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Metabolism of a hybrid algal galactan by members of the human gut microbiome. Nat Chem Biol 2022; 18:501-510. [PMID: 35289327 DOI: 10.1038/s41589-022-00983-y] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Accepted: 01/27/2022] [Indexed: 12/12/2022]
Abstract
Native porphyran is a hybrid of porphryan and agarose. As a common element of edible seaweed, this algal galactan is a frequent component of the human diet. Bacterial members of the human gut microbiota have acquired polysaccharide utilization loci (PULs) that enable the metabolism of porphyran or agarose. However, the molecular mechanisms that underlie the deconstruction and use of native porphyran remains incompletely defined. Here, we have studied two human gut bacteria, porphyranolytic Bacteroides plebeius and agarolytic Bacteroides uniformis, that target native porphyran. This reveals an exo-based cycle of porphyran depolymerization that incorporates a keystone sulfatase. In both PULs this cycle also works together with a PUL-encoded agarose depolymerizing machinery to synergistically reduce native porphyran to monosaccharides. This provides a framework for understanding the deconstruction of a hybrid algal galactan, and insight into the competitive and/or syntrophic relationship of gut microbiota members that target rare nutrients.
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Hettle AG, Hobbs JK, Pluvinage B, Vickers C, Abe KT, Salama-Alber O, McGuire BE, Hehemann JH, Hui JPM, Berrue F, Banskota A, Zhang J, Bottos EM, Van Hamme J, Boraston AB. Insights into the κ/ι-carrageenan metabolism pathway of some marine Pseudoalteromonas species. Commun Biol 2019; 2:474. [PMID: 31886414 PMCID: PMC6923384 DOI: 10.1038/s42003-019-0721-y] [Citation(s) in RCA: 33] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Accepted: 12/02/2019] [Indexed: 01/07/2023] Open
Abstract
Pseudoalteromonas is a globally distributed marine-associated genus that can be found in a broad range of aquatic environments, including in association with macroalgal surfaces where they may take advantage of these rich sources of polysaccharides. The metabolic systems that confer the ability to metabolize this abundant form of photosynthetically fixed carbon, however, are not yet fully understood. Through genomics, transcriptomics, microbiology, and specific structure-function studies of pathway components we address the capacity of newly isolated marine pseudoalteromonads to metabolize the red algal galactan carrageenan. The results reveal that the κ/ι-carrageenan specific polysaccharide utilization locus (CarPUL) enables isolates possessing this locus the ability to grow on this substrate. Biochemical and structural analysis of the enzymatic components of the CarPUL promoted the development of a detailed model of the κ/ι-carrageenan metabolic pathway deployed by pseudoalteromonads, thus furthering our understanding of how these microbes have adapted to a unique environmental niche.
