1
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DeWinter MA, Wong DA, Fernandez R, Kightlinger W, Thames AH, DeLisa MP, Jewett MC. Establishing a Cell-Free Glycoprotein Synthesis System for Enzymatic N-GlcNAcylation. ACS Chem Biol 2024. [PMID: 38934647 DOI: 10.1021/acschembio.4c00228] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/28/2024]
Abstract
N-linked glycosylation plays a key role in the efficacy of many therapeutic proteins. One limitation to the bacterial glycoengineering of human N-linked glycans is the difficulty of installing a single N-acetylglucosamine (GlcNAc), the reducing end sugar of many human-type glycans, onto asparagine in a single step (N-GlcNAcylation). Here, we develop an in vitro method for N-GlcNAcylating proteins using the oligosaccharyltransferase PglB from Campylobacter jejuni. We use cell-free protein synthesis (CFPS) to test promiscuous PglB variants previously reported in the literature for the ability to produce N-GlcNAc and successfully determine that PglB with an N311V mutation (PglBN311V) exhibits increased GlcNAc transferase activity relative to the wild-type enzyme. We then improve the transfer efficiency by producing CFPS extracts enriched with PglBN311V and further optimize the reaction conditions, achieving a 98.6 ± 0.5% glycosylation efficiency. We anticipate this method will expand the glycoengineering toolbox for therapeutic research and biomanufacturing.
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Affiliation(s)
- Madison A DeWinter
- Medical Scientist Training Program, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611, United States
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, Illinois 60208, United States
- Chemistry of Life Processes Institute, Northwestern University, Evanston, Illinois 60208, United States
- Center for Synthetic Biology, Northwestern University, Evanston, Illinois 60208, United States
| | - Derek A Wong
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, Illinois 60208, United States
- Chemistry of Life Processes Institute, Northwestern University, Evanston, Illinois 60208, United States
- Center for Synthetic Biology, Northwestern University, Evanston, Illinois 60208, United States
| | - Regina Fernandez
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, Illinois 60208, United States
- Chemistry of Life Processes Institute, Northwestern University, Evanston, Illinois 60208, United States
- Center for Synthetic Biology, Northwestern University, Evanston, Illinois 60208, United States
| | - Weston Kightlinger
- Cell-free Protein Synthesis and Microbial Process Development, National Resilience Inc.,, Oakland, California 94606, United States
| | - Ariel Helms Thames
- Medical Scientist Training Program, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611, United States
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, Illinois 60208, United States
- Chemistry of Life Processes Institute, Northwestern University, Evanston, Illinois 60208, United States
- Center for Synthetic Biology, Northwestern University, Evanston, Illinois 60208, United States
- Division of Allergy and Immunology, Department of Medicine, Northwestern University Feinberg School of Medicine, Chicago, Illinois 60611, United States
| | - Matthew P DeLisa
- Robert Frederick Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York 14853, United States
- Cornell Institute of Biotechnology, Cornell University, Ithaca, New York 14853, United States
| | - Michael C Jewett
- Department of Bioengineering, Stanford University, Stanford, California 94305, United States
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2
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Suh D, Arattu Thodika AR, Kim S, Nam K, Im W. CHARMM-GUI QM/MM Interfacer for a Quantum Mechanical and Molecular Mechanical (QM/MM) Simulation Setup: 1. Semiempirical Methods. J Chem Theory Comput 2024; 20:5337-5351. [PMID: 38856971 PMCID: PMC11209942 DOI: 10.1021/acs.jctc.4c00439] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2024] [Revised: 05/17/2024] [Accepted: 05/24/2024] [Indexed: 06/11/2024]
Abstract
Quantum mechanical (QM) treatments, when combined with molecular mechanical (MM) force fields, can effectively handle enzyme-catalyzed reactions without significantly increasing the computational cost. In this context, we present CHARMM-GUI QM/MM Interfacer, a web-based cyberinfrastructure designed to streamline the preparation of various QM/MM simulation inputs with ligand modification. The development of QM/MM Interfacer has been achieved through integration with existing CHARMM-GUI modules, such as PDB Reader and Manipulator, Solution Builder, and Membrane Builder. In addition, new functionalities have been developed to facilitate the one-stop preparation of QM/MM systems and enable interactive and intuitive ligand modifications and QM atom selections. QM/MM Interfacer offers support for a range of semiempirical QM methods, including AM1(+/d), PM3(+/PDDG), MNDO(+/d, +/PDDG), PM6, RM1, and SCC-DFTB, tailored for both AMBER and CHARMM. A nontrivial setup related to ligand modification, link-atom insertion, and charge distribution is automatized through intuitive user interfaces. To illustrate the robustness of QM/MM Interfacer, we conducted QM/MM simulations of three enzyme-substrate systems: dihydrofolate reductase, insulin receptor kinase, and oligosaccharyltransferase. In addition, we have created three tutorial videos about building these systems, which can be found at https://www.charmm-gui.org/demo/qmi. QM/MM Interfacer is expected to be a valuable and accessible web-based tool that simplifies and accelerates the setup process for hybrid QM/MM simulations.
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Affiliation(s)
- Donghyuk Suh
- Department
of Biological Sciences, Chemistry, Bioengineering, and Computer Science
and Engineering, Lehigh University, Bethlehem, Pennsylvania 18015, United States
| | - Abdul Raafik Arattu Thodika
- Department
of Chemistry and Biochemistry, The University
of Texas at Arlington, Arlington, Texas 76019-9800, United States
| | - Seonghoon Kim
- Department
of Biological Sciences, Chemistry, Bioengineering, and Computer Science
and Engineering, Lehigh University, Bethlehem, Pennsylvania 18015, United States
| | - Kwangho Nam
- Department
of Chemistry and Biochemistry, The University
of Texas at Arlington, Arlington, Texas 76019-9800, United States
| | - Wonpil Im
- Department
of Biological Sciences, Chemistry, Bioengineering, and Computer Science
and Engineering, Lehigh University, Bethlehem, Pennsylvania 18015, United States
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3
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Lehri B, Atkins E, Scott TA, Abouelhadid S, Wren BW, Cuccui J. Investigation into the efficiency of diverse N-linking oligosaccharyltransferases for glycoengineering using a standardised cell-free assay. Microb Biotechnol 2024; 17:e14480. [PMID: 38858807 PMCID: PMC11164674 DOI: 10.1111/1751-7915.14480] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2024] [Revised: 03/26/2024] [Accepted: 05/03/2024] [Indexed: 06/12/2024] Open
Abstract
The application of bacterial oligosaccharyltransferases (OSTs) such as the Campylobacter jejuni PglB for glycoengineering has attracted considerable interest in glycoengineering and glycoconjugate vaccine development. However, PglB has limited specificity for glycans that can be transferred to candidate proteins, which along with other factors is dependent on the reducing end sugar of glycans. In this study, we developed a cell-free glycosylation assay that offers the speed and simplicity of a 'yes' or 'no' determination. Using the assay, we tested the activity of eleven PglBs from Campylobacter species and more distantly related bacteria. The following assorted glycans with diverse reducing end sugars were tested for transfer, including Streptococcus pneumoniae capsule serotype 4, Salmonella enterica serovar Typhimurium O antigen (B1), Francisella tularensis O antigen, Escherichia coli O9 antigen and Campylobacter jejuni heptasaccharide. Interestingly, while PglBs from the same genus showed high activity, whereas divergent PglBs differed in their transfer of glycans to an acceptor protein. Notably for glycoengineering purposes, Campylobacter hepaticus and Campylobacter subantarcticus PglBs showed high glycosylation efficiency, with C. hepaticus PglB potentially being useful for glycoconjugate vaccine production. This study demonstrates the versatility of the cell-free assay in rapidly assessing an OST to couple glycan/carrier protein combinations and lays the foundation for future screening of PglBs by linking amino acid similarity to glycosyltransferase activity.
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Affiliation(s)
- Burhan Lehri
- Department of Infection BiologyLondon School of Hygiene and Tropical MedicineLondonUK
| | - Elizabeth Atkins
- Department of Infection BiologyLondon School of Hygiene and Tropical MedicineLondonUK
| | - Timothy A. Scott
- Department of Medicine, Cambridge Institute of Therapeutic Immunology & Infectious Disease (CITIID), Jeffrey Cheah Biomedical CentreUniversity of CambridgeCambridgeUK
| | - Sherif Abouelhadid
- Department of Infection BiologyLondon School of Hygiene and Tropical MedicineLondonUK
| | - Brendan W. Wren
- Department of Infection BiologyLondon School of Hygiene and Tropical MedicineLondonUK
| | - Jon Cuccui
- Department of Infection BiologyLondon School of Hygiene and Tropical MedicineLondonUK
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4
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Ramírez AS, Locher KP. Structural and mechanistic studies of the N-glycosylation machinery: from lipid-linked oligosaccharide biosynthesis to glycan transfer. Glycobiology 2023; 33:861-872. [PMID: 37399117 PMCID: PMC10859629 DOI: 10.1093/glycob/cwad053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2023] [Revised: 06/26/2023] [Accepted: 06/27/2023] [Indexed: 07/05/2023] Open
Abstract
N-linked protein glycosylation is a post-translational modification that exists in all domains of life. It involves two consecutive steps: (i) biosynthesis of a lipid-linked oligosaccharide (LLO), and (ii) glycan transfer from the LLO to asparagine residues in secretory proteins, which is catalyzed by the integral membrane enzyme oligosaccharyltransferase (OST). In the last decade, structural and functional studies of the N-glycosylation machinery have increased our mechanistic understanding of the pathway. The structures of bacterial and eukaryotic glycosyltransferases involved in LLO elongation provided an insight into the mechanism of LLO biosynthesis, whereas structures of OST enzymes revealed the molecular basis of sequon recognition and catalysis. In this review, we will discuss approaches used and insight obtained from these studies with a special emphasis on the design and preparation of substrate analogs.
