1
|
Zhang X, Chen G, Kang J, Bello A, Fan Z, Liu P, Su E, Lang K, Ma B, Li H, Xu X. β-Glucosidase-producing microbial community in composting: Response to different carbon metabolic pressure influenced by biochar. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2024; 349:119506. [PMID: 37951109 DOI: 10.1016/j.jenvman.2023.119506] [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: 07/18/2023] [Revised: 10/12/2023] [Accepted: 10/27/2023] [Indexed: 11/13/2023]
Abstract
Poor management of agricultural waste will cause a lot of environment pollution and the composting process is one of the most effective measures for resource reuse of agricultural waste. β-Glucosidase-producing microbial communities play a vital role in cellulose degradation during composting and regulate cellulase production via differentially expressed glucose/non-glucose tolerant β-glucosidase genes. Biochar is widely used as an amendment in compost to accelerate cellulose degradation during composting. However, Biochar-mediated impacts on β-glucosidase-producing microbial communities in compost are unclear. Here, different carbon metabolism pressures were set in natural and biochar compost to elucidate the regulation mechanism and interaction of the β-glucosidase microbial community. Results showed that the addition of biochar decreased the transcription of β-glucosidase genes and led to a reduction of β-glucosidase activity. Micromonospora and Cellulosimicrobium were the predominant functional communities determining cellulose degradation during biochar compost. Biochar addition strengthened the response of the functional microbial community to carbon metabolism pressure. And adding biochar altered the key β-glucosidase-producing microbial communities, influencing cellulase and the interaction between these communities to respond to the different carbon metabolic pressure of compost. Biochar also shifted the co-occurrence network of β-glucosidase-producing microbial community by changing the keystone species. Furthermore, co-occurrence network analysis revealed that high glucose decreased the complexity and stability of the functional microbial network. Most functional microorganisms from Streptomyces produce non-glucose tolerant β-glucosidase, which were the key bacterial communities affecting β-glucosidase activity in the non-glucose treatment. This study provides new insights into the response of functional microbial communities and the regulation of enzyme production during the transformation of cellulosic biomass.
Collapse
Affiliation(s)
- Xinyue Zhang
- College of Resources and Environmental Sciences, Northeast Agricultural University, Harbin, 150030, China
| | - Guangxin Chen
- College of Resources and Environmental Sciences, Northeast Agricultural University, Harbin, 150030, China
| | - Jingxue Kang
- College of Resources and Environmental Sciences, Northeast Agricultural University, Harbin, 150030, China
| | - Ayodeji Bello
- College of Resources and Environmental Sciences, Northeast Agricultural University, Harbin, 150030, China
| | - Zhihua Fan
- College of Resources and Environmental Sciences, Northeast Agricultural University, Harbin, 150030, China
| | - Peizhu Liu
- College of Resources and Environmental Sciences, Northeast Agricultural University, Harbin, 150030, China
| | - Erlie Su
- College of Resources and Environmental Sciences, Northeast Agricultural University, Harbin, 150030, China
| | - Kaice Lang
- College of Resources and Environmental Sciences, Northeast Agricultural University, Harbin, 150030, China
| | - Bo Ma
- School of Animal Medicine, Northeast Agricultural University, Harbin, 150030, China
| | - Hongtao Li
- College of Resources and Environmental Sciences, Northeast Agricultural University, Harbin, 150030, China.
| | - Xiuhong Xu
- College of Resources and Environmental Sciences, Northeast Agricultural University, Harbin, 150030, China.
| |
Collapse
|
2
|
Moraïs S, Stern J, Artzi L, Fontes CMGA, Bayer EA, Mizrahi I. Carbohydrate Depolymerization by Intricate Cellulosomal Systems. Methods Mol Biol 2023; 2657:53-77. [PMID: 37149522 DOI: 10.1007/978-1-0716-3151-5_4] [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: 05/08/2023]
Abstract
Cellulosomes are multi-enzymatic nanomachines that have been fine-tuned through evolution to efficiently deconstruct plant biomass. Integration of cellulosomal components occurs via highly ordered protein-protein interactions between the various enzyme-borne dockerin modules and the multiple copies of the cohesin modules located on the scaffoldin subunit. Recently, designer cellulosome technology was established to provide insights into the architectural role of catalytic (enzymatic) and structural (scaffoldin) cellulosomal constituents for the efficient degradation of plant cell wall polysaccharides. Owing to advances in genomics and proteomics, highly structured cellulosome complexes have recently been unraveled, and the information gained has inspired the development of designer-cellulosome technology to new levels of complex organization. These higher-order designer cellulosomes have in turn fostered our capacity to enhance the catalytic potential of artificial cellulolytic complexes. In this chapter, methods to produce and employ such intricate cellulosomal complexes are reported.
Collapse
Affiliation(s)
- Sarah Moraïs
- Faculty of Natural Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| | - Johanna Stern
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot, Israel
| | - Lior Artzi
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot, Israel
| | | | - Edward A Bayer
- Faculty of Natural Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel.
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot, Israel.
| | - Itzhak Mizrahi
- Faculty of Natural Sciences, Ben-Gurion University of the Negev, Beer-Sheva, Israel
| |
Collapse
|
3
|
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]
|
4
|
Monterrey DT, Ayuso-Fernández I, Oroz-Guinea I, García-Junceda E. Design and biocatalytic applications of genetically fused multifunctional enzymes. Biotechnol Adv 2022; 60:108016. [PMID: 35781046 DOI: 10.1016/j.biotechadv.2022.108016] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Revised: 06/27/2022] [Accepted: 06/27/2022] [Indexed: 01/01/2023]
Abstract
Fusion proteins, understood as those created by joining two or more genes that originally encoded independent proteins, have numerous applications in biotechnology, from analytical methods to metabolic engineering. The use of fusion enzymes in biocatalysis may be even more interesting due to the physical connection of enzymes catalyzing successive reactions into covalently linked complexes. The proximity of the active sites of two enzymes in multi-enzyme complexes can make a significant contribution to the catalytic efficiency of the reaction. However, the physical proximity of the active sites does not guarantee this result. Other aspects, such as the nature and length of the linker used for the fusion or the order in which the enzymes are fused, must be considered and optimized to achieve the expected increase in catalytic efficiency. In this review, we will relate the new advances in the design, creation, and use of fused enzymes with those achieved in biocatalysis over the past 20 years. Thus, we will discuss some examples of genetically fused enzymes and their application in carbon‑carbon bond formation and oxidative reactions, generation of chiral amines, synthesis of carbohydrates, biodegradation of plant biomass and plastics, and in the preparation of other high-value products.
Collapse
Affiliation(s)
- Dianelis T Monterrey
- Departamento de Química Bioorgánica, Instituto de Química Orgánica General (IQOG), CSIC, Juan de la Cierva 3, 28006 Madrid, Spain.
| | - Iván Ayuso-Fernández
- Departamento de Química Bioorgánica, Instituto de Química Orgánica General (IQOG), CSIC, Juan de la Cierva 3, 28006 Madrid, Spain.
| | - Isabel Oroz-Guinea
- Departamento de Química Bioorgánica, Instituto de Química Orgánica General (IQOG), CSIC, Juan de la Cierva 3, 28006 Madrid, Spain.
| | - Eduardo García-Junceda
- Departamento de Química Bioorgánica, Instituto de Química Orgánica General (IQOG), CSIC, Juan de la Cierva 3, 28006 Madrid, Spain.
| |
Collapse
|
5
|
Vanderstraeten J, da Fonseca MJM, De Groote P, Grimon D, Gerstmans H, Kahn A, Moraïs S, Bayer EA, Briers Y. Combinatorial assembly and optimisation of designer cellulosomes: a galactomannan case study. BIOTECHNOLOGY FOR BIOFUELS AND BIOPRODUCTS 2022; 15:60. [PMID: 35637485 PMCID: PMC9153192 DOI: 10.1186/s13068-022-02158-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/23/2021] [Accepted: 05/14/2022] [Indexed: 11/10/2022]
Abstract
BACKGROUND Designer cellulosomes are self-assembled chimeric enzyme complexes that can be used to improve lignocellulosic biomass degradation. They are composed of a synthetic multimodular backbone protein, termed the scaffoldin, and a range of different chimeric docking enzymes that degrade polysaccharides. Over the years, several functional designer cellulosomes have been constructed. Since many parameters influence the efficiency of these multi-enzyme complexes, there is a need to optimise designer cellulosome architecture by testing combinatorial arrangements of docking enzyme and scaffoldin variants. However, the modular cloning procedures are tedious and cumbersome. RESULTS VersaTile is a combinatorial DNA assembly method, allowing the rapid construction and thus comparison of a range of modular proteins. Here, we present the extension of the VersaTile platform to facilitate the construction of designer cellulosomes. We have constructed a tile repository, composed of dockerins, cohesins, linkers, tags and enzymatically active modules. The developed toolbox allows us to efficiently create and optimise designer cellulosomes at an unprecedented speed. As a proof of concept, a trivalent designer cellulosome able to degrade the specific hemicellulose substrate, galactomannan, was constructed and optimised. The main factors influencing cellulosome efficiency were found to be the selected dockerins and linkers and the docking enzyme ratio on the scaffoldin. The optimised designer cellulosome was able to hydrolyse the galactomannan polysaccharide and release mannose and galactose monomers. CONCLUSION We have eliminated one of the main technical hurdles in the designer cellulosome field and anticipate the VersaTile platform to be a starting point in the development of more elaborate multi-enzyme complexes.
Collapse
Affiliation(s)
- Julie Vanderstraeten
- Laboratory of Applied Biotechnology, Department of Biotechnology, Ghent University, Valentin Vaerwyckweg 1, 9000, Ghent, Belgium
| | - Maria João Maurício da Fonseca
- Laboratory of Applied Biotechnology, Department of Biotechnology, Ghent University, Valentin Vaerwyckweg 1, 9000, Ghent, Belgium
| | - Philippe De Groote
- Laboratory of Applied Biotechnology, Department of Biotechnology, Ghent University, Valentin Vaerwyckweg 1, 9000, Ghent, Belgium
| | - Dennis Grimon
- Laboratory of Applied Biotechnology, Department of Biotechnology, Ghent University, Valentin Vaerwyckweg 1, 9000, Ghent, Belgium
| | - Hans Gerstmans
- Laboratory of Applied Biotechnology, Department of Biotechnology, Ghent University, Valentin Vaerwyckweg 1, 9000, Ghent, Belgium.,Laboratory for Biomolecular Discovery and Engineering, Department of Biology, VIB-KU Leuven Center for Microbiology, Kasteelpark Arenberg 31, 3001, Louvain, Belgium
| | - Amaranta Kahn
- Department of Biomolecular Sciences, The Weizmann Institute of Science, 7610001, Rehovot, Israel.,Interdisciplinary Centre of Marine and Environmental Research (CIIMAR/CIMAR), University of Porto, Avenida General Norton de Matos, s/n, 4450-208, Matosinhos, Portugal
| | - Sarah Moraïs
- 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
| | - 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
| | - Yves Briers
- Laboratory of Applied Biotechnology, Department of Biotechnology, Ghent University, Valentin Vaerwyckweg 1, 9000, Ghent, Belgium.
