLECULAR NMR ASSIGNMENTS 2021; 15:329-334. [PMID: 33876380 DOI: 10.1007/s12104-021-10025-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Accepted: 04/10/2021] [Indexed: 06/12/2023]
Abstract
The cellulosome is a highly efficient cellulolytic complex containing cellulolytic enzymes and non-catalytic subunits, i.e. scaffoldins, which are assembled by the interactions between the dockerin modules of the enzymes and the cohesin modules of the primary scaffoldins. The cellulosome attaches to the cell surface via the S-layer homology (SLH) modules of the anchoring scaffoldins. Clostridium thermocellum DSM1313 is a thermophilic cellulosome-producing bacterium with great potential in lignocellulose bioconversion and biofuel production. The bacterium contains four anchoring scaffoldins ScaB, ScaC, ScaD and ScaF, among which ScaF is the only one that contains an additional module of unknown function (ScaF-X) between the cohesin and SLH modules. The gene of ScaF is located outside the scaffoldin gene cluster of scaA, scaB, scaC and scaD. Previous studies showed unique regulation properties and function of ScaF compared to other anchoring scaffoldins, which might be related to the additional ScaF-X module. Here we report the NMR chemical shift assignments of ScaF-X from C. thermocellum DSM1313. The well-dispersed NMR spectrum and the secondary structure prediction based on the chemical shifts of ScaF-X indicated that ScaF-X is a well-folded protein module. The chemical shift assignments provide the basis for future studies on the structure of this module and its function in cellulosomes.
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Affiliation(s)
- Jie Li
- CAS Key Laboratory of Biofuels, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101, Shandong, China
- Shandong Provincial Key Laboratory of Synthetic Biology, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101, Shandong, China
- Shandong Engineering Laboratory of Single Cell Oil, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101, Shandong, China
- Shandong Energy Institute, Qingdao, 266101, Shandong, China
- New Energy Shandong Laboratory, Qingdao, 266101, Shandong, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Chao Chen
- CAS Key Laboratory of Biofuels, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101, Shandong, China
- Shandong Provincial Key Laboratory of Synthetic Biology, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101, Shandong, China
- Shandong Engineering Laboratory of Single Cell Oil, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101, Shandong, China
- Shandong Energy Institute, Qingdao, 266101, Shandong, China
- New Energy Shandong Laboratory, Qingdao, 266101, Shandong, China
| | - Ya-Jun Liu
- CAS Key Laboratory of Biofuels, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101, Shandong, China
- Shandong Provincial Key Laboratory of Synthetic Biology, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101, Shandong, China
- Shandong Engineering Laboratory of Single Cell Oil, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101, Shandong, China
- Shandong Energy Institute, Qingdao, 266101, Shandong, China
- New Energy Shandong Laboratory, Qingdao, 266101, Shandong, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Qiu Cui
- CAS Key Laboratory of Biofuels, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101, Shandong, China
- Shandong Provincial Key Laboratory of Synthetic Biology, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101, Shandong, China
- Shandong Engineering Laboratory of Single Cell Oil, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101, Shandong, China
- Shandong Energy Institute, Qingdao, 266101, Shandong, China
- New Energy Shandong Laboratory, Qingdao, 266101, Shandong, China
- University of Chinese Academy of Sciences, Beijing, 100049, China
| | - Edward A Bayer
- Department of Biomolecular Sciences, The Weizmann Institute of Science, 7610001, Rehovot, Israel
- Department of Life Sciences and the National Institute for Biotechnology in the Negev, Ben-Gurion University of the Negev, 8499000, Beer-Sheva, Israel
| | - Yingang Feng
- CAS Key Laboratory of Biofuels, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101, Shandong, China.
- Shandong Provincial Key Laboratory of Synthetic Biology, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101, Shandong, China.
- Shandong Engineering Laboratory of Single Cell Oil, Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao, 266101, Shandong, China.