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Affiliation(s)
- Andrew G. Hettle
- Department of Biochemistry and Microbiology, University of Victoria, PO Box 1700 STN CSC, Victoria, British Columbia V8W 2Y2 Canada
| | - Joanne K. Hobbs
- Department of Biochemistry and Microbiology, University of Victoria, PO Box 1700 STN CSC, Victoria, British Columbia V8W 2Y2 Canada
| | - Benjamin Pluvinage
- Department of Biochemistry and Microbiology, University of Victoria, PO Box 1700 STN CSC, Victoria, British Columbia V8W 2Y2 Canada
| | - Chelsea Vickers
- Department of Biochemistry and Microbiology, University of Victoria, PO Box 1700 STN CSC, Victoria, British Columbia V8W 2Y2 Canada
- Present Address: School of Biological Sciences, Victoria University, PO Box 600, Wellington, 6012 New Zealand
| | - Kento T. Abe
- Department of Biochemistry and Microbiology, University of Victoria, PO Box 1700 STN CSC, Victoria, British Columbia V8W 2Y2 Canada
- Present Address: Lunenfeld-Tanenbaum Research Institute, Sinai Health System, and Department of Molecular Genetics, University of Toronto, 600 University Ave, Rm 992, Toronto, ON M5G1X5 Canada
| | - Orly Salama-Alber
- Department of Biochemistry and Microbiology, University of Victoria, PO Box 1700 STN CSC, Victoria, British Columbia V8W 2Y2 Canada
| | - Bailey E. McGuire
- Department of Biochemistry and Microbiology, University of Victoria, PO Box 1700 STN CSC, Victoria, British Columbia V8W 2Y2 Canada
| | - Jan-Hendrik Hehemann
- Department of Biochemistry and Microbiology, University of Victoria, PO Box 1700 STN CSC, Victoria, British Columbia V8W 2Y2 Canada
- Present Address: Marum and Max Planck Institute for Marine Microbiology, Celsiusstraße 1, 28359 Bremen, Germany
| | - Joseph P. M. Hui
- Aquatic and Crop Resource Development Research Centre, National Research Council of Canada, 1411 Oxford Street, Halifax, NS B3H 3Z1 Canada
| | - Fabrice Berrue
- Aquatic and Crop Resource Development Research Centre, National Research Council of Canada, 1411 Oxford Street, Halifax, NS B3H 3Z1 Canada
| | - Arjun Banskota
- Aquatic and Crop Resource Development Research Centre, National Research Council of Canada, 1411 Oxford Street, Halifax, NS B3H 3Z1 Canada
| | - Junzeng Zhang
- Aquatic and Crop Resource Development Research Centre, National Research Council of Canada, 1411 Oxford Street, Halifax, NS B3H 3Z1 Canada
| | - Eric M. Bottos
- Department of Biological Sciences, Thompson Rivers University, 805 TRU Way, Kamloops, British Columbia V2C 0C8 Canada
| | - Jonathan Van Hamme
- Department of Biological Sciences, Thompson Rivers University, 805 TRU Way, Kamloops, British Columbia V2C 0C8 Canada
| | - Alisdair B. Boraston
- Department of Biochemistry and Microbiology, University of Victoria, PO Box 1700 STN CSC, Victoria, British Columbia V8W 2Y2 Canada
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Hobbs JK, Pluvinage B, Robb M, Smith SP, Boraston AB. Two complementary α-fucosidases from Streptococcus pneumoniae promote complete degradation of host-derived carbohydrate antigens. J Biol Chem 2019; 294:12670-12682. [PMID: 31266803 DOI: 10.1074/jbc.ra119.009368] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2019] [Revised: 06/24/2019] [Indexed: 12/13/2022] Open
Abstract
An important aspect of the interaction between the opportunistic bacterial pathogen Streptococcus pneumoniae and its human host is its ability to harvest host glycans. The pneumococcus can degrade a variety of complex glycans, including N- and O-linked glycans, glycosaminoglycans, and carbohydrate antigens, an ability that is tightly linked to the virulence of S. pneumoniae Although S. pneumoniae is known to use a sophisticated enzyme machinery to attack the human glycome, how it copes with fucosylated glycans, which are primarily histo-blood group antigens, is largely unknown. Here, we identified two pneumococcal enzymes, SpGH29C and SpGH95C, that target α-(1→3/4) and α-(1→2) fucosidic linkages, respectively. X-ray crystallography studies combined with functional assays revealed that SpGH29C is specific for the LewisA and LewisX antigen motifs and that SpGH95C is specific for the H(O)-antigen motif. Together, these enzymes could defucosylate LewisY and LewisB antigens in a complementary fashion. In vitro reconstruction of glycan degradation cascades disclosed that the individual or combined activities of these enzymes expose the underlying glycan structure, promoting the complete deconstruction of a glycan that would otherwise be resistant to pneumococcal enzymes. These experiments expand our understanding of the extensive capacity of S. pneumoniae to process host glycans and the likely roles of α-fucosidases in this. Overall, given the importance of enzymes that initiate glycan breakdown in pneumococcal virulence, such as the neuraminidase NanA and the mannosidase SpGH92, we anticipate that the α-fucosidases identified here will be important factors in developing more refined models of the S. pneumoniae-host interaction.