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Affiliation(s)
- Ana S Ramírez
- Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule (ETH), Zürich 8093, Switzerland
| | - Kaspar P Locher
- Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule (ETH), Zürich 8093, Switzerland
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5
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Hao Z, Guo Q, Feng Y, Zhang Z, Li T, Tian Z, Zheng J, Da LT, Peng W. Investigation of the Catalytic Mechanism of a Soluble N-glycosyltransferase Allows Synthesis of N-glycans at Noncanonical Sequons. JACS AU 2023; 3:2144-2155. [PMID: 37654596 PMCID: PMC10466321 DOI: 10.1021/jacsau.3c00214] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Revised: 07/21/2023] [Accepted: 07/24/2023] [Indexed: 09/02/2023]
Abstract
The soluble N-glycosyltransferase from Actinobacillus pleuropneumoniae (ApNGT) can establish an N-glycosidic bond at the asparagine residue in the Asn-Xaa-Ser/Thr consensus sequon and is one of the most promising tools for N-glycoprotein production. Here, by integrating computational and experimental strategies, we revealed the molecular mechanism of the substrate recognition and following catalysis of ApNGT. These findings allowed us to pinpoint a key structural motif (215DVYM218) in ApNGT responsible for the peptide substrate recognition. Moreover, Y222 and H371 of ApNGT were found to participate in activating the acceptor Asn. The constructed models were supported by further crystallographic studies and the functional roles of the identified residues were validated by measuring the glycosylation activity of various mutants against a library of synthetic peptides. Intriguingly, with particular mutants, site-selective N-glycosylation of canonical or noncanonical sequons within natural polypeptides from the SARS-CoV-2 spike protein could be achieved, which were used to investigate the biological roles of the N-glycosylation in membrane fusion during virus entry. Our study thus provides in-depth molecular mechanisms underlying the substrate recognition and catalysis for ApNGT, leading to the synthesis of previously unknown chemically defined N-glycoproteins for exploring the biological importance of the N-glycosylation at a specific site.
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Affiliation(s)
- Zhiqiang Hao
- Key
Laboratory of Systems Biomedicine (Ministry of Education), Shanghai
Center for Systems Biomedicine, Shanghai
Jiao Tong University, Shanghai 200240, China
| | - Qiang Guo
- Key
Laboratory of Systems Biomedicine (Ministry of Education), Shanghai
Center for Systems Biomedicine, Shanghai
Jiao Tong University, Shanghai 200240, China
| | - Yuanyuan Feng
- State
Key Laboratory of Microbial Metabolism, School of Life Sciences and
Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Zihan Zhang
- Shanghai
Key Laboratory of Chemical Assessment and Sustainability, School of
Chemical Science & Engineering, Tongji
University, Shanghai 200092, China
| | - Tiantian Li
- Key
Laboratory of Systems Biomedicine (Ministry of Education), Shanghai
Center for Systems Biomedicine, Shanghai
Jiao Tong University, Shanghai 200240, China
| | - Zhixin Tian
- Shanghai
Key Laboratory of Chemical Assessment and Sustainability, School of
Chemical Science & Engineering, Tongji
University, Shanghai 200092, China
| | - Jianting Zheng
- State
Key Laboratory of Microbial Metabolism, School of Life Sciences and
Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Lin-Tai Da
- Key
Laboratory of Systems Biomedicine (Ministry of Education), Shanghai
Center for Systems Biomedicine, Shanghai
Jiao Tong University, Shanghai 200240, China
| | - Wenjie Peng
- Key
Laboratory of Systems Biomedicine (Ministry of Education), Shanghai
Center for Systems Biomedicine, Shanghai
Jiao Tong University, Shanghai 200240, China
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6
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Ramírez AS, de Capitani M, Pesciullesi G, Kowal J, Bloch JS, Irobalieva RN, Reymond JL, Aebi M, Locher KP. Molecular basis for glycan recognition and reaction priming of eukaryotic oligosaccharyltransferase. Nat Commun 2022; 13:7296. [PMID: 36435935 PMCID: PMC9701220 DOI: 10.1038/s41467-022-35067-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2022] [Accepted: 11/17/2022] [Indexed: 11/28/2022] Open
Abstract
Oligosaccharyltransferase (OST) is the central enzyme of N-linked protein glycosylation. It catalyzes the transfer of a pre-assembled glycan, GlcNAc2Man9Glc3, from a dolichyl-pyrophosphate donor to acceptor sites in secretory proteins in the lumen of the endoplasmic reticulum. Precise recognition of the fully assembled glycan by OST is essential for the subsequent quality control steps of glycoprotein biosynthesis. However, the molecular basis of the OST-donor glycan interaction is unknown. Here we present cryo-EM structures of S. cerevisiae OST in distinct functional states. Our findings reveal that the terminal glucoses (Glc3) of a chemo-enzymatically generated donor glycan analog bind to a pocket formed by the non-catalytic subunits WBP1 and OST2. We further find that binding either donor or acceptor substrate leads to distinct primed states of OST, where subsequent binding of the other substrate triggers conformational changes required for catalysis. This alternate priming allows OST to efficiently process closely spaced N-glycosylation sites.
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Affiliation(s)
- Ana S. Ramírez
- grid.5801.c0000 0001 2156 2780Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule (ETH), Zürich, Switzerland
| | - Mario de Capitani
- grid.5734.50000 0001 0726 5157Department of Chemistry and Biochemistry, University of Bern, Bern, Switzerland
| | - Giorgio Pesciullesi
- grid.5734.50000 0001 0726 5157Department of Chemistry and Biochemistry, University of Bern, Bern, Switzerland
| | - Julia Kowal
- grid.5801.c0000 0001 2156 2780Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule (ETH), Zürich, Switzerland
| | - Joël S. Bloch
- grid.5801.c0000 0001 2156 2780Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule (ETH), Zürich, Switzerland
| | - Rossitza N. Irobalieva
- grid.5801.c0000 0001 2156 2780Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule (ETH), Zürich, Switzerland
| | - Jean-Louis Reymond
- grid.5734.50000 0001 0726 5157Department of Chemistry and Biochemistry, University of Bern, Bern, Switzerland
| | - Markus Aebi
- grid.5801.c0000 0001 2156 2780Institute of Microbiology, Eidgenössische Technische Hochschule (ETH), Zürich, Switzerland
| | - Kaspar P. Locher
- grid.5801.c0000 0001 2156 2780Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule (ETH), Zürich, Switzerland
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7
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Glycosyltransferase-Related Protein GtrA Is Essential for Localization of Type IX Secretion System Cargo Protein Cellulase Cel9A and Affects Cellulose Degradation in Cytophaga hutchinsonii. Appl Environ Microbiol 2022; 88:e0107622. [PMID: 36197104 PMCID: PMC9599414 DOI: 10.1128/aem.01076-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Gram-negative bacterium Cytophaga hutchinsonii digests cellulose through a novel cellulose degradation mechanism. It possesses the lately characterized type IX secretion system (T9SS). We recently discovered that N-glycosylation of the C-terminal domain (CTD) of a hypothetical T9SS substrate protein in the periplasmic space of C. hutchinsonii affects protein secretion and localization. In this study, green fluorescent protein (GFP)-CTDCel9A recombinant protein was found with increased molecular weight in the periplasm of C. hutchinsonii. Site-directed mutagenesis studies on the CTD of cellulase Cel9A demonstrated that asparagine residue 900 in the D-X-N-X-S motif is important for the processing of the recombinant protein. We found that the glycosyltransferase-related protein GtrA (CHU_0012) located in the cytoplasm of C. hutchinsonii is essential for outer membrane localization of the recombinant protein. The deletion of gtrA decreased the abundance of the outer membrane proteins and affected cellulose degradation by C. hutchinsonii. This study provided a link between the glycosylation system and cellulose degradation in C. hutchinsonii. IMPORTANCE N-Glycosylation systems are generally limited to some pathogenic bacteria in prokaryotes. The disruption of the N-glycosylation pathway is related to adherence, invasion, colonization, and other phenotypic characteristics. We recently found that the cellulolytic bacterium Cytophaga hutchinsonii also has an N-glycosylation system. The cellulose degradation mechanism of C. hutchinsonii is novel and mysterious; cellulases and other proteins on the cell surface are involved in utilizing cellulose. In this study, we identified an asparagine residue in the C-terminal domain of cellulase Cel9A that is necessary for the processing of the T9SS cargo protein. Moreover, the glycosyltransferase-related protein GtrA is essential for the localization of the GFP-CTDCel9A recombinant protein. Deletion of gtrA affected cellulose degradation and the abundance of outer membrane proteins. This study enriched the understanding of the N-glycosylation system in C. hutchinsonii and provided a link between N-glycosylation and cellulose degradation, which also expanded the role of the N-glycosylation system in bacteria.
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8
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Aquino AK, Manzer ZA, Daniel S, DeLisa MP. Glycosylation-on-a-Chip: A Flow-Based Microfluidic System for Cell-Free Glycoprotein Biosynthesis. Front Mol Biosci 2022; 8:782905. [PMID: 35004852 PMCID: PMC8733600 DOI: 10.3389/fmolb.2021.782905] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Accepted: 12/06/2021] [Indexed: 12/25/2022] Open
Abstract
In recent years, cell-free synthetic glycobiology technologies have emerged that enable production and remodeling of glycoproteins outside the confines of the cell. However, many of these systems combine multiple synthesis steps into one pot where there can be competing reactions and side products that ultimately lead to low yield of the desired product. In this work, we describe a microfluidic platform that integrates cell-free protein synthesis, glycosylation, and purification of a model glycoprotein in separate compartments where each step can be individually optimized. Microfluidics offer advantages such as reaction compartmentalization, tunable residence time, the ability to tether enzymes for reuse, and the potential for continuous manufacturing. Moreover, it affords an opportunity for spatiotemporal control of glycosylation reactions that is difficult to achieve with existing cell-based and cell-free glycosylation systems. In this work, we demonstrate a flow-based glycoprotein synthesis system that promotes enhanced cell-free protein synthesis, efficient protein glycosylation with an immobilized oligosaccharyltransferase, and enrichment of the protein product from cell-free lysate. Overall, this work represents a first-in-kind glycosylation-on-a-chip prototype that could find use as a laboratory tool for mechanistic dissection of the protein glycosylation process as well as a biomanufacturing platform for small batch, decentralized glycoprotein production.