- Shandong Energy Institute, Qingdao, 266101, Shandong, China.
- New Energy Shandong Laboratory, Qingdao, 266101, Shandong, China.
- University of Chinese Academy of Sciences, Beijing, 100049, China.
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Research progress and the biotechnological applications of multienzyme complex. Appl Microbiol Biotechnol 2021; 105:1759-1777. [PMID: 33564922 DOI: 10.1007/s00253-021-11121-4] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2020] [Revised: 01/07/2021] [Accepted: 01/16/2021] [Indexed: 11/26/2022]
Abstract
The multienzyme complex system has become a research focus in synthetic biology due to its highly efficient overall catalytic ability and has been applied to various fields. Multienzyme complexes are formed by cascading complexes, which are multiple functionally related enzymes that continuously and efficiently catalyze the production of substrates. Compared with current mainstream microbial cell catalytic systems, in vitro multienzyme molecular machines have many advantages, such as fewer side reactions, a high product yield, a fast reaction speed, easy product separation, a tolerable toxic environment, and robust system operability, showing increasing competitiveness in the field of biomanufacturing. In this review, the research progress of multienzyme complexes in nature and multienzyme cascades in vivo or in vitro will be introduced, and the discovered enzyme cascades concerning scaffolding proteins will also be discussed. This review is expected to provide a more theoretical basis for the modification of multienzyme complexes and broaden their application in the field of synthetic biology. KEY POINTS: • The cascade reactions of some natural multienzyme complexes are reviewed. • The main approaches of constructing artificial multienzyme complexes are summarized. • The structure and application of cellulosomes are discussed and prospected.
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Abstract
Cellulosomes are elaborate multienzyme complexes capable of efficiently deconstructing lignocellulosic substrates, produced by cellulolytic anaerobic microorganisms, colonizing a large variety of ecological niches. These macromolecular structures have a modular architecture and are composed of two main elements: the cohesin-bearing scaffoldins, which are non-catalytic structural proteins, and the various dockerin-bearing enzymes that tenaciously bind to the scaffoldins. Cellulosome assembly is mediated by strong and highly specific interactions between the cohesin modules, present in the scaffoldins, and the dockerin modules, present in the catalytic units. Cellulosomal architecture and composition varies between species and can even change within the same organism. These differences seem to be largely influenced by external factors, including the nature of the available carbon-source. Even though cellulosome producing organisms are relatively few, the development of new genomic and proteomic technologies has allowed the identification of cellulosomal components in many archea, bacteria and even some primitive eukaryotes. This reflects the importance of this cellulolytic strategy and suggests that cohesin-dockerin interactions could be involved in other non-cellulolytic processes. Due to their building-block nature and highly cellulolytic capabilities, cellulosomes hold many potential biotechnological applications, such as the conversion of lignocellulosic biomass in the production of biofuels or the development of affinity based technologies.
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Affiliation(s)
- Victor D Alves
- CIISA, Faculdade de Medicina Veterinária, ULisboa, Pólo Universitário do Alto da Ajuda, Avenida da Universidade Técnica, 1300-477, Lisbon, Portugal
| | - Carlos M G A Fontes
- CIISA, Faculdade de Medicina Veterinária, ULisboa, Pólo Universitário do Alto da Ajuda, Avenida da Universidade Técnica, 1300-477, Lisbon, Portugal
| | - Pedro Bule
- CIISA, Faculdade de Medicina Veterinária, ULisboa, Pólo Universitário do Alto da Ajuda, Avenida da Universidade Técnica, 1300-477, Lisbon, Portugal.
