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Li X, Lippens G, Parrou JL, Cioci G, Esque J, Wang Z, Laville E, Potocki-Veronese G, Labourel A. Biochemical characterization of a SusD-like protein involved in β-1,3-glucan utilization by an uncultured cow rumen Bacteroides. mSphere 2024; 9:e0027824. [PMID: 39012103 PMCID: PMC11351036 DOI: 10.1128/msphere.00278-24] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2024] [Accepted: 06/18/2024] [Indexed: 07/17/2024] Open
Abstract
In ruminants, the rumen is a specialized stomach that is adapted to the breakdown of plant-derived complex polysaccharides through the coordinated activities of a diverse microbial community. Bacteroidota is a major phylum in this bovine rumen microbiota. They contain several clusters of genes called polysaccharide utilization loci (PULs) that encode proteins working in concert to capture, degrade, and transport polysaccharides. Despite the critical role of SusD-like proteins for efficient substrate transport, they remain largely unexplored. Here, we present the biochemical characterization of a SusD-like protein encoded by a β-glucan utilization locus from an Escherichia coli metagenomic clone previously isolated by functional screening of the bovine rumen microbiome. In this study, we show that clone 41O1 can grow on laminaritriose, cellotriose, and a mixture of cellobiosyl-cellobiose and glucosyl-cellotriose as sole carbon sources. Based on this, we used various in vitro analyses to investigate the binding ability of 41O1_SusD-like towards these oligosaccharides and the corresponding polysaccharides. We observed a clear binding affinity for β-1,6 branched β-1,3-glucans (laminarins, yeast β-glucan) and laminaritriose. Comparison of the AlphaFold2 model of 41O1_SusD-like with its closest structural homologs highlights a similar pattern of substrate recognition. In particular, three tryptophan residues are shown to be crucial for laminarin recognition. In the context of the cow rumen, we discuss the possible substrates targeted by the 41O1_PUL, such as the (1,3;1,4)-β-d-glucans present in cereal grains or the β-1,3- and (1,3;1,6)-β-d-glucans that are components of the cell wall of ruminal yeasts.IMPORTANCEThe rumen microbiota can majorly impact overall animal health, feed efficiency, and release of harmful substances into the environment. This microbiota is involved in the fermentation of organic matter to provide the host with valuable and assimilable nutrients. Bacteroidota efficiently captures, breaks down, and imports complex polysaccharides through the concerted action of proteins encoded by polysaccharide utilization loci (PULs). Within this system, SusD-like protein has proven necessary for the active internalization of the substrate. Nevertheless, the vast majority of SusD-like proteins characterized to date originate from cultured bacteria. With regard to the diversity and importance of uncultured bacteria in the rumen, further studies are required to better understand the role of polysaccharide utilization loci in ruminal polysaccharide degradation. Our detailed characterization of the 41O1_SusD-like therefore contributes to a better understanding of the carbohydrate metabolism of an uncultured Bacteroides from the cow rumen.
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Affiliation(s)
- Xiaoqian Li
- TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France
| | - Guy Lippens
- TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France
| | - Jean-Luc Parrou
- TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France
| | - Gianluca Cioci
- TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France
| | - Jérémy Esque
- TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France
| | - Zhi Wang
- TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France
| | | | | | - Aurore Labourel
- TBI, Université de Toulouse, CNRS, INRAE, INSA, Toulouse, France
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Silverio MP, Neumann T, Schaubruch K, Heermann R, Pérez-García P, Chow J, Streit WR. Metagenome-derived SusD-homologs affiliated with Bacteroidota bind to synthetic polymers. Appl Environ Microbiol 2024; 90:e0093324. [PMID: 38953372 PMCID: PMC11267923 DOI: 10.1128/aem.00933-24] [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: 05/17/2024] [Accepted: 06/04/2024] [Indexed: 07/04/2024] Open
Abstract
Starch utilization system (Sus)D-homologs are well known for their carbohydrate-binding capabilities and are part of the sus operon in microorganisms affiliated with the phylum Bacteroidota. Until now, SusD-like proteins have been characterized regarding their affinity toward natural polymers. In this study, three metagenomic SusD homologs (designated SusD1, SusD38489, and SusD70111) were identified and tested with respect to binding to natural and non-natural polymers. SusD1 and SusD38489 are cellulose-binding modules, while SusD70111 preferentially binds chitin. Employing translational fusion proteins with superfolder GFP (sfGFP), pull-down assays, and surface plasmon resonance (SPR) has provided evidence for binding to polyethylene terephthalate (PET) and other synthetic polymers. Structural analysis suggested that a Trp triad might be involved in protein adsorption. Mutation of these residues to Ala resulted in an impaired adsorption to microcrystalline cellulose (MC), but not so to PET and other synthetic polymers. We believe that the characterized SusDs, alongside the methods and considerations presented in this work, will aid further research regarding bioremediation of plastics. IMPORTANCE SusD1 and SusD38489 can be considered for further applications regarding their putative adsorption toward fossil-fuel based polymers. This is the first time that SusD homologs from the polysaccharide utilization loci (PUL), largely described for the phylum Bacteroidota, are characterized as synthetic polymer-binding proteins.