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Affiliation(s)
- Alicia K Aquino
- Robert Frederick Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, NY, United States
| | - Zachary A Manzer
- Robert Frederick Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, NY, United States
| | - Susan Daniel
- Robert Frederick Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, NY, United States
| | - Matthew P DeLisa
- Robert Frederick Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, NY, United States.,Cornell Institute of Biotechnology, Cornell University, Ithaca, NY, United States
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9
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Cain JA, Dale AL, Cordwell SJ. Exploiting pglB Oligosaccharyltransferase-Positive and -Negative Campylobacter jejuni and a Multiprotease Digestion Strategy to Identify Novel Sites Modified by N-Linked Protein Glycosylation. J Proteome Res 2021; 20:4995-5009. [PMID: 34677046 DOI: 10.1021/acs.jproteome.1c00482] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Campylobacter jejuni is a bacterial pathogen encoding a unique N-linked glycosylation (pgl) system that mediates attachment of a heptasaccharide to N-sequon-containing membrane proteins by the PglB oligosaccharyltransferase (OST). Many targets of PglB are known, yet only a fraction of sequons are experimentally confirmed, and site occupancy remains elusive. We exploited pglB-positive (wild-type; WT) and -negative (ΔpglB) proteomes to identify potential glycosites. The nonglycosylated forms of known glycopeptides were typically increased in protein normalized abundance in ΔpglB relative to WT and restored by pglB reintroduction (ΔpglB::pglB). Sequon-containing peptide abundances were thus consistent with significant site occupancy in the presence of the OST. Peptides with novel sequons were either unaltered (likely not glycosylated) or showed abundance consistent with known glycopeptides. Topology analysis revealed that unaltered sequons often displayed cytoplasmic localization, despite originating from membrane proteins. Novel glycosites were confirmed using parallel multiprotease digestion, LC-MS/MS, and FAIMS-MS to define the glycoproteomes of WT and ΔpglB::pglB C. jejuni. We identified 142 glycosites, of which 32 were novel, and 83% of sites predicted by proteomics were validated. There are now 166 experimentally verified C. jejuni glycosites and evidence for occupancy or nonoccupancy of 31 additional sites. This study serves as a model for the use of OST-negative cells and proteomics for highlighting novel glycosites and determining occupancy in a range of organisms.
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Affiliation(s)
- Joel A Cain
- Charles Perkins Centre, The University of Sydney, Sydney 2006, Australia.,School of Life and Environmental Sciences, The University of Sydney, Sydney 2006, Australia
| | - Ashleigh L Dale
- Charles Perkins Centre, The University of Sydney, Sydney 2006, Australia.,School of Life and Environmental Sciences, The University of Sydney, Sydney 2006, Australia
| | - Stuart J Cordwell
- Charles Perkins Centre, The University of Sydney, Sydney 2006, Australia.,School of Life and Environmental Sciences, The University of Sydney, Sydney 2006, Australia.,Sydney Mass Spectrometry, The University of Sydney, Sydney 2006, Australia
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10
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Morgan BR, Massi F. The Role of Substrate Mediated Allostery in the Catalytic Competency of the Bacterial Oligosaccharyltransferase PglB. Front Mol Biosci 2021; 8:740904. [PMID: 34604309 PMCID: PMC8479172 DOI: 10.3389/fmolb.2021.740904] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Accepted: 08/24/2021] [Indexed: 11/30/2022] Open
Abstract
The oligosaccharyltransferase of Campylobacter lari (PglB) catalyzes the glycosylation of asparagine in the consensus sequence N-X-S/T, where X is any residue except proline. Molecular dynamics simulations of PglB bound to two different substrates were used to characterize the differences in the structure and dynamics of the substrate-enzyme complexes that can explain the higher catalytic efficiency observed for substrates containing threonine at the +2 position rather than serine. We observed that a threonine-containing substrate is more tightly bound than a serine-containing substrate. Because serine lacks a methyl group relative to threonine, the serine-containing peptide cannot stably form simultaneous van der Waals interactions with T316 and I572 as the threonine-containing substrate can. As a result, the peptide-PglB interaction is destabilized and the allosteric communication between the periplasmic domain and external loop EL5 is disrupted. These changes ultimately lead to the reorientation of the periplasmic domain relative to the transmembrane domain such that the two domains are further apart compared to PglB bound to the threonine-containing peptide. The crystal structure of PglB bound to the peptide and a lipid-linked oligosaccharide analog shows a pronounced closing of the periplasmic domain over the transmembrane domain in comparison to structures of PglB with peptide only, indicating that a closed conformation of the domains is needed for catalysis. The results of our studies suggest that lower enzymatic activity observed for serine versus threonine results from a combination of less stable binding and structural changes in PglB that influence the ability to form a catalytically competent state. This study illustrates a mechanism for substrate specificity via modulation of dynamic allosteric pathways.
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Affiliation(s)
- Brittany R Morgan
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA, United States
| | - Francesca Massi
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA, United States
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11
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The structure of an archaeal oligosaccharyltransferase provides insight into the strict exclusion of proline from the N-glycosylation sequon. Commun Biol 2021; 4:941. [PMID: 34354228 PMCID: PMC8342417 DOI: 10.1038/s42003-021-02473-8] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Accepted: 07/21/2021] [Indexed: 02/07/2023] Open
Abstract
Oligosaccharyltransferase (OST) catalyzes oligosaccharide transfer to the Asn residue in the N-glycosylation sequon, Asn-X-Ser/Thr, where Pro is strictly excluded at position X. Considering the unique structural properties of proline, this exclusion may not be surprising, but the structural basis for the rejection of Pro residues should be explained explicitly. Here we determined the crystal structure of an archaeal OST in a complex with a sequon-containing peptide and dolichol-phosphate to a 2.7 Å resolution. The sequon part in the peptide forms two inter-chain hydrogen bonds with a conserved amino acid motif, TIXE. We confirmed the essential role of the TIXE motif and the adjacent regions by extensive alanine-scanning of the external loop 5. A Ramachandran plot revealed that the ring structure of the Pro side chain is incompatible with the ϕ backbone dihedral angle around -150° in the rigid sequon-TIXE structure. The present structure clearly provides the structural basis for the exclusion of Pro residues from the N-glycosylation sequon.
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12
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Cain JA, Dale AL, Sumer-Bayraktar Z, Solis N, Cordwell SJ. Identifying the targets and functions of N-linked protein glycosylation in Campylobacter jejuni. Mol Omics 2021; 16:287-304. [PMID: 32347268 DOI: 10.1039/d0mo00032a] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Campylobacter jejuni is a major cause of bacterial gastroenteritis in humans that is primarily associated with the consumption of inadequately prepared poultry products, since the organism is generally thought to be asymptomatic in avian species. Unlike many other microorganisms, C. jejuni is capable of performing extensive post-translational modification (PTM) of proteins by N- and O-linked glycosylation, both of which are required for optimal chicken colonization and human virulence. The biosynthesis and attachment of N-glycans to C. jejuni proteins is encoded by the pgl (protein glycosylation) locus, with the PglB oligosaccharyltransferase (OST) enabling en bloc transfer of a heptasaccharide N-glycan from a lipid carrier in the inner membrane to proteins exposed within the periplasm. Seventy-eight C. jejuni glycoproteins (represented by 134 sites of experimentally verified N-glycosylation) have now been identified, and include inner and outer membrane proteins, periplasmic proteins and lipoproteins, which are generally of poorly defined or unknown function. Despite our extensive knowledge of the targets of this apparently widespread process, we still do not fully understand the role N-glycosylation plays biologically, although several phenotypes, including wild-type stress resistance, biofilm formation, motility and chemotaxis have been related to a functional pgl system. Recent work has described enzymatic processes (nitrate reductase NapAB) and antibiotic efflux (CmeABC) as major targets requiring N-glycan attachment for optimal function, and experimental evidence also points to roles in cell binding via glycan-glycan interactions, protein complex formation and protein stability by conferring protection against host and bacterial proteolytic activity. Here we examine the biochemistry of the N-linked glycosylation system, define its currently known protein targets and discuss evidence for the structural and functional roles of this PTM in individual proteins and globally in C. jejuni pathogenesis.