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Affiliation(s)
- Joanne K Hobbs
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia V8P 5C2, Canada
| | - Benjamin Pluvinage
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia V8P 5C2, Canada
| | - Melissa Robb
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia V8P 5C2, Canada
| | - Steven P Smith
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario K7L 3N6, Canada
| | - Alisdair B Boraston
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia V8P 5C2, Canada
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Biochemical Reconstruction of a Metabolic Pathway from a Marine Bacterium Reveals Its Mechanism of Pectin Depolymerization. Appl Environ Microbiol 2018; 85:AEM.02114-18. [PMID: 30341080 DOI: 10.1128/aem.02114-18] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2018] [Accepted: 10/11/2018] [Indexed: 12/26/2022] Open
Abstract
Pectin is a complex uronic acid-containing polysaccharide typically found in plant cell walls, though forms of pectin are also found in marine diatoms and seagrasses. Genetic loci that target pectin have recently been identified in two phyla of marine bacteria. These loci appear to encode a pectin saccharification pathway that is distinct from the canonical pathway typically associated with phytopathogenic terrestrial bacteria. However, very few components of the marine pectin metabolism pathway have been experimentally validated. Here, we biochemically reconstructed the pectin saccharification pathway from a marine Pseudoalteromonas sp. in vitro and show that it results in the production of galacturonate and the key metabolic intermediate 5-keto-4-deoxyuronate (DKI). We demonstrate the sequential de-esterification and depolymerization of pectin into oligosaccharides and the synergistic action of glycoside hydrolases (GHs) to fully degrade these oligosaccharides into monosaccharides. Furthermore, we show that this pathway relies on enzymes belonging to GH family 105 to carry out the equivalent chemistry afforded by an exolytic polysaccharide lyase (PL) and KdgF in the canonical pectin pathway. Finally, we synthesize our findings into a model of marine pectin degradation and compare it with the canonical pathway. Our results underline the shifting view of pectin as a solely terrestrial polysaccharide and highlight the importance of marine pectin as a carbon source for suitably adapted marine heterotrophs. This alternate pathway has the potential to be exploited in the growing field of biofuel production from plant waste.IMPORTANCE Marine polysaccharides, found in the cell walls of seaweeds and other marine macrophytes, represent a vast sink of photosynthetically fixed carbon. As such, their breakdown by marine microbes contributes significantly to global carbon cycling. Pectin is an abundant polysaccharide found in the cell walls of terrestrial plants, but it has recently been reported that some marine bacteria possess the genetic capacity to degrade it. In this study, we biochemically characterized seven key enzymes from a marine bacterium that, together, fully degrade the backbone of pectin into its constituent monosaccharides. Our findings highlight the importance of pectin as a marine carbon source available to bacteria that possess this pathway. The characterized enzymes also have the potential to be utilized in the production of biofuels from plant waste.
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The Molecular Basis of Polysaccharide Sulfatase Activity and a Nomenclature for Catalytic Subsites in this Class of Enzyme. Structure 2018; 26:747-758.e4. [PMID: 29681469 DOI: 10.1016/j.str.2018.03.012] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2017] [Revised: 02/26/2018] [Accepted: 03/20/2018] [Indexed: 12/11/2022]
Abstract
Sulfatases play a biologically important role by cleaving sulfate groups from molecules. They can be identified on the basis of signature sequences within their primary structures, and the largest family, S1, has predictable features that contribute specifically to the recognition and catalytic removal of sulfate groups. However, despite advances in the prediction and understanding of S1 sulfatases, a major question regards the molecular determinants that drive substrate recognition beyond the targeted sulfate group. Here, through analysis of an endo-4S-ι-carrageenan sulfatase (PsS1_19A) from Pseudoalteromonas sp. PS47, particularly X-ray crystal structures in complex with intact substrates, we show that specific recognition of the substrate leaving group components, in this case carbohydrate, provides the enzyme with specificity for its substrate. On the basis of these results we propose a catalytic subsite nomenclature that we anticipate will form a general foundation for understanding and describing the molecular basis of substrate recognition by sulfatases.
