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Wardman JF, Sim L, Liu J, Howard TA, Geissner A, Danby PM, Boraston AB, Wakarchuk WW, Withers SG. A high-throughput screening platform for enzymes active on mucin-type O-glycoproteins. Nat Chem Biol 2023; 19:1246-1255. [PMID: 37592157 DOI: 10.1038/s41589-023-01405-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2022] [Accepted: 07/12/2023] [Indexed: 08/19/2023]
Abstract
Mucin-type O-glycosylation is a post-translational modification present at the interface between cells where it has important roles in cellular communication. However, deciphering the function of O-glycoproteins and O-glycans can be challenging, especially as few enzymes are available for their assembly or selective degradation. Here, to address this deficiency, we developed a genetically encoded screening methodology for the discovery and engineering of the diverse classes of enzymes that act on O-glycoproteins. The method uses Escherichia coli that have been engineered to produce an O-glycosylated fluorescence resonance energy transfer probe that can be used to screen for O-glycopeptidase activity. Subsequent cleavage of the substrate by O-glycopeptidases provides a read-out of the glycosylation state of the probe, allowing the method to also be used to assay glycosidases and glycosyltransferases. We further show the potential of this methodology in the first ultrahigh-throughput-directed evolution of an O-glycopeptidase.
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Affiliation(s)
- Jacob F Wardman
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada.
- Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, Canada.
| | - Lyann Sim
- Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia, Canada
| | - Jennifer Liu
- Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, Canada
| | - Teresa A Howard
- Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia, Canada
| | - Andreas Geissner
- Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, Canada
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia, Canada
| | - Phillip M Danby
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia, Canada
| | - Alisdair B Boraston
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada
| | - Warren W Wakarchuk
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Stephen G Withers
- Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, Canada.
- Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, Canada.
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia, Canada.
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2
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Bhosale S, Deen MC, Proceviat C, Hettle A, Winter DK, Brockerman J, Levene M, Bennet AJ, Spino C, Boraston AB, Vocadlo DJ. A Fluorogenic Disaccharide Substrate for α-Mannosidases Enables High-Throughput Screening and Identification of an Inhibitor of the GH92 Virulence Factor from Streptococcus pneumoniae. ACS Chem Biol 2023; 18:1730-1737. [PMID: 37531094 DOI: 10.1021/acschembio.3c00053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/03/2023]
Abstract
Trimming of host glycans is a mechanism that is broadly employed by both commensal and pathogenic microflora to enable colonization. Host glycan trimming by the opportunistic Gram-positive bacterium Streptococcus pneumoniae has been demonstrated to be an important mechanism of virulence. While S. pneumoniae employs a multitude of glycan processing enzymes, the exo-mannosidase SpGH92 has been shown to be an important virulence factor. Accordingly, SpGH92 is hypothesized to be a target for much-needed new treatments of S. pneumoniae infection. Here we report the synthesis of 4-methylumbelliferyl α-d-mannopyranosyl-(1→2)-β-d-mannopyranoside (Manα1,2Manβ-4MU) as a fluorogenic disaccharide substrate and development of an assay for SpGH92 that overcomes its requirement for +1 binding site occupancy. We miniaturize our in vitro assay and apply it to a high-throughput screen of >65 000 compounds, identifying a single inhibitory chemotype, LIPS-343. We further show that Manα1,2Manβ-4MU is also a substrate of the human Golgi-localized α-mannosidase MAN1A1, suggesting that this substrate should be useful for assessing the activity of this and other mammalian α-mannosidases.
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Affiliation(s)
- Sandeep Bhosale
- Department of Chemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
| | - Matthew C Deen
- Department of Chemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
| | - Cameron Proceviat
- Department of Chemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
| | - Andrew Hettle
- Department of Biochemistry & Microbiology, University of Victoria, P.O. Box 3055 STN CSC, Victoria, British Columbia V8W 3P6, Canada
| | - Dana K Winter
- Département de Chimie, Université de Sherbrooke, Sherbrooke, Québec J1K 2R1, Canada
| | - Jacob Brockerman
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
| | - Marina Levene
- Department of Chemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
| | - Andrew J Bennet
- Department of Chemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
| | - Claude Spino
- Département de Chimie, Université de Sherbrooke, Sherbrooke, Québec J1K 2R1, Canada
| | - Alisdair B Boraston
- Department of Biochemistry & Microbiology, University of Victoria, P.O. Box 3055 STN CSC, Victoria, British Columbia V8W 3P6, Canada
| | - David J Vocadlo
- Department of Chemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
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3
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Robb M, Hobbs JK, Boraston AB. Separation and Visualization of Glycans by Fluorophore-Assisted Carbohydrate Electrophoresis. Methods Mol Biol 2023; 2657:215-222. [PMID: 37149534 DOI: 10.1007/978-1-0716-3151-5_16] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Fluorophore-assisted carbohydrate electrophoresis (FACE) is a method in which a fluorophore is covalently attached to the reducing end of carbohydrates, thereby allowing high-resolution separation by electrophoresis and visualization. This method can be used for carbohydrate profiling and sequencing, as well as for determining the specificity of carbohydrate-active enzymes. Here we describe and demonstrate the use of FACE to separate and visualize the glycans released following digestion of oligosaccharides by glycoside hydrolases (GHs) using two examples: (i) the digestion of chitobiose by the streptococcal β-hexosaminidase GH20C and (ii) the digestion of glycogen by the GH13 member SpuA.
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Affiliation(s)
- Mélissa Robb
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC, Canada
| | - Joanne K Hobbs
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC, Canada
| | - Alisdair B Boraston
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC, Canada.
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4
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Santana AG, Robinson K, Vickers C, Deen MC, Chen H, Zhou S, Dai B, Fuller M, Boraston AB, Vocadlo DJ, Clarke LA, Withers SG. Pharmacological Chaperones for GCase that Switch Conformation with pH Enhance Enzyme Levels in Gaucher Animal Models. Angew Chem Int Ed Engl 2022; 61:e202207974. [DOI: 10.1002/anie.202207974] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2022] [Indexed: 11/06/2022]
Affiliation(s)
- Andrés G. Santana
- Dept. of Chemistry University of British Columbia Vancouver BC, V6T 1Z1 Canada
| | - Kyle Robinson
- Dept. of Chemistry University of British Columbia Vancouver BC, V6T 1Z1 Canada
| | - Chelsea Vickers
- Dept. of Biochemistry and Microbiology University of Victoria Victoria BC, V8W 3P6 Canada
| | - Matthew C. Deen
- Dept. of Chemistry and Dept. of Mol. Biology and Biochemistry Simon Fraser University Burnaby BC, V5A 1S6 Canada
| | - Hong‐Ming Chen
- Dept. of Chemistry University of British Columbia Vancouver BC, V6T 1Z1 Canada
| | - Stephen Zhou
- Dept. of Medical Genetics University of British Columbia Women's Hospital & Health Centre Vancouver BC, V6H 3N1 Canada
| | - Ben Dai
- Dept. of Medical Genetics University of British Columbia Women's Hospital & Health Centre Vancouver BC, V6H 3N1 Canada
| | - Maria Fuller
- Genetics and Molecular Pathology SA Pathology at Women's and Children's Hospital N. Adelaide South Australia 5006 Australia
| | - Alisdair B. Boraston
- Dept. of Biochemistry and Microbiology University of Victoria Victoria BC, V8W 3P6 Canada
| | - David J. Vocadlo
- Dept. of Chemistry and Dept. of Mol. Biology and Biochemistry Simon Fraser University Burnaby BC, V5A 1S6 Canada
| | - Lorne A. Clarke
- Dept. of Medical Genetics University of British Columbia Women's Hospital & Health Centre Vancouver BC, V6H 3N1 Canada
| | - Stephen G. Withers
- Dept. of Chemistry University of British Columbia Vancouver BC, V6T 1Z1 Canada
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5
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Medley BJ, Leclaire L, Thompson N, Mahoney KE, Pluvinage B, Parson MAH, Burke JE, Malaker S, Wakarchuk W, Boraston AB. A previously uncharacterized O-glycopeptidase from Akkermansia muciniphila requires the Tn-antigen for cleavage of the peptide bond. J Biol Chem 2022; 298:102439. [PMID: 36049519 PMCID: PMC9513282 DOI: 10.1016/j.jbc.2022.102439] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2022] [Revised: 08/25/2022] [Accepted: 08/26/2022] [Indexed: 10/27/2022] Open
Abstract
Akkermansia muciniphila is key member of the human gut microbiota, impacting many features of host health. A major characteristic of this bacterium is its interaction with host mucin, which is abundant in the gut environment, and its ability to metabolize mucin as a nutrient source. The machinery deployed by A. muciniphila to enable this interaction appears to be extensive and sophisticated, yet it is incompletely defined. The uncharacterized protein AMUC_1438 is encoded by a gene that was previously shown to be upregulated when the bacterium is grown on mucin. This uncharacterized protein has features suggestive of carbohydrate-recognition and peptidase activity, which led us to hypothesize that it has a role in mucin depolymerization. Here we provide structural and functional support for the assignment of AMUC_1438 as a unique O-glycopeptidase with mucin degrading capacity. O-glycopeptidase enzymes recognize glycans but hydrolyze the peptide backbone and are common in host-adapted microbes that colonize or invade mucus layers. Structural, kinetic, and mutagenic analyses point to a metzincin metalloprotease catalytic motif but specific recognition of a GalNAc residue α-linked to serine or threonine (i.e. the Tn-antigen) within the AMUC_1438 active site. The enzyme catalyzes hydrolysis of the bond immediately N-terminal to the glycosylated residue. Additional modelling analyses suggest the presence of a carbohydrate-binding module that may assist in substrate recognition. We anticipate that these results will be fundamental to a wider understanding of the O-glycopeptidase class of enzymes and how they may contribute to host-adaptation.
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Affiliation(s)
- Brendon J Medley
- Department of Biochemistry and Microbiology, University of Victoria, PO Box 1700 STN CSC, Victoria, British Columbia, V8W 2Y2, Canada
| | - Leif Leclaire
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada
| | - Nicole Thompson
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, Canada
| | - Keira E Mahoney
- Department of Chemistry, Yale University, 350 Edward St., New Haven CT, 06511
| | - Benjamin Pluvinage
- Department of Biochemistry and Microbiology, University of Victoria, PO Box 1700 STN CSC, Victoria, British Columbia, V8W 2Y2, Canada
| | - Matthew A H Parson
- Department of Biochemistry and Microbiology, University of Victoria, PO Box 1700 STN CSC, Victoria, British Columbia, V8W 2Y2, Canada
| | - John E Burke
- Department of Biochemistry and Microbiology, University of Victoria, PO Box 1700 STN CSC, Victoria, British Columbia, V8W 2Y2, Canada; Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, British Columbia, V6T 1Z3, Canada
| | - Stacy Malaker
- Department of Chemistry, Yale University, 350 Edward St., New Haven CT, 06511
| | - Warren Wakarchuk
- Department of Biological Sciences, University of Alberta, Edmonton, AB T6G 2E9, 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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6
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Hettle AG, Vickers CJ, Boraston AB. Sulfatases: Critical Enzymes for Algal Polysaccharide Processing. Front Plant Sci 2022; 13:837636. [PMID: 35574087 PMCID: PMC9096561 DOI: 10.3389/fpls.2022.837636] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/16/2021] [Accepted: 04/04/2022] [Indexed: 06/15/2023]
Abstract
Microbial sulfatases are important biocatalysts in the marine environment where they play a key role in the catabolic biotransformation of abundant sulphated algal polysaccharides. The sulphate esters decorating algal polysaccharides, such as carrageenan, fucoidan and ulvan, can constitute up to 40% of the biopolymer dry weight. The use of this plentiful carbon and energy source by heterotrophic microbes is enabled in part by the sulfatases encoded in their genomes. Sulfatase catalysed hydrolytic removal of sulphate esters is a key reaction at various stages of the enzymatic cascade that depolymerises sulphated polysaccharides into monosaccharides that can enter energy yielding metabolic pathways. As the critical roles of sulfatases in the metabolism of sulphated polysaccharides from marine algae is increasingly revealed, the structural and functional analysis of these enzymes becomes an important component of understanding these metabolic pathways. The S1 family of formylglycine-dependent sulfatases is the largest and most functionally diverse sulfatase family that is frequently active on polysaccharides. Here, we review this important sulfatase family with emphasis on recent developments in studying the structural and functional relationship between sulfatases and their sulphated algal polysaccharide substrates. This analysis utilises the recently proposed active site nomenclature for sulfatases. We will highlight the key role of sulfatases, not only in marine carbon cycling, but also as potential biocatalysts for the production of a variety of novel tailor made sulphated oligomers, which are useful products in, for example, pharmaceutical or cosmetic applications.