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10
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Arntzen MØ, Bengtsson O, Várnai A, Delogu F, Mathiesen G, Eijsink VGH. Quantitative comparison of the biomass-degrading enzyme repertoires of five filamentous fungi. Sci Rep 2020; 10:20267. [PMID: 33219291 PMCID: PMC7679414 DOI: 10.1038/s41598-020-75217-z] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2019] [Accepted: 10/07/2020] [Indexed: 12/26/2022] Open
Abstract
The efficiency of microorganisms to degrade lignified plants is of great importance in the Earth's carbon cycle, but also in industrial biorefinery processes, such as for biofuel production. Here, we present a large-scale proteomics approach to investigate and compare the enzymatic response of five filamentous fungi when grown on five very different substrates: grass (sugarcane bagasse), hardwood (birch), softwood (spruce), cellulose and glucose. The five fungi included the ascomycetes Aspergillus terreus, Trichoderma reesei, Myceliophthora thermophila, Neurospora crassa and the white-rot basidiomycete Phanerochaete chrysosporium, all expressing a diverse repertoire of enzymes. In this study, we present comparable quantitative protein abundance values across five species and five diverse substrates. The results allow for direct comparison of fungal adaptation to the different substrates, give indications as to the substrate specificity of individual carbohydrate-active enzymes (CAZymes), and reveal proteins of unknown function that are co-expressed with CAZymes. Based on the results, we present a quantitative comparison of 34 lytic polysaccharide monooxygenases (LPMOs), which are crucial enzymes in biomass deconstruction.
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Affiliation(s)
- Magnus Ø Arntzen
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences (NMBU), P.O. Box 5003, 1432, Ås, Norway.
| | - Oskar Bengtsson
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences (NMBU), P.O. Box 5003, 1432, Ås, Norway
| | - Anikó Várnai
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences (NMBU), P.O. Box 5003, 1432, Ås, Norway
| | - Francesco Delogu
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences (NMBU), P.O. Box 5003, 1432, Ås, Norway
| | - Geir Mathiesen
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences (NMBU), P.O. Box 5003, 1432, Ås, Norway
| | - Vincent G H Eijsink
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences (NMBU), P.O. Box 5003, 1432, Ås, Norway
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11
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Dadwal A, Sharma S, Satyanarayana T. Progress in Ameliorating Beneficial Characteristics of Microbial Cellulases by Genetic Engineering Approaches for Cellulose Saccharification. Front Microbiol 2020; 11:1387. [PMID: 32670240 PMCID: PMC7327088 DOI: 10.3389/fmicb.2020.01387] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Accepted: 05/29/2020] [Indexed: 12/15/2022] Open
Abstract
Lignocellulosic biomass is a renewable and sustainable energy source. Cellulases are the enzymes that cleave β-1, 4-glycosidic linkages in cellulose to liberate sugars that can be fermented to ethanol, butanol, and other products. Low enzyme activity and yield, and thermostability are, however, some of the limitations posing hurdles in saccharification of lignocellulosic residues. Recent advancements in synthetic and systems biology have generated immense interest in metabolic and genetic engineering that has led to the development of sustainable technology for saccharification of lignocellulosics in the last couple of decades. There have been several attempts in applying genetic engineering in the production of a repertoire of cellulases at a low cost with a high biomass saccharification. A diverse range of cellulases are produced by different microbes, some of which are being engineered to evolve robust cellulases. This review summarizes various successful genetic engineering strategies employed for improving cellulase kinetics and cellulolytic efficiency.