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Jones DR, Thomas D, Alger N, Ghavidel A, Inglis GD, Abbott DW. SACCHARIS: an automated pipeline to streamline discovery of carbohydrate active enzyme activities within polyspecific families and de novo sequence datasets. BIOTECHNOLOGY FOR BIOFUELS 2018; 11:27. [PMID: 29441125 PMCID: PMC5798181 DOI: 10.1186/s13068-018-1027-x] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2017] [Accepted: 01/18/2018] [Indexed: 05/19/2023]
Abstract
BACKGROUND Deposition of new genetic sequences in online databases is expanding at an unprecedented rate. As a result, sequence identification continues to outpace functional characterization of carbohydrate active enzymes (CAZymes). In this paradigm, the discovery of enzymes with novel functions is often hindered by high volumes of uncharacterized sequences particularly when the enzyme sequence belongs to a family that exhibits diverse functional specificities (i.e., polyspecificity). Therefore, to direct sequence-based discovery and characterization of new enzyme activities we have developed an automated in silico pipeline entitled: Sequence Analysis and Clustering of CarboHydrate Active enzymes for Rapid Informed prediction of Specificity (SACCHARIS). This pipeline streamlines the selection of uncharacterized sequences for discovery of new CAZyme or CBM specificity from families currently maintained on the CAZy website or within user-defined datasets. RESULTS SACCHARIS was used to generate a phylogenetic tree of a GH43, a CAZyme family with defined subfamily designations. This analysis confirmed that large datasets can be organized into sequence clusters of manageable sizes that possess related functions. Seeding this tree with a GH43 sequence from Bacteroides dorei DSM 17855 (BdGH43b, revealed it partitioned as a single sequence within the tree. This pattern was consistent with it possessing a unique enzyme activity for GH43 as BdGH43b is the first described α-glucanase described for this family. The capacity of SACCHARIS to extract and cluster characterized carbohydrate binding module sequences was demonstrated using family 6 CBMs (i.e., CBM6s). This CBM family displays a polyspecific ligand binding profile and contains many structurally determined members. Using SACCHARIS to identify a cluster of divergent sequences, a CBM6 sequence from a unique clade was demonstrated to bind yeast mannan, which represents the first description of an α-mannan binding CBM. Additionally, we have performed a CAZome analysis of an in-house sequenced bacterial genome and a comparative analysis of B. thetaiotaomicron VPI-5482 and B. thetaiotaomicron 7330, to demonstrate that SACCHARIS can generate "CAZome fingerprints", which differentiate between the saccharolytic potential of two related strains in silico. CONCLUSIONS Establishing sequence-function and sequence-structure relationships in polyspecific CAZyme families are promising approaches for streamlining enzyme discovery. SACCHARIS facilitates this process by embedding CAZyme and CBM family trees generated from biochemically to structurally characterized sequences, with protein sequences that have unknown functions. In addition, these trees can be integrated with user-defined datasets (e.g., genomics, metagenomics, and transcriptomics) to inform experimental characterization of new CAZymes or CBMs not currently curated, and for researchers to compare differential sequence patterns between entire CAZomes. In this light, SACCHARIS provides an in silico tool that can be tailored for enzyme bioprospecting in datasets of increasing complexity and for diverse applications in glycobiotechnology.