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Affiliation(s)
- Andrew G. Hettle
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC, Canada
| | - Chelsea J. Vickers
- School of Biological Sciences, Victoria University of Wellington, Wellington, New Zealand
| | - Alisdair B. Boraston
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC, Canada
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7
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McGuire BE, Hettle AG, Vickers C, King DT, Vocadlo DJ, Boraston AB. The structure of a family 110 glycoside hydrolase provides insight into the hydrolysis of α-1,3-galactosidic linkages in λ-carrageenan and blood group antigens. J Biol Chem 2020; 295:18426-18435. [PMID: 33127644 PMCID: PMC7939477 DOI: 10.1074/jbc.ra120.015776] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2020] [Revised: 10/23/2020] [Indexed: 11/30/2022] Open
Abstract
α-Linked galactose is a common carbohydrate motif in nature that is processed by a variety of glycoside hydrolases from different families. Terminal Galα1-3Gal motifs are found as a defining feature of different blood group and tissue antigens, as well as the building block of the marine algal galactan λ-carrageenan. The blood group B antigen and linear α-Gal epitope can be processed by glycoside hydrolases in family GH110, whereas the presence of genes encoding GH110 enzymes in polysaccharide utilization loci from marine bacteria suggests a role in processing λ-carrageenan. However, the structure-function relationships underpinning the α-1,3-galactosidase activity within family GH110 remain unknown. Here we focus on a GH110 enzyme (PdGH110B) from the carrageenolytic marine bacterium Pseudoalteromonas distincta U2A. We showed that the enzyme was active on Galα1-3Gal but not the blood group B antigen. X-ray crystal structures in complex with galactose and unhydrolyzed Galα1-3Gal revealed the parallel β-helix fold of the enzyme and the structural basis of its inverting catalytic mechanism. Moreover, an examination of the active site reveals likely adaptations that allow accommodation of fucose in blood group B active GH110 enzymes or, in the case of PdGH110, accommodation of the sulfate groups found on λ-carrageenan. Overall, this work provides insight into the first member of a predominantly marine clade of GH110 enzymes while also illuminating the structural basis of α-1,3-galactoside processing by the family as a whole.
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Affiliation(s)
- Bailey E McGuire
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada
| | - Andrew G Hettle
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada
| | - Chelsea Vickers
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada
| | - Dustin T King
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia, Canada
| | - David J Vocadlo
- Department of Molecular Biology and Biochemistry, Simon Fraser University, Burnaby, British Columbia, Canada; Department of Chemistry, Simon Fraser University, Burnaby, British Columbia, Canada
| | - Alisdair B Boraston
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada.
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8
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Noach I, Boraston AB. Structural evidence for a proline-specific glycopeptide recognition domain in an O-glycopeptidase. Glycobiology 2020; 31:385-390. [PMID: 33030205 DOI: 10.1093/glycob/cwaa095] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2020] [Revised: 09/21/2020] [Accepted: 10/02/2020] [Indexed: 12/12/2022] Open
Abstract
The glycosylation of proteins is typically considered as a stabilizing modification, including resistance to proteolysis. A class of peptidases, referred to as glycopeptidases or O-glycopeptidases, circumvent the protective effect of glycans against proteolysis by accommodating the glycans in their active sites as specific features of substrate recognition. IMPa from Pseudomonas aeruginosa is such an O-glycopeptidase that cleaves the peptide bond immediately preceding a site of O-glycosylation, and through this glycoprotein-degrading function contributes to the host-pathogen interaction. IMPa, however, is a relatively large multidomain protein and how its additional domains may contribute to its function remains unknown. Here, through the determination of a crystal structure of IMPa in complex with an O-glycopeptide, we reveal that the N-terminal domain of IMPa, which is classified in Pfam as IMPa_N_2, is a proline recognition domain that also shows the properties of recognizing an O-linked glycan on the serine/threonine residue following the proline. The proline is bound in the center of a bowl formed by four functionally conserved aromatic amino acid side chains while the glycan wraps around one of the tyrosine residues in the bowl to make classic aromatic ring-carbohydrate CH-π interactions. This structural evidence provides unprecedented insight into how the ancillary domains in glycoprotein-specific peptidases can noncatalytically recognize specific glycosylated motifs that are common in mucin and mucin-like molecules.
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Affiliation(s)
- Ilit Noach
- Biochemistry & Microbiology, University of Victoria, PO Box 3055 STN CSC, Victoria, BC V8W 3P6, Canada
| | - Alisdair B Boraston
- Biochemistry & Microbiology, University of Victoria, PO Box 3055 STN CSC, Victoria, BC V8W 3P6, Canada
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9
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Pluvinage B, Robb CS, Jeffries R, Boraston AB. The structure of PfGH50B, an agarase from the marine bacterium Pseudoalteromonas fuliginea PS47. Acta Crystallogr F Struct Biol Commun 2020; 76:422-427. [PMID: 32880590 PMCID: PMC7470041 DOI: 10.1107/s2053230x20010328] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Accepted: 07/24/2020] [Indexed: 11/10/2022] Open
Abstract
The recently identified marine bacterium Pseudoalteromonas fuliginea sp. PS47 possesses a polysaccharide-utilization locus dedicated to agarose degradation. In particular, it contains a gene (locus tag EU509_06755) encoding a β-agarase that belongs to glycoside hydrolase family 50 (GH50), PfGH50B. The 2.0 Å resolution X-ray crystal structure of PfGH50B reveals a rare complex multidomain fold that was found in two of the three previously determined GH50 structures. The structure comprises an N-terminal domain with a carbohydrate-binding module (CBM)-like fold fused to a C-terminal domain by a rigid linker. The CBM-like domain appears to function by extending the catalytic groove of the enzyme. Furthermore, the PfGH50B structure highlights key structural features in the mobile loops that may function to restrict the degree of polymerization of the neoagaro-oligosaccharide products and the enzyme processivity.
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Affiliation(s)
- Benjamin Pluvinage
- Department of Biochemistry and Microbiology, University of Victoria, PO Box 1700 STN CSC, Victoria, BC V8W 2Y2, Canada
| | - Craig S. Robb
- Department of Biochemistry and Microbiology, University of Victoria, PO Box 1700 STN CSC, Victoria, BC V8W 2Y2, Canada
- Department of Biochemistry and Molecular Biology, University of British Columbia, Life Sciences Centre, 2350 Health Sciences Mall, Vancouver, BC V6T 1Z3, Canada
| | - Roderick Jeffries
- Department of Biochemistry and Microbiology, University of Victoria, PO Box 1700 STN CSC, Victoria, BC V8W 2Y2, Canada
| | - Alisdair B. Boraston
- Department of Biochemistry and Microbiology, University of Victoria, PO Box 1700 STN CSC, Victoria, BC V8W 2Y2, Canada
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10
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Low KE, Smith SP, Abbott DW, Boraston AB. The glycoconjugate-degrading enzymes of Clostridium perfringens: Tailored catalysts for breaching the intestinal mucus barrier. Glycobiology 2020; 31:681-690. [PMID: 32472136 DOI: 10.1093/glycob/cwaa050] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 05/21/2020] [Accepted: 06/01/2020] [Indexed: 01/07/2023] Open
Abstract
The gastrointestinal (GI) tract of humans and animals is lined with mucus that serves as a barrier between the gut microbiota and the epithelial layer of the intestine. As the proteins present in mucus are typically heavily glycosylated, such as the mucins, several enteric commensal and pathogenic bacterial species are well-adapted to this rich carbon source and their genomes are replete with carbohydrate-active enzymes targeted toward dismantling the glycans and proteins present in mucus. One such species is Clostridium perfringens, a Gram-positive opportunistic pathogen indigenous to the gut of humans and animals. The genome of C. perfringens encodes numerous carbohydrate-active enzymes that are predicted or known to target glycosidic linkages within or on the termini of mucus glycans. Through this enzymatic activity, the degradation of the mucosal layer by C. perfringens has been implicated in a number of GI diseases, the most severe of which is necrotic enteritis. In this review, we describe the wide array of extracellular glycoside hydrolases, and their accessory modules, that is possessed by C. perfringens, and examine the unique multimodularity of these proteins in the context of degrading the glycoconjugates in mucus as a potential component of disease.
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Affiliation(s)
- Kristin E Low
- Lethbridge Research and Development Centre, Agriculture and Agri-Food Canada, 5403 1 Ave S, Lethbridge T1J 4B1, Canada
| | - Steven P Smith
- Department of Biomedical and Molecular Sciences, Queen's University, 99 University Ave, Kingston K7L 3N6, Canada
| | - D Wade Abbott
- Lethbridge Research and Development Centre, Agriculture and Agri-Food Canada, 5403 1 Ave S, Lethbridge T1J 4B1, Canada
| | - Alisdair B Boraston
- Faculty of Biochemistry and Microbiology, University of Victoria, Victoria V8P 5C2, Canada
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11
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Pluvinage B, Massel PM, Burak K, Boraston AB. Structural and functional analysis of four family 84 glycoside hydrolases from the opportunistic pathogen Clostridium perfringens. Glycobiology 2020; 30:49-57. [PMID: 31701135 DOI: 10.1093/glycob/cwz069] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2019] [Revised: 08/29/2019] [Accepted: 08/30/2019] [Indexed: 11/13/2022] Open
Abstract
The opportunistic pathogen Clostridium perfringens possesses the ability to colonize the protective mucin layer in the gastrointestinal tract. To assist this, the C. perfringens genome contains a battery of genes encoding glycoside hydrolases (GHs) that are likely active on mucin glycans, including four genes encoding family 84 GHs: CpGH84A (NagH), CpGH84B (NagI), CpGH84C (NagJ) and CpGH84D (NagK). To probe the potential advantage gained by the expansion of GH84 enzymes in C. perfringens, we undertook the structural and functional characterization of the CpGH84 catalytic modules. Here, we show that these four CpGH84 catalytic modules act as β-N-acetyl-D-glucosaminidases able to hydrolyze N- and O-glycan motifs. CpGH84A and CpGH84D displayed a substrate specificity restricted to terminal β-1,2- and β-1,6-linked N-acetyl-D-glucosamine (GlcNAc). CpGH84B and CpGH84C appear more promiscuous with activity on terminal β-1,2-, β-1,3- and β-1,6-linked GlcNAc; both possess some activity toward β-1,4-linked GlcNAc, but this is dependent upon which monosaccharide it is linked to. Furthermore, all the CpGH84s have different optimum pHs ranging from 5.2 to 7.0. Consistent with their β-N-acetyl-D-glucosaminidase activities, the structures of the four catalytic modules revealed similar folds with a catalytic site including a conserved -1 subsite that binds GlcNAc. However, nonconserved residues in the vicinity of the +1 subsite suggest different accommodation of the sugar preceding the terminal GlcNAc, resulting in subtly different substrate specificities. This structure-function comparison of the four GH84 catalytic modules from C. perfringens reveals their different biochemical properties, which may relate to how they are deployed in the bacterium's niche in the host.