| |
Collapse
|
6
|
Vanderstraeten J, Briers Y. Synthetic protein scaffolds for the colocalisation of co-acting enzymes. Biotechnol Adv 2020; 44:107627. [DOI: 10.1016/j.biotechadv.2020.107627] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Revised: 08/17/2020] [Accepted: 08/25/2020] [Indexed: 02/06/2023]
|
7
|
Wang Y, Leng L, Islam MK, Liu F, Lin CSK, Leu SY. Substrate-Related Factors Affecting Cellulosome-Induced Hydrolysis for Lignocellulose Valorization. Int J Mol Sci 2019; 20:ijms20133354. [PMID: 31288425 PMCID: PMC6651384 DOI: 10.3390/ijms20133354] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Revised: 06/30/2019] [Accepted: 07/03/2019] [Indexed: 11/22/2022] Open
Abstract
Cellulosomes are an extracellular supramolecular multienzyme complex that can efficiently degrade cellulose and hemicelluloses in plant cell walls. The structural and unique subunit arrangement of cellulosomes can promote its adhesion to the insoluble substrates, thus providing individual microbial cells with a direct competence in the utilization of cellulosic biomass. Significant progress has been achieved in revealing the structures and functions of cellulosomes, but a knowledge gap still exists in understanding the interaction between cellulosome and lignocellulosic substrate for those derived from biorefinery pretreatment of agricultural crops. The cellulosomic saccharification of lignocellulose is affected by various substrate-related physical and chemical factors, including native (untreated) wood lignin content, the extent of lignin and xylan removal by pretreatment, lignin structure, substrate size, and of course substrate pore surface area or substrate accessibility to cellulose. Herein, we summarize the cellulosome structure, substrate-related factors, and regulatory mechanisms in the host cells. We discuss the latest advances in specific strategies of cellulosome-induced hydrolysis, which can function in the reaction kinetics and the overall progress of biorefineries based on lignocellulosic feedstocks.
Collapse
Affiliation(s)
- Ying Wang
- Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Guangdong Institute of Eco-Environmental Science & Technology, Guangzhou 510650, China
- Department of Civil and Environmental Engineering, the Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong SAR, China
| | - Ling Leng
- Bioproduction Research Institute, National Institute of Advanced Industrial Science and Technology (AIST), Central 6, Higashi 1-1-1, Tsukuba, Ibaraki 305-8566, Japan
| | - Md Khairul Islam
- Department of Civil and Environmental Engineering, the Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong SAR, China
| | - Fanghua Liu
- Guangdong Key Laboratory of Integrated Agro-environmental Pollution Control and Management, Guangdong Institute of Eco-Environmental Science & Technology, Guangzhou 510650, China
| | - Carol Sze Ki Lin
- School of Energy and Environment, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong SAR, China
| | - Shao-Yuan Leu
- Department of Civil and Environmental Engineering, the Hong Kong Polytechnic University, Hung Hom, Kowloon, Hong Kong SAR, China.
| |
Collapse
|
8
|
Zhang S, Xu Z, Wang T, Kong J. Endoglucanase improve the growth of homofermentative Lactobacillus spp. in ensilages. J Biotechnol 2019; 295:55-62. [PMID: 30853632 DOI: 10.1016/j.jbiotec.2019.02.010] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2018] [Revised: 01/25/2019] [Accepted: 02/05/2019] [Indexed: 10/27/2022]
Abstract
Endoglucanase, an important component of cellulases, is used as additives in ensiling of forage crops. However, its detailed role is unclear in ensilages. In the present study, two endoglucanases Cel5 and Cel9 produced by strain Paenibacillus panacisoli SDMCC050309, previously isolated from ensiled corn stover, were identified in the cultures by microcrystalline cellulose absorption coupled with zymogram analysis. After heterologously expressed in Escherichia coli DE3 and purified, these two proteins were biochemically characterized. Cel5 was 61 kDa and showed maximal activity at pH 7.0 and 45 °C, while the maximum activity was at pH 8.0 and 65 °C for Cel9 with 97 kDa in size. Both of them could degrade carboxymethyl cellulose into cellooligosaccharides, in which cellobiose and cellotriose could be used as substrates for the growth of homofermentative strains Lactobacillus plantarum CGMCC6888 and L. farciminis CCTCC AB2016237, but not for the heterofermentative strains L. brevis SDMCC050297 and L. parafarraginis SDMCC050300. Therefore, we concluded that the added endoglucanase contributed to enhance the growth of homofermentative lactic acid bacteria for high level of lactic acid production in ensilages.
Collapse
Affiliation(s)
- Susu Zhang
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, 266237, PR China
| | - Zhenshang Xu
- State Key Laboratory of Biobased Material and Green Papermaking, Qilu University of Technology, Shandong Academy of Science, Jinan, 250353, PR China
| | - Ting Wang
- State Key Laboratory of Biobased Material and Green Papermaking, Qilu University of Technology, Shandong Academy of Science, Jinan, 250353, PR China
| | - Jian Kong
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, 266237, PR China.
| |
Collapse
|
9
|
Kahn A, Moraïs S, Galanopoulou AP, Chung D, Sarai NS, Hengge N, Hatzinikolaou DG, Himmel ME, Bomble YJ, Bayer EA. Creation of a functional hyperthermostable designer cellulosome. BIOTECHNOLOGY FOR BIOFUELS 2019; 12:44. [PMID: 30858881 PMCID: PMC6394049 DOI: 10.1186/s13068-019-1386-y] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Accepted: 02/20/2019] [Indexed: 05/28/2023]
Abstract
BACKGROUND Renewable energy has become a field of high interest over the past decade, and production of biofuels from cellulosic substrates has a particularly high potential as an alternative source of energy. Industrial deconstruction of biomass, however, is an onerous, exothermic process, the cost of which could be decreased significantly by use of hyperthermophilic enzymes. An efficient way of breaking down cellulosic substrates can also be achieved by highly efficient enzymatic complexes called cellulosomes. The modular architecture of these multi-enzyme complexes results in substrate targeting and proximity-based synergy among the resident enzymes. However, cellulosomes have not been observed in hyperthermophilic bacteria. RESULTS Here, we report the design and function of a novel hyperthermostable "designer cellulosome" system, which is stable and active at 75 °C. Enzymes from Caldicellulosiruptor bescii, a highly cellulolytic hyperthermophilic anaerobic bacterium, were selected and successfully converted to the cellulosomal mode by grafting onto them divergent dockerin modules that can be inserted in a precise manner into a thermostable chimaeric scaffoldin by virtue of their matching cohesins. Three pairs of cohesins and dockerins, selected from thermophilic microbes, were examined for their stability at extreme temperatures and were determined stable at 75 °C for at least 72 h. The resultant hyperthermostable cellulosome complex exhibited the highest levels of enzymatic activity on microcrystalline cellulose at 75 °C, compared to those of previously reported designer cellulosome systems and the native cellulosome from Clostridium thermocellum. CONCLUSION The functional hyperthermophilic platform fulfills the appropriate physico-chemical properties required for exothermic processes. This system can thus be adapted for other types of thermostable enzyme systems and could serve as a basis for a variety of cellulolytic and non-cellulolytic industrial objectives at high temperatures.
Collapse
Affiliation(s)
- Amaranta Kahn
- Department of Biomolecular Sciences, The Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Sarah Moraïs
- Department of Biomolecular Sciences, The Weizmann Institute of Science, 7610001 Rehovot, Israel
- Faculty of Natural Sciences, Ben-Gurion University of the Negev, 8499000 Beer-Sheva, Israel
| | - Anastasia P. Galanopoulou
- Microbiology Group, Faculty of Biology, National and Kapodistrian University of Athens, Zografou Campus, 15784 Athens, Greece
| | - Daehwan Chung
- Biosciences Center, National Renewable Energy Laboratory, Golden, CO USA
| | - Nicholas S. Sarai
- Biosciences Center, National Renewable Energy Laboratory, Golden, CO USA
- Present Address: Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA 91125 USA
| | - Neal Hengge
- Biosciences Center, National Renewable Energy Laboratory, Golden, CO USA
| | - Dimitris G. Hatzinikolaou
- Microbiology Group, Faculty of Biology, National and Kapodistrian University of Athens, Zografou Campus, 15784 Athens, Greece
| | - Michael E. Himmel
- Biosciences Center, National Renewable Energy Laboratory, Golden, CO USA
| | - Yannick J. Bomble
- Biosciences Center, National Renewable Energy Laboratory, Golden, CO USA
| | - Edward A. Bayer
- Department of Biomolecular Sciences, The Weizmann Institute of Science, 7610001 Rehovot, Israel
| |
Collapse
|
10
|
Liew KJ, Teo SC, Shamsir MS, Sani RK, Chong CS, Chan KG, Goh KM. Complete genome sequence of Rhodothermaceae bacterium RA with cellulolytic and xylanolytic activities. 3 Biotech 2018; 8:376. [PMID: 30105201 PMCID: PMC6087703 DOI: 10.1007/s13205-018-1391-z] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2018] [Accepted: 08/06/2018] [Indexed: 11/26/2022] Open
Abstract
Rhodothermaceae bacterium RA is a halo-thermophile isolated from a saline hot spring. Previously, the genome of this bacterium was sequenced using a HiSeq 2500 platform culminating in 91 contigs. In this report, we report on the resequencing of its complete genome using a PacBio RSII platform. The genome has a GC content of 68.3%, is 4,653,222 bp in size, and encodes 3711 genes. We are interested in understanding the carbohydrate metabolic pathway, in particular the lignocellulosic biomass degradation pathway. Strain RA harbors 57 glycosyl hydrolase (GH) genes that are affiliated with 30 families. The bacterium consists of cellulose-acting (GH 3, 5, 9, and 44) and hemicellulose-acting enzymes (GH 3, 10, and 43). A crude cell-free extract of the bacterium exhibited endoglucanase, xylanase, β-glucosidase, and β-xylosidase activities. The complete genome information coupled with biochemical assays confirms that strain RA is able to degrade cellulose and xylan. Therefore, strain RA is another excellent member of family Rhodothermaceae as a repository of novel and thermostable cellulolytic and hemicellulolytic enzymes.
