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Gruninger RJ, Puniya AK, Callaghan TM, Edwards JE, Youssef N, Dagar SS, Fliegerova K, Griffith GW, Forster R, Tsang A, McAllister T, Elshahed MS. Anaerobic fungi (phylum Neocallimastigomycota): advances in understanding their taxonomy, life cycle, ecology, role and biotechnological potential. FEMS Microbiol Ecol 2014; 90:1-17. [PMID: 25046344 DOI: 10.1111/1574-6941.12383] [Citation(s) in RCA: 202] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2014] [Revised: 07/03/2014] [Accepted: 07/07/2014] [Indexed: 02/05/2023] Open
Abstract
Anaerobic fungi (phylum Neocallimastigomycota) inhabit the gastrointestinal tract of mammalian herbivores, where they play an important role in the degradation of plant material. The Neocallimastigomycota represent the earliest diverging lineage of the zoosporic fungi; however, understanding of the relationships of the different taxa (both genera and species) within this phylum is in need of revision. Issues exist with the current approaches used for their identification and classification, and recent evidence suggests the presence of several novel taxa (potential candidate genera) that remain to be characterised. The life cycle and role of anaerobic fungi has been well characterised in the rumen, but not elsewhere in the ruminant alimentary tract. Greater understanding of the 'resistant' phase(s) of their life cycle is needed, as is study of their role and significance in other herbivores. Biotechnological application of anaerobic fungi, and their highly active cellulolytic and hemi-cellulolytic enzymes, has been a rapidly increasing area of research and development in the last decade. The move towards understanding of anaerobic fungi using -omics based (genomic, transcriptomic and proteomic) approaches is starting to yield valuable insights into the unique cellular processes, evolutionary history, metabolic capabilities and adaptations that exist within the Neocallimastigomycota.
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Cheng YS, Chen CC, Huang CH, Ko TP, Luo W, Huang JW, Liu JR, Guo RT. Structural analysis of a glycoside hydrolase family 11 xylanase from Neocallimastix patriciarum: insights into the molecular basis of a thermophilic enzyme. J Biol Chem 2014; 289:11020-11028. [PMID: 24619408 DOI: 10.1074/jbc.m114.550905] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The catalytic domain of XynCDBFV, a glycoside hydrolase family 11 (GH11) xylanase from ruminal fungus Neocallimastix patriciarum previously engineered to exhibit higher specific activity and broader pH adaptability, holds great potential in commercial applications. Here, the crystal structures of XynCDBFV and its complex with substrate were determined to 1.27-1.43 Å resolution. These structures revealed a typical GH11 β-jelly-roll fold and detailed interaction networks between the enzyme and ligands. Notably, an extended N-terminal region (NTR) consisting of 11 amino acids was identified in the XynCDBFV structure, which is found unique among GH11 xylanases. The NTR is attached to the catalytic core by hydrogen bonds and stacking forces along with a disulfide bond between Cys-4 and Cys-172. Interestingly, the NTR deletion mutant retained 61.5% and 19.5% enzymatic activity at 55 °C and 75 °C, respectively, compared with the wild-type enzyme, whereas the C4A/C172A mutant showed 86.8% and 23.3% activity. These results suggest that NTR plays a role in XynCDBFV thermostability, and the Cys-4/Cys-172 disulfide bond is critical to the NTR-mediated interactions. Furthermore, we also demonstrated that Pichia pastoris produces XynCDBFV with higher catalytic activity at higher temperature than Escherichia coli, in which incorrect NTR folding and inefficient disulfide bond formation might have occurred. In conclusion, these structural and functional analyses of the industrially favored XynCDBFV provide a molecular basis of NTR contribution to its thermostability.