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Affiliation(s)
- Benjamin Pluvinage
- Biochemistry and Microbiology, University of Victoria, PO Box 3055 STN CSC, Victoria, BC V8W 3P6, Canada
| | - Patricia M Massel
- Biochemistry and Microbiology, University of Victoria, PO Box 3055 STN CSC, Victoria, BC V8W 3P6, Canada
| | - Kristyn Burak
- Biochemistry and Microbiology, University of Victoria, PO Box 3055 STN CSC, Victoria, BC V8W 3P6, Canada
| | - Alisdair B Boraston
- Biochemistry and Microbiology, University of Victoria, PO Box 3055 STN CSC, Victoria, BC V8W 3P6, Canada
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12
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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13
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Hobbs JK, Meier EPW, Pluvinage B, Mey MA, Boraston AB. Molecular analysis of an enigmatic Streptococcus pneumoniae virulence factor: The raffinose-family oligosaccharide utilization system. J Biol Chem 2019; 294:17197-17208. [PMID: 31591266 PMCID: PMC6873169 DOI: 10.1074/jbc.ra119.010280] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2019] [Revised: 10/02/2019] [Indexed: 01/07/2023] Open
Abstract
Streptococcus pneumoniae is an opportunistic respiratory pathogen that can spread to other body sites, including the ears, brain, and blood. The ability of this bacterium to break down, import, and metabolize a wide range of glycans is key to its virulence. Intriguingly, S. pneumoniae can utilize several plant oligosaccharides for growth in vitro, including raffinose-family oligosaccharides (RFOs, which are α-(1→6)-galactosyl extensions of sucrose). An RFO utilization locus has been identified in the pneumococcal genome; however, none of the proteins encoded by this locus have been biochemically characterized. The enigmatic ability of S. pneumoniae to utilize RFOs has recently received attention because mutations in two of the RFO locus genes have been linked to the tissue tropism of clinical pneumococcal isolates. Here, we use functional studies combined with X-ray crystallography to show that although the pneumococcal RFO locus encodes for all the machinery required for uptake and degradation of RFOs, the individual pathway components are biochemically inefficient. We also demonstrate that the initiating enzyme in this pathway, the α-galactosidase Aga (a family 36 glycoside hydrolase), can cleave α-(1→3)-linked galactose units from a linear blood group antigen. We propose that the pneumococcal RFO pathway is an evolutionary relic that is not utilized in this streptococcal species and, as such, is under no selection pressure to maintain binding affinity and/or catalytic efficiency. We speculate that the apparent contribution of RFO utilization to pneumococcal tissue tropism may, in fact, be due to the essential role the ATPase RafK plays in the transport of other carbohydrates.
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Affiliation(s)
- Joanne K. Hobbs
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia V8P 5C2, Canada
| | - Edward P. W. Meier
- 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
| | - Mackenzie A. Mey
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia V8P 5C2, Canada
| | - Alisdair B. Boraston
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia V8P 5C2, Canada, To whom correspondence should be addressed:
Dept. of Biochemistry and Microbiology, University of Victoria, Victoria, BC V8P 5C2, Canada. Tel.:
250-472-4168; Fax:
250-721-8855; E-mail:
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14
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MacMillan JL, Vicaretti SD, Noyovitz B, Xing X, Low KE, Inglis GD, Zaytsoff SJ, Boraston AB, Smith SP, Uwiera RR, Selinger LB, Zandberg WF, Abbott DW. Structural analysis of broiler chicken small intestinal mucin O-glycan modification by Clostridium perfringens. Poult Sci 2019; 98:5074-5088. [DOI: 10.3382/ps/pez297] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2019] [Accepted: 05/03/2019] [Indexed: 12/12/2022] Open
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15
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Abstract
In 1969, Cashel and Gallant first observed the presence of (p)ppGpp-the signaling molecule of the stringent response-in starved bacterial cells. Fifty years later, (p)ppGpp and the stringent response have emerged as essential master regulators of not only the bacterial response to stress but also almost all aspects of bacterial physiology, virulence, and immune evasion. More worryingly, a wealth of data now indicate that (p)ppGpp and stringent response activation pose a serious threat to the efficacy and clinical success of antimicrobial therapy. Here, we focus on the central role that (p)ppGpp and the stringent response play in the phenomenon of antibiotic tolerance, as well as the acquisition, development, and expression of antibiotic resistance. We review these consequences of stringent response activation in relation to the main proteins involved in (p)ppGpp production and control, in particular the complex interplay between monofunctional and bifunctional long RelA/SpoT homologues (RSHs) and small alarmone synthetases (SASs). We also review the growing evidence to suggest that there are multiple other indirect pathways of stringent response induction that can affect antibiotic efficacy. Finally, we summarize recent studies that indicate the in vivo and clinical impact of (p)ppGpp production on antibiotic treatment outcomes. We conclude by reviewing the progress to date in the search for novel therapeutics that target the stringent response.
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Affiliation(s)
- Joanne K. Hobbs
- Department of Biochemistry and Microbiology, University of Victoria, 3800 Finnerty Road, Victoria, BC V8P 5C2, Canada
| | - Alisdair B. Boraston
- Department of Biochemistry and Microbiology, University of Victoria, 3800 Finnerty Road, Victoria, BC V8P 5C2, Canada
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16
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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17
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Vickers C, Liu F, Abe K, Salama-Alber O, Jenkins M, Springate CMK, Burke JE, Withers SG, Boraston AB. Endo-fucoidan hydrolases from glycoside hydrolase family 107 (GH107) display structural and mechanistic similarities to α-l-fucosidases from GH29. J Biol Chem 2018; 293:18296-18308. [PMID: 30282808 DOI: 10.1074/jbc.ra118.005134] [Citation(s) in RCA: 32] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Revised: 09/25/2018] [Indexed: 11/06/2022] Open
Abstract
Fucoidans are chemically complex and highly heterogeneous sulfated marine fucans from brown macro algae. Possessing a variety of physicochemical and biological activities, fucoidans are used as gelling and thickening agents in the food industry and have anticoagulant, antiviral, antitumor, antibacterial, and immune activities. Although fucoidan-depolymerizing enzymes have been identified, the molecular basis of their activity on these chemically complex polysaccharides remains largely uninvestigated. In this study, we focused on three glycoside hydrolase family 107 (GH107) enzymes: MfFcnA and two newly identified members, P5AFcnA and P19DFcnA, from a bacterial species of the genus Psychromonas Using carbohydrate-PAGE, we show that P5AFcnA and P19DFcnA are active on fucoidans that differ from those depolymerized by MfFcnA, revealing differential substrate specificity within the GH107 family. Using a combination of X-ray crystallography and NMR analyses, we further show that GH107 family enzymes share features of their structures and catalytic mechanisms with GH29 α-l-fucosidases. However, we found that GH107 enzymes have the distinction of utilizing a histidine side chain as the proposed acid/base catalyst in its retaining mechanism. Further interpretation of the structural data indicated that the active-site architectures within this family are highly variable, likely reflecting the specificity of GH107 enzymes for different fucoidan substructures. Together, these findings begin to illuminate the molecular details underpinning the biological processing of fucoidans.
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Affiliation(s)
- Chelsea Vickers
- From the Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia 8W 3P6, Canada
| | - Feng Liu
- the Department of Chemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada, and
| | - Kento Abe
- From the Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia 8W 3P6, Canada
| | - Orly Salama-Alber
- From the Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia 8W 3P6, Canada
| | - Meredith Jenkins
- From the Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia 8W 3P6, Canada
| | | | - John E Burke
- From the Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia 8W 3P6, Canada
| | - Stephen G Withers
- the Department of Chemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada, and
| | - Alisdair B Boraston
- From the Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia 8W 3P6, Canada,.
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18
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Hobbs JK, Pluvinage B, Boraston AB. Glycan-metabolizing enzymes in microbe-host interactions: the Streptococcus pneumoniae paradigm. FEBS Lett 2018; 592:3865-3897. [PMID: 29608212 DOI: 10.1002/1873-3468.13045] [Citation(s) in RCA: 31] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2018] [Revised: 03/21/2018] [Accepted: 03/22/2018] [Indexed: 12/31/2022]
Abstract
Streptococcus pneumoniae is a frequent colonizer of the upper airways; however, it is also an accomplished pathogen capable of causing life-threatening diseases. To colonize and cause invasive disease, this bacterium relies on a complex array of factors to mediate the host-bacterium interaction. The respiratory tract is rich in functionally important glycoconjugates that display a vast range of glycans, and, thus, a key component of the pneumococcus-host interaction involves an arsenal of bacterial carbohydrate-active enzymes to depolymerize these glycans and carbohydrate transporters to import the products. Through the destruction of host glycans, the glycan-specific metabolic machinery deployed by S. pneumoniae plays a variety of roles in the host-pathogen interaction. Here, we review the processing and metabolism of the major host-derived glycans, including N- and O-linked glycans, Lewis and blood group antigens, proteoglycans, and glycogen, as well as some dietary glycans. We discuss the role of these metabolic pathways in the S. pneumoniae-host interaction, speculate on the potential of key enzymes within these pathways as therapeutic targets, and relate S. pneumoniae as a model system to glycan processing in other microbial pathogens.
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Affiliation(s)
- Joanne K Hobbs
- Department of Biochemistry and Microbiology, University of Victoria, British Columbia, Canada
| | - Benjamin Pluvinage
- Department of Biochemistry and Microbiology, University of Victoria, British Columbia, Canada
| | - Alisdair B Boraston
- Department of Biochemistry and Microbiology, University of Victoria, British Columbia, Canada
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19
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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] [What about the content of this article? (0)] [Affiliation(s)] [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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20
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Jones DR, Uddin MS, Gruninger RJ, Pham TTM, Thomas D, Boraston AB, Briggs J, Pluvinage B, McAllister TA, Forster RJ, Tsang A, Selinger LB, Abbott DW. Discovery and characterization of family 39 glycoside hydrolases from rumen anaerobic fungi with polyspecific activity on rare arabinosyl substrates. J Biol Chem 2017; 292:12606-12620. [PMID: 28588026 DOI: 10.1074/jbc.m117.789008] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2017] [Revised: 05/30/2017] [Indexed: 11/06/2022] Open
Abstract
Enzyme activities that improve digestion of recalcitrant plant cell wall polysaccharides may offer solutions for sustainable industries. To this end, anaerobic fungi in the rumen have been identified as a promising source of novel carbohydrate active enzymes (CAZymes) that modify plant cell wall polysaccharides and other complex glycans. Many CAZymes share insufficient sequence identity to characterized proteins from other microbial ecosystems to infer their function; thus presenting challenges to their identification. In this study, four rumen fungal genes (nf2152, nf2215, nf2523, and pr2455) were identified that encode family 39 glycoside hydrolases (GH39s), and have conserved structural features with GH51s. Two recombinant proteins, NF2152 and NF2523, were characterized using a variety of biochemical and structural techniques, and were determined to have distinct catalytic activities. NF2152 releases a single product, β1,2-arabinobiose (Ara2) from sugar beet arabinan (SBA), and β1,2-Ara2 and α-1,2-galactoarabinose (Gal-Ara) from rye arabinoxylan (RAX). NF2523 exclusively releases α-1,2-Gal-Ara from RAX, which represents the first description of a galacto-(α-1,2)-arabinosidase. Both β-1,2-Ara2 and α-1,2-Gal-Ara are disaccharides not previously described within SBA and RAX. In this regard, the enzymes studied here may represent valuable new biocatalytic tools for investigating the structures of rare arabinosyl-containing glycans, and potentially for facilitating their modification in industrial applications.