Collapse
Affiliation(s)
- Kok Jun Liew
- Faculty of Science, Universiti Teknologi Malaysia, 81300 Skudai, Johor Malaysia
| | - Seng Chong Teo
- Faculty of Science, Universiti Teknologi Malaysia, 81300 Skudai, Johor Malaysia
| | - Mohd Shahir Shamsir
- Faculty of Science, Universiti Teknologi Malaysia, 81300 Skudai, Johor Malaysia
| | - Rajesh Kumar Sani
- Department of Chemical and Biological Engineering, South Dakota School of Mines and Technology, Rapid City, USA
| | - Chun Shiong Chong
- Faculty of Science, Universiti Teknologi Malaysia, 81300 Skudai, Johor Malaysia
| | - Kok-Gan Chan
- Institute of Biological Sciences, Faculty of Science, University of Malaya, 50603 Kuala Lumpur, Malaysia
- International Genome Centre, Jiangsu University, Zhenjiang, 212013 People’s Republic of China
| | - Kian Mau Goh
- Faculty of Science, Universiti Teknologi Malaysia, 81300 Skudai, Johor Malaysia
| |
Collapse
|
11
|
Setter-Lamed E, Moraïs S, Stern J, Lamed R, Bayer EA. Modular Organization of the Thermobifida fusca Exoglucanase Cel6B Impacts Cellulose Hydrolysis and Designer Cellulosome Efficiency. Biotechnol J 2017; 12. [PMID: 28901714 DOI: 10.1002/biot.201700205] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Revised: 09/06/2017] [Indexed: 11/09/2022]
Abstract
Cellulose deconstruction can be achieved by three distinct enzymatic paradigms: free enzymes, multifunctional enzymes, and self-assembled, multi-enzyme complexes (cellulosomes). To study their comparative efficiency, the simple and efficient cellulolytic system of the aerobic bacterium, Thermobifida fusca, is developed as an enzymatic model. In previous studies, most of its cellulases are successfully converted to the cellulosomal mode and exhibited high cellulolytic activities, except for Cel6B, a key exoglucanase of the T. fusca enzymatic system. Here, the impact of the modular organization of Cel6B on enzymatic activity is investigated. The position of the cellulose-binding module (CBM), its family and linker segment are shown to affect activity. Surprisingly, exchange of the native family-2 CBM to family-3 generates an increase in Cel6B activity on cellulosic substrates. Conversion of Cel6B to the cellulosomal mode by fusing a cohesin to the catalytic module enables formation of divalent enzyme complexes with dockerin-bearing enzymes. The resultant pseudo-cellulosomes, containing Cel6B combined with endoglucanase Cel5A, exhibits enhanced enzymatic activity, compared to mixtures of wild-type enzymes or bifunctional enzymes, unlike similar pseudo-cellulosomes containing endoglucanase Cel6A or proccessive endoglucanase Cel9A. Insight into the different enzymatic paradigms benefits ongoing development of efficient cellulolytic systems for conversion of plant-derived biomass into valuable sugars. NOVELTY STATEMENT The protein engineering of the modular arrangement of a key exoglucanase from a highly cellulolytic bacterium, Thermobifida fusca, served to explore and compare three major enzymatic paradigms for cellulose degradation. This approach revealed highly active chimaeric forms of the exoglucanase that act in synergy together with a potent endoglucanase in bifunctional enzymes or divalent pseudo-cellulosome-like complexes. Such engineered enzymes could be further integrated into larger enzymatic complexes, thereby providing a significant step forward towards conversion of the entire T. fusca free cellulolytic system into the cellulosomal modex and the enhanced conversion of cellulosic biomass into soluble sugars.
Collapse
Affiliation(s)
- Eva Setter-Lamed
- 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
| | - Johanna Stern
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - Raphael Lamed
- Department of Molecular Microbiology and Biotechnology, Tel Aviv University, Ramat Aviv, Israel
| | - Edward A Bayer
- Department of Biomolecular Sciences, The Weizmann Institute of Science, Rehovot 76100, Israel
| |
Collapse
|
12
|
Stern J, Artzi L, Moraïs S, Fontes CMGA, Bayer EA. Carbohydrate Depolymerization by Intricate Cellulosomal Systems. Methods Mol Biol 2017; 1588:93-116. [PMID: 28417363 DOI: 10.1007/978-1-4939-6899-2_8] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Cellulosomes are multi-enzymatic nanomachines that have been fine-tuned through evolution to efficiently deconstruct plant biomass. Integration of cellulosomal components occurs via highly ordered protein-protein interactions between the various enzyme-borne dockerin modules and the multiple copies of the cohesin modules located on the scaffoldin subunit. Recently, designer cellulosome technology has been established to provide insights into the architectural role of catalytic (enzymatic) and structural (scaffoldin) cellulosomal constituents for the efficient degradation of plant cell wall polysaccharides. Owing to advances in genomics and proteomics, highly structured cellulosome complexes have recently been unraveled, and the information gained has inspired the development of designer cellulosome technology to new levels of complex organization. These higher-order designer cellulosomes have in turn fostered our capacity to enhance the catalytic potential of artificial cellulolytic complexes. In this chapter, methods to produce and employ such intricate cellulosomal complexes are reported.
Collapse
Affiliation(s)
- Johanna Stern
- Faculty of Biochemistry, Department of Biomolecular Sciences, The Weizmann Institute of Science, Ullmann Building of Life Sciences, Room 226, Rehovot, 76100, Israel
| | - Lior Artzi
- Faculty of Biochemistry, Department of Biomolecular Sciences, The Weizmann Institute of Science, Ullmann Building of Life Sciences, Room 226, Rehovot, 76100, Israel
| | - Sarah Moraïs
- Faculty of Biochemistry, Department of Biomolecular Sciences, The Weizmann Institute of Science, Ullmann Building of Life Sciences, Room 226, Rehovot, 76100, Israel
| | - Carlos M G A Fontes
- CIISA - Faculdade de Medicina Veterinária, Universidade de Lisboa, Avenida da Universidade Técnica, 1300-477, Lisbon, Portugal
| | - Edward A Bayer
- Faculty of Biochemistry, Department of Biomolecular Sciences, The Weizmann Institute of Science, Ullmann Building of Life Sciences, Room 226, Rehovot, 76100, Israel.
| |
Collapse
|
13
|
Galanopoulou AP, Moraïs S, Georgoulis A, Morag E, Bayer EA, Hatzinikolaou DG. Insights into the functionality and stability of designer cellulosomes at elevated temperatures. Appl Microbiol Biotechnol 2016; 100:8731-43. [PMID: 27207145 DOI: 10.1007/s00253-016-7594-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2016] [Revised: 04/23/2016] [Accepted: 04/28/2016] [Indexed: 01/21/2023]
Abstract
Enzymatic breakdown of lignocellulose is a major limiting step in second generation biorefineries. Assembly of the necessary activities into designer cellulosomes increases the productivity of this step by enhancing enzyme synergy through the proximity effect. However, most cellulosomal components are obtained from mesophilic microorganisms, limiting the applications to temperatures up to 50 °C. We hypothesized that a scaffoldin, comprising modular components of mainly mesophilic origin, can function at higher temperatures when combined with thermophilic enzymes, and the resulting designer cellulosomes could be employed in higher temperature reactions. For this purpose, we used a tetravalent scaffoldin constituted of three cohesins of mesophilic origin as well as a cohesin and cellulose-binding module derived from the thermophilic bacterium Clostridium thermocellum. The scaffoldin was combined with four thermophilic enzymes from Geobacillus and Caldicellulosiruptor species, each fused with a dockerin whose specificity matched one of the cohesins. We initially verified that the biochemical properties and thermal stability of the resulting chimeric enzymes were not affected by the presence of the mesophilic dockerins. Then we examined the stability of the individual single-enzyme-scaffoldin complexes and the full tetravalent cellulosome showing that all complexes are stable and functional for at least 6 h at 60 °C. Finally, within this time frame and conditions, the full complex appeared over 50 % more efficient in the hydrolysis of corn stover compared to the free enzymes. Overall, the results support the utilization of scaffoldin components of mesophilic origin at relatively high temperatures and provide a framework for the production of designer cellulosomes suitable for high temperature biorefinery applications.
Collapse
Affiliation(s)
- Anastasia P Galanopoulou
- Faculty of Biology, Microbiology Group, National and Kapodistrian University of Athens, Zografou Campus, 15784, Zografou, Attica, Greece
| | - Sarah Moraïs
- Department of Biomolecular Sciences, The Weizmann Institute of Science, 76100, Rehovot, Israel
| | - Anastasios Georgoulis
- Faculty of Biology, Microbiology Group, National and Kapodistrian University of Athens, Zografou Campus, 15784, Zografou, Attica, Greece
| | - Ely Morag
- Department of Biomolecular Sciences, The Weizmann Institute of Science, 76100, Rehovot, Israel
| | - Edward A Bayer
- Department of Biomolecular Sciences, The Weizmann Institute of Science, 76100, Rehovot, Israel
| | - Dimitris G Hatzinikolaou
- Faculty of Biology, Microbiology Group, National and Kapodistrian University of Athens, Zografou Campus, 15784, Zografou, Attica, Greece.
| |
Collapse
|
14
|
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.
Collapse
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;
| |
Collapse
|
15
|
Gunnoo M, Cazade PA, Galera-Prat A, Nash MA, Czjzek M, Cieplak M, Alvarez B, Aguilar M, Karpol A, Gaub H, Carrión-Vázquez M, Bayer EA, Thompson D. Nanoscale Engineering of Designer Cellulosomes. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2016; 28:5619-47. [PMID: 26748482 DOI: 10.1002/adma.201503948] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Revised: 10/01/2015] [Indexed: 05/27/2023]
Abstract
Biocatalysts showcase the upper limit obtainable for high-speed molecular processing and transformation. Efforts to engineer functionality in synthetic nanostructured materials are guided by the increasing knowledge of evolving architectures, which enable controlled molecular motion and precise molecular recognition. The cellulosome is a biological nanomachine, which, as a fundamental component of the plant-digestion machinery from bacterial cells, has a key potential role in the successful development of environmentally-friendly processes to produce biofuels and fine chemicals from the breakdown of biomass waste. Here, the progress toward so-called "designer cellulosomes", which provide an elegant alternative to enzyme cocktails for lignocellulose breakdown, is reviewed. Particular attention is paid to rational design via computational modeling coupled with nanoscale characterization and engineering tools. Remaining challenges and potential routes to industrial application are put forward.
Collapse
Affiliation(s)
- Melissabye Gunnoo
- Materials and Surface Science Institute and Department of Physics and Energy, University of Limerick, Limerick, Ireland
| | - Pierre-André Cazade
- Materials and Surface Science Institute and Department of Physics and Energy, University of Limerick, Limerick, Ireland
| | - Albert Galera-Prat
- Instituto Cajal, Consejo Superior de Investigaciones Cientificas (CSIC), IMDEA Nanociencias and CIBERNED, Madrid, Spain
| | - Michael A Nash
- Lehrstuhl für Angewandte Physik and Center for Nanoscience, Ludwig-Maximilians-University, 80799, Munich, Germany
| | - Mirjam Czjzek
- Sorbonne Universités, UPMC, Université Paris 06, and Centre National de la Recherche Scientifique, UMR 8227, Integrative Biology of Marine Models, Station Biologique, de Roscoff, CS 90074, F-29688, Roscoff cedex, Bretagne, France
| | - Marek Cieplak
- Laboratory of Biological Physics, Institute of Physics, Polish Academy of Sciences, Warsaw, Poland
| | - Beatriz Alvarez
- Biopolis S.L., Parc Científic de la Universitat de Valencia, Edificio 2, C/Catedrático Agustín Escardino 9, 46980, Paterna (Valencia), Spain
| | - Marina Aguilar
- Abengoa, S.A., Palmas Altas, Calle Energía Solar nº 1, 41014, Seville, Spain
| | - Alon Karpol
- Designer Energy Ltd., 2 Bergman St., Tamar Science Park, Rehovot, 7670504, Israel
| | - Hermann Gaub
- Lehrstuhl für Angewandte Physik and Center for Nanoscience, Ludwig-Maximilians-University, 80799, Munich, Germany
| | - Mariano Carrión-Vázquez
- Instituto Cajal, Consejo Superior de Investigaciones Cientificas (CSIC), IMDEA Nanociencias and CIBERNED, Madrid, Spain
| | - Edward A Bayer
- Department of Biological Chemistry, Weizmann Institute of Science, Rehovot, 76100, Israel
| | - Damien Thompson
- Materials and Surface Science Institute and Department of Physics and Energy, University of Limerick, Limerick, Ireland
| |
Collapse
|
16
|
Cellulases: Classification, Methods of Determination and Industrial Applications. Appl Biochem Biotechnol 2016; 179:1346-80. [PMID: 27068832 DOI: 10.1007/s12010-016-2070-3] [Citation(s) in RCA: 91] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2015] [Accepted: 03/31/2016] [Indexed: 10/22/2022]
Abstract
Microbial cellulases have been receiving worldwide attention, as they have enormous potential to process the most abundant cellulosic biomass on this planet and transform it into sustainable biofuels and other value added products. The synergistic action of endoglucanases, exoglucanases, and β-glucosidases is required for the depolymerization of cellulose to fermentable sugars for transformation in to useful products using suitable microorganisms. The lack of a better understanding of the mechanisms of individual cellulases and their synergistic actions is the major hurdles yet to be overcome for large-scale commercial applications of cellulases. We have reviewed various microbial cellulases with a focus on their classification with mechanistic aspects of cellulase hydrolytic action, insights into novel approaches for determining cellulase activity, and potential industrial applications of cellulases.