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Affiliation(s)
- Joel A Cain
- School of Life and Environmental Sciences, The University of Sydney, 2006, Australia and Charles Perkins Centre, The University of Sydney, Level 4 East, The Hub Building (D17), 2006, Australia.
| | - Ashleigh L Dale
- School of Life and Environmental Sciences, The University of Sydney, 2006, Australia and Charles Perkins Centre, The University of Sydney, Level 4 East, The Hub Building (D17), 2006, Australia.
| | - Zeynep Sumer-Bayraktar
- School of Life and Environmental Sciences, The University of Sydney, 2006, Australia and Charles Perkins Centre, The University of Sydney, Level 4 East, The Hub Building (D17), 2006, Australia.
| | - Nestor Solis
- School of Life and Environmental Sciences, The University of Sydney, 2006, Australia
| | - Stuart J Cordwell
- School of Life and Environmental Sciences, The University of Sydney, 2006, Australia and Charles Perkins Centre, The University of Sydney, Level 4 East, The Hub Building (D17), 2006, Australia. and Discipline of Pathology, School of Medical Sciences, The University of Sydney, 2006, Australia and Sydney Mass Spectrometry, The University of Sydney, 2006, Australia
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13
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Eyring J, Lin CW, Ngwa EM, Boilevin J, Pesciullesi G, Locher KP, Darbre T, Reymond JL, Aebi M. Substrate specificities and reaction kinetics of the yeast oligosaccharyltransferase isoforms. J Biol Chem 2021; 296:100809. [PMID: 34023382 PMCID: PMC8191290 DOI: 10.1016/j.jbc.2021.100809] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2020] [Revised: 05/07/2021] [Accepted: 05/19/2021] [Indexed: 12/02/2022] Open
Abstract
Oligosaccharyltransferase (OST) catalyzes the central step in N-linked protein glycosylation, the transfer of a preassembled oligosaccharide from its lipid carrier onto asparagine residues of secretory proteins. The prototypic hetero-octameric OST complex from the yeast Saccharomyces cerevisiae exists as two isoforms that contain either Ost3p or Ost6p, both noncatalytic subunits. These two OST complexes have different protein substrate specificities in vivo. However, their detailed biochemical mechanisms and the basis for their different specificities are not clear. The two OST complexes were purified from genetically engineered strains expressing only one isoform. The kinetic properties and substrate specificities were characterized using a quantitative in vitro glycosylation assay with short peptides and different synthetic lipid-linked oligosaccharide (LLO) substrates. We found that the peptide sequence close to the glycosylation sequon affected peptide affinity and turnover rate. The length of the lipid moiety affected LLO affinity, while the lipid double-bond stereochemistry had a greater influence on LLO turnover rates. The two OST complexes had similar affinities for both the peptide and LLO substrates but showed significantly different turnover rates. These data provide the basis for a functional analysis of the Ost3p and Ost6p subunits.
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Affiliation(s)
- Jillianne Eyring
- Institute of Microbiology, Department of Biology, ETH Zürich, Zürich, Switzerland
| | - Chia-Wei Lin
- Institute of Microbiology, Department of Biology, ETH Zürich, Zürich, Switzerland; Functional Genomics Center Zürich, University of Zürich/ETH Zürich, Zürich, Switzerland
| | - Elsy Mankah Ngwa
- Institute of Microbiology, Department of Biology, ETH Zürich, Zürich, Switzerland
| | - Jérémy Boilevin
- Department of Chemistry and Biochemistry, University of Berne, Bern, Switzerland
| | - Giorgio Pesciullesi
- Department of Chemistry and Biochemistry, University of Berne, Bern, Switzerland
| | - Kaspar P Locher
- Institute of Molecular Biology and Biophysics, Department of Biology, ETH Zürich, Zürich, Switzerland
| | - Tamis Darbre
- Department of Chemistry and Biochemistry, University of Berne, Bern, Switzerland
| | - Jean-Louis Reymond
- Department of Chemistry and Biochemistry, University of Berne, Bern, Switzerland
| | - Markus Aebi
- Institute of Microbiology, Department of Biology, ETH Zürich, Zürich, Switzerland.
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14
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Knoot CJ, Robinson LS, Harding CM. A minimal sequon sufficient for O-linked glycosylation by the versatile oligosaccharyltransferase PglS. Glycobiology 2021; 31:1192-1203. [PMID: 33997889 PMCID: PMC8457361 DOI: 10.1093/glycob/cwab043] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Revised: 04/29/2021] [Accepted: 05/07/2021] [Indexed: 11/19/2022] Open
Abstract
Bioconjugate vaccines, consisting of polysaccharides attached to carrier proteins, are enzymatically generated using prokaryotic glycosylation systems in a process termed bioconjugation. Key to bioconjugation are a group of enzymes known as oligosaccharyltransferases (OTases) that transfer polysaccharides to engineered carrier proteins containing conserved amino acid sequences known as sequons. The most recently discovered OTase, PglS, has been shown to have the broadest substrate scope, transferring many different types of bacterial glycans including those with glucose at the reducing end. However, PglS is currently the least understood in terms of the sequon it recognizes. PglS is a pilin-specific O-linking OTase that naturally glycosylates a single protein, ComP. In addition to ComP, we previously demonstrated that an engineered carrier protein containing a large fragment of ComP is also glycosylated by PglS. Here we sought to identify the minimal ComP sequon sufficient for PglS glycosylation. We tested >100 different ComP fragments individually fused to Pseudomonas aeruginosa exotoxin A (EPA), leading to the identification of an 11-amino acid sequence sufficient for robust glycosylation by PglS. We also demonstrate that the placement of the ComP sequon on the carrier protein is critical for stability and subsequent glycosylation. Moreover, we identify novel sites on the surface of EPA that are amenable to ComP sequon insertion and find that Cross-Reactive Material 197 fused to a ComP fragment is also glycosylated. These results represent a significant expansion of the glycoengineering toolbox as well as our understanding of bacterial O-linking sequons.
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15
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Derking R, Allen JD, Cottrell CA, Sliepen K, Seabright GE, Lee WH, Aldon Y, Rantalainen K, Antanasijevic A, Copps J, Yasmeen A, Cupo A, Cruz Portillo VM, Poniman M, Bol N, van der Woude P, de Taeye SW, van den Kerkhof TLGM, Klasse PJ, Ozorowski G, van Gils MJ, Moore JP, Ward AB, Crispin M, Sanders RW. Enhancing glycan occupancy of soluble HIV-1 envelope trimers to mimic the native viral spike. Cell Rep 2021; 35:108933. [PMID: 33826885 PMCID: PMC8804554 DOI: 10.1016/j.celrep.2021.108933] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Revised: 12/10/2020] [Accepted: 03/11/2021] [Indexed: 12/31/2022] Open
Abstract
Artificial glycan holes on recombinant Env-based vaccines occur when a potential N-linked glycosylation site (PNGS) is under-occupied, but not on their viral counterparts. Native-like SOSIP trimers, including clinical candidates, contain such holes in the glycan shield that induce strain-specific neutralizing antibodies (NAbs) or non-NAbs. To eliminate glycan holes and mimic the glycosylation of native BG505 Env, we replace all 12 NxS sequons on BG505 SOSIP with NxT. All PNGS, except N133 and N160, are nearly fully occupied. Occupancy of the N133 site is increased by changing N133 to NxS, whereas occupancy of the N160 site is restored by reverting the nearby N156 sequon to NxS. Hence, PNGS in close proximity, such as in the N133-N137 and N156-N160 pairs, affect each other's occupancy. We further apply this approach to improve the occupancy of several Env strains. Increasing glycan occupancy should reduce off-target immune responses to vaccine antigens.
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Affiliation(s)
- Ronald Derking
- Department of Medical Microbiology, Amsterdam Infection and Immunity Institute, Amsterdam UMC, University of Amsterdam, Amsterdam 1105 AZ, the Netherlands
| | - Joel D Allen
- School of Biological Sciences, University of Southampton, Southampton SO17 1BJ, UK
| | - Christopher A Cottrell
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Kwinten Sliepen
- Department of Medical Microbiology, Amsterdam Infection and Immunity Institute, Amsterdam UMC, University of Amsterdam, Amsterdam 1105 AZ, the Netherlands
| | - Gemma E Seabright
- School of Biological Sciences, University of Southampton, Southampton SO17 1BJ, UK; Oxford Glycobiology Institute, Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| | - Wen-Hsin Lee
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Yoann Aldon
- Department of Medical Microbiology, Amsterdam Infection and Immunity Institute, Amsterdam UMC, University of Amsterdam, Amsterdam 1105 AZ, the Netherlands
| | - Kimmo Rantalainen
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Aleksandar Antanasijevic
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Jeffrey Copps
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Anila Yasmeen
- Department of Microbiology and Immunology, Weill Cornell Medical College, Cornell University, New York, NY, USA
| | - Albert Cupo
- Department of Microbiology and Immunology, Weill Cornell Medical College, Cornell University, New York, NY, USA
| | - Victor M Cruz Portillo
- Department of Microbiology and Immunology, Weill Cornell Medical College, Cornell University, New York, NY, USA
| | - Meliawati Poniman
- Department of Medical Microbiology, Amsterdam Infection and Immunity Institute, Amsterdam UMC, University of Amsterdam, Amsterdam 1105 AZ, the Netherlands
| | - Niki Bol
- Department of Medical Microbiology, Amsterdam Infection and Immunity Institute, Amsterdam UMC, University of Amsterdam, Amsterdam 1105 AZ, the Netherlands
| | - Patricia van der Woude
- Department of Medical Microbiology, Amsterdam Infection and Immunity Institute, Amsterdam UMC, University of Amsterdam, Amsterdam 1105 AZ, the Netherlands
| | - Steven W de Taeye
- Department of Medical Microbiology, Amsterdam Infection and Immunity Institute, Amsterdam UMC, University of Amsterdam, Amsterdam 1105 AZ, the Netherlands
| | - Tom L G M van den Kerkhof
- Department of Medical Microbiology, Amsterdam Infection and Immunity Institute, Amsterdam UMC, University of Amsterdam, Amsterdam 1105 AZ, the Netherlands
| | - P J Klasse
- Department of Microbiology and Immunology, Weill Cornell Medical College, Cornell University, New York, NY, USA
| | - Gabriel Ozorowski
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA; Center for HIV/AIDS Vaccine Development, IAVI Neutralizing Antibody Center and the Collaboration for AIDS Vaccine Discovery (CAVD), The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Marit J van Gils
- Department of Medical Microbiology, Amsterdam Infection and Immunity Institute, Amsterdam UMC, University of Amsterdam, Amsterdam 1105 AZ, the Netherlands
| | - John P Moore
- Department of Microbiology and Immunology, Weill Cornell Medical College, Cornell University, New York, NY, USA
| | - Andrew B Ward
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA 92037, USA; Center for HIV/AIDS Vaccine Development, IAVI Neutralizing Antibody Center and the Collaboration for AIDS Vaccine Discovery (CAVD), The Scripps Research Institute, La Jolla, CA 92037, USA
| | - Max Crispin
- School of Biological Sciences, University of Southampton, Southampton SO17 1BJ, UK.
| | - Rogier W Sanders
- Department of Medical Microbiology, Amsterdam Infection and Immunity Institute, Amsterdam UMC, University of Amsterdam, Amsterdam 1105 AZ, the Netherlands; Department of Microbiology and Immunology, Weill Cornell Medical College, Cornell University, New York, NY, USA.