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Affiliation(s)
- Darryl R Jones
- Agriculture and Agri-Food Canada, Lethbridge Research and Development Centre, Lethbridge, Alberta T1J 4B1, Canada
| | - Muhammed Salah Uddin
- Agriculture and Agri-Food Canada, Lethbridge Research and Development Centre, Lethbridge, Alberta T1J 4B1, Canada; Department of Biological Sciences, University of Lethbridge, Lethbridge, Alberta T1K 6T5, Canada
| | - Robert J Gruninger
- Agriculture and Agri-Food Canada, Lethbridge Research and Development Centre, Lethbridge, Alberta T1J 4B1, Canada
| | - Thi Thanh My Pham
- Centre for Structural and Functional Genomics, Concordia University, Montreal, Quebec H4B 1R6, Canada
| | - Dallas Thomas
- Agriculture and Agri-Food Canada, Lethbridge Research and Development Centre, Lethbridge, Alberta T1J 4B1, Canada
| | - Alisdair B Boraston
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia V8W 3P6, Canada
| | - Jonathan Briggs
- School of Biology, Ridley Building 2, Newcastle University, Claremont Road, Newcastle upon Tyne NE1 7RU, United Kingdom
| | - Benjamin Pluvinage
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia V8W 3P6, Canada
| | - Tim A McAllister
- Agriculture and Agri-Food Canada, Lethbridge Research and Development Centre, Lethbridge, Alberta T1J 4B1, Canada
| | - Robert J Forster
- Agriculture and Agri-Food Canada, Lethbridge Research and Development Centre, Lethbridge, Alberta T1J 4B1, Canada
| | - Adrian Tsang
- Centre for Structural and Functional Genomics, Concordia University, Montreal, Quebec H4B 1R6, Canada
| | - L Brent Selinger
- Department of Biological Sciences, University of Lethbridge, Lethbridge, Alberta T1K 6T5, Canada
| | - D Wade Abbott
- Agriculture and Agri-Food Canada, Lethbridge Research and Development Centre, Lethbridge, Alberta T1J 4B1, Canada; Department of Biological Sciences, University of Lethbridge, Lethbridge, Alberta T1K 6T5, Canada.
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21
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Higgins MA, Hamilton AM, Boraston AB. Structural characterization of the PTS IIA and IIB proteins associated with pneumococcal fucose utilization. Proteins 2017; 85:963-968. [DOI: 10.1002/prot.25264] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Revised: 01/17/2017] [Accepted: 01/30/2017] [Indexed: 11/06/2022]
Affiliation(s)
- Melanie A. Higgins
- Biochemistry and Microbiology; University of Victoria; PO Box 3055 STN CSC Victoria British Columbia V8W 3P6 Canada
| | - Aileen M. Hamilton
- Biochemistry and Microbiology; University of Victoria; PO Box 3055 STN CSC Victoria British Columbia V8W 3P6 Canada
| | - Alisdair B. Boraston
- Biochemistry and Microbiology; University of Victoria; PO Box 3055 STN CSC Victoria British Columbia V8W 3P6 Canada
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22
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Grondin JM, Duan D, Kirlin AC, Abe KT, Chitayat S, Spencer HL, Spencer C, Campigotto A, Houliston S, Arrowsmith CH, Allingham JS, Boraston AB, Smith SP. Diverse modes of galacto-specific carbohydrate recognition by a family 31 glycoside hydrolase from Clostridium perfringens. PLoS One 2017; 12:e0171606. [PMID: 28158290 PMCID: PMC5291390 DOI: 10.1371/journal.pone.0171606] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2016] [Accepted: 01/23/2017] [Indexed: 02/03/2023] Open
Abstract
Clostridium perfringens is a commensal member of the human gut microbiome and an opportunistic pathogen whose genome encodes a suite of putative large, multi-modular carbohydrate-active enzymes that appears to play a role in the interaction of the bacterium with mucin-based carbohydrates. Among the most complex of these is an enzyme that contains a presumed catalytic module belonging to glycoside hydrolase family 31 (GH31). This large enzyme, which based on its possession of a GH31 module is a predicted α-glucosidase, contains a variety of non-catalytic ancillary modules, including three CBM32 modules that to date have not been characterized. NMR-based experiments demonstrated a preference of each module for galacto-configured sugars, including the ability of all three CBM32s to recognize the common mucin monosaccharide GalNAc. X-ray crystal structures of the CpGH31 CBM32s, both in apo form and bound to GalNAc, revealed the finely-tuned molecular strategies employed by these sequentially variable CBM32s in coordinating a common ligand. The data highlight that sequence similarities to previously characterized CBMs alone are insufficient for identifying the molecular mechanism of ligand binding by individual CBMs. Furthermore, the overlapping ligand binding profiles of the three CBMs provide a fail-safe mechanism for the recognition of GalNAc among the dense eukaryotic carbohydrate networks of the colonic mucosa. These findings expand our understanding of ligand targeting by large, multi-modular carbohydrate-active enzymes, and offer unique insights into of the expanding ligand-binding preferences and binding site topologies observed in CBM32s.
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Affiliation(s)
- Julie M. Grondin
- Department of Biomedical and Molecular Sciences, Queen’s University, Kingston, Ontario, Canada
- Lethbridge Research Centre, Agriculture and Agri-Food Canada, Lethbridge, Alberta, Canada
| | - Da Duan
- Department of Biomedical and Molecular Sciences, Queen’s University, Kingston, Ontario, Canada
| | - Alyssa C. Kirlin
- Department of Biomedical and Molecular Sciences, Queen’s University, Kingston, Ontario, Canada
| | - Kento T. Abe
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada
| | - Seth Chitayat
- Department of Biomedical and Molecular Sciences, Queen’s University, Kingston, Ontario, Canada
| | - Holly L. Spencer
- Department of Biomedical and Molecular Sciences, Queen’s University, Kingston, Ontario, Canada
| | - Craig Spencer
- Department of Biomedical and Molecular Sciences, Queen’s University, Kingston, Ontario, Canada
| | - Alisha Campigotto
- Department of Biomedical and Molecular Sciences, Queen’s University, Kingston, Ontario, Canada
| | - Scott Houliston
- Princess Margaret Cancer Centre and Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
| | - Cheryl H. Arrowsmith
- Princess Margaret Cancer Centre and Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
| | - John S. Allingham
- Department of Biomedical and Molecular Sciences, Queen’s University, Kingston, Ontario, Canada
| | - Alisdair B. Boraston
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada
| | - Steven P. Smith
- Department of Biomedical and Molecular Sciences, Queen’s University, Kingston, Ontario, Canada
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23
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Robb M, Hobbs JK, Woodiga SA, Shapiro-Ward S, Suits MDL, McGregor N, Brumer H, Yesilkaya H, King SJ, Boraston AB. Molecular Characterization of N-glycan Degradation and Transport in Streptococcus pneumoniae and Its Contribution to Virulence. PLoS Pathog 2017; 13:e1006090. [PMID: 28056108 PMCID: PMC5215778 DOI: 10.1371/journal.ppat.1006090] [Citation(s) in RCA: 51] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Accepted: 11/27/2016] [Indexed: 11/19/2022] Open
Abstract
The carbohydrate-rich coating of human tissues and cells provide a first point of contact for colonizing and invading bacteria. Commensurate with N-glycosylation being an abundant form of protein glycosylation that has critical functional roles in the host, some host-adapted bacteria possess the machinery to process N-linked glycans. The human pathogen Streptococcus pneumoniae depolymerizes complex N-glycans with enzymes that sequentially trim a complex N-glycan down to the Man3GlcNAc2 core prior to the release of the glycan from the protein by endo-β-N-acetylglucosaminidase (EndoD), which cleaves between the two GlcNAc residues. Here we examine the capacity of S. pneumoniae to process high-mannose N-glycans and transport the products. Through biochemical and structural analyses we demonstrate that S. pneumoniae also possesses an α-(1,2)-mannosidase (SpGH92). This enzyme has the ability to trim the terminal α-(1,2)-linked mannose residues of high-mannose N-glycans to generate Man5GlcNAc2. Through this activity SpGH92 is able to produce a substrate for EndoD, which is not active on high-mannose glycans with α-(1,2)-linked mannose residues. Binding studies and X-ray crystallography show that NgtS, the solute binding protein of an ABC transporter (ABCNG), is able to bind Man5GlcNAc, a product of EndoD activity, with high affinity. Finally, we evaluated the contribution of EndoD and ABCNG to growth of S. pneumoniae on a model N-glycosylated glycoprotein, and the contribution of these enzymes and SpGH92 to virulence in a mouse model. We found that both EndoD and ABCNG contribute to growth of S. pneumoniae, but that only SpGH92 and EndoD contribute to virulence. Therefore, N-glycan processing, but not transport of the released glycan, is required for full virulence in S. pneumoniae. To conclude, we synthesize our findings into a model of N-glycan processing by S. pneumoniae in which both complex and high-mannose N-glycans are targeted, and in which the two arms of this degradation pathway converge at ABCNG. Streptococcus pneumoniae (pneumococcus) is a bacterium that causes extensive morbidity and mortality in humans. Vaccines and antibiotics are effective forms of prevention and treatment, respectively, but present challenges as it is a constant race to vaccinate against the enormous and ever evolving pool of different serotypes of the bacterium while resistance to antibiotics continues to trend upwards. It is thus necessary to better understand the molecular aspects of the host-pneumococcus interaction in order to inform the potential generation of alternative treatment strategies. S. pneumoniae relies on its ability to process the carbohydrates presented on the surface of host cells for full-virulence. In this study, we examine the capability of the bacterium to process high-mannose N-linked sugars, a heretofore unknown ability for S. pneumoniae. The results show that the pneumococcal genome encodes enzymes capable of processing these sugars and that, remarkably, the initiating reaction performed by an enzyme that removes terminal α-(1,2)-linked mannose residues is critical to virulence in a mouse model. This study illuminates an extensive pathway in S. pneumoniae that targets N-linked sugars and is key to the host-pathogen interaction, therefore revealing a potential target for therapeutic intervention.