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Affiliation(s)
- Ya-Shan Cheng
- Genozyme biotechnology Inc., Taipei 106, Taiwan,; AsiaPac Biotechnology Co., Ltd., Dongguan, 523808, China
| | - Chun-Chi Chen
- Industrial Enzymes National Engineering Laboratory, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China
| | - Chun-Hsiang Huang
- Industrial Enzymes National Engineering Laboratory, Tianjin Institute of Industrial Biotechnology, Chinese Academy of Sciences, Tianjin 300308, China
| | - Tzu-Ping Ko
- Institute of Biological Chemistry, Academia Sinica, Taipei 115, Taiwan
| | - Wenhua Luo
- College of Food Science, South China Agricultural University, Guangzhou 510642, China, and
| | - Jian-Wen Huang
- Institute of Biotechnology, National Taiwan University, Taipei 106, Taiwan
| | - Je-Ruei Liu
- Institute of Biotechnology, National Taiwan University, Taipei 106, Taiwan
| | - Rey-Ting Guo
- AsiaPac Biotechnology Co., Ltd., Dongguan, 523808, China,.
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The genome of the anaerobic fungus Orpinomyces sp. strain C1A reveals the unique evolutionary history of a remarkable plant biomass degrader. Appl Environ Microbiol 2013; 79:4620-34. [PMID: 23709508 DOI: 10.1128/aem.00821-13] [Citation(s) in RCA: 156] [Impact Index Per Article: 14.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Anaerobic gut fungi represent a distinct early-branching fungal phylum (Neocallimastigomycota) and reside in the rumen, hindgut, and feces of ruminant and nonruminant herbivores. The genome of an anaerobic fungal isolate, Orpinomyces sp. strain C1A, was sequenced using a combination of Illumina and PacBio single-molecule real-time (SMRT) technologies. The large genome (100.95 Mb, 16,347 genes) displayed extremely low G+C content (17.0%), large noncoding intergenic regions (73.1%), proliferation of microsatellite repeats (4.9%), and multiple gene duplications. Comparative genomic analysis identified multiple genes and pathways that are absent in Dikarya genomes but present in early-branching fungal lineages and/or nonfungal Opisthokonta. These included genes for posttranslational fucosylation, the production of specific intramembrane proteases and extracellular protease inhibitors, the formation of a complete axoneme and intraflagellar trafficking machinery, and a near-complete focal adhesion machinery. Analysis of the lignocellulolytic machinery in the C1A genome revealed an extremely rich repertoire, with evidence of horizontal gene acquisition from multiple bacterial lineages. Experimental analysis indicated that strain C1A is a remarkable biomass degrader, capable of simultaneous saccharification and fermentation of the cellulosic and hemicellulosic fractions in multiple untreated grasses and crop residues examined, with the process significantly enhanced by mild pretreatments. This capability, acquired during its separate evolutionary trajectory in the rumen, along with its resilience and invasiveness compared to prokaryotic anaerobes, renders anaerobic fungi promising agents for consolidated bioprocessing schemes in biofuels production.
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Paës G, Berrin JG, Beaugrand J. GH11 xylanases: Structure/function/properties relationships and applications. Biotechnol Adv 2011; 30:564-92. [PMID: 22067746 DOI: 10.1016/j.biotechadv.2011.10.003] [Citation(s) in RCA: 284] [Impact Index Per Article: 21.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2011] [Revised: 10/06/2011] [Accepted: 10/13/2011] [Indexed: 01/02/2023]
Abstract
For technical, environmental and economical reasons, industrial demands for process-fitted enzymes have evolved drastically in the last decade. Therefore, continuous efforts are made in order to get insights into enzyme structure/function relationships to create improved biocatalysts. Xylanases are hemicellulolytic enzymes, which are responsible for the degradation of the heteroxylans constituting the lignocellulosic plant cell wall. Due to their variety, xylanases have been classified in glycoside hydrolase families GH5, GH8, GH10, GH11, GH30 and GH43 in the CAZy database. In this review, we focus on GH11 family, which is one of the best characterized GH families with bacterial and fungal members considered as true xylanases compared to the other families because of their high substrate specificity. Based on an exhaustive analysis of the sequences and 3D structures available so far, in relation with biochemical properties, we assess biochemical aspects of GH11 xylanases: structure, catalytic machinery, focus on their "thumb" loop of major importance in catalytic efficiency and substrate selectivity, inhibition, stability to pH and temperature. GH11 xylanases have for a long time been used as biotechnological tools in various industrial applications and represent in addition promising candidates for future other uses.