Collapse
|
17
|
Abstract
Designer cellulosomes consist of chimeric cohesin-bearing scaffoldins for the controlled incorporation of recombinant dockerin-containing enzymes. The largest designer cellulosome reported to date is a chimeric scaffoldin that contains 6 cohesins. This scaffoldin represented a technical limit of sorts, since adding another cohesin proved problematic, owing to resultant low expression levels, instability (cleavage) of the scaffoldin polypeptide, and limited numbers of available cohesin-dockerin specificities—the hallmark of designer cellulosomes. Nevertheless, increasing the number of enzymes integrated into designer cellulosomes is critical, in order to further enhance degradation of plant cell wall material. Adaptor scaffoldins comprise an intermediate type of scaffoldin that can both incorporate various enzymes and attach to an additional scaffoldin. Using this strategy, we constructed an efficient form of adaptor scaffoldin that possesses three type I cohesins for enzyme integration, a single type II dockerin for interaction with an additional scaffoldin, and a carbohydrate-binding module for targeting to the cellulosic substrate. In parallel, we designed a hexavalent scaffoldin capable of connecting to the adaptor scaffoldin by the incorporation of an appropriate type II cohesin. The resultant extended designer cellulosome comprised 8 recombinant enzymes—4 xylanases and 4 cellulases—thereby representing a potent enzymatic cocktail for solubilization of natural lignocellulosic substrates. The contribution of the adaptor scaffoldin clearly demonstrated that proximity between the two scaffoldins and their composite set of enzymes is crucial for optimized degradation. After 72 h of incubation, the performance of the extended designer cellulosome was determined to be approximately 70% compared to that of native cellulosomes. Plant cell wall residues represent a major source of renewable biomass for the production of biofuels such as ethanol via breakdown to soluble sugars. The natural microbial degradation process, however, is inefficient for achieving cost-effective processes in the conversion of plant-derived biomass to biofuels, either from dedicated crops or human-generated cellulosic wastes. The accumulation of the latter is considered a major environmental pollutant. The development of designer cellulosome nanodevices for enhanced plant cell wall degradation thus has major impacts in the fields of environmental pollution, bioenergy production, and biotechnology in general. The findings reported in this article comprise a true breakthrough in our capacity to produce extended designer cellulosomes via synthetic biology means, thus enabling the assembly of higher-order complexes that can supersede the number of enzymes included in a single multienzyme complex.
Collapse
|
18
|
Arora R, Behera S, Sharma NK, Kumar S. Bioprospecting thermostable cellulosomes for efficient biofuel production from lignocellulosic biomass. BIORESOUR BIOPROCESS 2015. [DOI: 10.1186/s40643-015-0066-4] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
|
19
|
Slutzki M, Reshef D, Barak Y, Haimovitz R, Rotem-Bamberger S, Lamed R, Bayer EA, Schueler-Furman O. Crucial roles of single residues in binding affinity, specificity, and promiscuity in the cellulosomal cohesin-dockerin interface. J Biol Chem 2015; 290:13654-66. [PMID: 25833947 PMCID: PMC4447945 DOI: 10.1074/jbc.m115.651208] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Indexed: 11/06/2022] Open
Abstract
Interactions between cohesin and dockerin modules play a crucial role in the assembly of multienzyme cellulosome complexes. Although intraspecies cohesin and dockerin modules bind in general with high affinity but indiscriminately, cross-species binding is rare. Here, we combined ELISA-based experiments with Rosetta-based computational design to evaluate the contribution of distinct residues at the Clostridium thermocellum cohesin-dockerin interface to binding affinity, specificity, and promiscuity. We found that single mutations can show distinct and significant effects on binding affinity and specificity. In particular, mutations at cohesin position Asn(37) show dramatic variability in their effect on dockerin binding affinity and specificity: the N37A mutant binds promiscuously both to cognate (C. thermocellum) as well as to non-cognate Clostridium cellulolyticum dockerin. N37L in turn switches binding specificity: compared with the wild-type C. thermocellum cohesin, this mutant shows significantly increased preference for C. cellulolyticum dockerin combined with strongly reduced binding to its cognate C. thermocellum dockerin. The observation that a single mutation can overcome the naturally observed specificity barrier provides insights into the evolutionary dynamics of this system that allows rapid modulation of binding specificity within a high affinity background.
Collapse
Affiliation(s)
- Michal Slutzki
- From the Department of Biological Chemistry, The Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Dan Reshef
- Department of Microbiology and Molecular Genetics, Institute for Medical Research Israel-Canada, Hadassah Medical School, The Hebrew University, 9112102 Jerusalem, Israel, and
| | - Yoav Barak
- From the Department of Biological Chemistry, The Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Rachel Haimovitz
- From the Department of Biological Chemistry, The Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Shahar Rotem-Bamberger
- Department of Microbiology and Molecular Genetics, Institute for Medical Research Israel-Canada, Hadassah Medical School, The Hebrew University, 9112102 Jerusalem, Israel, and
| | - Raphael Lamed
- Department of Molecular Microbiology and Biotechnology, Tel Aviv University, 6997801 Ramat Aviv, Israel
| | - Edward A Bayer
- From the Department of Biological Chemistry, The Weizmann Institute of Science, 7610001 Rehovot, Israel
| | - Ora Schueler-Furman
- Department of Microbiology and Molecular Genetics, Institute for Medical Research Israel-Canada, Hadassah Medical School, The Hebrew University, 9112102 Jerusalem, Israel, and
| |
Collapse
|
20
|
Stern J, Kahn A, Vazana Y, Shamshoum M, Moraïs S, Lamed R, Bayer EA. Significance of relative position of cellulases in designer cellulosomes for optimized cellulolysis. PLoS One 2015; 10:e0127326. [PMID: 26024227 PMCID: PMC4449128 DOI: 10.1371/journal.pone.0127326] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2014] [Accepted: 04/13/2015] [Indexed: 11/23/2022] Open
Abstract
Degradation of cellulose is of major interest in the quest for alternative sources of renewable energy, for its positive effects on environment and ecology, and for use in advanced biotechnological applications. Due to its microcrystalline organization, celluose is extremely difficult to degrade, although numerous microbes have evolved that produce the appropriate enzymes. The most efficient known natural cellulolytic system is produced by anaerobic bacteria, such as C. thermocellum, that possess a multi-enzymatic complex termed the cellulosome. Our laboratory has devised and developed the designer cellulosome concept, which consists of chimaeric scaffoldins for controlled incorporation of recombinant polysaccharide-degrading enzymes. Recently, we reported the creation of a combinatorial library of four cellulosomal modules comprising a basic chimaeric scaffoldin, i.e., a CBM and 3 divergent cohesin modules. Here, we employed selected members of this library to determine whether the position of defined cellulolytic enzymes is important for optimized degradation of a microcrystalline cellulosic substrate. For this purpose, 10 chimaeric scaffoldins were used for incorporation of three recombinant Thermobifida fusca enzymes: the processive endoglucanase Cel9A, endoglucanase Cel5A and exoglucanase Cel48A. In addition, we examined whether the characteristic properties of the T. fusca enzymes as designer cellulosome components are unique to this bacterium by replacing them with parallel enzymes from Clostridium thermocellum. The results support the contention that for a given set of cellulosomal enzymes, their relative position within a scaffoldin can be critical for optimal degradation of microcrystaline cellulosic substrates.
Collapse
Affiliation(s)
- Johanna Stern
- Department of Biological Chemistry, The Weizmann Institute of Science, Rehovot, Israel
| | - Amaranta Kahn
- Department of Biological Chemistry, The Weizmann Institute of Science, Rehovot, Israel
| | - Yael Vazana
- Department of Biological Chemistry, The Weizmann Institute of Science, Rehovot, Israel
| | - Melina Shamshoum
- Department of Biological Chemistry, The Weizmann Institute of Science, Rehovot, Israel
| | - Sarah Moraïs
- Department of Biological Chemistry, The Weizmann Institute of Science, Rehovot, Israel
| | - Raphael Lamed
- Department of Molecular Microbiology and Biotechnology, Tel Aviv University, Ramat Aviv 69978, Israel
| | - Edward A. Bayer
- Department of Biological Chemistry, The Weizmann Institute of Science, Rehovot, Israel
- * E-mail:
| |
Collapse
|
21
|
Koeck DE, Pechtl A, Zverlov VV, Schwarz WH. Genomics of cellulolytic bacteria. Curr Opin Biotechnol 2014; 29:171-83. [PMID: 25104562 DOI: 10.1016/j.copbio.2014.07.002] [Citation(s) in RCA: 101] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2014] [Revised: 07/10/2014] [Accepted: 07/15/2014] [Indexed: 10/24/2022]
Abstract
The heterogeneous plant biomass is efficiently decomposed by the interplay of a great number of different enzymes. The enzyme systems in cellulolytic bacteria have been investigated by sequencing and bioinformatic analysis of genomes from plant biomass degrading microorganisms with valuable insights into the variety of the involved enzymes. This broadened our understanding of the biochemical mechanisms of plant polymer degradation and made the enzymes applicable for modern biotechnology. A list of the truly cellulolytic bacteria described and the available genomic information was examined for proteins with cellulolytic and hemicellulolytic capability. The importance of the isolation, characterization and genomic sequencing of cellulolytic microorganisms and their usage for sustainable energy production from biomass and other residues, is emphasized.