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Affiliation(s)
| | - Tabea Neumann
- Department of Microbiology and Biotechnology, University of Hamburg, Hamburg, Germany
| | - Kirsten Schaubruch
- Institute of Molecular Physiology, Johannes-Gutenberg University of Mainz, Mainz, Germany
| | - Ralf Heermann
- Institute of Molecular Physiology, Johannes-Gutenberg University of Mainz, Mainz, Germany
| | - Pablo Pérez-García
- Department of Microbiology and Biotechnology, University of Hamburg, Hamburg, Germany
| | - Jennifer Chow
- Department of Microbiology and Biotechnology, University of Hamburg, Hamburg, Germany
| | - Wolfgang R. Streit
- Department of Microbiology and Biotechnology, University of Hamburg, Hamburg, Germany
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3
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Zühlke MK, Ficko-Blean E, Bartosik D, Terrapon N, Jeudy A, Jam M, Wang F, Welsch N, Dürwald A, Martin LT, Larocque R, Jouanneau D, Eisenack T, Thomas F, Trautwein-Schult A, Teeling H, Becher D, Schweder T, Czjzek M. Unveiling the role of novel carbohydrate-binding modules in laminarin interaction of multimodular proteins from marine Bacteroidota during phytoplankton blooms. Environ Microbiol 2024; 26:e16624. [PMID: 38757353 DOI: 10.1111/1462-2920.16624] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2023] [Accepted: 04/05/2024] [Indexed: 05/18/2024]
Abstract
Laminarin, a β(1,3)-glucan, serves as a storage polysaccharide in marine microalgae such as diatoms. Its abundance, water solubility and simple structure make it an appealing substrate for marine bacteria. Consequently, many marine bacteria have evolved strategies to scavenge and decompose laminarin, employing carbohydrate-binding modules (CBMs) as crucial components. In this study, we characterized two previously unassigned domains as laminarin-binding CBMs in multimodular proteins from the marine bacterium Christiangramia forsetii KT0803T, thereby introducing the new laminarin-binding CBM families CBM102 and CBM103. We identified four CBM102s in a surface glycan-binding protein (SGBP) and a single CBM103 linked to a glycoside hydrolase module from family 16 (GH16_3). Our analysis revealed that both modular proteins have an elongated shape, with GH16_3 exhibiting greater flexibility than SGBP. This flexibility may aid in the recognition and/or degradation of laminarin, while the constraints in SGBP could facilitate the docking of laminarin onto the bacterial surface. Exploration of bacterial metagenome-assembled genomes (MAGs) from phytoplankton blooms in the North Sea showed that both laminarin-binding CBM families are widespread among marine Bacteroidota. The high protein abundance of CBM102- and CBM103-containing proteins during phytoplankton blooms further emphasizes their significance in marine laminarin utilization.
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Affiliation(s)
- Marie-Katherin Zühlke
- Pharmaceutical Biotechnology, Institute of Pharmacy, University Greifswald, Greifswald, Germany
- Institute of Marine Biotechnology, Greifswald, Germany
| | - Elizabeth Ficko-Blean
- Integrative Biology of Marine Models (LBI2M), Station Biologique de Roscoff (SBR), Sorbonne Université, CNRS, Roscoff, France
| | - Daniel Bartosik
- Pharmaceutical Biotechnology, Institute of Pharmacy, University Greifswald, Greifswald, Germany
- Institute of Marine Biotechnology, Greifswald, Germany
| | - Nicolas Terrapon
- Architecture et Fonction des Macromolécules Biologiques (AFMB), Aix-Marseille Université (AMU, UMR7257), CNRS, Marseille, France
| | - Alexandra Jeudy
- Integrative Biology of Marine Models (LBI2M), Station Biologique de Roscoff (SBR), Sorbonne Université, CNRS, Roscoff, France
| | - Murielle Jam
- Integrative Biology of Marine Models (LBI2M), Station Biologique de Roscoff (SBR), Sorbonne Université, CNRS, Roscoff, France
| | - Fengqing Wang
- Max Planck Institute for Marine Microbiology, Bremen, Germany
| | - Norma Welsch
- Pharmaceutical Biotechnology, Institute of Pharmacy, University Greifswald, Greifswald, Germany
- Institute of Marine Biotechnology, Greifswald, Germany
| | - Alexandra Dürwald
- Pharmaceutical Biotechnology, Institute of Pharmacy, University Greifswald, Greifswald, Germany
- Helmholtz Institute for One Health, Helmholtz Centre for Infection Research HZI, Greifswald, Germany
| | - Laura Torres Martin
- Pharmaceutical Biotechnology, Institute of Pharmacy, University Greifswald, Greifswald, Germany
| | - Robert Larocque
- Integrative Biology of Marine Models (LBI2M), Station Biologique de Roscoff (SBR), Sorbonne Université, CNRS, Roscoff, France
| | - Diane Jouanneau
- Integrative Biology of Marine Models (LBI2M), Station Biologique de Roscoff (SBR), Sorbonne Université, CNRS, Roscoff, France
| | - Tom Eisenack
- Pharmaceutical Biotechnology, Institute of Pharmacy, University Greifswald, Greifswald, Germany
| | - François Thomas
- Integrative Biology of Marine Models (LBI2M), Station Biologique de Roscoff (SBR), Sorbonne Université, CNRS, Roscoff, France
| | - Anke Trautwein-Schult
- Microbial Proteomics, Institute of Microbiology, University Greifswald, Greifswald, Germany
| | - Hanno Teeling
- Max Planck Institute for Marine Microbiology, Bremen, Germany
| | - Dörte Becher
- Microbial Proteomics, Institute of Microbiology, University Greifswald, Greifswald, Germany
| | - Thomas Schweder
- Pharmaceutical Biotechnology, Institute of Pharmacy, University Greifswald, Greifswald, Germany
- Institute of Marine Biotechnology, Greifswald, Germany
| | - Mirjam Czjzek
- Integrative Biology of Marine Models (LBI2M), Station Biologique de Roscoff (SBR), Sorbonne Université, CNRS, Roscoff, France
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4
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Yang J, Zhang L, Lin S, Li W, Liu C, Yan J, Li S, Long L. Structural insights of a SusD-like protein in marine Bacteroidetes bacteria reveal the molecular basis for chitin recognition and acquisition. FEBS J 2024; 291:584-595. [PMID: 37845429 DOI: 10.1111/febs.16974] [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: 07/24/2023] [Revised: 09/02/2023] [Accepted: 10/12/2023] [Indexed: 10/18/2023]
Abstract
Efficient recognition and transportation of chitin oligosaccharides are crucial steps for the utilization of chitin by heterotrophic bacteria. In this study, we employed structural biological and biochemical approaches to investigate the substrate recognition and acquisition mechanism of a novel chitin-binding SusD-like protein, AqSusD, which is derived from the chitin utilization gene cluster of a marine Bacteroides strain (Aquimarina sp. SCSIO 21287). We resolved the crystal structures of the AqSusD apo-protein and its complex with chitin oligosaccharides. Our results revealed that some crucial residues (Gln67, Phe87, and Asp276) underwent significant conformational changes to form tighter substrate binding sites for ligand binding. Moreover, we identified the functions of key amino acid residues and discovered that π-π stacking and hydrogen bonding between AqSusD and the ligand played significant roles in recognition of the protein for chitin oligosaccharide binding. Based on our findings and previous investigations, we put forward a model for the mechanism of chitin oligosaccharide recognition, capture, and transport by AqSusD, in collaboration with the membrane protein AqSusC. Our study deepens the understanding of the molecular-level "selfish" use of polysaccharides such as chitin by Bacteroides.