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Affiliation(s)
- Anica Dadwal
- Department of Biological Sciences and Engineering, Netaji Subhas University of Technology, New Delhi, India
| | - Shilpa Sharma
- Department of Biological Sciences and Engineering, Netaji Subhas University of Technology, New Delhi, India
| | - Tulasi Satyanarayana
- Department of Biological Sciences and Engineering, Netaji Subhas University of Technology, New Delhi, India
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Consolidated bio-saccharification: Leading lignocellulose bioconversion into the real world. Biotechnol Adv 2020; 40:107535. [DOI: 10.1016/j.biotechadv.2020.107535] [Citation(s) in RCA: 66] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2019] [Revised: 02/03/2020] [Accepted: 02/12/2020] [Indexed: 11/22/2022]
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13
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Engineering of industrially important microorganisms for assimilation of cellulosic biomass: towards consolidated bioprocessing. Biochem Soc Trans 2020; 47:1781-1794. [PMID: 31845725 DOI: 10.1042/bst20190293] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2019] [Revised: 11/28/2019] [Accepted: 11/28/2019] [Indexed: 01/01/2023]
Abstract
Conversion of cellulosic biomass (non-edible plant material) to products such as chemical feedstocks and liquid fuels is a major goal of industrial biotechnology and an essential component of plans to move from an economy based on fossil carbon to one based on renewable materials. Many microorganisms can effectively degrade cellulosic biomass, but attempts to engineer this ability into industrially useful strains have met with limited success, suggesting an incomplete understanding of the process. The recent discovery and continuing study of enzymes involved in oxidative depolymerisation, as well as more detailed study of natural cellulose degradation processes, may offer a way forward.
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Tarraran L, Mazzoli R. Alternative strategies for lignocellulose fermentation through lactic acid bacteria: the state of the art and perspectives. FEMS Microbiol Lett 2019; 365:4995910. [PMID: 30007320 DOI: 10.1093/femsle/fny126] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Accepted: 05/11/2018] [Indexed: 12/22/2022] Open
Abstract
Lactic acid bacteria (LAB) have a long history in industrial processes as food starters and biocontrol agents, and also as producers of high-value compounds. Lactic acid, their main product, is among the most requested chemicals because of its multiple applications, including the synthesis of biodegradable plastic polymers. Moreover, LAB are attractive candidates for the production of ethanol, polyhydroalkanoates, sweeteners and exopolysaccharides. LAB generally have complex nutritional requirements. Furthermore, they cannot directly ferment inexpensive feedstocks such as lignocellulose. This significantly increases the cost of LAB fermentation and hinders its application in the production of high volumes of low-cost chemicals. Different strategies have been explored to extend LAB fermentation to lignocellulosic biomass. Fermentation of lignocellulose hydrolysates by LAB has been frequently reported and is the most mature technology. However, current economic constraints of this strategy have driven research for alternative approaches. Co-cultivation of LAB with native cellulolytic microorganisms may reduce the high cost of exogenous cellulase supplementation. Special attention is given in this review to the construction of recombinant cellulolytic LAB by metabolic engineering, which may generate strains able to directly ferment plant biomass. The state of the art of these strategies is illustrated along with perspectives of their applications to industrial second generation biorefinery processes.
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Affiliation(s)
- Loredana Tarraran
- Structural and Functional Biochemistry, Laboratory of Proteomics and Metabolic Engineering of Prokaryotes, Department of Life Sciences and Systems Biology, University of Turin, Via Accademia Albertina 13, 10123 Torino, Italy
| | - Roberto Mazzoli
- Structural and Functional Biochemistry, Laboratory of Proteomics and Metabolic Engineering of Prokaryotes, Department of Life Sciences and Systems Biology, University of Turin, Via Accademia Albertina 13, 10123 Torino, Italy
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The Cellulosome Paradigm in An Extreme Alkaline Environment. Microorganisms 2019; 7:microorganisms7090347. [PMID: 31547347 PMCID: PMC6780208 DOI: 10.3390/microorganisms7090347] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Revised: 09/01/2019] [Accepted: 09/10/2019] [Indexed: 11/19/2022] Open
Abstract
Rapid decomposition of plant biomass in soda lakes is associated with microbial activity of anaerobic cellulose-degrading communities. The alkaliphilic bacterium, Clostridium alkalicellulosi, is the single known isolate from a soda lake that demonstrates cellulolytic activity. This microorganism secretes cellulolytic enzymes that degrade cellulose under anaerobic and alkaliphilic conditions. A previous study indicated that the protein fraction of cellulose-grown cultures showed similarities in composition and size to known components of the archetypical cellulosome Clostridium thermocellum. Bioinformatic analysis of the C. alkalicellulosi draft genome sequence revealed 44 cohesins, organized into 22 different scaffoldins, and 142 dockerin-containing proteins. The modular organization of the scaffoldins shared similarities to those of C. thermocellum and Acetivibrio cellulolyticus, whereas some exhibited unconventional arrangements containing peptidases and oxidative enzymes. The binding interactions among cohesins and dockerins assessed by ELISA, revealed a complex network of cellulosome assemblies and suggested both cell-associated and cell-free systems. Based on these interactions, C. alkalicellulosi cellulosomal systems have the genetic potential to create elaborate complexes, which could integrate up to 105 enzymatic subunits. The alkalistable C. alkalicellulosi cellulosomal systems and their enzymes would be amenable to biotechnological processes, such as treatment of lignocellulosic biomass following prior alkaline pretreatment.