Collapse
Affiliation(s)
- Daniela E Koeck
- Department of Microbiology, Technische Universität München, Emil-Ramann-Str. 4, D-85350 Freising-Weihenstephan, Germany
| | - Alexander Pechtl
- Department of Microbiology, Technische Universität München, Emil-Ramann-Str. 4, D-85350 Freising-Weihenstephan, Germany
| | - Vladimir V Zverlov
- Department of Microbiology, Technische Universität München, Emil-Ramann-Str. 4, D-85350 Freising-Weihenstephan, Germany; Institute of Molecular Genetics, Russian Academy of Science, Kurchatov Sq. 2, 123182 Moscow, Russia
| | - Wolfgang H Schwarz
- Department of Microbiology, Technische Universität München, Emil-Ramann-Str. 4, D-85350 Freising-Weihenstephan, Germany.
| |
Collapse
|
22
|
Jindou S, Ito Y, Mito N, Uematsu K, Hosoda A, Tamura H. Engineered platform for bioethylene production by a cyanobacterium expressing a chimeric complex of plant enzymes. ACS Synth Biol 2014; 3:487-96. [PMID: 24933350 DOI: 10.1021/sb400197f] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Ethylene is an industrially important compound, but more sustainable production methods are desirable. Since cellulosomes increase the ability of cellulolytic enzymes by physically linking the relevant enzymes via dockerin-cohesin interactions, in this study, we genetically engineered a chimeric cellulosome-like complex of two ethylene-generating enzymes from tomato using cohesin-dockerins from the bacteria Clostridium thermocellum and Acetivibrio cellulolyticus. This complex was transformed into Escherichia coli to analyze kinetic parameters and enzyme complex formation and into the cyanobacterium Synechococcus elongatus PCC 7942, which was then grown with and without 0.1 mM isopropyl β-D-1-thiogalactopyranoside (IPTG) induction. Only at minimal protein expression levels (without IPTG), the chimeric complex produced 3.7 times more ethylene in vivo than did uncomplexed enzymes. Thus, cyanobacteria can be used to sustainably generate ethylene, and the synthetic enzyme complex greatly enhanced production efficiency. Artificial synthetic enzyme complexes hold great promise for improving the production efficiency of other industrial compounds.
Collapse
Affiliation(s)
- Sadanari Jindou
- Faculty of Science and Technology, Meijo University , Nagoya, Aichi 468-8502 Japan
| | | | | | | | | | | |
Collapse
|
23
|
Chen M, Kostylev M, Bomble YJ, Crowley MF, Himmel ME, Wilson DB, Brady JW. Experimental and Modeling Studies of an Unusual Water-Filled Pore Structure with Possible Mechanistic Implications in Family 48 Cellulases. J Phys Chem B 2014; 118:2306-15. [DOI: 10.1021/jp408767j] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Mo Chen
- Department
of Food Science, Cornell University, Ithaca, New York 14853, United States
| | - Maxim Kostylev
- Department
of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14853, United States
| | - Yannick J. Bomble
- Biosciences
Center, National Renewable Energy Laboratory, 1617 Cole Boulevard, Golden, Colorado 80401-3393, United States
| | - Michael F. Crowley
- Biosciences
Center, National Renewable Energy Laboratory, 1617 Cole Boulevard, Golden, Colorado 80401-3393, United States
| | - Michael E. Himmel
- Biosciences
Center, National Renewable Energy Laboratory, 1617 Cole Boulevard, Golden, Colorado 80401-3393, United States
| | - David B. Wilson
- Department
of Molecular Biology and Genetics, Cornell University, Ithaca, New York 14853, United States
| | - John W. Brady
- Department
of Food Science, Cornell University, Ithaca, New York 14853, United States
| |
Collapse
|
24
|
Kellermann SJ, Rentmeister A. Current Developments in Cellulase Engineering. CHEMBIOENG REVIEWS 2014. [DOI: 10.1002/cben.201300006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
|
25
|
Lambertz C, Garvey M, Klinger J, Heesel D, Klose H, Fischer R, Commandeur U. Challenges and advances in the heterologous expression of cellulolytic enzymes: a review. BIOTECHNOLOGY FOR BIOFUELS 2014; 7:135. [PMID: 25356086 PMCID: PMC4212100 DOI: 10.1186/s13068-014-0135-5] [Citation(s) in RCA: 104] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Accepted: 09/03/2014] [Indexed: 05/03/2023]
Abstract
Second generation biofuel development is increasingly reliant on the recombinant expression of cellulases. Designing or identifying successful expression systems is thus of preeminent importance to industrial progress in the field. Recombinant production of cellulases has been performed using a wide range of expression systems in bacteria, yeasts and plants. In a number of these systems, particularly when using bacteria and plants, significant challenges have been experienced in expressing full-length proteins or proteins at high yield. Further difficulties have been encountered in designing recombinant systems for surface-display of cellulases and for use in consolidated bioprocessing in bacteria and yeast. For establishing cellulase expression in plants, various strategies are utilized to overcome problems, such as the auto-hydrolysis of developing plant cell walls. In this review, we investigate the major challenges, as well as the major advances made to date in the recombinant expression of cellulases across the commonly used bacterial, plant and yeast systems. We review some of the critical aspects to be considered for industrial-scale cellulase production.
Collapse
Affiliation(s)
- Camilla Lambertz
- />Institute for Molecular Biotechnology, RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany
| | - Megan Garvey
- />Institute for Molecular Biotechnology, RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany
- />Present address: School of Medicine, Deakin University, CSIRO Australian Animal Health Laboratory, 5 Portarlington Rd, Newcomb, VIC 3219 Australia
| | - Johannes Klinger
- />Institute for Molecular Biotechnology, RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany
| | - Dirk Heesel
- />Institute for Molecular Biotechnology, RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany
| | - Holger Klose
- />Institute for Molecular Biotechnology, RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany
- />Present address: Institute for Botany and Molecular Genetics, RWTH Aachen University, Worringerweg 3, 52074 Aachen, Germany
| | - Rainer Fischer
- />Institute for Molecular Biotechnology, RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany
- />Fraunhofer Institute for Molecular Biology and Applied Ecology, Forckenbeckstrasse 6, 52074 Aachen, Germany
| | - Ulrich Commandeur
- />Institute for Molecular Biotechnology, RWTH Aachen University, Worringerweg 1, 52074 Aachen, Germany
| |
Collapse
|
26
|
Vazana Y, Barak Y, Unger T, Peleg Y, Shamshoum M, Ben-Yehezkel T, Mazor Y, Shapiro E, Lamed R, Bayer EA. A synthetic biology approach for evaluating the functional contribution of designer cellulosome components to deconstruction of cellulosic substrates. BIOTECHNOLOGY FOR BIOFUELS 2013; 6:182. [PMID: 24341331 PMCID: PMC3878649 DOI: 10.1186/1754-6834-6-182] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2013] [Accepted: 11/27/2013] [Indexed: 05/04/2023]
Abstract
BACKGROUND Select cellulolytic bacteria produce multi-enzymatic cellulosome complexes that bind to the plant cell wall and catalyze its efficient degradation. The multi-modular interconnecting cellulosomal subunits comprise dockerin-containing enzymes that bind cohesively to cohesin-containing scaffoldins. The organization of the modules into functional polypeptides is achieved by intermodular linkers of different lengths and composition, which provide flexibility to the complex and determine its overall architecture. RESULTS Using a synthetic biology approach, we systematically investigated the spatial organization of the scaffoldin subunit and its effect on cellulose hydrolysis by designing a combinatorial library of recombinant trivalent designer scaffoldins, which contain a carbohydrate-binding module (CBM) and 3 divergent cohesin modules. The positions of the individual modules were shuffled into 24 different arrangements of chimaeric scaffoldins. This basic set was further extended into three sub-sets for each arrangement with intermodular linkers ranging from zero (no linkers), 5 (short linkers) and native linkers of 27-35 amino acids (long linkers). Of the 72 possible scaffoldins, 56 were successfully cloned and 45 of them expressed, representing 14 full sets of chimaeric scaffoldins. The resultant 42-component scaffoldin library was used to assemble designer cellulosomes, comprising three model C. thermocellum cellulases. Activities were examined using Avicel as a pure microcrystalline cellulose substrate and pretreated cellulose-enriched wheat straw as a model substrate derived from a native source. All scaffoldin combinations yielded active trivalent designer cellulosome assemblies on both substrates that exceeded the levels of the free enzyme systems. A preferred modular arrangement for the trivalent designer scaffoldin was not observed for the three enzymes used in this study, indicating that they could be integrated at any position in the designer cellulosome without significant effect on cellulose-degrading activity. Designer cellulosomes assembled with the long-linker scaffoldins achieved higher levels of activity, compared to those assembled with short-and no-linker scaffoldins. CONCLUSIONS The results demonstrate the robustness of the cellulosome system. Long intermodular scaffoldin linkers are preferable, thus leading to enhanced degradation of cellulosic substrates, presumably due to the increased flexibility and spatial positioning of the attached enzymes in the complex. These findings provide a general basis for improved designer cellulosome systems as a platform for bioethanol production.
Collapse
Affiliation(s)
- Yael Vazana
- Department of Biological Chemistry, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - Yoav Barak
- Chemical Research Support, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - Tamar Unger
- Structural Proteomics, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - Yoav Peleg
- Structural Proteomics, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - Melina Shamshoum
- Department of Biological Chemistry, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - Tuval Ben-Yehezkel
- Department of Biological Chemistry, The Weizmann Institute of Science, Rehovot 76100, Israel
- Department of Computer Science and Applied Mathematics, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - Yair Mazor
- Department of Biological Chemistry, The Weizmann Institute of Science, Rehovot 76100, Israel
- Department of Computer Science and Applied Mathematics, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - Ehud Shapiro
- Department of Biological Chemistry, The Weizmann Institute of Science, Rehovot 76100, Israel
- Department of Computer Science and Applied Mathematics, The Weizmann Institute of Science, Rehovot 76100, Israel
| | - Raphael Lamed
- Department of Molecular Microbiology and Biotechnology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Ramat Aviv 69978, Israel
| | - Edward A Bayer
- Department of Biological Chemistry, The Weizmann Institute of Science, Rehovot 76100, Israel
| |
Collapse
|
27
|
Establishment of a simple Lactobacillus plantarum cell consortium for cellulase-xylanase synergistic interactions. Appl Environ Microbiol 2013; 79:5242-9. [PMID: 23811500 DOI: 10.1128/aem.01211-13] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Lactobacillus plantarum is an attractive candidate for bioprocessing of lignocellulosic biomass due to its high metabolic variability, including its ability to ferment both pentoses and hexoses, as well as its high acid tolerance, a quality often utilized in industrial processes. This bacterium grows naturally on biomass; however, it lacks the inherent ability to deconstruct lignocellulosic substrates. As a first step toward engineering lignocellulose-converting lactobacilli, we have introduced genes coding for a GH6 cellulase and a GH11 xylanase from a highly active cellulolytic bacterium into L. plantarum. For this purpose, we employed the recently developed pSIP vectors for efficient secretion of heterologous proteins. Both enzymes were secreted by L. plantarum at levels estimated at 0.33 nM and 3.3 nM, for the cellulase and xylanase, respectively, in culture at an optical density at 600 nm (OD600) of 1. Transformed cells demonstrated the ability to degrade individually either cellulose or xylan and wheat straw. When mixed together to form a two-strain cell-based consortium secreting both cellulase and xylanase, they exhibited synergistic activity in the overall release of soluble sugar from wheat straw. This result paves the way toward metabolic harnessing of L. plantarum for novel biorefining applications, such as production of ethanol and polylactic acid directly from plant biomass.
