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Walt HK, Ahn SJ, Hoffmann FG. Horizontally transferred glycoside hydrolase 26 may aid hemipteran insects in plant tissue digestion. Mol Phylogenet Evol 2024; 198:108134. [PMID: 38901473 DOI: 10.1016/j.ympev.2024.108134] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2024] [Revised: 05/28/2024] [Accepted: 06/15/2024] [Indexed: 06/22/2024]
Abstract
Glycoside hydrolases are enzymes that break down complex carbohydrates into simple sugars by catalyzing the hydrolysis of glycosidic bonds. There have been multiple instances of adaptive horizontal gene transfer of genes belonging to various glycoside hydrolase families from microbes to insects, as glycoside hydrolases can metabolize constituents of the carbohydrate-rich plant cell wall. In this study, we characterize the horizontal transfer of a gene from the glycoside hydrolase family 26 (GH26) from bacteria to insects of the order Hemiptera. Our phylogenies trace the horizontal gene transfer to the common ancestor of the superfamilies Pentatomoidea and Lygaeoidea, which include stink bugs and seed bugs. After horizontal transfer, the gene was assimilated into the insect genome as indicated by the gain of an intron, and a eukaryotic signal peptide. Subsequently, the gene has undergone independent losses and expansions in copy number in multiple lineages, suggesting an adaptive role of GH26s in some insects. Finally, we measured tissue-level gene expression of multiple stink bugs and the large milkweed bug using publicly available RNA-seq datasets. We found that the GH26 genes are highly expressed in tissues associated with plant digestion, especially in the principal salivary glands of the stink bugs. Our results are consistent with the hypothesis that this horizontally transferred GH26 was co-opted by the insect to aid in plant tissue digestion and that this HGT event was likely adaptive.
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Affiliation(s)
- Hunter K Walt
- Department of Biochemistry, Molecular Biology, Entomology, and Plant Pathology, Mississippi State University, Mississippi State, MS 39762, USA
| | - Seung-Joon Ahn
- Department of Biochemistry, Molecular Biology, Entomology, and Plant Pathology, Mississippi State University, Mississippi State, MS 39762, USA
| | - Federico G Hoffmann
- Department of Biochemistry, Molecular Biology, Entomology, and Plant Pathology, Mississippi State University, Mississippi State, MS 39762, USA; Institute for Genomics, Biotechnology and Biocomputing, Mississippi State University, Mississippi State, MS 39762, USA.
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2
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Mafa MS, Malgas S. Towards an understanding of the enzymatic degradation of complex plant mannan structures. World J Microbiol Biotechnol 2023; 39:302. [PMID: 37688610 PMCID: PMC10492685 DOI: 10.1007/s11274-023-03753-7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Accepted: 09/04/2023] [Indexed: 09/11/2023]
Abstract
Plant cell walls are composed of a heterogeneous mixture of polysaccharides that require several different enzymes to degrade. These enzymes are important for a variety of biotechnological processes, from biofuel production to food processing. Several classical mannanolytic enzyme functions of glycoside hydrolases (GH), such as β-mannanase, β-mannosidase and α-galactosidase activities, are helpful for efficient mannan hydrolysis. In this light, we bring three enzymes into the model of mannan degradation that have received little or no attention. By linking their three-dimensional structures and substrate specificities, we have predicted the interactions and cooperativity of these novel enzymes with classical mannanolytic enzymes for efficient mannan hydrolysis. The novel exo-β-1,4-mannobiohydrolases are indispensable for the production of mannobiose from the terminal ends of mannans, this product being the preferred product for short-chain mannooligosaccharides (MOS)-specific β-mannosidases. Second, the side-chain cleaving enzymes, acetyl mannan esterases (AcME), remove acetyl decorations on mannan that would have hindered backbone cleaving enzymes, while the backbone cleaving enzymes liberate MOS, which are preferred substrates of the debranching and sidechain cleaving enzymes. The nonhydrolytic expansins and swollenins disrupt the crystalline regions of the biomass, improving their accessibility for AcME and GH activities. Finally, lytic polysaccharide monooxygenases have also been implicated in promoting the degradation of lignocellulosic biomass or mannan degradation by classical mannanolytic enzymes, possibly by disrupting adsorbed mannan residues. Modelling effective enzymatic mannan degradation has implications for improving the saccharification of biomass for the synthesis of value-added and upcycling of lignocellulosic wastes.