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Affiliation(s)
- Jian Yang
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China
- Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), China
- University of the Chinese Academy of Sciences, Beijing, China
| | - Liping Zhang
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China
- University of the Chinese Academy of Sciences, Beijing, China
| | - Shanshan Lin
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China
- University of the Chinese Academy of Sciences, Beijing, China
| | - Wei Li
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China
- University of the Chinese Academy of Sciences, Beijing, China
| | - Chen Liu
- Guangzhou Quality Supervision and Testing Institute, China
| | - Jingheng Yan
- Guangzhou Quality Supervision and Testing Institute, China
| | - Shubo Li
- College of Light Industry and Food Engineering, Guangxi University, Nanning, China
| | - Lijuan Long
- CAS Key Laboratory of Tropical Marine Bio-resources and Ecology, Guangdong Key Laboratory of Marine Materia Medica, South China Sea Institute of Oceanology, Chinese Academy of Sciences, Guangzhou, China
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Clerc EE, Raina JB, Keegstra JM, Landry Z, Pontrelli S, Alcolombri U, Lambert BS, Anelli V, Vincent F, Masdeu-Navarro M, Sichert A, De Schaetzen F, Sauer U, Simó R, Hehemann JH, Vardi A, Seymour JR, Stocker R. Strong chemotaxis by marine bacteria towards polysaccharides is enhanced by the abundant organosulfur compound DMSP. Nat Commun 2023; 14:8080. [PMID: 38057294 DOI: 10.1038/s41467-023-43143-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2023] [Accepted: 11/01/2023] [Indexed: 12/08/2023] Open
Abstract
The ability of marine bacteria to direct their movement in response to chemical gradients influences inter-species interactions, nutrient turnover, and ecosystem productivity. While many bacteria are chemotactic towards small metabolites, marine organic matter is predominantly composed of large molecules and polymers. Yet, the signalling role of these large molecules is largely unknown. Using in situ and laboratory-based chemotaxis assays, we show that marine bacteria are strongly attracted to the abundant algal polysaccharides laminarin and alginate. Unexpectedly, these polysaccharides elicited stronger chemoattraction than their oligo- and monosaccharide constituents. Furthermore, chemotaxis towards laminarin was strongly enhanced by dimethylsulfoniopropionate (DMSP), another ubiquitous algal-derived metabolite. Our results indicate that DMSP acts as a methyl donor for marine bacteria, increasing their gradient detection capacity and facilitating their access to polysaccharide patches. We demonstrate that marine bacteria are capable of strong chemotaxis towards large soluble polysaccharides and uncover a new ecological role for DMSP in enhancing this attraction. These navigation behaviours may contribute to the rapid turnover of polymers in the ocean, with important consequences for marine carbon cycling.
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Affiliation(s)
- Estelle E Clerc
- Institute of Environmental Engineering, Department of Civil, Environmental and Geomatic Engineering, ETH Zurich, Zurich, Switzerland
| | | | - Johannes M Keegstra
- Institute of Environmental Engineering, Department of Civil, Environmental and Geomatic Engineering, ETH Zurich, Zurich, Switzerland
| | - Zachary Landry
- Institute of Environmental Engineering, Department of Civil, Environmental and Geomatic Engineering, ETH Zurich, Zurich, Switzerland
| | - Sammy Pontrelli
- Institute of Molecular Systems Biology, Department of Biology, ETH Zurich, Zurich, Switzerland
| | - Uria Alcolombri
- Institute of Environmental Engineering, Department of Civil, Environmental and Geomatic Engineering, ETH Zurich, Zurich, Switzerland
- Institute for Life Sciences, Department of Plant and Environmental Sciences, The Hebrew University of Jerusalem, Jerusalem, Israel
| | - Bennett S Lambert
- Institute of Environmental Engineering, Department of Civil, Environmental and Geomatic Engineering, ETH Zurich, Zurich, Switzerland
| | - Valerio Anelli
- Institute of Environmental Engineering, Department of Civil, Environmental and Geomatic Engineering, ETH Zurich, Zurich, Switzerland
| | - Flora Vincent
- Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot, Israel
- Developmental Biology Unit, European Molecular Biological Laboratory, Heidelberg, 69117, Germany
| | | | - Andreas Sichert
- Max Planck Institute for Marine Microbiology, Bremen, Germany
| | - Frédéric De Schaetzen
- Institute of Environmental Engineering, Department of Civil, Environmental and Geomatic Engineering, ETH Zurich, Zurich, Switzerland
| | - Uwe Sauer
- Institute of Molecular Systems Biology, Department of Biology, ETH Zurich, Zurich, Switzerland
| | - Rafel Simó
- Institut de Ciències del Mar, CSIC, Barcelona, Catalonia, Spain
| | | | - Assaf Vardi
- Department of Plant and Environmental Sciences, Weizmann Institute of Science, Rehovot, Israel
| | - Justin R Seymour
- Climate Change Cluster, University of Technology Sydney, Ultimo, Australia
| | - Roman Stocker
- Institute of Environmental Engineering, Department of Civil, Environmental and Geomatic Engineering, ETH Zurich, Zurich, Switzerland.