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16
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Hsu TW, Hsu HC, Chan HY, Fang JM. A Terpyridine Zinc Complex for Selective Detection of Lipid Pyrophosphates: A Model System for Monitoring Bacterial O- and N-Transglycosylations. J Org Chem 2020; 85:12747-12753. [PMID: 32885656 DOI: 10.1021/acs.joc.0c01252] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
To develop an effective method for probing O- and N-glycosyltransfer reactions that are accompanied by the release of undecaprenyl pyrophosphate, solanesyl pyrophosphate (SPP) is used as a surrogate to bind a terpyridine zinc complex (Tpy-Zn), forming a fluorescent [Tpy-Zn]-SPP complex (Kass 106,000 M-1 in EtOH-CHCl3) with 5.8 μM LOD in HEPES buffer (10 mM, pH 7.4) containing 10 mM CaCl2 and 0.08% decyl PEG, which is similar to the bioassay conditions for lipid II polymerization.
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Affiliation(s)
- Tse-Wei Hsu
- Department of Chemistry, National Taiwan University, Taipei 106, Taiwan
| | - Hsin-Chuan Hsu
- Department of Chemistry, National Taiwan University, Taipei 106, Taiwan
| | - Hsin-Yu Chan
- Department of Chemistry, National Taiwan University, Taipei 106, Taiwan
| | - Jim-Min Fang
- Department of Chemistry, National Taiwan University, Taipei 106, Taiwan.,The Genomics Research Center, Academia Sinica, Taipei 115, Taiwan
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17
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Dow JM, Mauri M, Scott TA, Wren BW. Improving protein glycan coupling technology (PGCT) for glycoconjugate vaccine production. Expert Rev Vaccines 2020; 19:507-527. [DOI: 10.1080/14760584.2020.1775077] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Jennifer Mhairi Dow
- Department of Infection Biology, London School of Hygiene & Tropical Medicine, London, UK
| | - Marta Mauri
- Department of Infection Biology, London School of Hygiene & Tropical Medicine, London, UK
| | | | - Brendan William Wren
- Department of Infection Biology, London School of Hygiene & Tropical Medicine, London, UK
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18
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Structural Insight into the Mechanism of N-Linked Glycosylation by Oligosaccharyltransferase. Biomolecules 2020; 10:biom10040624. [PMID: 32316603 PMCID: PMC7226087 DOI: 10.3390/biom10040624] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Revised: 04/06/2020] [Accepted: 04/10/2020] [Indexed: 02/06/2023] Open
Abstract
Asparagine-linked glycosylation, also known as N-linked glycosylation is an essential and highly conserved post-translational protein modification that occurs in all three domains of life. This modification is essential for specific molecular recognition, protein folding, sorting in the endoplasmic reticulum, cell-cell communication, and stability. Defects in N-linked glycosylation results in a class of inherited diseases known as congenital disorders of glycosylation (CDG). N-linked glycosylation occurs in the endoplasmic reticulum (ER) lumen by a membrane associated enzyme complex called the oligosaccharyltransferase (OST). In the central step of this reaction, an oligosaccharide group is transferred from a lipid-linked dolichol pyrophosphate donor to the acceptor substrate, the side chain of a specific asparagine residue of a newly synthesized protein. The prokaryotic OST enzyme consists of a single polypeptide chain, also known as single subunit OST or ssOST. In contrast, the eukaryotic OST is a complex of multiple non-identical subunits. In this review, we will discuss the biochemical and structural characterization of the prokaryotic, yeast, and mammalian OST enzymes. This review explains the most recent high-resolution structures of OST determined thus far and the mechanistic implication of N-linked glycosylation throughout all domains of life. It has been shown that the ssOST enzyme, AglB protein of the archaeon Archaeoglobus fulgidus, and the PglB protein of the bacterium Campylobactor lari are structurally and functionally similar to the catalytic Stt3 subunit of the eukaryotic OST enzyme complex. Yeast OST enzyme complex contains a single Stt3 subunit, whereas the human OST complex is formed with either STT3A or STT3B, two paralogues of Stt3. Both human OST complexes, OST-A (with STT3A) and OST-B (containing STT3B), are involved in the N-linked glycosylation of proteins in the ER. The cryo-EM structures of both human OST-A and OST-B complexes were reported recently. An acceptor peptide and a donor substrate (dolichylphosphate) were observed to be bound to the OST-B complex whereas only dolichylphosphate was bound to the OST-A complex suggesting disparate affinities of two OST complexes for the acceptor substrates. However, we still lack an understanding of the independent role of each eukaryotic OST subunit in N-linked glycosylation or in the stabilization of the enzyme complex. Discerning the role of each subunit through structure and function studies will potentially reveal the mechanistic details of N-linked glycosylation in higher organisms. Thus, getting an insight into the requirement of multiple non-identical subunits in the N-linked glycosylation process in eukaryotes poses an important future goal.
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19
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Ramírez AS, Kowal J, Locher KP. Cryo–electron microscopy structures of human oligosaccharyltransferase complexes OST-A and OST-B. Science 2019; 366:1372-1375. [DOI: 10.1126/science.aaz3505] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2019] [Accepted: 11/13/2019] [Indexed: 12/22/2022]
Abstract
Oligosaccharyltransferase (OST) catalyzes the transfer of a high-mannose glycan onto secretory proteins in the endoplasmic reticulum. Mammals express two distinct OST complexes that act in a cotranslational (OST-A) or posttranslocational (OST-B) manner. Here, we present high-resolution cryo–electron microscopy structures of human OST-A and OST-B. Although they have similar overall architectures, structural differences in the catalytic subunits STT3A and STT3B facilitate contacts to distinct OST subunits, DC2 in OST-A and MAGT1 in OST-B. In OST-A, interactions with TMEM258 and STT3A allow ribophorin-I to form a four-helix bundle that can bind to a translating ribosome, whereas the equivalent region is disordered in OST-B. We observed an acceptor peptide and dolichylphosphate bound to STT3B, but only dolichylphosphate in STT3A, suggesting distinct affinities of the two OST complexes for protein substrates.
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Affiliation(s)
- Ana S. Ramírez
- Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule (ETH), CH-8093 Zürich, Switzerland
| | - Julia Kowal
- Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule (ETH), CH-8093 Zürich, Switzerland
| | - Kaspar P. Locher
- Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule (ETH), CH-8093 Zürich, Switzerland
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20
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21
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Cherepanova NA, Venev SV, Leszyk JD, Shaffer SA, Gilmore R. Quantitative glycoproteomics reveals new classes of STT3A- and STT3B-dependent N-glycosylation sites. J Cell Biol 2019; 218:2782-2796. [PMID: 31296534 PMCID: PMC6683751 DOI: 10.1083/jcb.201904004] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Revised: 06/13/2019] [Accepted: 06/18/2019] [Indexed: 11/24/2022] Open
Abstract
Cherepanova et al. provide quantitative glycoproteomic analyses of human cells that lack either the STT3A or STT3B oligosaccharyltransferase (OST) complex, revealing new classes of STT3A- and STT3B-dependent glycosylation sites and indicating how cooperation between the OST complexes maximizes acceptor site occupancy in cellular glycoproteins. Human cells express two oligosaccharyltransferase complexes (STT3A and STT3B) with partially overlapping functions. The STT3A complex interacts directly with the protein translocation channel to mediate cotranslational glycosylation, while the STT3B complex can catalyze posttranslocational glycosylation. We used a quantitative glycoproteomics procedure to compare glycosylation of roughly 1,000 acceptor sites in wild type and mutant cells. Analysis of site occupancy data disclosed several new classes of STT3A-dependent acceptor sites including those with suboptimal flanking sequences and sites located within cysteine-rich protein domains. Acceptor sites located in short loops of multi-spanning membrane proteins represent a new class of STT3B-dependent site. Remarkably, the lumenal ER chaperone GRP94 was hyperglycosylated in STT3A-deficient cells, bearing glycans on five silent sites in addition to the normal glycosylation site. GRP94 was also hyperglycosylated in wild-type cells treated with ER stress inducers including thapsigargin, dithiothreitol, and NGI-1.
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Affiliation(s)
- Natalia A Cherepanova
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA
| | - Sergey V Venev
- Program in Bioinformatics and Integrative Biology, University of Massachusetts Medical School, Worcester, MA
| | - John D Leszyk
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA.,Mass Spectrometry Facility, University of Massachusetts Medical School, Shrewsbury, MA
| | - Scott A Shaffer
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA.,Mass Spectrometry Facility, University of Massachusetts Medical School, Shrewsbury, MA
| | - Reid Gilmore
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA
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22
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Shrimal S, Gilmore R. Oligosaccharyltransferase structures provide novel insight into the mechanism of asparagine-linked glycosylation in prokaryotic and eukaryotic cells. Glycobiology 2019; 29:288-297. [PMID: 30312397 DOI: 10.1093/glycob/cwy093] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2018] [Revised: 09/26/2018] [Accepted: 10/09/2018] [Indexed: 11/12/2022] Open
Abstract
Asparagine-linked (N-linked) glycosylation is one of the most common protein modification reactions in eukaryotic cells, occurring upon the majority of proteins that enter the secretory pathway. X-ray crystal structures of the single subunit OSTs from eubacterial and archaebacterial organisms revealed the location of donor and acceptor substrate binding sites and provided the basis for a catalytic mechanism. Cryoelectron microscopy structures of the octameric yeast OST provided substantial insight into the organization and assembly of the multisubunit oligosaccharyltransferases. Furthermore, the cryoelectron microscopy structure of a complex consisting of a mammalian OST complex, the protein translocation channel and a translating ribosome revealed new insight into the mechanism of cotranslational glycosylation.