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Affiliation(s)
- Gabriel Paës
- INRA, UMR614 FARE, 2 esplanade Roland-Garros, F-51686 Reims, France.
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Wang TY, Chen HL, Lu MYJ, Chen YC, Sung HM, Mao CT, Cho HY, Ke HM, Hwa TY, Ruan SK, Hung KY, Chen CK, Li JY, Wu YC, Chen YH, Chou SP, Tsai YW, Chu TC, Shih CCA, Li WH, Shih MC. Functional characterization of cellulases identified from the cow rumen fungus Neocallimastix patriciarum W5 by transcriptomic and secretomic analyses. BIOTECHNOLOGY FOR BIOFUELS 2011; 4:24. [PMID: 21849025 PMCID: PMC3177772 DOI: 10.1186/1754-6834-4-24] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/07/2011] [Accepted: 08/17/2011] [Indexed: 05/10/2023]
Abstract
BACKGROUND Neocallimastix patriciarum is one of the common anaerobic fungi in the digestive tracts of ruminants that can actively digest cellulosic materials, and its cellulases have great potential for hydrolyzing cellulosic feedstocks. Due to the difficulty in culture and lack of a genome database, it is not easy to gain a global understanding of the glycosyl hydrolases (GHs) produced by this anaerobic fungus. RESULTS We have developed an efficient platform that uses a combination of transcriptomic and proteomic approaches to N. patriciarum to accelerate gene identification, enzyme classification and application in rice straw degradation. By conducting complementary studies of transcriptome (Roche 454 GS and Illumina GA IIx) and secretome (ESI-Trap LC-MS/MS), we identified 219 putative GH contigs and classified them into 25 GH families. The secretome analysis identified four major enzymes involved in rice straw degradation: β-glucosidase, endo-1,4-β-xylanase, xylanase B and Cel48A exoglucanase. From the sequences of assembled contigs, we cloned 19 putative cellulase genes, including the GH1, GH3, GH5, GH6, GH9, GH18, GH43 and GH48 gene families, which were highly expressed in N. patriciarum cultures grown on different feedstocks. CONCLUSIONS These GH genes were expressed in Pichia pastoris and/or Saccharomyces cerevisiae for functional characterization. At least five novel cellulases displayed cellulytic activity for glucose production. One β-glucosidase (W5-16143) and one exocellulase (W5-CAT26) showed strong activities and could potentially be developed into commercial enzymes.
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Affiliation(s)
- Tzi-Yuan Wang
- Biodiversity Research Center, Academia Sinica, Taipei 115, Taiwan
| | - Hsin-Liang Chen
- Biodiversity Research Center, Academia Sinica, Taipei 115, Taiwan
| | - Mei-Yeh J Lu
- Biodiversity Research Center, Academia Sinica, Taipei 115, Taiwan
- Genomics Research Center, Academia Sinica, Taipei 115, Taiwan
| | - Yo-Chia Chen
- Graduate Institute of Biotechnology, National Pingtung University of Science & Technology, Neipu Hsiang, Pingtung 91201, Taiwan
| | - Huang-Mo Sung
- Department of Life Sciences, National Cheng Kung University, Tainan 701, Taiwan
| | - Chi-Tang Mao
- Biodiversity Research Center, Academia Sinica, Taipei 115, Taiwan
- Molecular and Biological Agricultural Sciences Program, Taiwan International Graduate Program, National Chung-Hsing University - Academia Sinica, Taipei 115, Taiwan
- Graduate Institute of Biotechnology, National Chung-Hsing University, Taichung 402, Taiwan
| | - Hsing-Yi Cho
- Molecular and Biological Agricultural Sciences Program, Taiwan International Graduate Program, National Chung-Hsing University - Academia Sinica, Taipei 115, Taiwan
- Graduate Institute of Biotechnology, National Chung-Hsing University, Taichung 402, Taiwan
- Agricultural Biotechnology Research Center, Academia Sinica, Taipei 115, Taiwan
| | - Huei-Mien Ke
- Biodiversity Research Center, Academia Sinica, Taipei 115, Taiwan