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Wanke A, van Boerdonk S, Mahdi LK, Wawra S, Neidert M, Chandrasekar B, Saake P, Saur IML, Derbyshire P, Holton N, Menke FLH, Brands M, Pauly M, Acosta IF, Zipfel C, Zuccaro A. A GH81-type β-glucan-binding protein enhances colonization by mutualistic fungi in barley. Curr Biol 2023; 33:5071-5084.e7. [PMID: 37977140 DOI: 10.1016/j.cub.2023.10.048] [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: 04/01/2023] [Revised: 08/06/2023] [Accepted: 10/25/2023] [Indexed: 11/19/2023]
Abstract
Cell walls are important interfaces of plant-fungal interactions, acting as robust physical and chemical barriers against invaders. Upon fungal colonization, plants deposit phenolics and callose at the sites of fungal penetration to prevent further fungal progression. Alterations in the composition of plant cell walls significantly impact host susceptibility. Furthermore, plants and fungi secrete glycan hydrolases acting on each other's cell walls. These enzymes release various sugar oligomers into the apoplast, some of which activate host immunity via surface receptors. Recent characterization of cell walls from plant-colonizing fungi has emphasized the abundance of β-glucans in different cell wall layers, which makes them suitable targets for recognition. To characterize host components involved in immunity against fungi, we performed a protein pull-down with the biotinylated β-glucan laminarin. Thereby, we identified a plant glycoside hydrolase family 81-type glucan-binding protein (GBP) as a β-glucan interactor. Mutation of GBP1 and its only paralog, GBP2, in barley led to decreased colonization by the beneficial root endophytes Serendipita indica and S. vermifera, as well as the arbuscular mycorrhizal fungus Rhizophagus irregularis. The reduction of colonization was accompanied by enhanced responses at the host cell wall, including an extension of callose-containing cell wall appositions. Moreover, GBP mutation in barley also reduced fungal biomass in roots by the hemibiotrophic pathogen Bipolaris sorokiniana and inhibited the penetration success of the obligate biotrophic leaf pathogen Blumeria hordei. These results indicate that GBP1 is involved in the establishment of symbiotic associations with beneficial fungi-a role that has potentially been appropriated by barley-adapted pathogens.
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Affiliation(s)
- Alan Wanke
- Institute for Plant Sciences, University of Cologne, Cologne, Germany; Max Planck Institute for Plant Breeding Research, Cologne, Germany
| | - Sarah van Boerdonk
- Institute for Plant Sciences, University of Cologne, Cologne, Germany; Max Planck Institute for Plant Breeding Research, Cologne, Germany
| | - Lisa Katharina Mahdi
- Institute for Plant Sciences, University of Cologne, Cologne, Germany; Max Planck Institute for Plant Breeding Research, Cologne, Germany
| | - Stephan Wawra
- Institute for Plant Sciences, University of Cologne, Cologne, Germany
| | - Miriam Neidert
- Institute for Plant Sciences, University of Cologne, Cologne, Germany
| | - Balakumaran Chandrasekar
- Institute for Plant Sciences, University of Cologne, Cologne, Germany; Cluster of Excellence on Plant Sciences (CEPLAS), Cologne, Germany
| | - Pia Saake
- Institute for Plant Sciences, University of Cologne, Cologne, Germany; Cluster of Excellence on Plant Sciences (CEPLAS), Cologne, Germany
| | - Isabel M L Saur
- Institute for Plant Sciences, University of Cologne, Cologne, Germany; Cluster of Excellence on Plant Sciences (CEPLAS), Cologne, Germany
| | - Paul Derbyshire
- The Sainsbury Laboratory, University of East Anglia, Norwich, UK
| | - Nicholas Holton
- The Sainsbury Laboratory, University of East Anglia, Norwich, UK
| | - Frank L H Menke
- The Sainsbury Laboratory, University of East Anglia, Norwich, UK
| | - Mathias Brands
- Institute for Plant Sciences, University of Cologne, Cologne, Germany
| | - Markus Pauly
- Institute of Plant Cell Biology and Biotechnology, Heinrich-Heine University Düsseldorf, Düsseldorf, Germany; Cluster of Excellence on Plant Sciences (CEPLAS), Düsseldorf, Germany
| | - Ivan F Acosta
- Max Planck Institute for Plant Breeding Research, Cologne, Germany
| | - Cyril Zipfel
- The Sainsbury Laboratory, University of East Anglia, Norwich, UK; Institute of Plant and Microbial Biology, University of Zurich, and Zurich-Basel Plant Science Center, Zurich, Switzerland
| | - Alga Zuccaro
- Institute for Plant Sciences, University of Cologne, Cologne, Germany; Cluster of Excellence on Plant Sciences (CEPLAS), Cologne, Germany.