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Ribeiro LF, Amarelle V, Alves LDF, Viana de Siqueira GM, Lovate GL, Borelli TC, Guazzaroni ME. Genetically Engineered Proteins to Improve Biomass Conversion: New Advances and Challenges for Tailoring Biocatalysts. Molecules 2019; 24:molecules24162879. [PMID: 31398877 PMCID: PMC6719137 DOI: 10.3390/molecules24162879] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2019] [Revised: 07/30/2019] [Accepted: 08/06/2019] [Indexed: 01/02/2023] Open
Abstract
Protein engineering emerged as a powerful approach to generate more robust and efficient biocatalysts for bio-based economy applications, an alternative to ecologically toxic chemistries that rely on petroleum. On the quest for environmentally friendly technologies, sustainable and low-cost resources such as lignocellulosic plant-derived biomass are being used for the production of biofuels and fine chemicals. Since most of the enzymes used in the biorefinery industry act in suboptimal conditions, modification of their catalytic properties through protein rational design and in vitro evolution techniques allows the improvement of enzymatic parameters such as specificity, activity, efficiency, secretability, and stability, leading to better yields in the production lines. This review focuses on the current application of protein engineering techniques for improving the catalytic performance of enzymes used to break down lignocellulosic polymers. We discuss the use of both classical and modern methods reported in the literature in the last five years that allowed the boosting of biocatalysts for biomass degradation.
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Affiliation(s)
- Lucas Ferreira Ribeiro
- Department of Biology, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, University of São Paulo, Ribeirão Preto 14040-901, Brazil.
| | - Vanesa Amarelle
- Department of Microbial Biochemistry and Genomics, Biological Research Institute Clemente Estable, Montevideo, PC 11600, Uruguay
| | - Luana de Fátima Alves
- Department of Biochemistry and Immunology, Faculdade de Medicina de Ribeirão Preto, University of São Paulo, Ribeirão Preto 14049-900, Brazil
| | | | - Gabriel Lencioni Lovate
- Department of Biochemistry and Immunology, Faculdade de Medicina de Ribeirão Preto, University of São Paulo, Ribeirão Preto 14049-900, Brazil
| | - Tiago Cabral Borelli
- Department of Biology, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, University of São Paulo, Ribeirão Preto 14040-901, Brazil
| | - María-Eugenia Guazzaroni
- Department of Biology, Faculdade de Filosofia, Ciências e Letras de Ribeirão Preto, University of São Paulo, Ribeirão Preto 14040-901, Brazil.