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Affiliation(s)
- Melissa Robb
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada
| | - Joanne K. Hobbs
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada
| | - Shireen A. Woodiga
- Center for Microbial Pathogenesis, The Research Institute at Nationwide Children’s Hospital, Columbus, Ohio, United States of America
| | - Sarah Shapiro-Ward
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada
| | - Michael D. L. Suits
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada
| | - Nicholas McGregor
- Michael Smith Laboratories and Department of Chemistry, University of British Columbia, 2185 East Mall, Vancouver, British Columbia, Canada
| | - Harry Brumer
- Michael Smith Laboratories and Department of Chemistry, University of British Columbia, 2185 East Mall, Vancouver, British Columbia, Canada
| | - Hasan Yesilkaya
- Department of Infection, Immunity & Inflammation, University of Leicester, Leicester, United Kingdom
| | - Samantha J. King
- Center for Microbial Pathogenesis, The Research Institute at Nationwide Children’s Hospital, Columbus, Ohio, United States of America
| | - Alisdair B. Boraston
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada
- * E-mail:
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24
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Giles K, Pluvinage B, Boraston AB. Structure of a glycoside hydrolase family 50 enzyme from a subfamily that is enriched in human gut microbiome bacteroidetes. Proteins 2016; 85:182-187. [DOI: 10.1002/prot.25189] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Revised: 10/06/2016] [Accepted: 10/10/2016] [Indexed: 11/09/2022]
Affiliation(s)
- Kaleigh Giles
- Biochemistry & Microbiology; University of Victoria; PO Box 3055 STN CSC Victoria British Columbia V8W 3P6 Canada
| | - Benjamin Pluvinage
- Biochemistry & Microbiology; University of Victoria; PO Box 3055 STN CSC Victoria British Columbia V8W 3P6 Canada
| | - Alisdair B. Boraston
- Biochemistry & Microbiology; University of Victoria; PO Box 3055 STN CSC Victoria British Columbia V8W 3P6 Canada
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25
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Robb M, Robb CS, Higgins MA, Hobbs JK, Paton JC, Boraston AB. A Second β-Hexosaminidase Encoded in the Streptococcus pneumoniae Genome Provides an Expanded Biochemical Ability to Degrade Host Glycans. J Biol Chem 2015; 290:30888-900. [PMID: 26491009 DOI: 10.1074/jbc.m115.688630] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2015] [Indexed: 12/19/2022] Open
Abstract
An important facet of the interaction between the pathogen Streptococcus pneumoniae (pneumococcus) and its human host is the ability of this bacterium to process host glycans. To achieve cleavage of the glycosidic bonds in host glycans, S. pneumoniae deploys a wide array of glycoside hydrolases. Here, we identify and characterize a new family 20 glycoside hydrolase, GH20C, from S. pneumoniae. Recombinant GH20C possessed the ability to hydrolyze the β-linkages joining either N-acetylglucosamine or N-acetylgalactosamine to a wide variety of aglycon residues, thus revealing this enzyme to be a generalist N-acetylhexosaminidase in vitro. X-ray crystal structures were determined for GH20C in a ligand-free form, in complex with the N-acetylglucosamine and N-acetylgalactosamine products of catalysis and in complex with both gluco- and galacto-configured inhibitors O-(2-acetamido-2-deoxy-D-glucopyranosylidene)amino N-phenyl carbamate (PUGNAc), O-(2-acetamido-2-deoxy-D-galactopyranosylidene)amino N-phenyl carbamate (GalPUGNAc), N-acetyl-D-glucosamine-thiazoline (NGT), and N-acetyl-D-galactosamine-thiazoline (GalNGT) at resolutions from 1.84 to 2.7 Å. These structures showed N-acetylglucosamine and N-acetylgalactosamine to be recognized via identical sets of molecular interactions. Although the same sets of interaction were maintained with the gluco- and galacto-configured inhibitors, the inhibition constants suggested preferred recognition of the axial O4 when an aglycon moiety was present (Ki for PUGNAc > GalPUGNAc) but preferred recognition of an equatorial O4 when the aglycon was absent (Ki for GalNGT > NGT). Overall, this study reveals GH20C to be another tool that is unique in the arsenal of S. pneumoniae and that it may implement the effort of the bacterium to utilize and/or destroy the wide array of host glycans that it may encounter.
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Affiliation(s)
- Melissa Robb
- From the Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada V8W 3P6 and
| | - Craig S Robb
- From the Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada V8W 3P6 and
| | - Melanie A Higgins
- the Research Centre for Infectious Diseases, School of Biological Sciences, University of Adelaide, South Australia 5005, Australia
| | - Joanne K Hobbs
- From the Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada V8W 3P6 and
| | - James C Paton
- the Research Centre for Infectious Diseases, School of Biological Sciences, University of Adelaide, South Australia 5005, Australia
| | - Alisdair B Boraston
- From the Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada V8W 3P6 and
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26
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Gregg KJ, Suits MDL, Deng L, Vocadlo DJ, Boraston AB. Structural Analysis of a Family 101 Glycoside Hydrolase in Complex with Carbohydrates Reveals Insights into Its Mechanism. J Biol Chem 2015; 290:25657-69. [PMID: 26304114 DOI: 10.1074/jbc.m115.680470] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Indexed: 11/06/2022] Open
Abstract
O-Linked glycosylation is one of the most abundant post-translational modifications of proteins. Within the secretory pathway of higher eukaryotes, the core of these glycans is frequently an N-acetylgalactosamine residue that is α-linked to serine or threonine residues. Glycoside hydrolases in family 101 are presently the only known enzymes to be able to hydrolyze this glycosidic linkage. Here we determine the high-resolution structures of the catalytic domain comprising a fragment of GH101 from Streptococcus pneumoniae TIGR4, SpGH101, in the absence of carbohydrate, and in complex with reaction products, inhibitor, and substrate analogues. Upon substrate binding, a tryptophan lid (residues 724-WNW-726) closes on the substrate. The closing of this lid fully engages the substrate in the active site with Asp-764 positioned directly beneath C1 of the sugar residue bound within the -1 subsite, consistent with its proposed role as the catalytic nucleophile. In all of the bound forms of the enzyme, however, the proposed catalytic acid/base residue was found to be too distant from the glycosidic oxygen (>4.3 Å) to serve directly as a general catalytic acid/base residue and thereby facilitate cleavage of the glycosidic bond. These same complexes, however, revealed a structurally conserved water molecule positioned between the catalytic acid/base and the glycosidic oxygen. On the basis of these structural observations we propose a new variation of the retaining glycoside hydrolase mechanism wherein the intervening water molecule enables a Grotthuss proton shuttle between Glu-796 and the glycosidic oxygen, permitting this residue to serve as the general acid/base catalytic residue.
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Affiliation(s)
- Katie J Gregg
- From the Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, V8W 3P6 and
| | - Michael D L Suits
- From the Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, V8W 3P6 and
| | - Lehua Deng
- the Department of Chemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
| | - David J Vocadlo
- the Department of Chemistry, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
| | - Alisdair B Boraston
- From the Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, V8W 3P6 and
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27
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McLean R, Hobbs JK, Suits MD, Tuomivaara ST, Jones DR, Boraston AB, Abbott DW. Functional Analyses of Resurrected and Contemporary Enzymes Illuminate an Evolutionary Path for the Emergence of Exolysis in Polysaccharide Lyase Family 2. J Biol Chem 2015; 290:21231-43. [PMID: 26160170 DOI: 10.1074/jbc.m115.664847] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2015] [Indexed: 11/06/2022] Open
Abstract
Family 2 polysaccharide lyases (PL2s) preferentially catalyze the β-elimination of homogalacturonan using transition metals as catalytic cofactors. PL2 is divided into two subfamilies that have been generally associated with secretion, Mg(2+) dependence, and endolysis (subfamily 1) and with intracellular localization, Mn(2+) dependence, and exolysis (subfamily 2). When present within a genome, PL2 genes are typically found as tandem copies, which suggests that they provide complementary activities at different stages along a catabolic cascade. This relationship most likely evolved by gene duplication and functional divergence (i.e. neofunctionalization). Although the molecular basis of subfamily 1 endolytic activity is understood, the adaptations within the active site of subfamily 2 enzymes that contribute to exolysis have not been determined. In order to investigate this relationship, we have conducted a comparative enzymatic analysis of enzymes dispersed within the PL2 phylogenetic tree and elucidated the structure of VvPL2 from Vibrio vulnificus YJ016, which represents a transitional member between subfamiles 1 and 2. In addition, we have used ancestral sequence reconstruction to functionally investigate the segregated evolutionary history of PL2 progenitor enzymes and illuminate the molecular evolution of exolysis. This study highlights that ancestral sequence reconstruction in combination with the comparative analysis of contemporary and resurrected enzymes holds promise for elucidating the origins and activities of other carbohydrate active enzyme families and the biological significance of cryptic metabolic pathways, such as pectinolysis within the zoonotic marine pathogen V. vulnificus.
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Affiliation(s)
- Richard McLean
- From the Lethbridge Research Centre, Agriculture and Agri-Food Canada, Lethbridge, Alberta T1J 4B1, Canada
| | - Joanne K Hobbs
- the Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia V8W 3P6, Canada
| | - Michael D Suits
- the Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia V8W 3P6, Canada, the Department of Chemistry and Biochemistry, Wilfred Laurier University, Waterloo, Ontario N2L 3C5, Canada, and
| | - Sami T Tuomivaara
- the Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia 30602
| | - Darryl R Jones
- From the Lethbridge Research Centre, Agriculture and Agri-Food Canada, Lethbridge, Alberta T1J 4B1, Canada
| | - Alisdair B Boraston
- the Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia V8W 3P6, Canada
| | - D Wade Abbott
- From the Lethbridge Research Centre, Agriculture and Agri-Food Canada, Lethbridge, Alberta T1J 4B1, Canada,
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28
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Kwan DH, Constantinescu I, Chapanian R, Higgins MA, Kötzler MP, Samain E, Boraston AB, Kizhakkedathu JN, Withers SG. Toward Efficient Enzymes for the Generation of Universal Blood through Structure-Guided Directed Evolution. J Am Chem Soc 2015; 137:5695-705. [PMID: 25870881 DOI: 10.1021/ja5116088] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Blood transfusions are critically important in many medical procedures, but the presence of antigens on red blood cells (RBCs, erythrocytes) means that careful blood-typing must be carried out prior to transfusion to avoid adverse and sometimes fatal reactions following transfusion. Enzymatic removal of the terminal N-acetylgalactosamine or galactose of A- or B-antigens, respectively, yields universal O-type blood, but is inefficient. Starting with the family 98 glycoside hydrolase from Streptococcus pneumoniae SP3-BS71 (Sp3GH98), which cleaves the entire terminal trisaccharide antigenic determinants of both A- and B-antigens from some of the linkages on RBC surface glycans, through several rounds of evolution, we developed variants with vastly improved activity toward some of the linkages that are resistant to cleavage by the wild-type enzyme. The resulting enzyme effects more complete removal of blood group antigens from cell surfaces, demonstrating the potential for engineering enzymes to generate antigen-null blood from donors of various types.