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7
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Structural and Biochemical Characterization of a Nonbinding SusD-Like Protein Involved in Xylooligosaccharide Utilization by an Uncultured Human Gut Bacteroides Strain. mSphere 2022; 7:e0024422. [PMID: 36043703 PMCID: PMC9599597 DOI: 10.1128/msphere.00244-22] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In the human gut microbiota, Bacteroidetes break down dietary and endogenous glycosides through highly specific polysaccharide utilization loci (PULs). PULs encode a variety of sensor regulators, binding proteins, transporters, and carbohydrate-active enzymes (CAZymes). Surface glycan-binding proteins (SGBPs) are essential for the efficient capture of the glycosides present on the cell surface, providing Bacteroidetes with a competitive advantage in colonizing their habitats. Here, we present the functional and structural characterization of a SusD-like protein encoded by a xylooligosaccharide (XOS) PUL from an uncultured human gut Bacteroides strain. This locus is also conserved in Bacteroides vulgatus, thereby providing new mechanistic insights into the role of SGBPs in the metabolism of dietary fiber of importance for gut health. Various in vitro analyses, including saturation transfer difference nuclear magnetic resonance (STD-NMR) spectroscopy, revealed that the SusD-like protein cannot bind to the cognate substrate of the XOS PUL, although its presence is essential for the PUL to function. Analysis of the crystal structure of the SusD-like protein reveals an unfolded binding surface and the absence or inappropriate orientation of several key residues compared with other known SusD-like structures. These results highlight the critical role of the SusD-like protein in the transport of oligosaccharides and provide fundamental knowledge about the structure-function of SusC/D-like transporters, revealing that the binding specificity of SusD-like SGBPs does not necessarily reflect the uptake specificity of the transporter. IMPORTANCE The metabolization of dietary fiber is a crucial function for many gut bacteria, especially Bacteroidetes, which are particularly well adapted for recognizing, binding, transporting, and degrading glycosides. In this study, we report the functional and structural characterization of a SusD-like protein involved in xylooligosaccharide utilization by an uncultured gut Bacteroides strain. We demonstrate that while this protein is structurally similar to many canonical Bacteroidetes surface glycan-binding proteins, it cannot bind the substrate taken up by the cognate SusC-like transporter. This lack of binding might be explained by the absence of several key residues known to be involved in oligosaccharide binding and/or the possible necessity of the SusC-like protein to be present to create a cooperative binding site. The term “surface glycan-binding proteins” generally used for SusD-like proteins is thus not generic. Overall, this study allowed us to revisit the concept of glycoside utilization by Bacteroidetes, in particular those strains that feed on the short fibers naturally present in some dietary compounds or on the leftovers of other microbes.
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8
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Glycoside hydrolase from the GH76 family indicates that marine Salegentibacter sp. Hel_I_6 consumes alpha-mannan from fungi. THE ISME JOURNAL 2022; 16:1818-1830. [PMID: 35414716 PMCID: PMC9213526 DOI: 10.1038/s41396-022-01223-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/30/2021] [Revised: 02/10/2022] [Accepted: 03/11/2022] [Indexed: 11/08/2022]
Abstract
AbstractMicrobial glycan degradation is essential to global carbon cycling. The marine bacterium Salegentibacter sp. Hel_I_6 (Bacteroidota) isolated from seawater off Helgoland island (North Sea) contains an α-mannan inducible gene cluster with a GH76 family endo-α-1,6-mannanase (ShGH76). This cluster is related to genetic loci employed by human gut bacteria to digest fungal α-mannan. Metagenomes from the Hel_I_6 isolation site revealed increasing GH76 gene frequencies in free-living bacteria during microalgae blooms, suggesting degradation of α-1,6-mannans from fungi. Recombinant ShGH76 protein activity assays with yeast α-mannan and synthetic oligomannans showed endo-α-1,6-mannanase activity. Resolved structures of apo-ShGH76 (2.0 Å) and of mutants co-crystalized with fungal mannan-mimicking α-1,6-mannotetrose (1.90 Å) and α-1,6-mannotriose (1.47 Å) retained the canonical (α/α)6 fold, despite low identities with sequences of known GH76 structures (GH76s from gut bacteria: <27%). The apo-form active site differed from those known from gut bacteria, and co-crystallizations revealed a kinked oligomannan conformation. Co-crystallizations also revealed precise molecular-scale interactions of ShGH76 with fungal mannan-mimicking oligomannans, indicating adaptation to this particular type of substrate. Our data hence suggest presence of yet unknown fungal α-1,6-mannans in marine ecosystems, in particular during microalgal blooms.
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Mi F, Hu C, Wang Y, Wang L, Peng F, Geng P, Guan M. Recent advancements in microfluidic chip biosensor detection of foodborne pathogenic bacteria: a review. Anal Bioanal Chem 2022; 414:2883-2902. [PMID: 35064302 PMCID: PMC8782221 DOI: 10.1007/s00216-021-03872-w] [Citation(s) in RCA: 53] [Impact Index Per Article: 26.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 12/16/2021] [Accepted: 12/28/2021] [Indexed: 12/19/2022]
Abstract
Foodborne diseases caused by pathogenic bacteria pose a serious threat to human health. Early and rapid detection of foodborne pathogens is an urgent task for preventing disease outbreaks. Microfluidic devices are simple, automatic, and portable miniaturized systems. Compared with traditional techniques, microfluidic devices have attracted much attention because of their high efficiency and convenience in the concentration and detection of foodborne pathogens. This article firstly reviews the bio-recognition elements integrated on microfluidic chips in recent years and the progress of microfluidic chip development for pathogen pretreatment. Furthermore, the research progress of microfluidic technology based on optical and electrochemical sensors for the detection of foodborne pathogenic bacteria is summarized and discussed. Finally, the future prospects for the application and challenges of microfluidic chips based on biosensors are presented.