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Affiliation(s)
- Mpho Stephen Mafa
- Carbohydrates and Enzymology Laboratory (CHEM-LAB), Department of Plant Sciences, University of the Free State, Bloemfontein, 9300 South Africa
| | - Samkelo Malgas
- Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Hatfield, 0028 South Africa
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Malgas S, Thoresen M, Moses V, Prinsloo E, Susan van Dyk J, Pletschke BI. Analysis of the galactomannan binding ability of β-mannosidases, BtMan2A and CmMan5A, regarding their activity and synergism with a β-mannanase. Comput Struct Biotechnol J 2022; 20:3140-3150. [PMID: 35782739 PMCID: PMC9232400 DOI: 10.1016/j.csbj.2022.06.038] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2022] [Revised: 06/14/2022] [Accepted: 06/14/2022] [Indexed: 11/28/2022] Open
Abstract
BtMan2A preferred short manno-oligomers, while CmMan5A preferred longer ones; DP >2. BtMan2A displayed stronger irreversible binding to galactomannan than CmMan5A. BtMan2A binding to galactomannan did not affect its activity, while CmMan5A lost activity. BtMan2A binding was pH-dependent, with increased binding ability at lower pH. CmMan5A synergised with CcManA, while BtMan2A did not – even though the enzyme was active. High loadings of BtMan2A abolished CcManA activity; at protein ratios ≥ 5:1.
Both β-mannanases and β-mannosidases are required for mannan-backbone degradation into mannose. In this study, two β-mannosidases of glycoside hydrolase (GH) families 2 (BtMan2A) and 5 (CmMan5A) were evaluated for their substrate specificities and galactomannan binding ability. BtMan2A preferred short manno-oligomers, while CmMan5A preferred longer ones; DP >2, and galactomannans. BtMan2A displayed irreversible galactomannan binding, which was pH-dependent, with higher binding observed at low pH, while CmMan5A had limited binding. Docking and molecular dynamics (MD) simulations showed that BtMan2A galactomannan binding was stronger under acidic conditions (-8.4 kcal/mol) than in a neutral environment (-7.6 kcal/mol), and the galactomannan ligand was more unstable under neutral conditions than acidic conditions. Qualitative surface plasmon resonance (SPR) experimentally confirmed the reduced binding capacity of BtMan2A at pH 7. Finally, synergistic β-mannanase to β-mannosidase (BtMan2A or CmMan5A) ratios required for maximal galactomannan hydrolysis were determined. All CcManA to CmMan5A combinations were synergistic (≈1.2-fold), while combinations of CcManA with BtMan2A (≈1.0-fold) yielded no hydrolysis improvement. In conclusion, the low specific activity of BtMan2A towards long and galactose-containing oligomers and its non-catalytic galactomannan binding ability led to no synergy with the mannanase, making GH2 mannosidases ineffective for use in cocktails for mannan degradation.