Collapse
|
28
|
|
29
|
Gomez del Pulgar EM, Saadeddin A. The cellulolytic system ofThermobifida fusca. Crit Rev Microbiol 2013; 40:236-47. [DOI: 10.3109/1040841x.2013.776512] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
|
30
|
Currie DH, Herring CD, Guss AM, Olson DG, Hogsett DA, Lynd LR. Functional heterologous expression of an engineered full length CipA from Clostridium thermocellum in Thermoanaerobacterium saccharolyticum. BIOTECHNOLOGY FOR BIOFUELS 2013; 6:32. [PMID: 23448319 PMCID: PMC3598777 DOI: 10.1186/1754-6834-6-32] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2012] [Accepted: 02/08/2013] [Indexed: 05/04/2023]
Abstract
BACKGROUND Cellulose is highly recalcitrant and thus requires a specialized suite of enzymes to solubilize it into fermentable sugars. In C. thermocellum, these extracellular enzymes are present as a highly active multi-component system known as the cellulosome. This study explores the expression of a critical C. thermocellum cellulosomal component in T. saccharolyticum as a step toward creating a thermophilic bacterium capable of consolidated bioprocessing by employing heterologously expressed cellulosomes. RESULTS We developed an inducible promoter system based on the native T. saccharolyticum xynA promoter, which was shown to be induced by xylan and xylose. The promoter was used to express the cellulosomal component cipA*, an engineered form of the wild-type cipA from C. thermocellum. Expression and localization to the supernatant were both verified for CipA*. When a ΔcipA mutant C. thermocellum strain was cultured with a CipA*-expressing T. saccharolyticum strain, hydrolysis and fermentation of 10 grams per liter SigmaCell 101, a highly crystalline cellulose, were observed. This trans-species complementation of a cipA deletion demonstrated the ability for CipA* to assemble a functional cellulosome. CONCLUSION This study is the first example of an engineered thermophile heterologously expressing a structural component of a cellulosome. To achieve this goal we developed and tested an inducible promoter for controlled expression in T. saccharolyticum as well as a synthetic cipA. In addition, we demonstrate a high degree of hydrolysis (up to 93%) on microcrystalline cellulose.
Collapse
Affiliation(s)
- Devin H Currie
- Thayer School of Engineering, Dartmouth College, Hanover, NH 03755, USA
- Mascoma Corporation, Lebanon, NH 03766, USA
| | | | - Adam M Guss
- Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Daniel G Olson
- Thayer School of Engineering, Dartmouth College, Hanover, NH 03755, USA
| | | | - Lee R Lynd
- Thayer School of Engineering, Dartmouth College, Hanover, NH 03755, USA
- Mascoma Corporation, Lebanon, NH 03766, USA
| |
Collapse
|
31
|
Abstract
Lignocellulosic biomass, the most abundant polymer on Earth, is typically composed of three major constituents: cellulose, hemicellulose, and lignin. The crystallinity of cellulose, hydrophobicity of lignin, and encapsulation of cellulose by the lignin-hemicellulose matrix are three major factors that contribute to the observed recalcitrance of lignocellulose. By means of designer cellulosome technology, we can overcome the recalcitrant properties of lignocellulosic substrates and thus increase the level of native enzymatic degradation. In this context, we have integrated six dockerin-bearing cellulases and xylanases from the highly cellulolytic bacterium, Thermobifida fusca, into a chimeric scaffoldin engineered to bear a cellulose-binding module and the appropriate matching cohesin modules. The resultant hexavalent designer cellulosome represents the most elaborate artificial enzyme composite yet constructed, and the fully functional complex achieved enhanced levels (up to 1.6-fold) of degradation of untreated wheat straw compared to those of the wild-type free enzymes. The action of these designer cellulosomes on wheat straw was 33 to 42% as efficient as the natural cellulosomes of Clostridium thermocellum. In contrast, the reduction of substrate complexity by chemical or biological pretreatment of the substrate removed the advantage of the designer cellulosomes, as the free enzymes displayed higher levels of activity, indicating that enzyme proximity between these selected enzymes was less significant on pretreated substrates. Pretreatment of the substrate caused an increase in activity for all the systems, and the native cellulosome completely converted the substrate into soluble saccharides. IMPORTANCE Cellulosic biomass is a potential alternative resource which could satisfy future demands of transportation fuel. However, overcoming the natural lignocellulose recalcitrance remains challenging. Current research and development efforts have concentrated on the efficient cellulose-degrading strategies of cellulosome-producing anaerobic bacteria. Cellulosomes are multienzyme complexes capable of converting the plant cell wall polysaccharides into soluble sugar products en route to biofuels as an alternative to fossil fuels. Using a designer cellulosome approach, we have constructed the largest form of homogeneous artificial cellulosomes reported to date, which bear a total of six different cellulases and xylanases from the highly cellulolytic bacterium Thermobifida fusca. These designer cellulosomes were comparable in size to natural cellulosomes and displayed enhanced synergistic activities compared to their free wild-type enzyme counterparts. Future efforts should be invested to improve these processes to approach or surpass the efficiency of natural cellulosomes for cost-effective production of biofuels.
Collapse
|
32
|
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.
Collapse
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
| |
Collapse
|
33
|
Mini-scaffoldin enhanced mini-cellulosome hydrolysis performance on low-accessibility cellulose (Avicel) more than on high-accessibility amorphous cellulose. Biochem Eng J 2012. [DOI: 10.1016/j.bej.2012.01.011] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
|
34
|
Moraïs S, Lamed R, Bayer EA. Affinity electrophoresis as a method for determining substrate-binding specificity of carbohydrate-active enzymes for soluble polysaccharides. Methods Mol Biol 2012; 908:119-127. [PMID: 22843395 DOI: 10.1007/978-1-61779-956-3_12] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Affinity electrophoresis is a simple and rapid tool for the analysis of protein-binding affinities to soluble polysaccharides. This approach is particularly suitable for the characterization of the carbohydrate-active enzymes that contain a carbohydrate-binding module and for their mutants and chimeras. Knowledge of the binding characteristics of these enzymes can be the first step to elucidate the enzymatic activity of a putative enzyme; moreover in some cases, enzymes are able to bind polysaccharides targets other than their specified substrate, and this knowledge can be essential to understand the basics of the intrinsic mechanism of these enzymes in their natural environment.
Collapse
Affiliation(s)
- Sarah Moraïs
- Department of Biological Chemistry, The Weizmann Institute of Science, Rehovot, Israel
| | | | | |
Collapse
|
35
|
Vazana Y, Moraïs S, Barak Y, Lamed R, Bayer EA. Designer cellulosomes for enhanced hydrolysis of cellulosic substrates. Methods Enzymol 2012; 510:429-52. [PMID: 22608740 DOI: 10.1016/b978-0-12-415931-0.00023-9] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
During the past several years, major progress has been accomplished in the production of "designer cellulosomes," artificial enzymatic complexes that were demonstrated to efficiently degrade crystalline cellulose. This progress is part of a global attempt to promote biomass waste solutions and biofuel production. In designer cellulosomes, each enzyme is equipped with a dockerin module that interacts specifically with one of the cohesin modules of the chimeric scaffoldin. Artificial scaffoldins serve as docking backbones and contain a cellulose-specific carbohydrate-binding module that directs the enzymatic complex to the cellulosic substrate, and one or more cohesin modules from different natural cellulosomal species, each exhibiting a different specificity, that allows the specific incorporation of the desired matching dockerin-bearing enzymes. With natural cellulosomal components, the insertion of the enzymes in the scaffold would presumably be random, and we would not be able to control the contents of the resulting artificial cellulosome. There are an increasing number of papers describing the production of designer cellulosomes either in vitro, ex vivo, or in vivo. These types of studies are particularly intricate, and a number of such publications are less meaningful in the final analysis, as important controls are frequently excluded. In this chapter, we hope to give a complete overview of the methodologies essential for designing and examining cellulosome complexes.
Collapse
Affiliation(s)
- Yael Vazana
- Department of Biological Chemistry, The Weizmann Institute of Science, Rehovot, Israel
| | | | | | | | | |
Collapse
|
36
|
Assembly of xylanases into designer cellulosomes promotes efficient hydrolysis of the xylan component of a natural recalcitrant cellulosic substrate. mBio 2011; 2:mBio.00233-11. [PMID: 22086489 PMCID: PMC3221603 DOI: 10.1128/mbio.00233-11] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED In nature, the complex composition and structure of the plant cell wall pose a barrier to enzymatic degradation. Nevertheless, some anaerobic bacteria have evolved for this purpose an intriguing, highly efficient multienzyme complex, the cellulosome, which contains numerous cellulases and hemicellulases. The rod-like cellulose component of the plant cell wall is embedded in a colloidal blend of hemicelluloses, a major component of which is xylan. In order to enhance enzymatic degradation of the xylan component of a natural complex substrate (wheat straw) and to study the synergistic action among different xylanases, we have employed a variation of the designer cellulosome approach by fabricating a tetravalent complex that includes the three endoxylanases of Thermobifida fusca (Xyn10A, Xyn10B, and Xyn11A) and an Xyl43A β-xylosidase from the same bacterium. Here, we describe the conversion of Xyn10A and Xyl43A to the cellulosomal mode. The incorporation of the Xyl43A enzyme together with the three endoxylanases into a common designer cellulosome served to enhance the level of reducing sugars produced during wheat straw degradation. The enhanced synergistic action of the four xylanases reflected their immediate juxtaposition in the complex, and these tetravalent xylanolytic designer cellulosomes succeeded in degrading significant (~25%) levels of the total xylan component of the wheat straw substrate. The results suggest that the incorporation of xylanases into cellulosome complexes is advantageous for efficient decomposition of recalcitrant cellulosic substrates--a distinction previously reserved for cellulose-degrading enzymes. IMPORTANCE Xylanases are important enzymes for our society, due to their variety of industrial applications. Together with cellulases and other glycoside hydrolases, xylanases may also provide cost-effective conversion of plant-derived cellulosic biomass into soluble sugars en route to biofuels as an alternative to fossil fuels. Xylanases are commonly found in multienzyme cellulosome complexes, produced by anaerobic bacteria, which are considered to be among the most efficient systems for degradation of cellulosic biomass. Using a designer cellulosome approach, we have incorporated the entire xylanolytic system of the bacterium Thermobifida fusca into defined artificial cellulosome complexes. The combined action of these designer cellulosomes versus that of the wild-type free xylanase system was then compared. Our data demonstrated that xylanolytic designer cellulosomes displayed enhanced synergistic activities on a natural recalcitrant wheat straw substrate and could thus serve in the development of advanced systems for improved degradation of lignocellulosic material.