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Affiliation(s)
- Fang Mi
- College of Chemistry and Chemical Engineering, Xinjiang Normal University, Urumqi, 830017, China
- Department of Cuisine and Tourism, Xinjiang Bingtuan Xingxin Vocational and Technical College, Urumqi, 830074, China
| | - Cunming Hu
- College of Chemistry and Chemical Engineering, Xinjiang Normal University, Urumqi, 830017, China
| | - Ying Wang
- College of Chemistry and Chemical Engineering, Xinjiang Normal University, Urumqi, 830017, China
| | - Li Wang
- Department of Cuisine and Tourism, Xinjiang Bingtuan Xingxin Vocational and Technical College, Urumqi, 830074, China
| | - Fei Peng
- College of Chemistry and Chemical Engineering, Xinjiang Normal University, Urumqi, 830017, China
| | - PengFei Geng
- College of Chemistry and Chemical Engineering, Xinjiang Normal University, Urumqi, 830017, China
| | - Ming Guan
- College of Chemistry and Chemical Engineering, Xinjiang Normal University, Urumqi, 830017, China.
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10
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Golisch B, Lei Z, Tamura K, Brumer H. Configured for the Human Gut Microbiota: Molecular Mechanisms of Dietary β-Glucan Utilization. ACS Chem Biol 2021; 16:2087-2102. [PMID: 34709792 DOI: 10.1021/acschembio.1c00563] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The β-glucans are a disparate group of structurally diverse polysaccharides, whose members are widespread in human diets as components of the cell walls of plants, algae, and fungi (including yeasts), and as bacterial exopolysaccharides. Individual β-glucans from these sources have long been associated with positive effects on human health through metabolic and immunological effects. Remarkably, the β-configured glucosidic linkages that define these polysaccharides render them inaccessible to the limited repertoire of digestive enzymes encoded by the human genome. As a result, the various β-glucans become fodder for the human gut microbiota (HGM) in the lower gastrointestinal tract, where they influence community composition and metabolic output, including fermentation to short chain fatty acids (SCFAs). Only recently, however, have the specific molecular systems that enable the utilization of β-glucans by select members of the HGM been fully elucidated by combined genetic, biochemical, and structural biological approaches. In the context of β-glucan structures and their effects on human nutrition and health, we summarize here the functional characterization of individual polysaccharide utilization loci (PULs) responsible for the saccharification of mixed-linkage β(1→3)/β(1→4)-glucans, β(1→6)-glucans, β(1→3)-glucans, β(1→2)-glucans, and xyloglucans in symbiotic human gut bacteria. These exemplar PULs serve as well-defined biomarkers for the prediction of β-glucan metabolic capability in individual bacterial taxa and across the global human population.
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11
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Tamura K, Dejean G, Van Petegem F, Brumer H. Distinct protein architectures mediate species-specific beta-glucan binding and metabolism in the human gut microbiota. J Biol Chem 2021; 296:100415. [PMID: 33587952 PMCID: PMC7974029 DOI: 10.1016/j.jbc.2021.100415] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2021] [Revised: 02/02/2021] [Accepted: 02/10/2021] [Indexed: 12/12/2022] Open
Abstract
Complex glycans that evade our digestive system are major nutrients that feed the human gut microbiota (HGM). The prevalence of Bacteroidetes in the HGM of populations worldwide is engendered by the evolution of polysaccharide utilization loci (PULs), which encode concerted protein systems to utilize the myriad complex glycans in our diets. Despite their crucial roles in glycan recognition and transport, cell-surface glycan-binding proteins (SGBPs) remained understudied cogs in the PUL machinery. Here, we report the structural and biochemical characterization of a suite of SGBP-A and SGBP-B structures from three syntenic β(1,3)-glucan utilization loci (1,3GULs) from Bacteroides thetaiotaomicron (Bt), Bacteroides uniformis (Bu), and B. fluxus (Bf), which have varying specificities for distinct β-glucans. Ligand complexes provide definitive insight into β(1,3)-glucan selectivity in the HGM, including structural features enabling dual β(1,3)-glucan/mixed-linkage β(1,3)/β(1,4)-glucan-binding capability in some orthologs. The tertiary structural conservation of SusD-like SGBPs-A is juxtaposed with the diverse architectures and binding modes of the SGBPs-B. Specifically, the structures of the trimodular BtSGBP-B and BuSGBP-B revealed a tandem repeat of carbohydrate-binding module-like domains connected by long linkers. In contrast, BfSGBP-B comprises a bimodular architecture with a distinct β-barrel domain at the C terminus that bears a shallow binding canyon. The molecular insights obtained here contribute to our fundamental understanding of HGM function, which in turn may inform tailored microbial intervention therapies.
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Affiliation(s)
- Kazune Tamura
- Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, Canada; Department of Biochemistry and Molecular Biology, The Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Guillaume Dejean
- Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, Canada
| | - Filip Van Petegem
- Department of Biochemistry and Molecular Biology, The Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada
| | - Harry Brumer
- Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, Canada; Department of Biochemistry and Molecular Biology, The Life Sciences Institute, University of British Columbia, Vancouver, British Columbia, Canada; Department of Chemistry, University of British Columbia, Vancouver, British Columbia, Canada.
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12
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Glowacki RWP, Martens EC. If you eat it, or secrete it, they will grow: the expanding list of nutrients utilized by human gut bacteria. J Bacteriol 2020; 203:JB.00481-20. [PMID: 33168637 PMCID: PMC8092160 DOI: 10.1128/jb.00481-20] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
In order to persist, successful bacterial inhabitants of the human gut need to adapt to changing nutrient conditions, which are influenced by host diet and a variety of other factors. For members of the Bacteroidetes and several other phyla, this has resulted in diversification of a variety of enzyme-based systems that equip them to sense and utilize carbohydrate-based nutrients from host, diet, and bacterial origin. In this review, we focus first on human gut Bacteroides and describe recent findings regarding polysaccharide utilization loci (PULs) and the mechanisms of the multi-protein systems they encode, including their regulation and the expanding diversity of substrates that they target. Next, we highlight previously understudied substrates such as monosaccharides, nucleosides, and Maillard reaction products that can also affect the gut microbiota by feeding symbionts that possess specific systems for their metabolism. Since some pathogens preferentially utilize these nutrients, they may represent nutrient niches competed for by commensals and pathogens. Finally, we address recent work to describe nutrient acquisition mechanisms in other important gut species such as those belonging to the Gram-positive anaerobic phyla Actinobacteria and Firmicutes, as well as the Proteobacteria Because gut bacteria contribute to many aspects of health and disease, we showcase advances in the field of synthetic biology, which seeks to engineer novel, diet-controlled nutrient utilization pathways within gut symbionts to create rationally designed live therapeutics.