- PhD Program in Microbial Genomics, National Chung Hsing University, Taichung 402, Taiwan
| | - Teh-Yang Hwa
- Genomics Research Center, Academia Sinica, Taipei 115, Taiwan
| | - Sz-Kai Ruan
- Biodiversity Research Center, Academia Sinica, Taipei 115, Taiwan
| | - Kuo-Yen Hung
- Genomics Research Center, Academia Sinica, Taipei 115, Taiwan
| | - Chih-Kuan Chen
- Genomics Research Center, Academia Sinica, Taipei 115, Taiwan
- Department of Life Sciences, National Taiwan University, Taipei 106, Taiwan
| | - Jeng-Yi Li
- Genomics Research Center, Academia Sinica, Taipei 115, Taiwan
| | - Yueh-Chin Wu
- Genomics Research Center, Academia Sinica, Taipei 115, Taiwan
| | - Yu-Hsiang Chen
- Genomics Research Center, Academia Sinica, Taipei 115, Taiwan
| | - Shao-Pei Chou
- Genomics Research Center, Academia Sinica, Taipei 115, Taiwan
| | - Ya-Wen Tsai
- Biodiversity Research Center, Academia Sinica, Taipei 115, Taiwan
| | - Te-Chin Chu
- Institute of Information Science, Academia Sinica, Taipei 115, Taiwan
- Department of Computer Science and Information Engineering, National Taiwan Normal University, Taipei 116, Taiwan
| | - Chun-Chieh A Shih
- Institute of Information Science, Academia Sinica, Taipei 115, Taiwan
| | - Wen-Hsiung Li
- Biodiversity Research Center, Academia Sinica, Taipei 115, Taiwan
- Molecular and Biological Agricultural Sciences Program, Taiwan International Graduate Program, National Chung-Hsing University - Academia Sinica, Taipei 115, Taiwan
- Biotechnology Center, National Chung-Hsing University, Taichung 402, Taiwan
- Department of Ecology and Evolution, University of Chicago, Chicago, IL 60637, USA
| | - Ming-Che Shih
- Molecular and Biological Agricultural Sciences Program, Taiwan International Graduate Program, National Chung-Hsing University - Academia Sinica, Taipei 115, Taiwan
- Agricultural Biotechnology Research Center, Academia Sinica, Taipei 115, Taiwan
- Biotechnology Center, National Chung-Hsing University, Taichung 402, Taiwan
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Cloning of a rumen fungal xylanase gene and purification of the recombinant enzyme via artificial oil bodies. Appl Microbiol Biotechnol 2008; 79:225-33. [PMID: 18415096 DOI: 10.1007/s00253-008-1418-1] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2007] [Revised: 02/14/2008] [Accepted: 02/15/2008] [Indexed: 10/22/2022]
Abstract
A gene encoding a xylanase, named xynS20, was cloned from the ruminal fungus Neocallimastix patriciarum. The DNA sequence of xynS20 revealed that the gene was 1,008 bp in size and encoded amino acid sequences with a predicted molecular weight of 36 kDa. The amino acid sequence alignment showed that the highest sequence identity (28.4%) is with insect gut xylanase XYL6805. According to the sequence-based classification, a putative conserved domain of glycosyl hydrolase family 11 was detected at the N-terminus of XynS20 and a putative conserved domain of family 1 carbohydrate-binding module (CBM) was observed at the C-terminus of XynS20. An Asn-rich linker sequence was found between the N-terminal catalytic domain and the C-terminal CBM of XynS20. To examine the activity of the gene product, xynS20 gene was cloned as an oleosin-fused protein, expressed in Escherichia coli, affinity-purified by formation of artificial oil bodies, released from oleosin by intein-mediated peptide cleavage, and finally harvested by concentration of the supernatant. The specific activity of purified XynS20 toward oat spelt xylan was 1,982.8 U mg(-1). The recombinant XynS20 was stable in the mild acid pH range from 5.0 to 6.0, and the optimum pH was 6.0. The optimal reaction temperature of XynS20 was 45 degrees C; at temperatures below 30 and above 55 degrees C, enzyme activity was less than 50% of that at the optimal temperature.