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Affiliation(s)
- Shiteshu Shrimal
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, 364 Plantation Street, Worcester, MA, USA
| | - Reid Gilmore
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, 364 Plantation Street, Worcester, MA, USA
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23
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Yamasaki T, Kohda D. A Radioisotope-free Oligosaccharyltransferase Assay Method. Bio Protoc 2019; 9:e3186. [PMID: 33654988 DOI: 10.21769/bioprotoc.3186] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Revised: 01/29/2019] [Accepted: 02/26/2019] [Indexed: 01/03/2023] Open
Abstract
Glycosylation of asparagine residues is widespread in Eukarya, and occurs in virtually all Archaea and some eubacterial species. A membrane-bound enzyme, oligosaccharyltransferase, catalyzes the transfer of an oligosaccharide chain from a sugar donor (lipid-linked oligosaccharide, LLO) to an asparagine residue in the consensus sequence, Asn-X-Ser/Thr (X ≠ Pro), in proteins. The in vitro oligosaccharyl transfer assay reaction mixture contains a detergent-solubilized oligosaccharyltransferase (OST), a sugar donor LLO, and a sugar acceptor peptide. Previous assay methods are problematic, in terms of the use of radioactive compounds and the cumbersome separation procedures using lectin binding or two-phase partitioning. Here, we describe a new oligosaccharyl transfer assay method, which is radioisotope-free and relies on a different separation mechanism. The glycopeptide products are separated from unreacted peptides by SDS-PAGE. A fluorescent dye is attached to the peptide substrate during custom peptide synthesis. The fluorescent imaging of the SDS-PAGE gels ensures high sensitivity and quantitative performance. The user-friendly PAGE format is particularly suitable for presentation in scientific papers. For illustrative applications, time-course and peptide library experiments are shown.
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Affiliation(s)
- Takahiro Yamasaki
- Division of Structural Biology, Medical Institute of Bioregulation, Kyushu University, Maidashi 3-1-1, Higashi-ku, Fukuoka 812-8582, Japan
| | - Daisuke Kohda
- Division of Structural Biology, Medical Institute of Bioregulation, Kyushu University, Maidashi 3-1-1, Higashi-ku, Fukuoka 812-8582, Japan
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24
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Caillava AJ, Ortiz GE, Melli LJ, Ugalde JE, Ciocchini AE, Comerci DJ. Improving bioreactor production of a recombinant glycoprotein in
Escherichia coli
: Effect of specific growth rate on protein glycosylation and specific productivity. Biotechnol Bioeng 2019; 116:1427-1438. [DOI: 10.1002/bit.26953] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2018] [Revised: 12/30/2018] [Accepted: 02/07/2019] [Indexed: 11/11/2022]
Affiliation(s)
- Ana J. Caillava
- Instituto de Investigaciones Biotecnológicas Dr. Rodolfo A. Ugalde, Instituto Tecnológico de Chascomús (IIB‐INTECH), Universidad Nacional de San Martín, CONICET, San MartínBuenos Aires Argentina
| | - Gastón E. Ortiz
- Instituto de Investigaciones Biotecnológicas Dr. Rodolfo A. Ugalde, Instituto Tecnológico de Chascomús (IIB‐INTECH), Universidad Nacional de San Martín, CONICET, San MartínBuenos Aires Argentina
| | - Luciano J. Melli
- Instituto de Investigaciones Biotecnológicas Dr. Rodolfo A. Ugalde, Instituto Tecnológico de Chascomús (IIB‐INTECH), Universidad Nacional de San Martín, CONICET, San MartínBuenos Aires Argentina
| | - Juan E. Ugalde
- Instituto de Investigaciones Biotecnológicas Dr. Rodolfo A. Ugalde, Instituto Tecnológico de Chascomús (IIB‐INTECH), Universidad Nacional de San Martín, CONICET, San MartínBuenos Aires Argentina
| | - Andrés E. Ciocchini
- Instituto de Investigaciones Biotecnológicas Dr. Rodolfo A. Ugalde, Instituto Tecnológico de Chascomús (IIB‐INTECH), Universidad Nacional de San Martín, CONICET, San MartínBuenos Aires Argentina
| | - Diego J. Comerci
- Instituto de Investigaciones Biotecnológicas Dr. Rodolfo A. Ugalde, Instituto Tecnológico de Chascomús (IIB‐INTECH), Universidad Nacional de San Martín, CONICET, San MartínBuenos Aires Argentina
- Comisión Nacional de Energía Atómica, Grupo Pecuario, Centro Atómico EzeizaBuenos Aires Argentina
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25
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Perez C, Mehdipour AR, Hummer G, Locher KP. Structure of Outward-Facing PglK and Molecular Dynamics of Lipid-Linked Oligosaccharide Recognition and Translocation. Structure 2019; 27:669-678.e5. [PMID: 30799077 DOI: 10.1016/j.str.2019.01.013] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Revised: 11/29/2018] [Accepted: 01/25/2019] [Indexed: 12/21/2022]
Abstract
PglK is a lipid-linked oligosaccharide (LLO) flippase essential for asparagine-linked protein glycosylation in Campylobacter jejuni. Previously we have proposed a non-alternating-access LLO translocation mechanism, where postulated outward-facing states play a primary role. To investigate this unusual mechanistic proposal, we have determined a high-resolution structure of PglK that displays an outward semi-occluded state with the two nucleotide binding domains forming an asymmetric closed dimer with two bound ATPγS molecules. Based on this structure, we performed extensive molecular dynamics simulations to investigate LLO recognition and flipping. Our results suggest that PglK may employ a "substrate-hunting" mechanism to locally increase the LLO concentration and facilitate its jump into the translocation pathway, for which sugars from the LLO head group are essential. We further conclude that the release of LLO to the outside occurs before ATP hydrolysis and is followed by the closing of the periplasmic cavity of PglK.
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Affiliation(s)
- Camilo Perez
- Department of Biology, Institute of Molecular Biology and Biophysics, ETH Zürich, 8093 Zürich, Switzerland; Biozentrum, University of Basel, 4056 Basel, Switzerland
| | - Ahmad Reza Mehdipour
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, 60438 Frankfurt am Main, Germany
| | - Gerhard Hummer
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, 60438 Frankfurt am Main, Germany; Institute of Biophysics, Goethe University Frankfurt, 60438 Frankfurt am Main, Germany.
| | - Kaspar P Locher
- Department of Biology, Institute of Molecular Biology and Biophysics, ETH Zürich, 8093 Zürich, Switzerland.
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26
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Jervis AJ, Wood AG, Cain JA, Butler JA, Frost H, Lord E, Langdon R, Cordwell SJ, Wren BW, Linton D. Functional analysis of the Helicobacter pullorum N-linked protein glycosylation system. Glycobiology 2018; 28:233-244. [PMID: 29340583 PMCID: PMC6025236 DOI: 10.1093/glycob/cwx110] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2017] [Accepted: 01/10/2018] [Indexed: 11/23/2022] Open
Abstract
N-linked protein glycosylation systems operate in species from all three domains of life. The model bacterial N-linked glycosylation system from Campylobacter jejuni is encoded by pgl genes present at a single chromosomal locus. This gene cluster includes the pglB oligosaccharyltransferase responsible for transfer of glycan from lipid carrier to protein. Although all genomes from species of the Campylobacter genus contain a pgl locus, among the related Helicobacter genus only three evolutionarily related species (H. pullorum, H. canadensis and H. winghamensis) potentially encode N-linked protein glycosylation systems. Helicobacter putative pgl genes are scattered in five chromosomal loci and include two putative oligosaccharyltransferase-encoding pglB genes per genome. We have previously demonstrated the in vitro N-linked glycosylation activity of H. pullorum resulting in transfer of a pentasaccharide to a peptide at asparagine within the sequon (D/E)XNXS/T. In this study, we identified the first H. pullorum N-linked glycoprotein, termed HgpA. Production of histidine-tagged HgpA in the background of insertional knockout mutants of H. pullorum pgl/wbp genes followed by analysis of HgpA glycan structures demonstrated the role of individual gene products in the PglB1-dependent N-linked protein glycosylation pathway. Glycopeptide purification by zwitterionic-hydrophilic interaction liquid chromatography coupled with tandem mass spectrometry identified six glycosites from five H. pullorum proteins, which was consistent with proteins reactive with a polyclonal antiserum generated against glycosylated HgpA. This study demonstrates functioning of a H. pullorum N-linked general protein glycosylation system.