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Affiliation(s)
- Samkelo Malgas
- Enzyme Science Programme (ESP), Department of Biochemistry and Microbiology, Rhodes University, Makhanda, Eastern Cape 6140, South Africa
- Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Hatfield, Gauteng 0028, South Africa
- Corresponding author at: Department of Biochemistry, Genetics and Microbiology, University of Pretoria, Hatfield, Gauteng 0028, South Africa.
| | - Mariska Thoresen
- Enzyme Science Programme (ESP), Department of Biochemistry and Microbiology, Rhodes University, Makhanda, Eastern Cape 6140, South Africa
| | - Vuyani Moses
- Research Unit in Bioinformatics (RUBi), Department of Biochemistry and Microbiology, Rhodes University, Makhanda, Eastern Cape 6140, South Africa
| | - Earl Prinsloo
- Biotechnology Innovation Centre, Rhodes University, Makhanda, Eastern Cape 6140, South Africa
| | - J. Susan van Dyk
- Forest Products Biotechnology, University of British Columbia, 2424 Main Mall, Vancouver, British Columbia V6T1Z4, Canada
| | - Brett I. Pletschke
- Enzyme Science Programme (ESP), Department of Biochemistry and Microbiology, Rhodes University, Makhanda, Eastern Cape 6140, South Africa
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Hlalukana N, Magengelele M, Malgas S, Pletschke BI. Enzymatic Conversion of Mannan-Rich Plant Waste Biomass into Prebiotic Mannooligosaccharides. Foods 2021; 10:2010. [PMID: 34574120 PMCID: PMC8468410 DOI: 10.3390/foods10092010] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2021] [Revised: 08/20/2021] [Accepted: 08/22/2021] [Indexed: 01/16/2023] Open
Abstract
A growing demand in novel food products for well-being and preventative medicine has attracted global attention on nutraceutical prebiotics. Various plant agro-processes produce large amounts of residual biomass considered "wastes", which can potentially be used to produce nutraceutical prebiotics, such as manno-oligosaccharides (MOS). MOS can be produced from the degradation of mannan. Mannan has a main backbone consisting of β-1,4-linked mannose residues (which may be interspersed by glucose residues) with galactose substituents. Endo-β-1,4-mannanases cleave the mannan backbone at cleavage sites determined by the substitution pattern and thus give rise to different MOS products. These MOS products serve as prebiotics to stimulate various types of intestinal bacteria and cause them to produce fermentation products in different parts of the gastrointestinal tract which benefit the host. This article reviews recent advances in understanding the exploitation of plant residual biomass via the enzymatic production and characterization of MOS, and the influence of MOS on beneficial gut microbiota and their biological effects (i.e., immune modulation and lipidemic effects) as observed on human and animal health.
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Affiliation(s)
| | | | - Samkelo Malgas
- Enzyme Science Programme (ESP), Department of Biochemistry and Microbiology, Rhodes University, Makhanda 6140, Eastern Cape, South Africa; (N.H.); (M.M.); (B.I.P.)
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Arnal G, Stogios PJ, Asohan J, Attia MA, Skarina T, Viborg AH, Henrissat B, Savchenko A, Brumer H. Substrate specificity, regiospecificity, and processivity in glycoside hydrolase family 74. J Biol Chem 2019; 294:13233-13247. [PMID: 31324716 DOI: 10.1074/jbc.ra119.009861] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Revised: 07/16/2019] [Indexed: 12/11/2022] Open
Abstract
Glycoside hydrolase family 74 (GH74) is a historically important family of endo-β-glucanases. On the basis of early reports of detectable activity on cellulose and soluble cellulose derivatives, GH74 was originally considered to be a "cellulase" family, although more recent studies have generally indicated a high specificity toward the ubiquitous plant cell wall matrix glycan xyloglucan. Previous studies have indicated that GH74 xyloglucanases differ in backbone cleavage regiospecificities and can adopt three distinct hydrolytic modes of action: exo, endo-dissociative, and endo-processive. To improve functional predictions within GH74, here we coupled in-depth biochemical characterization of 17 recombinant proteins with structural biology-based investigations in the context of a comprehensive molecular phylogeny, including all previously characterized family members. Elucidation of four new GH74 tertiary structures, as well as one distantly related dual seven-bladed β-propeller protein from a marine bacterium, highlighted key structure-function relationships along protein evolutionary trajectories. We could define five phylogenetic groups, which delineated the mode of action and the regiospecificity of GH74 members. At the extremes, a major group of enzymes diverged to hydrolyze the backbone of xyloglucan nonspecifically with a dissociative mode of action and relaxed backbone regiospecificity. In contrast, a sister group of GH74 enzymes has evolved a large hydrophobic platform comprising 10 subsites, which facilitates processivity. Overall, the findings of our study refine our understanding of catalysis in GH74, providing a framework for future experimentation as well as for bioinformatics predictions of sequences emerging from (meta)genomic studies.