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Ljungdahl LG. The cellulase/hemicellulase system of the anaerobic fungus Orpinomyces PC-2 and aspects of its applied use. Ann N Y Acad Sci 2008; 1125:308-21. [PMID: 18378601 DOI: 10.1196/annals.1419.030] [Citation(s) in RCA: 110] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
Anaerobic fungi, first described in 1975 by Orpin, live in close contact with bacteria and other microorganisms in the rumen and caecum of herbivorous animals, where they digest ingested plant food. Seventeen distinct anaerobic fungi belonging to five different genera have been described. They have been found in at least 50 different herbivorous animals. Anaerobic fungi do not possess mitochondria, but instead have hydrogenosomes, which form hydrogen and carbon dioxide from pyruvate and malate during fermentation of carbohydrates. In addition, they are very oxygen- and temperature-sensitive, and their DNA has an unusually high AT content of from 72 to 87 mol%. My initial reason for studying anaerobic fungi was because they solubilize lignocellulose and produce all enzymes needed to efficiently hydrolyze cellulose and hemicelluloses. Although some of these enzymes are found free in the medium, most of them are associated with cellulosomal and polycellulosomal complexes, in which the enzymes are attached through fungal dockerins to scaffolding proteins; this is similar to what has been found for cellulosomes from anaerobic bacteria. Although cellulosomes from anaerobic fungi share many properties with cellulosomes of anaerobic cellulolytic bacteria and have comparable structures, their structures differ in their amino acid sequences. I discuss some features of the cellulosome of the anaerobic fungus Orpinomyces sp. PC-2 and some possible uses of its enzymes in industrial settings.
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Affiliation(s)
- Lars G Ljungdahl
- Department of Biochemistry and Molecular Biology, Fred C. Davison Life Sciences Complex, University of Georgia, Athens, GA 30602-7229, USA.
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Tsai CT, Huang CT. Overexpression of the Neocallimastix frontalis xylanase gene in the methylotrophic yeasts Pichia pastoris and Pichia methanolica. Enzyme Microb Technol 2008. [DOI: 10.1016/j.enzmictec.2008.01.018] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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9
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Tsai CF, Qiu X, Liu JH. A comparative analysis of two cDNA clones of the cellulase gene family from anaerobic fungus Piromyces rhizinflata. Anaerobe 2007; 9:131-40. [PMID: 16887700 DOI: 10.1016/s1075-9964(03)00087-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2003] [Revised: 05/12/2003] [Accepted: 05/30/2003] [Indexed: 11/28/2022]
Abstract
Cellulase family and some other glycosyl hydrolases of anaerobic fungi inhabiting the digestive tract of ruminants are believed to form an enzyme complex called cellulosome. Study of the individual component of cellulosome may shed light on understanding the organization of this complex and its functional mechanism. We have analysed the primary sequences of two cellulase clones, cel5B and cel6A, isolated from the cDNA library of ruminal fungus, Piromyces rhizinflata strain 2301. The deduced amino acid sequences of the catalytic domain of Cel5B, encoded by cel5B, showed homology with the subfamily 4 of the family 5 (subfamily 5(4)) of glycosyl hydrolases, while cel6A encoded Cel6A belonged to family 6 of glycosyl hydrolases. Phylogenetic tree analysis suggested that the genes of subfamily 5(4) glycosyl hydrolases of P. rhizinflata might have been acquired from rumen bacteria. Cel5B and Cel6A were modular enzymes consisting of a catalytic domain and dockerin domain(s), but not a cellulose binding domain. The occurrence of dockerin domains indicated that both enzymes were cellulosome components. The catalytic domain of the Cel5B (Cel5B') and Cel6A (Cel6A') recombinant proteins were purified. The optimal activity conditions with carboxymethyl cellulose (CMC) as the substrate were pH 6.0 and 50 degrees C for Cel5B', and pH 6.0 and 37-45 degrees C for Cel6A'. Both Cel5B' and Cel6A' exhibited activity against CMC, barley beta-glucan, Lichenan, and oat spelt xylan. Cel5B' could also hydrolyse p-nitrophenyl-beta-d-cellobioside, Avicel and filter paper while Cel6A' did not show any activity on these substrates. It is apparent that Cel6A' acted as an endoglucanase and Cel5B' possessed both endoglucanase and exoglucanase activities. No synergic effect was observed for these recombinant enzymes in vitro on Avicel and CMC.