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Affiliation(s)
- Adrian J Jervis
- Manchester Institute of Biotechnology, SYNBIOCHEM, University of Manchester, Manchester, UK
| | - Alison G Wood
- Department of Molecular Biology and Biotechnology, University of Sheffield, Sheffield S10 2TN, UK
| | - Joel A Cain
- School of Molecular Bioscience and Charles Perkins Centre, The University of Sydney, 2006Australia
| | - Jonathan A Butler
- School of Healthcare Science, Manchester Metropolitan University, Manchester M1 5GD, UK
| | - Helen Frost
- Faculty of Biology, Medicine and Health, Michael Smith Building, University of Manchester, Manchester M13 9PT, UK
| | - Elizabeth Lord
- Faculty of Biology, Medicine and Health, Michael Smith Building, University of Manchester, Manchester M13 9PT, UK
| | - Rebecca Langdon
- Pathogen Molecular Biology Unit, London School of Hygiene and Tropical Medicine, London WC1E 7HT, UK
| | - Stuart J Cordwell
- School of Molecular Bioscience and Charles Perkins Centre, The University of Sydney, 2006Australia
| | - Brendan W Wren
- Pathogen Molecular Biology Unit, London School of Hygiene and Tropical Medicine, London WC1E 7HT, UK
| | - Dennis Linton
- Faculty of Biology, Medicine and Health, Michael Smith Building, University of Manchester, Manchester M13 9PT, UK
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27
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Napiórkowska M, Boilevin J, Darbre T, Reymond JL, Locher KP. Structure of bacterial oligosaccharyltransferase PglB bound to a reactive LLO and an inhibitory peptide. Sci Rep 2018; 8:16297. [PMID: 30389987 PMCID: PMC6215017 DOI: 10.1038/s41598-018-34534-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2018] [Accepted: 10/15/2018] [Indexed: 12/12/2022] Open
Abstract
Oligosaccharyltransferase (OST) is a key enzyme of the N-glycosylation pathway, where it catalyzes the transfer of a glycan from a lipid-linked oligosaccharide (LLO) to an acceptor asparagine within the conserved sequon N-X-T/S. A previous structure of a ternary complex of bacterial single subunit OST, PglB, bound to a non-hydrolyzable LLO analog and a wild type acceptor peptide showed how both substrates bind and how an external loop (EL5) of the enzyme provided specific substrate-binding contacts. However, there was a relatively large separation of the substrates at the active site. Here we present the X-ray structure of PglB bound to a reactive LLO analog and an inhibitory peptide, revealing previously unobserved interactions in the active site. We found that the atoms forming the N-glycosidic bond (C-1 of the GlcNAc moiety of LLO and the –NH2 group of the peptide) are closer than in the previous structure, suggesting that we have captured a conformation closer to the transition state of the reaction. We find that the distance between the divalent metal ion and the glycosidic oxygen of LLO is now 4 Å, suggesting that the metal stabilizes the leaving group of the nucleophilic substitution reaction. Further, the carboxylate group of a conserved aspartate of PglB mediates an interaction network between the reducing-end sugar of the LLO, the asparagine side chain of the acceptor peptide, and a bound divalent metal ion. The interactions identified in this novel state are likely to be relevant in the catalytic mechanisms of all OSTs.
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Affiliation(s)
- Maja Napiórkowska
- Institute of Molecular Biology and Biophysics, ETH Zurich, Zurich, Switzerland
| | - Jérémy Boilevin
- Department of Chemistry and Biochemistry, University of Bern, Bern, Switzerland
| | - Tamis Darbre
- Department of Chemistry and Biochemistry, University of Bern, Bern, Switzerland
| | - Jean-Louis Reymond
- Department of Chemistry and Biochemistry, University of Bern, Bern, Switzerland
| | - Kaspar P Locher
- Institute of Molecular Biology and Biophysics, ETH Zurich, Zurich, Switzerland.
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28
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Abstract
Glycosylation is one of the most prevalent posttranslational modifications that profoundly affects the structure and functions of proteins in a wide variety of biological recognition events. However, the structural complexity and heterogeneity of glycoproteins, usually resulting from the variations of glycan components and/or the sites of glycosylation, often complicates detailed structure-function relationship studies and hampers the therapeutic applications of glycoproteins. To address these challenges, various chemical and biological strategies have been developed for producing glycan-defined homogeneous glycoproteins. This review highlights recent advances in the development of chemoenzymatic methods for synthesizing homogeneous glycoproteins, including the generation of various glycosynthases for synthetic purposes, endoglycosidase-catalyzed glycoprotein synthesis and glycan remodeling, and direct enzymatic glycosylation of polypeptides and proteins. The scope, limitation, and future directions of each method are discussed.
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Affiliation(s)
- Chao Li
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, United States
| | - Lai-Xi Wang
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, United States
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29
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Metabolic engineering of glycoprotein biosynthesis in bacteria. Emerg Top Life Sci 2018; 2:419-432. [PMID: 33525794 DOI: 10.1042/etls20180004] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2018] [Revised: 07/12/2018] [Accepted: 08/06/2018] [Indexed: 02/07/2023]
Abstract
The demonstration more than a decade ago that glycoproteins could be produced in Escherichia coli cells equipped with the N-linked protein glycosylation machinery from Campylobacter jejuni opened the door to using simple bacteria for the expression and engineering of complex glycoproteins. Since that time, metabolic engineering has played an increasingly important role in developing and optimizing microbial cell glyco-factories for the production of diverse glycoproteins and other glycoconjugates. It is becoming clear that future progress in creating efficient glycoprotein expression platforms in bacteria will depend on the adoption of advanced strain engineering strategies such as rational design and assembly of orthogonal glycosylation pathways, genome-wide identification of metabolic engineering targets, and evolutionary engineering of pathway performance. Here, we highlight recent advances in the deployment of metabolic engineering tools and strategies to develop microbial cell glyco-factories for the production of high-value glycoprotein targets with applications in research and medicine.
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30
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Corfield AP. The Interaction of the Gut Microbiota with the Mucus Barrier in Health and Disease in Human. Microorganisms 2018; 6:microorganisms6030078. [PMID: 30072673 PMCID: PMC6163557 DOI: 10.3390/microorganisms6030078] [Citation(s) in RCA: 81] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2018] [Revised: 07/25/2018] [Accepted: 07/30/2018] [Indexed: 02/07/2023] Open
Abstract
Glycoproteins are major players in the mucus protective barrier in the gastrointestinal and other mucosal surfaces. In particular the mucus glycoproteins, or mucins, are responsible for the protective gel barrier. They are characterized by their high carbohydrate content, present in their variable number, tandem repeat domains. Throughout evolution the mucins have been maintained as integral components of the mucosal barrier, emphasizing their essential biological status. The glycosylation of the mucins is achieved through a series of biosynthetic pathways processes, which generate the wide range of glycans found in these molecules. Thus mucins are decorated with molecules having information in the form of a glycocode. The enteric microbiota interacts with the mucosal mucus barrier in a variety of ways in order to fulfill its many normal processes. How bacteria read the glycocode and link to normal and pathological processes is outlined in the review.
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Affiliation(s)
- Anthony P Corfield
- Mucin Research Group, School of Clinical Sciences, Bristol Royal Infirmary, Level 7, Marlborough Street, Bristol BS2 8HW, UK.
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31
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Ramírez AS, Boilevin J, Biswas R, Gan BH, Janser D, Aebi M, Darbre T, Reymond JL, Locher KP. Characterization of the single-subunit oligosaccharyltransferase STT3A from Trypanosoma brucei using synthetic peptides and lipid-linked oligosaccharide analogs. Glycobiology 2018; 27:525-535. [PMID: 28204532 PMCID: PMC5421464 DOI: 10.1093/glycob/cwx017] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2017] [Accepted: 02/10/2017] [Indexed: 01/11/2023] Open
Abstract
The initial transfer of a complex glycan in protein N-glycosylation is catalyzed by oligosaccharyltransferase (OST), which is generally a multisubunit membrane protein complex in the endoplasmic reticulum but a single-subunit enzyme (ssOST) in some protists. To investigate the reaction mechanism of ssOST, we recombinantly expressed, purified and characterized the STT3A protein from Trypanosoma brucei (TbSTT3A). We analyzed the in vitro activity of TbSTT3A by synthesizing fluorescently labeled acceptor peptides as well as lipid-linked oligosaccharide (LLO) analogs containing a chitobiose moiety coupled to oligoprenyl carriers of distinct lengths (C10, C15, C20 and C25) and with different double bond stereochemistry. We found that in addition to proline, charged residues at the +1 position of the sequon inhibited glycan transfer. An acidic residue at the −2 position significantly increased catalytic turnover but was not essential, in contrast to the bacterial OST. While all synthetic LLO analogs were processed by TbSTT3A, the length of the polyprenyl tail, but not the stereochemistry of the double bonds, determined their apparent affinity. We also synthesized phosphonate analogs of the LLOs, which were found to be competitive inhibitors of the reaction, although with lower apparent affinity to TbSTT3A than the active pyrophosphate analogs.
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Affiliation(s)
- Ana S Ramírez
- Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule (ETH), CH-8093 Zürich, Switzerland
| | - Jérémy Boilevin
- Department of Chemistry and Biochemistry, University of Berne, CH-3012 Berne, Switzerland
| | - Rasomoy Biswas
- Department of Chemistry and Biochemistry, University of Berne, CH-3012 Berne, Switzerland
| | - Bee Ha Gan
- Department of Chemistry and Biochemistry, University of Berne, CH-3012 Berne, Switzerland
| | - Daniel Janser
- Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule (ETH), CH-8093 Zürich, Switzerland
| | - Markus Aebi
- Institute of Microbiology, Eidgenössische Technische Hochschule (ETH), CH-8093 Zürich, Switzerland
| | - Tamis Darbre
- Department of Chemistry and Biochemistry, University of Berne, CH-3012 Berne, Switzerland
| | - Jean-Louis Reymond
- Department of Chemistry and Biochemistry, University of Berne, CH-3012 Berne, Switzerland
| | - Kaspar P Locher
- Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule (ETH), CH-8093 Zürich, Switzerland
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32
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Ramírez AS, Boilevin J, Mehdipour AR, Hummer G, Darbre T, Reymond JL, Locher KP. Structural basis of the molecular ruler mechanism of a bacterial glycosyltransferase. Nat Commun 2018; 9:445. [PMID: 29386647 PMCID: PMC5792488 DOI: 10.1038/s41467-018-02880-2] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2017] [Accepted: 01/02/2018] [Indexed: 11/09/2022] Open
Abstract
The membrane-associated, processive and retaining glycosyltransferase PglH from Campylobacter jejuni is part of the biosynthetic pathway of the lipid-linked oligosaccharide (LLO) that serves as the glycan donor in bacterial protein N-glycosylation. Using an unknown counting mechanism, PglH catalyzes the transfer of exactly three α1,4 N-acetylgalactosamine (GalNAc) units to the growing LLO precursor, GalNAc-α1,4-GalNAc-α1,3-Bac-α1-PP-undecaprenyl. Here, we present crystal structures of PglH in three distinct states, including a binary complex with UDP-GalNAc and two ternary complexes containing a chemo-enzymatically generated LLO analog and either UDP or synthetic, nonhydrolyzable UDP-CH2-GalNAc. PglH contains an amphipathic helix ("ruler helix") that has a dual role of facilitating membrane attachment and glycan counting. The ruler helix contains three positively charged side chains that can bind the pyrophosphate group of the LLO substrate and thus limit the addition of GalNAc units to three. These results, combined with molecular dynamics simulations, provide the mechanism of glycan counting by PglH.