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Affiliation(s)
- Gregory Arnal
- Michael Smith Laboratories, University of British Columbia, 2185 East Mall, Vancouver, British Columbia V6T 1Z4, Canada
| | - Peter J Stogios
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario M5S 3E5, Canada
| | - Jathavan Asohan
- Michael Smith Laboratories, University of British Columbia, 2185 East Mall, Vancouver, British Columbia V6T 1Z4, Canada
| | - Mohamed A Attia
- Michael Smith Laboratories, University of British Columbia, 2185 East Mall, Vancouver, British Columbia V6T 1Z4, Canada; Department of Chemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - Tatiana Skarina
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario M5S 3E5, Canada
| | - Alexander Holm Viborg
- Michael Smith Laboratories, University of British Columbia, 2185 East Mall, Vancouver, British Columbia V6T 1Z4, Canada
| | - Bernard Henrissat
- Architecture et Fonction des Macromolécules Biologiques (AFMB), CNRS, Aix-Marseille University, 13007 Marseille, France; INRA, USC1408 Architecture et Fonction des Macromolécules Biologiques (AFMB), 13007 Marseille, France
| | - Alexei Savchenko
- Department of Chemical Engineering and Applied Chemistry, University of Toronto, Toronto, Ontario M5S 3E5, Canada; Department of Microbiology, Immunology and Infectious Diseases, University of Calgary, Calgary, Alberta T2N 4N1, Canada.
| | - Harry Brumer
- Michael Smith Laboratories, University of British Columbia, 2185 East Mall, Vancouver, British Columbia V6T 1Z4, Canada; Department of Chemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada; Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada; Department of Botany, University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada.
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6
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Xie S, Lan Y, Sun C, Shao Y. Insect microbial symbionts as a novel source for biotechnology. World J Microbiol Biotechnol 2019; 35:25. [PMID: 30666424 DOI: 10.1007/s11274-019-2599-8] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2018] [Accepted: 01/16/2019] [Indexed: 12/14/2022]
Abstract
Insecta is the most diverse and largest class of animals on Earth, appearing together with the emergence of the first terrestrial ecosystem. Owing to this great diversity and long-term coexistence, an amazing variety of symbiotic microorganisms have adapted specifically to insects as hosts. Insect symbionts not only participate in many relationships with the hosts but also represent a novel resource for biotechnological applications. The exploitation of mutualistic symbiosis represents a promising area to search for bioactive compounds and new enzymes for potential clinical, industrial or environmental applications. Moreover, the manipulation of parasitic symbiosis has particular potential to solve practical problems for the control of agricultural pests and disease vectors. Although the study of microbial symbionts has been impaired by the unculturability of most symbionts, the rapidly growing catalogue of microbial genomes and the application of modern genetic techniques provide an alternative approach to using these microbes. This minireview presents examples of microbial symbionts isolated from insects for emerging biotechnological use and illuminates new ways for discovering microorganisms of applied value from a particularly promising source.
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Affiliation(s)
- Sen Xie
- Institute of Sericulture and Apiculture, College of Animal Sciences, Zhejiang University, Hangzhou, People's Republic of China
| | - Yahua Lan
- Institute of Sericulture and Apiculture, College of Animal Sciences, Zhejiang University, Hangzhou, People's Republic of China
| | - Chao Sun
- Analysis Center of Agrobiology and Environmental Sciences, Zhejiang University, Hangzhou, People's Republic of China
| | - Yongqi Shao
- Institute of Sericulture and Apiculture, College of Animal Sciences, Zhejiang University, Hangzhou, People's Republic of China. .,Key Laboratory for Molecular Animal Nutrition, Ministry of Education, Beijing, People's Republic of China.