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Affiliation(s)
- Cheng-Fang Tsai
- Institute of BioAgricultural Sciences, Academia Sinica, Taipei, Taiwan 115, Republic of China
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Ximenes EA, Chen H, Kataeva IA, Cotta MA, Felix CR, Ljungdahl LG, Li XL. A mannanase, ManA, of the polycentric anaerobic fungus Orpinomyces sp. strain PC-2 has carbohydrate binding and docking modules. Can J Microbiol 2006; 51:559-68. [PMID: 16175204 PMCID: PMC6448567 DOI: 10.1139/w05-033] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The anaerobic fungus Orpinomyces sp. strain PC-2 produces a broad spectrum of glycoside hydrolases, most of which are components of a high molecular mass cellulosomal complex. Here we report about a cDNA (manA) having 1924 bp isolated from the fungus and found to encode a polypeptide of 579 amino acid residues. Analysis of the deduced sequence revealed that it had a mannanase catalytic module, a family 1 carbohydrate-binding module, and a noncatalytic docking module. The catalytic module was homologous to aerobic fungal mannanases belonging to family 5 glycoside hydrolases, but unrelated to the previously isolated mannanases (family 26) of the anaerobic fungus Piromyces. No mannanase activity could be detected in Escherichia coli harboring a manA-containing plasmid. The manA was expressed in Saccharomyces cerevisiae and ManA was secreted into the culture medium in multiple forms. The purified extracellular heterologous mannanase hydrolyzed several types of mannan but lacked activity against cellulose, chitin, or beta-glucan. The enzyme had high specific activity toward locust bean mannan and an extremely broad pH profile. It was stable for several hours at 50 degrees C, but was rapidly inactivated at 60 degrees C. The carbohydrate-binding module of the Man A produced separately in E. coli bound preferably to insoluble lignocellulosic substrates, suggesting that it might play an important role in the complex enzyme system of the fungus for lignocellulose degradation.
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Affiliation(s)
- Eduardo A. Ximenes
- Laboratorio De Enzimologia, Departmento De Biologia Celular, Universidade De Brasilia, Asa Norte, Brasilia-DF-Brazil 70910-900, Brazil
| | - Huizhong Chen
- Division of Microbiology, National Center for Toxicological Research, U.S. Food and Drug Administration, 3900 NCTR Road, Jefferson, AR 72079-9502, USA
| | - Irina A. Kataeva
- Department of Biochemistry and Molecular Biology and Center for Biological Resource Recovery, The University of Georgia, Athens, GA 30602-7229, USA
| | - Michael A. Cotta
- Fermentation Biotechnology Research Unit, National Center for Agricultural Utilization Research, USDA/ARS, 1815 N. University Street, Peoria, IL 61604, USA
| | - Carlos R. Felix
- Laboratorio De Enzimologia, Departmento De Biologia Celular, Universidade De Brasilia, Asa Norte, Brasilia-DF-Brazil 70910-900, Brazil
| | - Lars G. Ljungdahl
- Department of Biochemistry and Molecular Biology and Center for Biological Resource Recovery, The University of Georgia, Athens, GA 30602-7229, USA
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Liu JR, Yu B, Liu FH, Cheng KJ, Zhao X. Expression of rumen microbial fibrolytic enzyme genes in probiotic Lactobacillus reuteri. Appl Environ Microbiol 2005; 71:6769-75. [PMID: 16269708 PMCID: PMC1287615 DOI: 10.1128/aem.71.11.6769-6775.2005] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
This study was aimed at evaluating the cloning and expression of three rumen microbial fibrolytic enzyme genes in a strain of Lactobacillus reuteri and investigating the probiotic characteristics of these genetically modified lactobacilli. The Neocallimastix patriciarum xylanase gene xynCDBFV, the Fibrobacter succinogenes beta-glucanase (1,3-1,4-beta-D-glucan 4-glucanohydrolase [EC 3.2.1.73]) gene, and the Piromyces rhizinflata cellulase gene eglA were cloned in a strain of L. reuteri isolated from the gastrointestinal tract of broilers. The enzymes were expressed and secreted under the control of the Lactococcus lactis lacA promoter and its secretion signal. The L. reuteri transformed strains not only acquired the capacity to break down soluble carboxymethyl cellulose, beta-glucan, or xylan but also showed high adhesion efficiency to mucin and mucus and resistance to bile salt and acid.