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17
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Cellulosome assembly: paradigms are meant to be broken! Curr Opin Struct Biol 2018; 49:154-161. [DOI: 10.1016/j.sbi.2018.03.012] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2018] [Revised: 03/13/2018] [Accepted: 03/13/2018] [Indexed: 12/23/2022]
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Yadav SK. Technological advances and applications of hydrolytic enzymes for valorization of lignocellulosic biomass. BIORESOURCE TECHNOLOGY 2017; 245:1727-1739. [PMID: 28552567 DOI: 10.1016/j.biortech.2017.05.066] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Revised: 05/10/2017] [Accepted: 05/11/2017] [Indexed: 06/07/2023]
Abstract
Hydrolytic enzymes are indispensable tools in the production of various foodstuffs, drugs, and consumables owing to their applications in almost every industrial process nowadays. One of the foremost areas of interest involving the use of hydrolytic enzymes is in the transformation of lignocellulosic biomass into value added products. However, limitations of the processes due to inadequate enzyme activity and stability with a narrow range of pH and temperature optima often limit their effective usage. The innovative technologies, involving manipulation of enzyme activity and stability through mutagenesis, genetic engineering and metagenomics lead to a major leap in all the fields using hydrolytic enzymes. This article provides recent advancement towards the isolation and use of microbes for lignocellulosic biomass utilisation, microbes producing the hydrolytic enzymes, the modern age technologies used to manipulate and enhance the hydrolytic enzyme activity and the applications of such enzymes in value added products development from lignocellulosic biomass.
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Affiliation(s)
- Sudesh Kumar Yadav
- Center of Innovative and Applied Bioprocessing (CIAB), Knowledge City, Sector-81, Mohali, India.
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Affiliation(s)
- Daniel J. Cosgrove
- Department of Biology, Pennsylvania State University, University Park, Pennsylvania 16802
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20
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Continually emerging mechanistic complexity of the multi-enzyme cellulosome complex. Curr Opin Struct Biol 2017; 44:151-160. [DOI: 10.1016/j.sbi.2017.03.009] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2016] [Revised: 03/16/2017] [Accepted: 03/17/2017] [Indexed: 12/20/2022]
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Artzi L, Bayer EA, Moraïs S. Cellulosomes: bacterial nanomachines for dismantling plant polysaccharides. Nat Rev Microbiol 2017; 15:83-95. [PMID: 27941816 DOI: 10.1038/nrmicro.2016.164] [Citation(s) in RCA: 223] [Impact Index Per Article: 31.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Cellulosomes are multienzyme complexes that are produced by anaerobic cellulolytic bacteria for the degradation of lignocellulosic biomass. They comprise a complex of scaffoldin, which is the structural subunit, and various enzymatic subunits. The intersubunit interactions in these multienzyme complexes are mediated by cohesin and dockerin modules. Cellulosome-producing bacteria have been isolated from a large variety of environments, which reflects their prevalence and the importance of this microbial enzymatic strategy. In a given species, cellulosomes exhibit intrinsic heterogeneity, and between species there is a broad diversity in the composition and configuration of cellulosomes. With the development of modern technologies, such as genomics and proteomics, the full protein content of cellulosomes and their expression levels can now be assessed and the regulatory mechanisms identified. Owing to their highly efficient organization and hydrolytic activity, cellulosomes hold immense potential for application in the degradation of biomass and are the focus of much effort to engineer an ideal microorganism for the conversion of lignocellulose to valuable products, such as biofuels.