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Affiliation(s)
| | | | | | - Melanie A Higgins
- ⊥Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada V8W 3P6
| | | | - Eric Samain
- #Centre de Recherches sur les Macromolécules Végétales, Centre National de la Recherche Scientifique, Grenoble Cedex 9, France BP 53, 38041
| | - Alisdair B Boraston
- ⊥Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada V8W 3P6
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29
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Han L, Kitova EN, Li J, Nikjah S, Lin H, Pluvinage B, Boraston AB, Klassen JS. Protein–Glycolipid Interactions Studied in Vitro Using ESI-MS and Nanodiscs: Insights into the Mechanisms and Energetics of Binding. Anal Chem 2015; 87:4888-96. [DOI: 10.1021/acs.analchem.5b00678] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Ling Han
- Alberta
Glycomics Centre and Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2G2
| | - Elena N. Kitova
- Alberta
Glycomics Centre and Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2G2
| | - Jun Li
- Alberta
Glycomics Centre and Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2G2
| | - Sanaz Nikjah
- Alberta
Glycomics Centre and Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2G2
| | - Hong Lin
- Alberta
Glycomics Centre and Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2G2
| | - Benjamin Pluvinage
- Department
of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada V8W 3P6
| | - Alisdair B. Boraston
- Department
of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada V8W 3P6
| | - John S. Klassen
- Alberta
Glycomics Centre and Department of Chemistry, University of Alberta, Edmonton, Alberta, Canada T6G 2G2
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30
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Cuskin F, Lowe EC, Temple MJ, Zhu Y, Cameron EA, Pudlo NA, Porter NT, Urs K, Thompson AJ, Cartmell A, Rogowski A, Hamilton BS, Chen R, Tolbert TJ, Piens K, Bracke D, Vervecken W, Hakki Z, Speciale G, Munōz-Munōz JL, Day A, Peña MJ, McLean R, Suits MD, Boraston AB, Atherly T, Ziemer CJ, Williams SJ, Davies GJ, Abbott DW, Martens EC, Gilbert HJ. Corrigendum: Human gut Bacteroidetes can utilize yeast mannan through a selfish mechanism. Nature 2015; 520:388. [PMID: 25739504 DOI: 10.1038/nature14334] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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31
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Cuskin F, Lowe EC, Temple MJ, Zhu Y, Cameron E, Pudlo NA, Porter NT, Urs K, Thompson AJ, Cartmell A, Rogowski A, Hamilton BS, Chen R, Tolbert TJ, Piens K, Bracke D, Vervecken W, Hakki Z, Speciale G, Munōz-Munōz JL, Day A, Peña MJ, McLean R, Suits MD, Boraston AB, Atherly T, Ziemer CJ, Williams SJ, Davies GJ, Abbott DW, Martens EC, Gilbert HJ. Human gut Bacteroidetes can utilize yeast mannan through a selfish mechanism. Nature 2015; 517:165-169. [PMID: 25567280 PMCID: PMC4978465 DOI: 10.1038/nature13995] [Citation(s) in RCA: 350] [Impact Index Per Article: 38.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2014] [Accepted: 10/22/2014] [Indexed: 12/28/2022]
Abstract
Yeasts, which have been a component of the human diet for at least 7000 years, possess an elaborate cell wall α-mannan. The influence of yeast mannan on the ecology of the human microbiota is unknown. Here we show that yeast α-mannan is a viable food source for Bacteroides thetaiotaomicron (Bt), a dominant member of the microbiota. Detailed biochemical analysis and targeted gene disruption studies support a model whereby limited cleavage of α-mannan on the surface generates large oligosaccharides that are subsequently depolymerized to mannose by the action of periplasmic enzymes. Co-culturing studies showed that metabolism of yeast mannan by Bt presents a ‘selfish’ model for the catabolism of this recalcitrant polysaccharide. This report shows how a cohort of highly successful members of the microbiota has evolved to consume sterically-restricted yeast glycans, an adaptation that may reflect the incorporation of eukaryotic microorganisms into the human diet.
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Affiliation(s)
- Fiona Cuskin
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K.,Complex Carbohydrate Research Center, The University of Georgia, 315 Riverbend Road, Athens, GA 30602, USA
| | - Elisabeth C Lowe
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
| | - Max J Temple
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
| | - Yanping Zhu
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K.,Complex Carbohydrate Research Center, The University of Georgia, 315 Riverbend Road, Athens, GA 30602, USA
| | - Elizabeth Cameron
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Nicholas A Pudlo
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Nathan T Porter
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Karthik Urs
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI, USA
| | | | - Alan Cartmell
- School of Chemistry and Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Artur Rogowski
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
| | - Brian S Hamilton
- Dept. of Pharmaceutical Chemistry, University of Kansas School of Pharmacy, 2095 Constant Ave, Lawrence, KS 66047, USA
| | - Rui Chen
- Dept. of Pharmaceutical Chemistry, University of Kansas School of Pharmacy, 2095 Constant Ave, Lawrence, KS 66047, USA
| | - Thomas J Tolbert
- Dept. of Pharmaceutical Chemistry, University of Kansas School of Pharmacy, 2095 Constant Ave, Lawrence, KS 66047, USA
| | | | | | | | - Zalihe Hakki
- School of Chemistry and Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Gaetano Speciale
- School of Chemistry and Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Jose L Munōz-Munōz
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
| | - Andrew Day
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K
| | - Maria J Peña
- Complex Carbohydrate Research Center, The University of Georgia, 315 Riverbend Road, Athens, GA 30602, USA
| | - Richard McLean
- Agriculture and Agri-Food Canada, Lethbridge Research Centre, Lethbridge, AB, Canada
| | - Michael D Suits
- Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada
| | - Alisdair B Boraston
- Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada
| | - Todd Atherly
- USDA, Agricultural Research Service, National Laboratory for Agriculture and the Environment, Ames, Iowa, USA
| | - Cherie J Ziemer
- USDA, Agricultural Research Service, National Laboratory for Agriculture and the Environment, Ames, Iowa, USA
| | - Spencer J Williams
- School of Chemistry and Bio21 Molecular Science and Biotechnology Institute, University of Melbourne, Parkville, Victoria 3010, Australia
| | - Gideon J Davies
- Department of Chemistry, University of York, York YO10 5DD, U.K
| | - D Wade Abbott
- Complex Carbohydrate Research Center, The University of Georgia, 315 Riverbend Road, Athens, GA 30602, USA.,Agriculture and Agri-Food Canada, Lethbridge Research Centre, Lethbridge, AB, Canada
| | - Eric C Martens
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Harry J Gilbert
- Institute for Cell and Molecular Biosciences, Newcastle University, Newcastle upon Tyne NE2 4HH, U.K.,Complex Carbohydrate Research Center, The University of Georgia, 315 Riverbend Road, Athens, GA 30602, USA
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32
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Han L, Kitova EN, Tan M, Jiang X, Pluvinage B, Boraston AB, Klassen JS. Affinities of human histo-blood group antigens for norovirus capsid protein complexes. Glycobiology 2014; 25:170-80. [PMID: 25395406 DOI: 10.1093/glycob/cwu100] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
The binding profiles of many human noroviruses (huNoVs) for human histo-blood group antigens have been characterized. However, quantitative-binding data for these important virus-host interactions are lacking. Here, we report on the intrinsic (per binding site) affinities of HBGA oligosaccharides for the huNoV VA387 virus-like particles (VLPs) and the associated subviral P particles measured using electrospray ionization mass spectrometry. The affinities of 13 HBGA oligosaccharides, containing A, B and H epitopes, with variable sizes (disaccharide to tetrasaccharide) and different precursor chain types (types 1, 2, 3, 5 and 6), were measured for the P particle, while the affinities of the A and B trisaccharides and A and B type 6 tetrasaccharides for the VLP were determined. The intrinsic affinities of the HBGA oligosaccharides for the P particle range from 500 to 2300 M(-1), while those of the A and B trisaccharides and the A and B type 6 tetrasaccharides for the VLP range from 1000 to 4000 M(-1). Comparison of these binding data with those measured previously for the corresponding P dimer reveals that the HBGA oligosaccharides tested exhibit similar intrinsic affinities for the P dimer and P particle. The intrinsic affinities for the VLP are consistently higher than those measured for the P particle, but within a factor of three. While the cause of the subtle differences in HBGA oligosaccharide affinities for the P dimer and P particle and those for the VLP remains unknown, the present data support the use of P dimers or P particles as surrogates to the VLP for huNoV-receptor-binding studies.
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Affiliation(s)
- Ling Han
- Alberta Glycomics Centre, Department of Chemistry, University of Alberta, Edmonton, AB, Canada T6G 2G2
| | - Elena N Kitova
- Alberta Glycomics Centre, Department of Chemistry, University of Alberta, Edmonton, AB, Canada T6G 2G2
| | - Ming Tan
- Division of Infectious Diseases, Cincinnati Children's Hospital Medical Center Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Xi Jiang
- Division of Infectious Diseases, Cincinnati Children's Hospital Medical Center Department of Pediatrics, University of Cincinnati College of Medicine, Cincinnati, OH, USA
| | - Benjamin Pluvinage
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC, Canada V8W 3P6
| | - Alisdair B Boraston
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, BC, Canada V8W 3P6
| | - John S Klassen
- Alberta Glycomics Centre, Department of Chemistry, University of Alberta, Edmonton, AB, Canada T6G 2G2
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33
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Hehemann JH, Boraston AB, Czjzek M. A sweet new wave: structures and mechanisms of enzymes that digest polysaccharides from marine algae. Curr Opin Struct Biol 2014; 28:77-86. [DOI: 10.1016/j.sbi.2014.07.009] [Citation(s) in RCA: 74] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Revised: 07/16/2014] [Accepted: 07/17/2014] [Indexed: 10/24/2022]
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Singh AK, Pluvinage B, Higgins MA, Dalia AB, Woodiga SA, Flynn M, Lloyd AR, Weiser JN, Stubbs KA, Boraston AB, King SJ. Unravelling the multiple functions of the architecturally intricate Streptococcus pneumoniae β-galactosidase, BgaA. PLoS Pathog 2014; 10:e1004364. [PMID: 25210925 PMCID: PMC4161441 DOI: 10.1371/journal.ppat.1004364] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2014] [Accepted: 07/28/2014] [Indexed: 11/18/2022] Open
Abstract
Bacterial cell-surface proteins play integral roles in host-pathogen interactions. These proteins are often architecturally and functionally sophisticated and yet few studies of such proteins involved in host-pathogen interactions have defined the domains or modules required for specific functions. Streptococcus pneumoniae (pneumococcus), an opportunistic pathogen that is a leading cause of community acquired pneumonia, otitis media and bacteremia, is decorated with many complex surface proteins. These include β-galactosidase BgaA, which is specific for terminal galactose residues β-1-4 linked to glucose or N-acetylglucosamine and known to play a role in pneumococcal growth, resistance to opsonophagocytic killing, and adherence. This study defines the domains and modules of BgaA that are required for these distinct contributions to pneumococcal pathogenesis. Inhibitors of β-galactosidase activity reduced pneumococcal growth and increased opsonophagocytic killing in a BgaA dependent manner, indicating these functions require BgaA enzymatic activity. In contrast, inhibitors increased pneumococcal adherence suggesting that BgaA bound a substrate of the enzyme through a distinct module or domain. Extensive biochemical, structural and cell based studies revealed two newly identified non-enzymatic carbohydrate-binding modules (CBMs) mediate adherence to the host cell surface displayed lactose or N-acetyllactosamine. This finding is important to pneumococcal biology as it is the first adhesin-carbohydrate receptor pair identified, supporting the widely held belief that initial pneumococcal attachment is to a glycoconjugate. Perhaps more importantly, this is the first demonstration that a CBM within a carbohydrate-active enzyme can mediate adherence to host cells and thus this study identifies a new class of carbohydrate-binding adhesins and extends the paradigm of CBM function. As other bacterial species express surface-associated carbohydrate-active enzymes containing CBMs these findings have broad implications for bacterial adherence. Together, these data illustrate that comprehending the architectural sophistication of surface-attached proteins can increase our understanding of the different mechanisms by which these proteins can contribute to bacterial pathogenesis.