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Affiliation(s)
- Je-Ruei Liu
- Institute of BioAgricultural Sciences, Academia Sinica, Taipei, Taiwan
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12
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Huang YH, Huang CT, Hseu RS. Effects of dockerin domains onNeocallimastix frontalisxylanases. FEMS Microbiol Lett 2005; 243:455-60. [PMID: 15686849 DOI: 10.1016/j.femsle.2005.01.008] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2004] [Revised: 12/20/2004] [Accepted: 01/06/2005] [Indexed: 11/24/2022] Open
Abstract
Two xylanase genes were cloned from the anaerobic fungus Neocallimastix frontalis. Xyn11A had a modular structure of two catalytic domains and two dockerin domains, while Xyn11B had one catalytic domain and two dockerin domains. The characteristics of the xylanases with and without dockerin domains were investigated. The deletion of dockerin domains had little influence on the optimal pH of xylanases, while it significantly affected the optimal temperatures. The optimal temperatures increased from 55 to 60 degrees C for Xyn11A and 60 to 65 degrees C for Xyn11B after the deletion of dockerin domains. The increase of optimal temperatures was attributed to the lower stability of the second structure in full length xylanase than that in the truncated one as evidenced by the circular dichroism spectroscopy. The specific activity of Xyn11A and Xyn11B increased about 64% and 330%, respectively, after the deletion of the dockerin domains. The removal of dockerin domains appeared to increase the overall efficiency of Xyn11A' (1.2-) and Xyn11B' (2.9-) fold with oat spelts xylan as reflected by the values of k(cat)/K(m). The results suggest that the dockerin domain might play an important role in the characteristics of xylanases from anaerobic fungi.
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Affiliation(s)
- Ya-Hui Huang
- Institute of Microbiology and Biochemistry, National Taiwan University, Taipei 106, Taiwan, ROC
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13
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Chen YL, Tang TY, Cheng KJ. Directed evolution to produce an alkalophilic variant from a Neocallimastix patriciarum xylanase. Can J Microbiol 2001; 47:1088-94. [PMID: 11822834 DOI: 10.1139/w01-118] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The catalytic domain of a xylanase from the anaerobic fungus Neocallimastix patriciarum was made more alkalophilic through directed evolution using error-prone PCR. Transformants expressing the alkalophilic variant xylanases produced larger clear zones when overlaid with high pH, xylan-containing agar. Eight amino acid substitutions were identified in six selected mutant xylanases. Whereas the wild-type xylanase exhibited no activity at pH 8.5, the relative and specific activities of the six mutants were higher at pH 8.5 than at pH 6.0. Seven of the eight amino acid substitutions were assembled in one enzyme (xyn-CDBFV) by site-directed mutagenesis. Some or all of the seven mutations exerted positive and possibly synergistic effects on the alkalophilicity of the enzyme. The resulting composite mutant xylanase retained a greater proportion of its activity than did the wild type at pH above 7.0, maintaining 25% of its activity at pH 9.0, and its retention of activity at acid pH was no lower than that of the wild type. The composite xylanase (xyn-CDBFV) had a relatively high specific activity of 10128 micromol glucose x min(-1) x (mg protein)(-1) at pH 6.0. It was more thermostable at 60 degrees C and alkaline tolerant at pH 10.0 than the wild-type xylanase. These properties suggest that the composite mutant xylanase is a promising and suitable candidate for paper pulp bio-bleaching.
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Affiliation(s)
- Y L Chen
- Institute of BioAgricultural Sciences, Academia Sinica, Taipei, Taiwan, Republic of China
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