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Affiliation(s)
- Lior Artzi
- Department of Biomolecular Sciences, The Weizmann Institute of Science, 234 Herzl Street, Rehovot 7610001, Israel
| | - Edward A Bayer
- Department of Biomolecular Sciences, The Weizmann Institute of Science, 234 Herzl Street, Rehovot 7610001, Israel
| | - Sarah Moraïs
- Department of Biomolecular Sciences, The Weizmann Institute of Science, 234 Herzl Street, Rehovot 7610001, Israel
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Davidi L, Moraïs S, Artzi L, Knop D, Hadar Y, Arfi Y, Bayer EA. Toward combined delignification and saccharification of wheat straw by a laccase-containing designer cellulosome. Proc Natl Acad Sci U S A 2016; 113:10854-9. [PMID: 27621442 PMCID: PMC5047212 DOI: 10.1073/pnas.1608012113] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Efficient breakdown of lignocellulose polymers into simple molecules is a key technological bottleneck limiting the production of plant-derived biofuels and chemicals. In nature, plant biomass degradation is achieved by the action of a wide range of microbial enzymes. In aerobic microorganisms, these enzymes are secreted as discrete elements in contrast to certain anaerobic bacteria, where they are assembled into large multienzyme complexes termed cellulosomes. These complexes allow for very efficient hydrolysis of cellulose and hemicellulose due to the spatial proximity of synergistically acting enzymes and to the limited diffusion of the enzymes and their products. Recently, designer cellulosomes have been developed to incorporate foreign enzymatic activities in cellulosomes so as to enhance lignocellulose hydrolysis further. In this study, we complemented a cellulosome active on cellulose and hemicellulose by addition of an enzyme active on lignin. To do so, we designed a dockerin-fused variant of a recently characterized laccase from the aerobic bacterium Thermobifida fusca The resultant chimera exhibited activity levels similar to the wild-type enzyme and properly integrated into the designer cellulosome. The resulting complex yielded a twofold increase in the amount of reducing sugars released from wheat straw compared with the same system lacking the laccase. The unorthodox use of aerobic enzymes in designer cellulosome machinery effects simultaneous degradation of the three major components of the plant cell wall (cellulose, hemicellulose, and lignin), paving the way for more efficient lignocellulose conversion into soluble sugars en route to alternative fuels production.
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Affiliation(s)
- Lital Davidi
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - Sarah Moraïs
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - Lior Artzi
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - Doriv Knop
- Faculty of Agricultural, Food, and Environmental Quality Sciences, The Hebrew University of Jerusalem, Rehovot 76100, Israel
| | - Yitzhak Hadar
- Faculty of Agricultural, Food, and Environmental Quality Sciences, The Hebrew University of Jerusalem, Rehovot 76100, Israel
| | - Yonathan Arfi
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - Edward A Bayer
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot 76100, Israel;
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Abstract
The evolution of natural modular proteins and domain swapping by protein engineers have shown the disruptive potential of non-homologous recombination to create proteins with novel functions or traits. Bacteriophage endolysins, cellulosomes and polyketide synthases are 3 examples of natural modular proteins with each module having a dedicated function. These modular architectures have been created by extensive duplication, shuffling of domains and insertion/deletion of new domains. Protein engineers mimic these natural processes in vitro to create chimeras with altered properties or novel functions by swapping modules between different parental genes. Most domain swapping efforts are realized with traditional restriction and ligation techniques, which become particularly restrictive when either a large number of variants, or variants of proteins with multiple domains have to be constructed. Recent advances in homology-independent shuffling techniques increasingly address this need, but to realize the full potential of the synthetic biology of modular proteins a complete homology-independent method for both rational and random shuffling of modules from an unlimited number of parental genes is still needed.
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Affiliation(s)
- Veerle E T Maervoet
- a Laboratory of Applied Biotechnology, Department of Applied Biosciences , Ghent University , Ghent , Belgium
| | - Yves Briers
- a Laboratory of Applied Biotechnology, Department of Applied Biosciences , Ghent University , Ghent , Belgium
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Martinez-Anaya C. Understanding the structure and function of bacterial expansins: a prerequisite towards practical applications for the bioenergy and agricultural industries. Microb Biotechnol 2016; 9:727-736. [PMID: 27365165 PMCID: PMC5072189 DOI: 10.1111/1751-7915.12377] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2016] [Revised: 06/06/2016] [Accepted: 06/09/2016] [Indexed: 01/03/2023] Open
Abstract
Since the publication of a landmark article on the structure of EXLX1 from Bacillus subtilis in 2011, our knowledge of bacterial expansins has steadily increased and our view and understanding of these enigmatic proteins has advanced with relation to their structure, phylogenetic relationships and substrate interaction, although the molecular basis for their mechanism of action remains to be determined. Lignocellulosic material represents a source of fermentable sugars for the production of biofuels, and cell‐wall degrading activities are essential to efficiently release such sugars from their polymeric structures. Because expansins from fungi and bacteria seem to be required to properly colonize or cause disease to plant tissues, and because they share some characteristics with their plant counterparts for loosening the cell wall they have been seen as a promising tool to overcome the recalcitrance of these materials. However, microbial expansins activity is at best, very low compared with plant expansins activity. This revision analyses recent work on bacterial expansins structure, function and biological role, emphasizing our need to focus on their mechanism of action as a means to design better strategies for their use, in both in the energy and agricultural industries.