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Affiliation(s)
- Robert W. P. Glowacki
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Eric C. Martens
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA
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13
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Déjean G, Tamura K, Cabrera A, Jain N, Pudlo NA, Pereira G, Viborg AH, Van Petegem F, Martens EC, Brumer H. Synergy between Cell Surface Glycosidases and Glycan-Binding Proteins Dictates the Utilization of Specific Beta(1,3)-Glucans by Human Gut Bacteroides. mBio 2020; 11:e00095-20. [PMID: 32265336 PMCID: PMC7157763 DOI: 10.1128/mbio.00095-20] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2020] [Accepted: 03/09/2020] [Indexed: 01/06/2023] Open
Abstract
The human gut microbiota (HGM) has far-reaching impacts on human health and nutrition, which are fueled primarily by the metabolism of otherwise indigestible complex carbohydrates commonly known as dietary fiber. However, the molecular basis of the ability of individual taxa of the HGM to address specific dietary glycan structures remains largely unclear. In particular, the utilization of β(1,3)-glucans, which are widespread in the human diet as yeast, seaweed, and plant cell walls, had not previously been resolved. Through a systems-based approach, here we show that the symbiont Bacteroides uniformis deploys a single, exemplar polysaccharide utilization locus (PUL) to access yeast β(1,3)-glucan, brown seaweed β(1,3)-glucan (laminarin), and cereal mixed-linkage β(1,3)/β(1,4)-glucan. Combined biochemical, enzymatic, and structural analysis of PUL-encoded glycoside hydrolases (GHs) and surface glycan-binding proteins (SGBPs) illuminates a concerted molecular system by which B. uniformis recognizes and saccharifies these distinct β-glucans. Strikingly, the functional characterization of homologous β(1,3)-glucan utilization loci (1,3GUL) in other Bacteroides further demonstrated that the ability of individual taxa to utilize β(1,3)-glucan variants and/or β(1,3)/β(1,4)-glucans arises combinatorially from the individual specificities of SGBPs and GHs at the cell surface, which feed corresponding signals to periplasmic hybrid two-component sensors (HTCSs) via TonB-dependent transporters (TBDTs). These data reveal the importance of cooperativity in the adaptive evolution of GH and SGBP cohorts to address individual polysaccharide structures. We anticipate that this fine-grained knowledge of PUL function will inform metabolic network analysis and proactive manipulation of the HGM. Indeed, a survey of 2,441 public human metagenomes revealed the international, yet individual-specific, distribution of each 1,3GUL.IMPORTANCEBacteroidetes are a dominant phylum of the human gut microbiota (HGM) that target otherwise indigestible dietary fiber with an arsenal of polysaccharide utilization loci (PULs), each of which is dedicated to the utilization of a specific complex carbohydrate. Here, we provide novel insight into this paradigm through functional characterization of homologous PULs from three autochthonous Bacteroides species, which target the family of dietary β(1,3)-glucans. Through detailed biochemical and protein structural analysis, we observed an unexpected diversity in the substrate specificity of PUL glycosidases and glycan-binding proteins with regard to β(1,3)-glucan linkage and branching patterns. In combination, these individual enzyme and protein specificities support taxon-specific growth on individual β(1,3)-glucans. This detailed metabolic insight, together with a comprehensive survey of individual 1,3GULs across human populations, further expands the fundamental roadmap of the HGM, with potential application to the future development of microbial intervention therapies.
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Affiliation(s)
- Guillaume Déjean
- Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, Canada
| | - Kazune Tamura
- Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Adriana Cabrera
- Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, Canada
| | - Namrata Jain
- Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia, Canada
| | - Nicholas A Pudlo
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Gabriel Pereira
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Alexander Holm Viborg
- Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, Canada
| | - Filip Van Petegem
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada
| | - Eric C Martens
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Harry Brumer
- Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Botany, University of British Columbia, Vancouver, British Columbia, Canada
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14
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Becker S, Tebben J, Coffinet S, Wiltshire K, Iversen MH, Harder T, Hinrichs KU, Hehemann JH. Laminarin is a major molecule in the marine carbon cycle. Proc Natl Acad Sci U S A 2020; 117:6599-6607. [PMID: 32170018 PMCID: PMC7104365 DOI: 10.1073/pnas.1917001117] [Citation(s) in RCA: 93] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Marine microalgae sequester as much CO2 into carbohydrates as terrestrial plants. Polymeric carbohydrates (i.e., glycans) provide carbon for heterotrophic organisms and constitute a carbon sink in the global oceans. The quantitative contributions of different algal glycans to cycling and sequestration of carbon remain unknown, partly because of the analytical challenge to quantify glycans in complex biological matrices. Here, we quantified a glycan structural type using a recently developed biocatalytic strategy, which involves laminarinase enzymes that specifically cleave the algal glycan laminarin into readily analyzable fragments. We measured laminarin along transects in the Arctic, Atlantic, and Pacific oceans and during three time series in the North Sea. These data revealed a median of 26 ± 17% laminarin within the particulate organic carbon pool. The observed correlation between chlorophyll and laminarin suggests an annual production of algal laminarin of 12 ± 8 gigatons: that is, approximately three times the annual atmospheric carbon dioxide increase by fossil fuel burning. Moreover, our data revealed that laminarin accounted for up to 50% of organic carbon in sinking diatom-containing particles, thus substantially contributing to carbon export from surface waters. Spatially and temporally variable laminarin concentrations in the sunlit ocean are driven by light availability. Collectively, these observations highlight the prominent ecological role and biogeochemical function of laminarin in oceanic carbon export and energy flow to higher trophic levels.