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7
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Trp residue at subsite − 5 plays a critical role in the substrate binding of two protistan GH26 β-mannanases from a termite hindgut. Appl Microbiol Biotechnol 2018; 102:1737-1747. [DOI: 10.1007/s00253-017-8726-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Revised: 11/28/2017] [Accepted: 12/11/2017] [Indexed: 10/18/2022]
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Sakai K, Kimoto S, Shinzawa Y, Minezawa M, Suzuki K, Jindou S, Kato M, Shimizu M. Characterization of pH-tolerant and thermostable GH 134 β-1,4-mannanase SsGH134 possessing carbohydrate binding module 10 from Streptomyces sp. NRRL B-24484. J Biosci Bioeng 2017; 125:287-294. [PMID: 29153955 DOI: 10.1016/j.jbiosc.2017.10.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2017] [Revised: 09/25/2017] [Accepted: 10/15/2017] [Indexed: 10/18/2022]
Abstract
A GH 134 β-1,4-mannanase SsGH134 from Streptomyces sp. NRRL B-24484 possesses a carbohydrate binding module (CBM) 10 and a glycoside hydrolase 134 domain at the N- and C-terminal regions, respectively. Recombinant SsGH134 expressed in Escherichia coli. SsGH134 was maximally active within a pH range of 4.0-6.5 and retained >80% of this maximum after 90 min at 30°C within a pH range of 3.0-10.0. The β-1,4-mannanase activity of SsGH134 towards glucomannan was 30% of the maximal activity after an incubation at 100°C for 120 min, indicating that SsGH134 is pH-tolerant and thermostable β-1,4-mannanase. SsGH134, SsGH134-ΔCBM10 (CBM10-linker-truncated SsGH134) and SsGH134-G34W (substitution of Gly34 to Trp) bound to microcrystalline cellulose, β-mannan and chitin, regardless of the presence or absence of CBM10. These indicate that GH 134 domain strongly bind to the polysaccharides. Although deleting CBM10 increased the catalytic efficiency of the β-1,4-mannanase, its disruption decreased the pH, solvent and detergent stability of SsGH134. These findings indicate that CBM10 inhibits the β-1,4-mannanase activity of SsGH134, but it is involved in stabilizing its enzymatic activity within a neutral-to-alkaline pH range, and in the presence of various organic solvents and detergents. We believe that SsGH134 could be useful to a diverse range of industries.
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Affiliation(s)
- Kiyota Sakai
- Faculty of Agriculture, Meijo University, Nagoya, Aichi 468-8502, Japan
| | - Saran Kimoto
- Faculty of Agriculture, Meijo University, Nagoya, Aichi 468-8502, Japan
| | - Yuta Shinzawa
- Faculty of Agriculture, Meijo University, Nagoya, Aichi 468-8502, Japan
| | - Miho Minezawa
- Faculty of Agriculture, Meijo University, Nagoya, Aichi 468-8502, Japan
| | - Kengo Suzuki
- Faculty of Agriculture, Meijo University, Nagoya, Aichi 468-8502, Japan
| | - Sadanari Jindou
- Faculty of Science and Technology, Department of Culture Education, Meijo University, Nagoya, Aichi 468-8502, Japan
| | - Masashi Kato
- Faculty of Agriculture, Meijo University, Nagoya, Aichi 468-8502, Japan
| | - Motoyuki Shimizu
- Faculty of Agriculture, Meijo University, Nagoya, Aichi 468-8502, Japan.