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Affiliation(s)
- Anirudh K. Singh
- Center for Microbial Pathogenesis, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio, United States of America
| | - Benjamin Pluvinage
- Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada
| | - Melanie A. Higgins
- Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada
| | - Ankur B. Dalia
- Department of Microbiology, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Shireen A. Woodiga
- Center for Microbial Pathogenesis, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio, United States of America
| | - Matthew Flynn
- Center for Microbial Pathogenesis, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio, United States of America
- Department of Pediatrics, The Ohio State University, Columbus, Ohio, United States of America
| | - Audrey R. Lloyd
- Center for Microbial Pathogenesis, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio, United States of America
- Department of Pediatrics, The Ohio State University, Columbus, Ohio, United States of America
| | - Jeffrey N. Weiser
- Department of Microbiology, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America
| | - Keith A. Stubbs
- School of Biomedical, Biomolecular and Chemical Sciences, The University of Western Australia, Crawley, Western Australia, Australia
| | - Alisdair B. Boraston
- Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada
- * E-mail: (ABB); (SJK)
| | - Samantha J. King
- Center for Microbial Pathogenesis, The Research Institute at Nationwide Children's Hospital, Columbus, Ohio, United States of America
- Department of Pediatrics, The Ohio State University, Columbus, Ohio, United States of America
- * E-mail: (ABB); (SJK)
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Suits MDL, Pluvinage B, Law A, Liu Y, Palma AS, Chai W, Feizi T, Boraston AB. Conformational analysis of the Streptococcus pneumoniae hyaluronate lyase and characterization of its hyaluronan-specific carbohydrate-binding module. J Biol Chem 2014; 289:27264-27277. [PMID: 25100731 PMCID: PMC4175358 DOI: 10.1074/jbc.m114.578435] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
For a subset of pathogenic microorganisms, including Streptococcus pneumoniae, the recognition and degradation of host hyaluronan contributes to bacterial spreading through the extracellular matrix and enhancing access to host cell surfaces. The hyaluronate lyase (Hyl) presented on the surface of S. pneumoniae performs this role. Using glycan microarray screening, affinity electrophoresis, and isothermal titration calorimetry we show that the N-terminal module of Hyl is a hyaluronan-specific carbohydrate-binding module (CBM) and the founding member of CBM family 70. The 1.2 Å resolution x-ray crystal structure of CBM70 revealed it to have a β-sandwich fold, similar to other CBMs. The electrostatic properties of the binding site, which was identified by site-directed mutagenesis, are distinct from other CBMs and complementary to its acidic ligand, hyaluronan. Dynamic light scattering and solution small angle x-ray scattering revealed the full-length Hyl protein to exist as a monomer/dimer mixture in solution. Through a detailed analysis of the small angle x-ray scattering data, we report the pseudoatomic solution structures of the monomer and dimer forms of the full-length multimodular Hyl.
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Affiliation(s)
- Michael D L Suits
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia V8W 3P6, Canada
| | - Benjamin Pluvinage
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia V8W 3P6, Canada
| | - Adrienne Law
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia V8W 3P6, Canada
| | - Yan Liu
- Glycosciences Laboratory, Imperial College London, Burlington Danes Building, Du Cane Road, London W12 0NN, United Kingdom, and
| | - Angelina S Palma
- Glycosciences Laboratory, Imperial College London, Burlington Danes Building, Du Cane Road, London W12 0NN, United Kingdom, and; REQUIMTE, Department of Chemistry, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa, 2829-516 Caparica, Portugal
| | - Wengang Chai
- Glycosciences Laboratory, Imperial College London, Burlington Danes Building, Du Cane Road, London W12 0NN, United Kingdom, and
| | - Ten Feizi
- Glycosciences Laboratory, Imperial College London, Burlington Danes Building, Du Cane Road, London W12 0NN, United Kingdom, and
| | - Alisdair B Boraston
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia V8W 3P6, Canada,.
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36
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Hehemann JH, Law A, Redecke L, Boraston AB. The structure of RdDddP from Roseobacter denitrificans reveals that DMSP lyases in the DddP-family are metalloenzymes. PLoS One 2014; 9:e103128. [PMID: 25054772 PMCID: PMC4108388 DOI: 10.1371/journal.pone.0103128] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2014] [Accepted: 06/27/2014] [Indexed: 11/19/2022] Open
Abstract
Marine microbes degrade dimethylsulfoniopropionate (DMSP), which is produced in large quantities by marine algae and plants, with DMSP lyases into acrylate and the gas dimethyl sulfide (DMS). Approximately 10% of the DMS vents from the sea into the atmosphere and this emission returns sulfur, which arrives in the sea through rivers and runoff, back to terrestrial systems via clouds and rain. Despite their key role in this sulfur cycle DMSP lyases are poorly understood at the molecular level. Here we report the first X-ray crystal structure of the putative DMSP lyase RdDddP from Roseobacter denitrificans, which belongs to the abundant DddP family. This structure, determined to 2.15 Å resolution, shows that RdDddP is a homodimeric metalloprotein with a binuclear center of two metal ions located 2.7 Å apart in the active site of the enzyme. Consistent with the crystallographic data, inductively coupled plasma mass spectrometry (ICP-MS) and total reflection X-ray fluorescence (TRXF) revealed the bound metal species to be primarily iron. A 3D structure guided analysis of environmental DddP lyase sequences elucidated the critical residues for metal binding are invariant, suggesting all proteins in the DddP family are metalloenzymes.
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Affiliation(s)
- Jan-Hendrik Hehemann
- Department of Biochemistry & Microbiology, University of Victoria, Victoria, British Columbia, Canada
| | - Adrienne Law
- Department of Biochemistry & Microbiology, University of Victoria, Victoria, British Columbia, Canada
| | - Lars Redecke
- Joint Laboratory for Structural Biology of Infection and Inflammation of the Universities of Hamburg and Lübeck, c/o DESY, Hamburg, Germany
| | - Alisdair B. Boraston
- Department of Biochemistry & Microbiology, University of Victoria, Victoria, British Columbia, Canada
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37
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Higgins MA, Suits MD, Marsters C, Boraston AB. Structural and Functional Analysis of Fucose-Processing Enzymes from Streptococcus pneumoniae. J Mol Biol 2014; 426:1469-82. [DOI: 10.1016/j.jmb.2013.12.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2013] [Revised: 12/02/2013] [Accepted: 12/05/2013] [Indexed: 10/25/2022]
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Grondin JM, Chitayat S, Ficko-Blean E, Houliston S, Arrowsmith CH, Boraston AB, Smith SP. An Unusual Mode of Galactose Recognition by a Family 32 Carbohydrate-Binding Module. J Mol Biol 2014; 426:869-80. [DOI: 10.1016/j.jmb.2013.11.029] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2013] [Revised: 10/30/2013] [Accepted: 11/22/2013] [Indexed: 11/27/2022]
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39
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Gilbert HJ, Knox JP, Boraston AB. Advances in understanding the molecular basis of plant cell wall polysaccharide recognition by carbohydrate-binding modules. Curr Opin Struct Biol 2013; 23:669-77. [DOI: 10.1016/j.sbi.2013.05.005] [Citation(s) in RCA: 236] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2013] [Revised: 05/03/2013] [Accepted: 05/09/2013] [Indexed: 11/25/2022]
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40
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Abbott DW, Thomas D, Pluvinage B, Boraston AB. An ancestral member of the polysaccharide lyase family 2 displays endolytic activity and magnesium dependence. Appl Biochem Biotechnol 2013; 171:1911-23. [PMID: 24013861 DOI: 10.1007/s12010-013-0483-9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2013] [Accepted: 08/26/2013] [Indexed: 10/26/2022]
Abstract
Polysaccharide lyases (PLs) are enzymes that cleave glycosidic linkages in hexuronate polysaccharides, such as homogalacturonan (HG), using a β-elimination mechanism. Traditionally, PL activities on HG have been associated with catalytic calcium cofactors, unusually high pH optima, and arginine Brønstead bases. Recently, however, PL families that harness transition metal cofactors, utilize lysine and histidine Brønstead bases, and display more neutral pH optima have been described. One such family is PL2, which has members found primarily in phytopathogenic (e.g., Dickeya spp. and Pectobacterium spp.) or enteropathogenic (e.g., Yersinia spp.) bacterial species. PL2 is divided into two major subfamilies that are correlated with either an endolytic or exolytic activity. This study has focused on the activity of a PL2 member, which is not classified within either subfamily and helps to illuminate the origin of enzyme activities within the family. In addition, the role of Mg(2+) as a preferential catalytic metal for an intracellular PL2 (PaePL2) is described. The implications for the relationship between catalytic metal selectivity and the cellular location of pectate lyase-mediated catalysis are discussed.
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Affiliation(s)
- D Wade Abbott
- Lethbridge Research Station, Agriculture and Agri-Food Canada, 5403 1st Avenue South, Lethbridge, AB, T1J 4B1, Canada,
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41
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Deng L, Tsybina P, Gregg KJ, Mosi R, Zandberg WF, Boraston AB, Vocadlo DJ. Synthesis of 4-methylumbelliferyl α-d-mannopyranosyl-(1→6)-β-d-mannopyranoside and development of a coupled fluorescent assay for GH125 exo-α-1,6-mannosidases. Bioorg Med Chem 2013; 21:4839-45. [PMID: 23816041 DOI: 10.1016/j.bmc.2013.05.062] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2013] [Revised: 04/13/2013] [Accepted: 05/28/2013] [Indexed: 10/26/2022]
Abstract
Certain bacterial pathogens possess a repertoire of carbohydrate processing enzymes that process host N-linked glycans and many of these enzymes are required for full virulence of harmful human pathogens such as Clostridium perfringens and Streptococcus pneumoniae. One bacterial carbohydrate processing enzyme that has been studied is the pneumococcal virulence factor SpGH125 from S. pneumoniae and its homologue, CpGH125, from C. perfringens. These exo-α-1,6-mannosidases from glycoside hydrolase family 125 show poor activity toward aryl α-mannopyranosides. To circumvent this problem, we describe a convenient synthesis of the fluorogenic disaccharide substrate 4-methylumbelliferone α-d-mannopyranosyl-(1→6)-β-d-mannopyranoside. We show this substrate can be used in a coupled fluorescent assay by using β-mannosidases from either Cellulomonas fimi or Helix pomatia as the coupling enzyme. We find that this disaccharide substrate is processed much more efficiently than aryl α-mannopyranosides by CpGH125, most likely because inclusion of the second mannose residue makes this substrate more like the natural host glycan substrates of this enzyme, which enables it to bind better. Using this sensitive coupled assay, the detailed characterization of these metal-independent exo-α-mannosidases GH125 enzymes should be possible, as should screening chemical libraries for inhibitors of these virulence factors.
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Affiliation(s)
- Lehua Deng
- Department of Chemistry, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia V5A 1S6, Canada
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42
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Pluvinage B, Hehemann JH, Boraston AB. Substrate recognition and hydrolysis by a family 50 exo-β-agarase, Aga50D, from the marine bacterium Saccharophagus degradans. J Biol Chem 2013; 288:28078-88. [PMID: 23921382 DOI: 10.1074/jbc.m113.491068] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Abstract
The bacteria that metabolize agarose use multiple enzymes of complementary specificities to hydrolyze the glycosidic linkages in agarose, a linear polymer comprising the repeating disaccharide subunit of neoagarobiose (3,6-anhydro-l-galactose-α-(1,3)-d-galactose) that are β-(1,4)-linked. Here we present the crystal structure of a glycoside hydrolase family 50 exo-β-agarase, Aga50D, from the marine microbe Saccharophagus degradans. This enzyme catalyzes a critical step in the metabolism of agarose by S. degradans through cleaving agarose oligomers into neoagarobiose products that can be further processed into monomers. The crystal structure of Aga50D to 1.9 Å resolution reveals a (β/α)8-barrel fold that is elaborated with a β-sandwich domain and extensive loops. The structures of catalytically inactivated Aga50D in complex with non-hydrolyzed neoagarotetraose (2.05 Å resolution) and neoagarooctaose (2.30 Å resolution) provide views of Michaelis complexes for a β-agarase. In these structures, the d-galactose residue in the -1 subsite is distorted into a (1)S3 skew boat conformation. The relative positioning of the putative catalytic residues are most consistent with a retaining catalytic mechanism. Additionally, the neoagarooctaose complex showed that this extended substrate made substantial interactions with the β-sandwich domain, which resembles a carbohydrate-binding module, thus creating additional plus (+) subsites and funneling the polymeric substrate through the tunnel-shaped active site. A synthesis of these results in combination with an additional neoagarobiose product complex suggests a potential exo-processive mode of action of Aga50D on the agarose double helix.