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Affiliation(s)
- Claudia Martinez-Anaya
- Departamento de Ingeniería Celular y Biocatálisis, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad 2001, Chamilpa, Cuernavaca, 62210, Morelos, México.
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Artzi L, Morag E, Shamshoum M, Bayer EA. Cellulosomal expansin: functionality and incorporation into the complex. BIOTECHNOLOGY FOR BIOFUELS 2016; 9:61. [PMID: 26973715 PMCID: PMC4788839 DOI: 10.1186/s13068-016-0474-5] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2016] [Accepted: 03/02/2016] [Indexed: 05/24/2023]
Abstract
BACKGROUND Expansins are relatively small proteins that lack enzymatic activity and are found in plants and microorganisms. The function of these proteins is to disrupt the plant cell walls by interfering with the non-covalent interchain bonding of the polysaccharides. Expansins were found to be important for plant growth, but they are also expressed by various bacteria known to have interactions with plants. Clostridium clariflavum is a plant cell wall-degrading bacterium with a highly elaborate cellulosomal system. Among its numerous dockerin-containing genes, two expansin-like proteins, Clocl_1862 and Clocl_1298 (termed herein CclEXL1 and CclEXL2) were identified, and CclEXL1 was found to be expressed as part of the cellulosome system. This is the first time that an expansin-like protein is identified in a cellulosome complex, which implicates its possible role in biomass deconstruction. RESULTS In the present article, we analyzed the functionality of CclEXL1. Its dockerin was characterized and shown to bind selectively to type-I cohesins of C. clariflavum, with preferential binding to the cohesin of ScaG, and additionally to a type-I cohesin of C. cellulolyticum. We demonstrated experimentally that the expansin-like protein binds preferentially to microcrystalline cellulose, but it also binds to acid-swollen cellulose, xylan, and wheat straw. CclEXL1 exhibited a pronounced loosening effect on filter paper, which resulted in substantial decrease in tensile stress. The C. clariflavum expansin-like protein thus enhances significantly enzymatic hydrolysis of cellulose, both by C. clariflavum cellulosomes and two major cellulosomal cellulases from this bacterium: GH48 (exoglucanase) and GH9 (endoglucanase). Finally, we demonstrated CclEXL1-mediated enhancement of microcrystalline cellulose degradation by different cellulosome fractions and the two enzymes. CONCLUSIONS The results of this study confirm that the C. clariflavum expansin-like protein is part of the elaborate cellulosome system of this bacterium with capabilities of cellulose creeping. The data suggest that pretreatment of cellulosic materials with CclEXL1 can bring about substantial improvement of hydrolysis by cellulases.
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Affiliation(s)
- Lior Artzi
- Department of Molecular Biosciences, The Weizmann Institute of Science, Rehovot, Israel
| | - Ely Morag
- Department of Molecular Biosciences, The Weizmann Institute of Science, Rehovot, Israel
| | - Melina Shamshoum
- Department of Molecular Biosciences, The Weizmann Institute of Science, Rehovot, Israel
| | - Edward A. Bayer
- Department of Molecular Biosciences, The Weizmann Institute of Science, Rehovot, Israel
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