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Affiliation(s)
- Darryl R. Jones
- Lethbridge Research and Development Centre, Agriculture and Agri-Food Canada, 5403-1st Avenue South, Lethbridge, AB T1J 4B1 Canada
| | - Dallas Thomas
- Lethbridge Research and Development Centre, Agriculture and Agri-Food Canada, 5403-1st Avenue South, Lethbridge, AB T1J 4B1 Canada
| | - Nicholas Alger
- Lethbridge Research and Development Centre, Agriculture and Agri-Food Canada, 5403-1st Avenue South, Lethbridge, AB T1J 4B1 Canada
| | - Ata Ghavidel
- Lethbridge Research and Development Centre, Agriculture and Agri-Food Canada, 5403-1st Avenue South, Lethbridge, AB T1J 4B1 Canada
| | - G. Douglas Inglis
- Lethbridge Research and Development Centre, Agriculture and Agri-Food Canada, 5403-1st Avenue South, Lethbridge, AB T1J 4B1 Canada
| | - D. Wade Abbott
- Lethbridge Research and Development Centre, Agriculture and Agri-Food Canada, 5403-1st Avenue South, Lethbridge, AB T1J 4B1 Canada
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Hettle A, Fillo A, Abe K, Massel P, Pluvinage B, Langelaan DN, Smith SP, Boraston AB. Properties of a family 56 carbohydrate-binding module and its role in the recognition and hydrolysis of β-1,3-glucan. J Biol Chem 2017; 292:16955-16968. [PMID: 28827308 DOI: 10.1074/jbc.m117.806711] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Revised: 08/11/2017] [Indexed: 11/06/2022] Open
Abstract
BH0236 from Bacillus halodurans is a multimodular β-1,3-glucanase comprising an N-terminal family 81 glycoside hydrolase catalytic module, an internal family 6 carbohydrate-binding module (CBM) that binds the nonreducing end of β-1,3-glucan chains, and an uncharacterized C-terminal module classified into CBM family 56. Here, we determined that this latter CBM, BhCBM56, bound the soluble β-1,3-glucan laminarin with a dissociation constant (Kd ) of ∼26 μm and displayed higher affinity for insoluble β-1,3-glucans with Kd values of ∼2-10 μm but lacked affinity for β-1,3-glucooligosaccharides. The X-ray crystal structure of BhCBM56 and NMR-derived chemical shift mapping of the binding site revealed a β-sandwich fold, with the face of one β-sheet possessing the β-1,3-glucan-binding surface. On the basis of the functional and structural properties of BhCBM56, we propose that it binds a quaternary polysaccharide structure, most likely the triple helix adopted by polymerized β-1,3-glucans. Consistent with the BhCBM56 and BhCBM6/56 binding profiles, deletion of the CBM56 from BH0236 decreased activity of the enzyme on the insoluble β-1,3-glucan curdlan but not on soluble laminarin; additional deletion of the CBM6 also did not affect laminarin degradation but further decreased curdlan hydrolysis. The pseudo-atomic solution structure of BH0236 determined by small-angle X-ray scattering revealed structural insights into the nature of avid binding by the BhCBM6/56 pair and how the orientation of the active site in the catalytic module factors into recognition and degradation of β-1,3-glucans. Our findings reinforce the notion that catalytic modules and their cognate CBMs have complementary specificities, including targeting of polysaccharide quaternary structure.
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Affiliation(s)
- Andrew Hettle
- From the Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia V8W 3P6, Canada and
| | - Alexander Fillo
- From the Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia V8W 3P6, Canada and
| | - Kento Abe
- From the Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia V8W 3P6, Canada and
| | - Patricia Massel
- From the Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia V8W 3P6, Canada and
| | - Benjamin Pluvinage
- From the Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia V8W 3P6, Canada and
| | - David N Langelaan
- the Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario K7L 3N6, Canada
| | - Steven P Smith
- the Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario K7L 3N6, Canada
| | - Alisdair B Boraston
- From the Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia V8W 3P6, Canada and
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