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Affiliation(s)
- Benjamin Pluvinage
- From the Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia V8W 3P6, Canada and
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43
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Abstract
PfbA (plasmin- and fibronectin-binding protein A) is an extracellular Streptococcus pneumoniae cell-wall attached surface protein that binds to fibronectin, plasmin, and plasminogen. Here we present a structural analysis of the surface exposed domains of PfbA using a combined approach of X-ray crystallography and small-angle X-ray scattering (SAXS). The crystal structure of the PfbA core domain, here called PfbAβ, determined to 2.28 Å resolution revealed an elongated 12-stranded parallel β-helix fold, which structure-based comparisons reveal is most similar to proteins with carbohydrate modifying activity. A notable feature of the PfbAβ is an extensive cleft on one face of the protein with electrochemical and spatial features that are analogous to structurally similar carbohydrate-active enzymes utilizing this feature for substrate accommodation. Though this cleft displays a combination of basic amino acid residues and solvent exposed aromatic amino acids that are distinct features for recognition of carbohydrates, no obvious arrangement of amino acid side chains that would constitute catalytic machinery is evident. The pseudo-atomic SAXS model of a larger fragment of PfbA suggests that it has a relatively well-ordered structure with the N-terminal and core domains of PfbA adopting an extend organization and reveals a novel structural class of surface exposed pneumococcal matrix molecule adhesins.
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Affiliation(s)
- Michael D. Suits
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada
| | - Alisdair B. Boraston
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada
- * E-mail:
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44
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Robb CS, Assmus M, Nano FE, Boraston AB. Structure of the T6SS lipoprotein TssJ1 from Pseudomonas aeruginosa. Acta Crystallogr Sect F Struct Biol Cryst Commun 2013; 69:607-10. [PMID: 23722835 PMCID: PMC3668576 DOI: 10.1107/s1744309113012220] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2013] [Accepted: 05/04/2013] [Indexed: 11/10/2022]
Abstract
The type VI secretion system of Pseudomonas aeruginosa has been shown to be responsible for the translocation of bacteriolytic effectors into competing bacteria. A mechanistic understanding of this widely distributed secretion system is developing and structural studies of its components are ongoing. Two representative structures of one highly conserved component, TssJ, from Escherichia coli and Serratia marcescens have been published. Here, the X-ray crystal structure of TssJ1 from P. aeruginosa is presented at 1.4 Å resolution. The overall structure is conserved among the three proteins. This finding suggests that the homologues function in a similar manner and bolsters the understanding of the structure of this family of proteins.
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Affiliation(s)
- Craig S. Robb
- Department of Biochemistry and Microbiology, University of Victoria, PO Box 3055 STN CSC, Victoria, British Columbia V8W 3P6, Canada
| | - Mark Assmus
- Department of Biochemistry and Microbiology, University of Victoria, PO Box 3055 STN CSC, Victoria, British Columbia V8W 3P6, Canada
| | - Francis E. Nano
- Department of Biochemistry and Microbiology, University of Victoria, PO Box 3055 STN CSC, Victoria, British Columbia V8W 3P6, Canada
| | - Alisdair B. Boraston
- Department of Biochemistry and Microbiology, University of Victoria, PO Box 3055 STN CSC, Victoria, British Columbia V8W 3P6, Canada
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45
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Pluvinage B, Stubbs KA, Hattie M, Vocadlo DJ, Boraston AB. Inhibition of the family 20 glycoside hydrolase catalytic modules in the Streptococcus pneumoniae exo-β-d-N-acetylglucosaminidase, StrH. Org Biomol Chem 2013; 11:7907-15. [DOI: 10.1039/c3ob41579a] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
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46
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Pluvinage B, Chitayat S, Ficko-Blean E, Abbott DW, Kunjachen JM, Grondin J, Spencer HL, Smith SP, Boraston AB. Conformational Analysis of StrH, the Surface-Attached exo-β-d-N-Acetylglucosaminidase from Streptococcus pneumoniae. J Mol Biol 2013; 425:334-49. [DOI: 10.1016/j.jmb.2012.11.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2012] [Revised: 11/05/2012] [Accepted: 11/06/2012] [Indexed: 12/22/2022]
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47
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Grondin JM, Chitayat S, Ficko-Blean E, Boraston AB, Smith SP. 1H, 15N and 13C backbone and side-chain resonance assignments of a family 32 carbohydrate-binding module from the Clostridium perfringens NagH. Biomol NMR Assign 2012; 6:139-142. [PMID: 21912839 DOI: 10.1007/s12104-011-9342-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2011] [Accepted: 09/03/2011] [Indexed: 05/31/2023]
Abstract
The Gram-positive anaerobe Clostridium perfringens is an opportunistic bacterial pathogen that secretes a battery of enzymes involved in glycan degradation. These glycoside hydrolases are thought to be involved in turnover of mucosal layer glycans, and in the spread of major toxins commonly associated with the development of gastrointestinal diseases and gas gangrene in humans. These enzymes employ multi-modularity and carbohydrate-binding function to degrade extracellular eukaryotic host sugars. Here, we report the full (1)H, (15)N and (13)C chemical shift resonance assignments of the first family 32 carbohydrate-binding module from NagH, a secreted family 84 glycoside hydrolase.
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Affiliation(s)
- Julie M Grondin
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, ON K7L 3N6, Canada
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48
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Ficko-Blean E, Boraston AB. Insights into the recognition of the human glycome by microbial carbohydrate-binding modules. Curr Opin Struct Biol 2012; 22:570-7. [PMID: 22858095 DOI: 10.1016/j.sbi.2012.07.009] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2012] [Accepted: 07/10/2012] [Indexed: 10/28/2022]
Abstract
Mammalian glycans are often very complex and consequently both commensal bacteria and bacterial pathogens have developed specialized and often elaborate carbohydrate-active enzyme (CAZyme) systems to interact with these sugars. These enzymes are frequently multimodular, with modular functions most often conferring catalysis (glycoside hydrolase catalytic modules) or carbohydrate-binding (carbohydrate-binding modules or CBMs). Structure-function studies of five CBM families are revealing specificities for complex mammalian carbohydrates. Three of these CBM families (32, 47, and 51) show significant structural identity between their β-sandwich folds, suggesting a shared evolutionary precursor, but have divergent binding specificities. The family 40 and 41 CBMs recognize sialic acid and glycogen, respectively, through different modes of sugar binding, though they also adopt all β-structure folds. A structural view of new models generated for complete CAZymes suggests three distinct modes of CBM deployment: (i) formation of the catalytic site, (ii) coordinated catalysis and binding, and (iii) general substrate adherence.
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Affiliation(s)
- Elizabeth Ficko-Blean
- Biochemistry and Microbiology, University of Victoria, Victoria, BC, V8W 3P6, Canada
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49
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Ficko-Blean E, Stuart CP, Suits MD, Cid M, Tessier M, Woods RJ, Boraston AB. Carbohydrate recognition by an architecturally complex α-N-acetylglucosaminidase from Clostridium perfringens. PLoS One 2012; 7:e33524. [PMID: 22479408 PMCID: PMC3313936 DOI: 10.1371/journal.pone.0033524] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2011] [Accepted: 02/14/2012] [Indexed: 11/19/2022] Open
Abstract
CpGH89 is a large multimodular enzyme produced by the human and animal pathogen Clostridium perfringens. The catalytic activity of this exo-α-D-N-acetylglucosaminidase is directed towards a rare carbohydrate motif, N-acetyl-β-D-glucosamine-α-1,4-D-galactose, which is displayed on the class III mucins deep within the gastric mucosa. In addition to the family 89 glycoside hydrolase catalytic module this enzyme has six modules that share sequence similarity to the family 32 carbohydrate-binding modules (CBM32s), suggesting the enzyme has considerable capacity to adhere to carbohydrates. Here we suggest that two of the modules, CBM32-1 and CBM32-6, are not functional as carbohydrate-binding modules (CBMs) and demonstrate that three of the CBMs, CBM32-3, CBM32-4, and CBM32-5, are indeed capable of binding carbohydrates. CBM32-3 and CBM32-4 have a novel binding specificity for N-acetyl-β-D-glucosamine-α-1,4-D-galactose, which thus complements the specificity of the catalytic module. The X-ray crystal structure of CBM32-4 in complex with this disaccharide reveals a mode of recognition that is based primarily on accommodation of the unique bent shape of this sugar. In contrast, as revealed by a series of X-ray crystal structures and quantitative binding studies, CBM32-5 displays the structural and functional features of galactose binding that is commonly associated with CBM family 32. The functional CBM32s that CpGH89 contains suggest the possibility for multivalent binding events and the partitioning of this enzyme to highly specific regions within the gastrointestinal tract.
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Affiliation(s)
- Elizabeth Ficko-Blean
- Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada
| | - Christopher P. Stuart
- Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada
| | - Michael D. Suits
- Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada
| | - Melissa Cid
- Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada
| | - Matthew Tessier
- Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia, United States of America
| | - Robert J. Woods
- Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia, United States of America
- School of Chemistry, National University of Ireland, Galway, Ireland
| | - Alisdair B. Boraston
- Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia, Canada
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Hehemann JH, Smyth L, Yadav A, Vocadlo DJ, Boraston AB. Analysis of keystone enzyme in Agar hydrolysis provides insight into the degradation (of a polysaccharide from) red seaweeds. J Biol Chem 2012; 287:13985-95. [PMID: 22393053 DOI: 10.1074/jbc.m112.345645] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Agars are abundant polysaccharides from marine red algae, and their chemical structure consists of alternating D-galactose and 3,6-anhydro-L-galactose residues, the latter of which are presumed to make the polymer recalcitrant to degradation by most terrestrial bacteria. Here we study a family 117 glycoside hydrolase (BpGH117) encoded within a recently discovered locus from the human gut bacterium Bacteroides plebeius. Consistent with this locus being involved in agarocolloid degradation, we show that BpGH117 is an exo-acting 3,6-anhydro-α-(1,3)-L-galactosidase that removes the 3,6-anhydrogalactose from the non-reducing end of neoagaro-oligosaccharides. A Michaelis complex of BpGH117 with neoagarobiose reveals the distortion of the constrained 3,6-anhydro-L-galactose into a conformation that favors catalysis. Furthermore, this complex, supported by analysis of site-directed mutants, provides evidence for an organization of the active site and positioning of the catalytic residues that are consistent with an inverting mechanism of catalysis and suggests that a histidine residue acts as the general acid. This latter feature differs from the vast majority of glycoside hydrolases, which use a carboxylic acid, highlighting the alternative strategies that enzymes may utilize in catalyzing the cleavage of glycosidic bonds.
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Affiliation(s)
- Jan-Hendrik Hehemann
- Department of Biochemistry and Microbiology, University of Victoria, PO Box 3055 STN CSC, Victoria, British Columbia V8W 3P6, Canada
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