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Production, properties, and applications of endo-β-mannanases. Biotechnol Adv 2017; 35:1-19. [DOI: 10.1016/j.biotechadv.2016.11.001] [Citation(s) in RCA: 85] [Impact Index Per Article: 12.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2015] [Revised: 10/12/2016] [Accepted: 11/07/2016] [Indexed: 12/27/2022]
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Bågenholm V, Reddy SK, Bouraoui H, Morrill J, Kulcinskaja E, Bahr CM, Aurelius O, Rogers T, Xiao Y, Logan DT, Martens EC, Koropatkin NM, Stålbrand H. Galactomannan Catabolism Conferred by a Polysaccharide Utilization Locus of Bacteroides ovatus: ENZYME SYNERGY AND CRYSTAL STRUCTURE OF A β-MANNANASE. J Biol Chem 2016; 292:229-243. [PMID: 27872187 PMCID: PMC5217682 DOI: 10.1074/jbc.m116.746438] [Citation(s) in RCA: 77] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Revised: 11/18/2016] [Indexed: 01/15/2023] Open
Abstract
A recently identified polysaccharide utilization locus (PUL) from Bacteroides ovatus ATCC 8483 is transcriptionally up-regulated during growth on galacto- and glucomannans. It encodes two glycoside hydrolase family 26 (GH26) β-mannanases, BoMan26A and BoMan26B, and a GH36 α-galactosidase, BoGal36A. The PUL also includes two glycan-binding proteins, confirmed by β-mannan affinity electrophoresis. When this PUL was deleted, B. ovatus was no longer able to grow on locust bean galactomannan. BoMan26A primarily formed mannobiose from mannan polysaccharides. BoMan26B had higher activity on galactomannan with a high degree of galactosyl substitution and was shown to be endo-acting generating a more diverse mixture of oligosaccharides, including mannobiose. Of the two β-mannanases, only BoMan26B hydrolyzed galactoglucomannan. A crystal structure of BoMan26A revealed a similar structure to the exo-mannobiohydrolase CjMan26C from Cellvibrio japonicus, with a conserved glycone region (−1 and −2 subsites), including a conserved loop closing the active site beyond subsite −2. Analysis of cellular location by immunolabeling and fluorescence microscopy suggests that BoMan26B is surface-exposed and associated with the outer membrane, although BoMan26A and BoGal36A are likely periplasmic. In light of the cellular location and the biochemical properties of the two characterized β-mannanases, we propose a scheme of sequential action by the glycoside hydrolases encoded by the β-mannan PUL and involved in the β-mannan utilization pathway in B. ovatus. The outer membrane-associated BoMan26B initially acts on the polysaccharide galactomannan, producing comparably large oligosaccharide fragments. Galactomanno-oligosaccharides are further processed in the periplasm, degalactosylated by BoGal36A, and subsequently hydrolyzed into mainly mannobiose by the β-mannanase BoMan26A.
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Affiliation(s)
- Viktoria Bågenholm
- From the Department of Biochemistry and Structural Biology, Lund University P. O. Box 124, S-221 00 Lund, Sweden and
| | - Sumitha K Reddy
- From the Department of Biochemistry and Structural Biology, Lund University P. O. Box 124, S-221 00 Lund, Sweden and
| | - Hanene Bouraoui
- From the Department of Biochemistry and Structural Biology, Lund University P. O. Box 124, S-221 00 Lund, Sweden and
| | - Johan Morrill
- From the Department of Biochemistry and Structural Biology, Lund University P. O. Box 124, S-221 00 Lund, Sweden and
| | - Evelina Kulcinskaja
- From the Department of Biochemistry and Structural Biology, Lund University P. O. Box 124, S-221 00 Lund, Sweden and
| | - Constance M Bahr
- the Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan 48109
| | - Oskar Aurelius
- From the Department of Biochemistry and Structural Biology, Lund University P. O. Box 124, S-221 00 Lund, Sweden and
| | - Theresa Rogers
- the Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan 48109
| | - Yao Xiao
- the Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan 48109
| | - Derek T Logan
- From the Department of Biochemistry and Structural Biology, Lund University P. O. Box 124, S-221 00 Lund, Sweden and
| | - Eric C Martens
- the Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan 48109
| | - Nicole M Koropatkin
- the Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan 48109