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Affiliation(s)
- Stefan Becker
- MARUM Center for Marine Environmental Sciences, University of Bremen, 28359 Bremen, Germany
- Max Planck Institute for Marine Microbiology, 28359 Bremen, Germany
- Department of Geosciences, University of Bremen, 28359 Bremen, Germany
| | - Jan Tebben
- Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, 27570 Bremerhaven, Germany
| | - Sarah Coffinet
- MARUM Center for Marine Environmental Sciences, University of Bremen, 28359 Bremen, Germany
- Department of Geosciences, University of Bremen, 28359 Bremen, Germany
| | - Karen Wiltshire
- Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, 27570 Bremerhaven, Germany
| | - Morten Hvitfeldt Iversen
- MARUM Center for Marine Environmental Sciences, University of Bremen, 28359 Bremen, Germany
- Department of Geosciences, University of Bremen, 28359 Bremen, Germany
| | - Tilmann Harder
- Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, 27570 Bremerhaven, Germany
- Faculty of Biology and Chemistry, University of Bremen, 28359 Bremen, Germany
| | - Kai-Uwe Hinrichs
- MARUM Center for Marine Environmental Sciences, University of Bremen, 28359 Bremen, Germany
- Department of Geosciences, University of Bremen, 28359 Bremen, Germany
| | - Jan-Hendrik Hehemann
- MARUM Center for Marine Environmental Sciences, University of Bremen, 28359 Bremen, Germany;
- Max Planck Institute for Marine Microbiology, 28359 Bremen, Germany
- Department of Geosciences, University of Bremen, 28359 Bremen, Germany
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15
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Tamura K, Foley MH, Gardill BR, Dejean G, Schnizlein M, Bahr CME, Louise Creagh A, van Petegem F, Koropatkin NM, Brumer H. Surface glycan-binding proteins are essential for cereal beta-glucan utilization by the human gut symbiont Bacteroides ovatus. Cell Mol Life Sci 2019; 76:4319-4340. [PMID: 31062073 PMCID: PMC6810844 DOI: 10.1007/s00018-019-03115-3] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2019] [Revised: 04/03/2019] [Accepted: 04/23/2019] [Indexed: 02/07/2023]
Abstract
The human gut microbiota, which underpins nutrition and systemic health, is compositionally sensitive to the availability of complex carbohydrates in the diet. The Bacteroidetes comprise a dominant phylum in the human gut microbiota whose members thrive on dietary and endogenous glycans by employing a diversity of highly specific, multi-gene polysaccharide utilization loci (PUL), which encode a variety of carbohydrases, transporters, and sensor/regulators. PULs invariably also encode surface glycan-binding proteins (SGBPs) that play a central role in saccharide capture at the outer membrane. Here, we present combined biophysical, structural, and in vivo characterization of the two SGBPs encoded by the Bacteroides ovatus mixed-linkage β-glucan utilization locus (MLGUL), thereby elucidating their key roles in the metabolism of this ubiquitous dietary cereal polysaccharide. In particular, molecular insight gained through several crystallographic complexes of SGBP-A and SGBP-B with oligosaccharides reveals that unique shape complementarity of binding platforms underpins specificity for the kinked MLG backbone vis-à-vis linear β-glucans. Reverse-genetic analysis revealed that both the presence and binding ability of the SusD homolog BoSGBPMLG-A are essential for growth on MLG, whereas the divergent, multi-domain BoSGBPMLG-B is dispensable but may assist in oligosaccharide scavenging from the environment. The synthesis of these data illuminates the critical role SGBPs play in concert with other MLGUL components, reveals new structure-function relationships among SGBPs, and provides fundamental knowledge to inform future (meta)genomic, biochemical, and microbiological analyses of the human gut microbiota.
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Affiliation(s)
- Kazune Tamura
- Michael Smith Laboratories, University of British Columbia, 2185 East Mall, Vancouver, BC, V6T 1Z4, Canada
- Department of Biochemistry and Molecular Biology, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada
| | - Matthew H Foley
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
| | - Bernd R Gardill
- Department of Biochemistry and Molecular Biology, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada
| | - Guillaume Dejean
- Michael Smith Laboratories, University of British Columbia, 2185 East Mall, Vancouver, BC, V6T 1Z4, Canada
| | - Matthew Schnizlein
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
| | - Constance M E Bahr
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI, 48109, USA
| | - A Louise Creagh
- Michael Smith Laboratories, University of British Columbia, 2185 East Mall, Vancouver, BC, V6T 1Z4, Canada
- Department of Chemical and Biological Engineering, University of British Columbia, 2360 East Mall, Vancouver, BC, V6T 1Z3, Canada
| | - Filip van Petegem
- Department of Biochemistry and Molecular Biology, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada
| | - Nicole M Koropatkin
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI, 48109, USA.
| | - Harry Brumer
- Michael Smith Laboratories, University of British Columbia, 2185 East Mall, Vancouver, BC, V6T 1Z4, Canada.
- Department of Biochemistry and Molecular Biology, University of British Columbia, 2350 Health Sciences Mall, Vancouver, BC, V6T 1Z3, Canada.
- Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, BC, V6T 1Z1, Canada.
- Department of Botany, University of British Columbia, 3200 University Boulevard, Vancouver, BC, V6T 1Z4, Canada.
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