Collapse
|
37
|
Anderson TD, Robson SA, Jiang XW, Malmirchegini GR, Fierobe HP, Lazazzera BA, Clubb RT. Assembly of minicellulosomes on the surface of Bacillus subtilis. Appl Environ Microbiol 2011; 77:4849-58. [PMID: 21622797 PMCID: PMC3147385 DOI: 10.1128/aem.02599-10] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2010] [Accepted: 05/13/2011] [Indexed: 11/20/2022] Open
Abstract
To cost-efficiently produce biofuels, new methods are needed to convert lignocellulosic biomass into fermentable sugars. One promising approach is to degrade biomass using cellulosomes, which are surface-displayed multicellulase-containing complexes present in cellulolytic Clostridium and Ruminococcus species. In this study we created cellulolytic strains of Bacillus subtilis that display one or more cellulase enzymes. Proteins containing the appropriate cell wall sorting signal are covalently anchored to the peptidoglycan by coexpressing them with the Bacillus anthracis sortase A (SrtA) transpeptidase. This approach was used to covalently attach the Cel8A endoglucanase from Clostridium thermocellum to the cell wall. In addition, a Cel8A-dockerin fusion protein was anchored on the surface of B. subtilis via noncovalent interactions with a cell wall-attached cohesin module. We also demonstrate that it is possible to assemble multienzyme complexes on the cell surface. A three-enzyme-containing minicellulosome was displayed on the cell surface; it consisted of a cell wall-attached scaffoldin protein noncovalently bound to three cellulase-dockerin fusion proteins that were produced in Escherichia coli. B. subtilis has a robust genetic system and is currently used in a wide range of industrial processes. Thus, grafting larger, more elaborate minicellulosomes onto the surface of B. subtilis may yield cellulolytic bacteria with increased potency that can be used to degrade biomass.
Collapse
Affiliation(s)
| | | | | | | | | | - Beth A. Lazazzera
- Molecular Biology Institute
- Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, 611 Charles E. Young Drive, Los Angeles, California 90095-1570
| | - Robert T. Clubb
- Department of Chemistry and Biochemistry
- UCLA-DOE Institute for Genomics and Proteomics
- Molecular Biology Institute
| |
Collapse
|
38
|
Comparison of family 9 cellulases from mesophilic and thermophilic bacteria. Appl Environ Microbiol 2010; 77:1436-42. [PMID: 21169454 DOI: 10.1128/aem.01802-10] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cellulases containing a family 9 catalytic domain and a family 3c cellulose binding module (CBM3c) are important components of bacterial cellulolytic systems. We measured the temperature dependence of the activities of three homologs: Clostridium cellulolyticum Cel9G, Thermobifida fusca Cel9A, and C. thermocellum Cel9I. To directly compare their catalytic activities, we constructed six new versions of the enzymes in which the three GH9-CBM3c domains were fused to a dockerin both with and without a T. fusca fibronectin type 3 homology module (Fn3). We studied the activities of these enzymes on crystalline cellulose alone and in complex with a miniscaffoldin containing a cohesin and a CBM3a. The presence of Fn3 had no measurable effect on thermostability or cellulase activity. The GH9-CBM3c domains of Cel9A and Cel9I, however, were more active than the wild type when fused to a dockerin complexed to scaffoldin. The three cellulases in complex have similar activities on crystalline cellulose up to 60°C, but C. thermocellum Cel9I, the most thermostable of the three, remains highly active up to 80°C, where its activity is 1.9 times higher than at 60°C. We also compared the temperature-dependent activities of different versions of Cel9I (wild type or in complex with a miniscaffoldin) and found that the thermostable CBM is necessary for activity on crystalline cellulose at high temperatures. These results illustrate the significant benefits of working with thermostable enzymes at high temperatures, as well as the importance of retaining the stability of all modules involved in cellulose degradation.
Collapse
|
39
|
Cellulase-xylanase synergy in designer cellulosomes for enhanced degradation of a complex cellulosic substrate. mBio 2010; 1. [PMID: 21157512 PMCID: PMC2999897 DOI: 10.1128/mbio.00285-10] [Citation(s) in RCA: 89] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2010] [Accepted: 11/16/2010] [Indexed: 11/20/2022] Open
Abstract
Designer cellulosomes are precision-engineered multienzyme complexes in which the molecular architecture and enzyme content are exquisitely controlled. This system was used to examine enzyme cooperation for improved synergy among Thermobifida fusca glycoside hydrolases. Two T. fusca cellulases, Cel48A exoglucanase and Cel5A endoglucanase, and two T. fusca xylanases, endoxylanases Xyn10B and Xyn11A, were selected as enzymatic components of a mixed cellulase/xylanase-containing designer cellulosome. The resultant mixed multienzyme complex was fabricated on a single scaffoldin subunit bearing all four enzymes. Conversion of T. fusca enzymes to the cellulosomal mode followed by their subsequent incorporation into a tetravalent cellulosome led to assemblies with enhanced activity (~2.4-fold) on wheat straw as a complex cellulosic substrate. The enhanced synergy was caused by the proximity of the enzymes on the complex compared to the free-enzyme systems. The hydrolytic properties of the tetravalent designer cellulosome were compared with the combined action of two separate divalent cellulase- and xylanase-containing cellulosomes. Significantly, the tetravalent designer cellulosome system exhibited an ~2-fold enhancement in enzymatic activity compared to the activity of the mixture of two distinct divalent scaffoldin-borne enzymes. These results provide additional evidence that close proximity between cellulases and xylanases is key to the observed concerted degradation of the complex cellulosic substrate in which the integrated enzymes complement each other by promoting access to the relevant polysaccharide components of the substrate. The data demonstrate that cooperation among xylanases and cellulases can be augmented by their integration into a single designer cellulosome. Global efforts towards alternative energy programs are highlighted by processes for converting plant-derived carbohydrates to biofuels. The major barrier in such processes is the inherent recalcitrance to enzymatic degradation of cellulose combined with related associated polysaccharides. The multienzyme cellulosome complexes, produced by anaerobic bacteria, are considered to be the most efficient systems for degradation of plant cell wall biomass. In the present work, we have employed a synthetic biology approach by producing artificial designer cellulosomes of predefined enzyme composition and architecture. The engineered tetravalent cellulosome complexes contain two different types of cellulases and two distinct xylanases. Using this approach, enhanced synergistic activity was observed on wheat straw, a natural recalcitrant substrate. The present work strives to gain insight into the combined action of cellulosomal enzyme components towards the development of advanced systems for improved degradation of cellulosic material.
Collapse
|
40
|
Elkins JG, Raman B, Keller M. Engineered microbial systems for enhanced conversion of lignocellulosic biomass. Curr Opin Biotechnol 2010; 21:657-62. [DOI: 10.1016/j.copbio.2010.05.008] [Citation(s) in RCA: 76] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2010] [Accepted: 05/27/2010] [Indexed: 11/16/2022]
|
41
|
Dashtban M, Maki M, Leung KT, Mao C, Qin W. Cellulase activities in biomass conversion: measurement methods and comparison. Crit Rev Biotechnol 2010; 30:302-9. [DOI: 10.3109/07388551.2010.490938] [Citation(s) in RCA: 167] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
|
42
|
Moraïs S, Heyman A, Barak Y, Caspi J, Wilson DB, Lamed R, Shoseyov O, Bayer EA. Enhanced cellulose degradation by nano-complexed enzymes: Synergism between a scaffold-linked exoglucanase and a free endoglucanase. J Biotechnol 2010; 147:205-11. [PMID: 20438772 DOI: 10.1016/j.jbiotec.2010.04.012] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2010] [Revised: 04/13/2010] [Accepted: 04/23/2010] [Indexed: 11/19/2022]
Abstract
Protein molecular scaffolds are attracting interest as natural candidates for the presentation of enzymes and acceleration of catalytic reactions. We have previously reported evidence that the stable protein 1 (SP1) from Populustremula can be employed as a molecular scaffold for the presentation of either catalytic or structural binding (cellulosomal cohesin) modules. In the present work, we have displayed a potent exoglucanase (Cel6B) from the aerobic cellulolytic bacterium, Thermobifida fusca, on a cohesin-bearing SP1 scaffold. For this purpose, a chimaeric form of the enzyme, fused to a cellulosomal dockerin module, was prepared. Full incorporation of 12 dockerin-bearing exoglucanase molecules onto the cohesin-bearing scaffold was achieved. Cellulase activity was tested on two cellulosic substrates with different levels of crystallinity, and the activity of the scaffold-linked exoglucanase was significantly reduced, compared to the free dockerin-containing enzyme. However, addition of relatively low concentrations of a free wild-type endoglucanase (T. fusca Cel5A) that bears a cellulose-binding module, in combination with the complexed exoglucanase resulted in a marked rise in activity on both cellulosic substrates. The endoglucanase cleaves internal sites of the cellulose chains, and the new chain ends of the substrate were now readily accessible to the scaffold-borne exoglucanase, thereby resulting in highly effective, synergistic degradation of cellulosic substrates.
Collapse
Affiliation(s)
- Sarah Moraïs
- Department of Biological Chemistry, The Weizmann Institute of Science, Rehovot, Israel
| | | | | | | | | | | | | | | |
Collapse
|
43
|
LIU CL, WANG XF, WANG XJ, LI PP, CUI ZJ. The Character of Normal Temperature Straw-Rotting Microbial Community. ACTA ACUST UNITED AC 2010. [DOI: 10.1016/s1671-2927(09)60147-4] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
|
44
|
Vazana Y, Moraïs S, Barak Y, Lamed R, Bayer EA. Interplay between Clostridium thermocellum family 48 and family 9 cellulases in cellulosomal versus noncellulosomal states. Appl Environ Microbiol 2010; 76:3236-43. [PMID: 20348303 PMCID: PMC2869131 DOI: 10.1128/aem.00009-10] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2010] [Accepted: 03/16/2010] [Indexed: 11/20/2022] Open
Abstract
The anaerobic, thermophilic cellulolytic bacterium Clostridium thermocellum is known for its elaborate cellulosome complex, but it also produces a separate free cellulase system. Among the free enzymes, the noncellulosomal enzyme Cel9I is a processive endoglucanase whose sequence and architecture are very similar to those of the cellulosomal enzyme Cel9R; likewise, the noncellulosomal exoglucanase Cel48Y is analogous to the principal cellulosomal enzyme Cel48S. In this study we used the designer cellulosome approach to examine the interplay of prominent cellulosomal and noncellulosomal cellulases from C. thermocellum. Toward this end, we converted the cellulosomal enzymes to noncellulosomal chimeras by swapping the dockerin module of the cellulosomal enzymes with a carbohydrate-binding module from the free enzyme analogues and vice versa. This enabled us to study the importance of the targeting effect of the free enzymes due to their carbohydrate-binding module and the proximity effect for cellulases on the designer cellulosome. C. thermocellum is the only cellulosome-producing bacterium known to express two different glycoside hydrolase family 48 enzymes and thus the only bacterial system that can currently be used for such studies. The different activities with crystalline cellulose were examined, and the results demonstrated that the individual chimeric cellulases were essentially equivalent to the corresponding wild-type analogues. The wild-type cellulases displayed a synergism of about 1.5-fold; the cellulosomal pair acted synergistically when they were converted into free enzymes, whereas the free enzymes acted synergistically mainly in the wild-type state. The targeting effect was found to be the major factor responsible for the elevated activity observed for these specific enzyme combinations, whereas the proximity effect appeared to play a negligible role.