| | - Henrik Stålbrand
- From the Department of Biochemistry and Structural Biology, Lund University P. O. Box 124, S-221 00 Lund, Sweden and
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11
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A Novel Glycoside Hydrolase Family 113 Endo-β-1,4-Mannanase from Alicyclobacillus sp. Strain A4 and Insight into the Substrate Recognition and Catalytic Mechanism of This Family. Appl Environ Microbiol 2016; 82:2718-2727. [PMID: 26921423 DOI: 10.1128/aem.04071-15] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Accepted: 02/20/2016] [Indexed: 11/20/2022] Open
Abstract
Few members of glycoside hydrolase (GH) family 113 have been characterized, and information on substrate recognition by and the catalytic mechanism of this family is extremely limited. In the present study, a novel endo-β-1,4-mannanase of GH 113, Man113A, was identified in thermoacidophilic Alicyclobacillus sp. strain A4 and found to exhibit both hydrolytic and transglycosylation activities. The enzyme had a broad substrate spectrum, showed higher activities on glucomannan than on galactomannan, and released mannobiose and mannotriose as the main hydrolysis products after an extended incubation. Compared to the only functionally characterized and structure-resolved counter part Alicyclobacillus acidocaldarius ManA (AaManA) of GH 113, Man113A showed much higher catalytic efficiency on mannooligosaccharides, in the order mannohexaose ≈ mannopentaose > mannotetraose > mannotriose, and required at least four sugar units for efficient catalysis. Homology modeling, molecular docking analysis, and site-directed mutagenesis revealed the vital roles of eight residues (Trp13, Asn90, Trp96, Arg97, Tyr196, Trp274, Tyr292, and Cys143) related to substrate recognition by and catalytic mechanism of GH 113. Comparison of the binding pockets and key residues of β-mannanases of different families indicated that members of GH 113 and GH 5 have more residues serving as stacking platforms to support -4 to -1 subsites than those of GH 26 and that the residues preceding the acid/base catalyst are quite different. Taken as a whole, this study elucidates substrate recognition by and the catalytic mechanism of GH 113 β-mannanases and distinguishes them from counterparts of other families.
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Peterson BF, Scharf ME. Lower Termite Associations with Microbes: Synergy, Protection, and Interplay. Front Microbiol 2016; 7:422. [PMID: 27092110 PMCID: PMC4824777 DOI: 10.3389/fmicb.2016.00422] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Accepted: 03/16/2016] [Indexed: 11/15/2022] Open
Abstract
Lower-termites are one of the best studied symbiotic systems in insects. Their ability to feed on a nitrogen-poor, wood-based diet with help from symbiotic microbes has been under investigation for almost a century. A unique microbial consortium living in the guts of lower termites is essential for wood-feeding. Host and symbiont cellulolytic enzymes synergize each other in the termite gut to increase digestive efficiency. Because of their critical role in digestion, gut microbiota are driving forces in all aspects of termite biology. Social living also comes with risks for termites. The combination of group living and a microbe-rich habitat makes termites potentially vulnerable to pathogenic infections. However, the use of entomopathogens for termite control has been largely unsuccessful. One mechanism for this failure may be symbiotic collaboration; i.e., one of the very reasons termites have thrived in the first place. Symbiont contributions are thought to neutralize fungal spores as they pass through the termite gut. Also, when the symbiont community is disrupted pathogen susceptibility increases. These recent discoveries have shed light on novel interactions for symbiotic microbes both within the termite host and with pathogenic invaders. Lower termite biology is therefore tightly linked to symbiotic associations and their resulting physiological collaborations.
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Affiliation(s)
| | - Michael E Scharf
- Department of Entomology, Purdue University, West Lafayette IN, USA
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