Collapse
Affiliation(s)
- Yael Vazana
- Department of Biological Chemistry, Chemical Research Support, The Weizmann Institute of Science, Rehovot 76100, Israel, Department of Molecular Microbiology and Biotechnology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Ramat Aviv 69978, Israel
| | - Sarah Moraïs
- Department of Biological Chemistry, Chemical Research Support, The Weizmann Institute of Science, Rehovot 76100, Israel, Department of Molecular Microbiology and Biotechnology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Ramat Aviv 69978, Israel
| | - Yoav Barak
- Department of Biological Chemistry, Chemical Research Support, The Weizmann Institute of Science, Rehovot 76100, Israel, Department of Molecular Microbiology and Biotechnology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Ramat Aviv 69978, Israel
| | - Raphael Lamed
- Department of Biological Chemistry, Chemical Research Support, The Weizmann Institute of Science, Rehovot 76100, Israel, Department of Molecular Microbiology and Biotechnology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Ramat Aviv 69978, Israel
| | - Edward A. Bayer
- Department of Biological Chemistry, Chemical Research Support, The Weizmann Institute of Science, Rehovot 76100, Israel, Department of Molecular Microbiology and Biotechnology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Ramat Aviv 69978, Israel
| |
Collapse
|
45
|
Thermobifida fusca exoglucanase Cel6B is incompatible with the cellulosomal mode in contrast to endoglucanase Cel6A. SYSTEMS AND SYNTHETIC BIOLOGY 2010; 4:193-201. [PMID: 21886683 DOI: 10.1007/s11693-010-9056-1] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2009] [Revised: 04/06/2010] [Accepted: 04/15/2010] [Indexed: 10/19/2022]
Abstract
Cellulosomes are efficient cellulose-degradation systems produced by selected anaerobic bacteria. This multi-enzyme complex is assembled from a group of cellulases attached to a protein scaffold termed scaffoldin, mediated by a high-affinity protein-protein interaction between the enzyme-borne dockerin module and the cohesin module of the scaffoldin. The enzymatic complex is attached as a whole to the cellulosic substrate via a cellulose-binding module (CBM) on the scaffoldin subunit. In previous works, we have employed a synthetic biology approach to convert several of the free cellulases of the aerobic bacterium, Thermobifida fusca, into the cellulosomal mode by replacing each of the enzymes' CBM with a dockerin. Here we show that although family six enzymes are not a part of any known cellulosomal system, the two family six enzymes of the T. fusca system (endoglucanase Cel6A and exoglucanase Cel6B) can be converted to work as cellulosomal enzymes. Indeed, the chimaeric dockerin-containing family six endoglucanase worked well as a cellulosomal enzyme, and proved to be more efficient than the parent enzyme when present in designer cellulosomes. In stark contrast, the chimaeric family six exoglucanase was markedly less efficient than the wild-type enzyme when mixed with other T. fusca cellulases, thus indicating its incompatibility with the cellulosomal mode of action.
Collapse
|
46
|
Contribution of a xylan-binding module to the degradation of a complex cellulosic substrate by designer cellulosomes. Appl Environ Microbiol 2010; 76:3787-96. [PMID: 20400556 DOI: 10.1128/aem.00266-10] [Citation(s) in RCA: 48] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Conversion of components of the Thermobifida fusca free-enzyme system to the cellulosomal mode using the designer cellulosome approach can be employed to discover the properties and inherent advantages of the cellulosome system. In this article, we describe the conversion of the T. fusca xylanases Xyn11A and Xyn10B and their synergistic interaction in the free state or within designer cellulosome complexes in order to enhance specific degradation of hatched wheat straw as a model for a complex cellulosic substrate. Endoglucanase Cel5A from the same bacterium and its recombinant dockerin-containing chimera were also studied for their combined effect, together with the xylanases, on straw degradation. Synergism was demonstrated when Xyn11A was combined with Xyn10B and/or Cel5A, and approximately 1.5-fold activity enhancements were achieved by the designer cellulosome complexes compared to the free wild-type enzymes. These improvements in activity were due to both substrate-targeting and proximity effects among the enzymes contained in the designer cellulosome complexes. The intrinsic cellulose/xylan-binding module (XBM) of Xyn11A appeared to be essential for efficient substrate degradation. Indeed, only designer cellulosomes in which the XBM was maintained as a component of Xyn11A achieved marked enhancement in activity compared to the combination of wild-type enzymes. Moreover, integration of the XBM in designer cellulosomes via a dockerin module (separate from the Xyn11A catalytic module) failed to enhance activity, suggesting a role in orienting the parent xylanase toward its preferred polysaccharide component of the complex wheat straw substrate. The results provide novel mechanistic insight into the synergistic activity of designer cellulosome components on natural plant cell wall substrates.
Collapse
|
47
|
Fontes CMGA, Gilbert HJ. Cellulosomes: highly efficient nanomachines designed to deconstruct plant cell wall complex carbohydrates. Annu Rev Biochem 2010; 79:655-81. [PMID: 20373916 DOI: 10.1146/annurev-biochem-091208-085603] [Citation(s) in RCA: 362] [Impact Index Per Article: 25.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Cellulosomes can be described as one of nature's most elaborate and highly efficient nanomachines. These cell bound multienzyme complexes orchestrate the deconstruction of cellulose and hemicellulose, two of the most abundant polymers on Earth, and thus play a major role in carbon turnover. Integration of cellulosomal components occurs via highly ordered protein:protein interactions between cohesins and dockerins, whose specificity allows the incorporation of cellulases and hemicellulases onto a molecular scaffold. Cellulosome assembly promotes the exploitation of enzyme synergism because of spatial proximity and enzyme-substrate targeting. Recent structural and functional studies have revealed how cohesin-dockerin interactions mediate both cellulosome assembly and cell-surface attachment, while retaining the spatial flexibility required to optimize the catalytic synergy within the enzyme complex. These emerging advances in our knowledge of cellulosome function are reviewed here.
Collapse
Affiliation(s)
- Carlos M G A Fontes
- CIISA, Faculdade de Medicina Veterinária, Universidade Técnica de Lisboa, 1300-477 Lisboa, Portugal.
| | | |
Collapse
|
48
|
Yeast surface display of trifunctional minicellulosomes for simultaneous saccharification and fermentation of cellulose to ethanol. Appl Environ Microbiol 2009; 76:1251-60. [PMID: 20023102 DOI: 10.1128/aem.01687-09] [Citation(s) in RCA: 152] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
By combining cellulase production, cellulose hydrolysis, and sugar fermentation into a single step, consolidated bioprocessing (CBP) represents a promising technology for biofuel production. Here we report engineering of Saccharomyces cerevisiae strains displaying a series of uni-, bi-, and trifunctional minicellulosomes. These minicellulosomes consist of (i) a miniscaffoldin containing a cellulose-binding domain and three cohesin modules, which was tethered to the cell surface through the yeast a-agglutinin adhesion receptor, and (ii) up to three types of cellulases, an endoglucanase, a cellobiohydrolase, and a beta-glucosidase, each bearing a C-terminal dockerin. Cell surface assembly of the minicellulosomes was dependent on expression of the miniscaffoldin, indicating that formation of the complex was dictated by the high-affinity interactions between cohesins and dockerins. Compared to the unifunctional and bifunctional minicellulosomes, the quaternary trifunctional complexes showed enhanced enzyme-enzyme synergy and enzyme proximity synergy. More importantly, surface display of the trifunctional minicellulosomes gave yeast cells the ability to simultaneously break down and ferment phosphoric acid-swollen cellulose to ethanol with a titer of approximately 1.8 g/liter. To our knowledge, this is the first report of a recombinant yeast strain capable of producing cell-associated trifunctional minicellulosomes. The strain reported here represents a useful engineering platform for developing CBP-enabling microorganisms and elucidating principles of cellulosome construction and mode of action.
Collapse
|
49
|
Effect of linker length and dockerin position on conversion of a Thermobifida fusca endoglucanase to the cellulosomal mode. Appl Environ Microbiol 2009; 75:7335-42. [PMID: 19820154 DOI: 10.1128/aem.01241-09] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We have been developing the cellulases of Thermobifida fusca as a model to explore the conversion from a free cellulase system to the cellulosomal mode. Three of the six T. fusca cellulases (endoglucanase Cel6A and exoglucanases Cel6B and Cel48A) have been converted in previous work by replacing their cellulose-binding modules (CBMs) with a dockerin, and the resultant recombinant "cellulosomized" enzymes were incorporated into chimeric scaffolding proteins that contained cohesin(s) together with a CBM. The activities of the resultant designer cellulosomes were compared with an equivalent mixture of wild-type enzymes. In the present work, a fourth T. fusca cellulase, Cel5A, was equipped with a dockerin and intervening linker segments of different lengths to assess their contribution to the overall activity of simple one- and two-enzyme designer cellulosome complexes. The results demonstrated that cellulose binding played a major role in the degradation of crystalline cellulosic substrates. The combination of the converted Cel5A endoglucanase with the converted Cel48A exoglucanase also exhibited a measurable proximity effect for the most recalcitrant cellulosic substrate (Avicel). The length of the linker between the catalytic module and the dockerin had little, if any, effect on the activity. However, positioning of the dockerin on the opposite (C-terminal) side of the enzyme, consistent with the usual position of dockerins on most cellulosomal enzymes, resulted in an enhanced synergistic response. These results promote the development of more complex multienzyme designer cellulosomes, which may eventually be applied for improved degradation of plant cell wall biomass.
Collapse
|
50
|
Maki M, Leung KT, Qin W. The prospects of cellulase-producing bacteria for the bioconversion of lignocellulosic biomass. Int J Biol Sci 2009; 5:500-16. [PMID: 19680472 PMCID: PMC2726447 DOI: 10.7150/ijbs.5.500] [Citation(s) in RCA: 261] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2009] [Accepted: 07/21/2009] [Indexed: 11/05/2022] Open
Abstract
Lignocellulosic biomass is a renewable and abundant resource with great potential for bioconversion to value-added bioproducts. However, the biorefining process remains economically unfeasible due to a lack of biocatalysts that can overcome costly hurdles such as cooling from high temperature, pumping of oxygen/stirring, and, neutralization from acidic or basic pH. The extreme environmental resistance of bacteria permits screening and isolation of novel cellulases to help overcome these challenges. Rapid, efficient cellulase screening techniques, using cellulase assays and metagenomic libraries, are a must. Rare cellulases with activities on soluble and crystalline cellulose have been isolated from strains of Paenibacillus and Bacillus and shown to have high thermostability and/or activity over a wide pH spectrum. While novel cellulases from strains like Cellulomonas flavigena and Terendinibacter turnerae, produce multifunctional cellulases with broader substrate utilization. These enzymes offer a framework for enhancement of cellulases including: specific activity, thermalstability, or end-product inhibition. In addition, anaerobic bacteria like the clostridia offer potential due to species capable of producing compound multienzyme complexes called cellulosomes. Cellulosomes provide synergy and close proximity of enzymes to substrate, increasing activity towards crystalline cellulose. This has lead to the construction of designer cellulosomes enhanced for specific substrate activity. Furthermore, cellulosome-producing Clostridium thermocellum and its ability to ferment sugars to ethanol; its amenability to co-culture and, recent advances in genetic engineering, offer a promising future in biofuels. The exploitation of bacteria in the search for improved enzymes or strategies provides a means to upgrade feasibility for lignocellulosic biomass conversion, ultimately providing means to a 'greener' technology.
Collapse
Affiliation(s)
- Miranda Maki
- Biorefining Research Initiative, Lakehead University, Thunder Bay, Ontario, Canada
| | | | | |
Collapse
|