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Affiliation(s)
- Ana S Ramírez
- Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule (ETH), CH-8093, Zürich, Switzerland
| | - Jérémy Boilevin
- Department of Chemistry and Biochemistry, University of Berne, CH-3012, Berne, Switzerland
| | - Ahmad Reza Mehdipour
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, DE-60438, Frankfurt, Germany
| | - Gerhard Hummer
- Department of Theoretical Biophysics, Max Planck Institute of Biophysics, DE-60438, Frankfurt, Germany.,Institute of Biophysics, Goethe University, DE-60438, Frankfurt, Germany
| | - Tamis Darbre
- Department of Chemistry and Biochemistry, University of Berne, CH-3012, Berne, Switzerland
| | - Jean-Louis Reymond
- Department of Chemistry and Biochemistry, University of Berne, CH-3012, Berne, Switzerland
| | - Kaspar P Locher
- Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule (ETH), CH-8093, Zürich, Switzerland.
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33
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Wild R, Kowal J, Eyring J, Ngwa EM, Aebi M, Locher KP. Structure of the yeast oligosaccharyltransferase complex gives insight into eukaryotic N-glycosylation. Science 2018; 359:545-550. [PMID: 29301962 DOI: 10.1126/science.aar5140] [Citation(s) in RCA: 135] [Impact Index Per Article: 22.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2017] [Accepted: 12/22/2017] [Indexed: 12/18/2022]
Abstract
Oligosaccharyltransferase (OST) is an essential membrane protein complex in the endoplasmic reticulum, where it transfers an oligosaccharide from a dolichol-pyrophosphate-activated donor to glycosylation sites of secretory proteins. Here we describe the atomic structure of yeast OST determined by cryo-electron microscopy, revealing a conserved subunit arrangement. The active site of the catalytic STT3 subunit points away from the center of the complex, allowing unhindered access to substrates. The dolichol-pyrophosphate moiety binds to a lipid-exposed groove of STT3, whereas two noncatalytic subunits and an ordered N-glycan form a membrane-proximal pocket for the oligosaccharide. The acceptor polypeptide site faces an oxidoreductase domain in stand-alone OST complexes or is immediately adjacent to the translocon, suggesting how eukaryotic OSTs efficiently glycosylate a large number of polypeptides before their folding.
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Affiliation(s)
- Rebekka Wild
- Institute of Molecular Biology and Biophysics, Department of Biology, ETH Zurich, CH-8093 Zurich, Switzerland
| | - Julia Kowal
- Institute of Molecular Biology and Biophysics, Department of Biology, ETH Zurich, CH-8093 Zurich, Switzerland
| | - Jillianne Eyring
- Institute of Microbiology, Department of Biology, ETH Zurich, CH-8093 Zurich, Switzerland
| | - Elsy M Ngwa
- Institute of Microbiology, Department of Biology, ETH Zurich, CH-8093 Zurich, Switzerland
| | - Markus Aebi
- Institute of Microbiology, Department of Biology, ETH Zurich, CH-8093 Zurich, Switzerland.
| | - Kaspar P Locher
- Institute of Molecular Biology and Biophysics, Department of Biology, ETH Zurich, CH-8093 Zurich, Switzerland.
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34
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Kohda D. Structural Basis of Protein Asn-Glycosylation by Oligosaccharyltransferases. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2018; 1104:171-199. [PMID: 30484249 DOI: 10.1007/978-981-13-2158-0_9] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/04/2022]
Abstract
Glycosylation of asparagine residues is a ubiquitous protein modification. This N-glycosylation is essential in Eukaryotes, but principally nonessential in Prokaryotes (Archaea and Eubacteria), although it facilitates their survival and pathogenicity. In many reviews, Archaea have received far less attention than Eubacteria, but this review will cover the N-glycosylation in the three domains of life. The oligosaccharide chain is preassembled on a lipid-phospho carrier to form a donor substrate, lipid-linked oligosaccharide (LLO). The en bloc transfer of an oligosaccharide from LLO to selected Asn residues in the Asn-X-Ser/Thr (X≠Pro) sequons in a polypeptide chain is catalyzed by a membrane-bound enzyme, oligosaccharyltransferase (OST). Over the last 10 years, the three-dimensional structures of the catalytic subunits of the Stt3/AglB/PglB proteins, with an acceptor peptide and a donor LLO, have been determined by X-ray crystallography, and recently the complex structures with other subunits have been determined by cryo-electron microscopy . Structural comparisons within the same species and across the different domains of life yielded a unified view of the structures and functions of OSTs. A catalytic structure in the TM region accounts for the amide bond twisting, which increases the reactivity of the side-chain nitrogen atom of the acceptor Asn residue in the sequon. The Ser/Thr-binding pocket in the C-terminal domain explains the requirement for hydroxy amino acid residues in the sequon. As expected, the two functional structures are formed by the involvement of short amino acid motifs conserved across the three domains of life.
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Affiliation(s)
- Daisuke Kohda
- Division of Structural Biology, Medical Institute of Bioregulation, Kyushu University, Fukuoka, Japan.
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35
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Schoborg JA, Hershewe JM, Stark JC, Kightlinger W, Kath JE, Jaroentomeechai T, Natarajan A, DeLisa MP, Jewett MC. A cell-free platform for rapid synthesis and testing of active oligosaccharyltransferases. Biotechnol Bioeng 2017; 115:739-750. [PMID: 29178580 DOI: 10.1002/bit.26502] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2017] [Revised: 11/15/2017] [Accepted: 11/20/2017] [Indexed: 12/17/2022]
Abstract
Protein glycosylation, or the attachment of sugar moieties (glycans) to proteins, is important for protein stability, activity, and immunogenicity. However, understanding the roles and regulations of site-specific glycosylation events remains a significant challenge due to several technological limitations. These limitations include a lack of available tools for biochemical characterization of enzymes involved in glycosylation. A particular challenge is the synthesis of oligosaccharyltransferases (OSTs), which catalyze the attachment of glycans to specific amino acid residues in target proteins. The difficulty arises from the fact that canonical OSTs are large (>70 kDa) and possess multiple transmembrane helices, making them difficult to overexpress in living cells. Here, we address this challenge by establishing a bacterial cell-free protein synthesis platform that enables rapid production of a variety of OSTs in their active conformations. Specifically, by using lipid nanodiscs as cellular membrane mimics, we obtained yields of up to 420 μg/ml for the single-subunit OST enzyme, "Protein glycosylation B" (PglB) from Campylobacter jejuni, as well as for three additional PglB homologs from Campylobacter coli, Campylobacter lari, and Desulfovibrio gigas. Importantly, all of these enzymes catalyzed N-glycosylation reactions in vitro with no purification or processing needed. Furthermore, we demonstrate the ability of cell-free synthesized OSTs to glycosylate multiple target proteins with varying N-glycosylation acceptor sequons. We anticipate that this broadly applicable production method will advance glycoengineering efforts by enabling preparative expression of membrane-embedded OSTs from all kingdoms of life.
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Affiliation(s)
- Jennifer A Schoborg
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, Illinois.,Chemistry of Life Processes Institute, Evanston, Illinois
| | - Jasmine M Hershewe
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, Illinois.,Chemistry of Life Processes Institute, Evanston, Illinois.,Master of Biotechnology Program, Northwestern University, Evanston, Illinois
| | - Jessica C Stark
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, Illinois.,Chemistry of Life Processes Institute, Evanston, Illinois
| | - Weston Kightlinger
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, Illinois.,Chemistry of Life Processes Institute, Evanston, Illinois
| | - James E Kath
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, Illinois.,Chemistry of Life Processes Institute, Evanston, Illinois
| | - Thapakorn Jaroentomeechai
- Robert Frederick Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York
| | | | - Matthew P DeLisa
- Robert Frederick Smith School of Chemical and Biomolecular Engineering, Cornell University, Ithaca, New York.,Department of Microbiology, Cornell University, Ithaca, New York
| | - Michael C Jewett
- Department of Chemical and Biological Engineering, Northwestern University, Evanston, Illinois.,Chemistry of Life Processes Institute, Evanston, Illinois.,Master of Biotechnology Program, Northwestern University, Evanston, Illinois.,Robert H. Lurie Comprehensive Cancer Center, Northwestern University, Chicago, Illinois.,Simpson Querrey Institute, Northwestern University, Chicago, Illinois.,Center for Synthetic Biology, Northwestern University, Evanston, Illinois
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36
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Dutta D, Mandal C, Mandal C. Unusual glycosylation of proteins: Beyond the universal sequon and other amino acids. Biochim Biophys Acta Gen Subj 2017; 1861:3096-3108. [DOI: 10.1016/j.bbagen.2017.08.025] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2017] [Revised: 08/03/2017] [Accepted: 08/14/2017] [Indexed: 12/11/2022]
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37
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Napiórkowska M, Boilevin J, Sovdat T, Darbre T, Reymond JL, Aebi M, Locher KP. Molecular basis of lipid-linked oligosaccharide recognition and processing by bacterial oligosaccharyltransferase. Nat Struct Mol Biol 2017; 24:1100-1106. [PMID: 29058712 DOI: 10.1038/nsmb.3491] [Citation(s) in RCA: 61] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2017] [Accepted: 09/21/2017] [Indexed: 11/09/2022]
Abstract
Oligosaccharyltransferase (OST) is a membrane-integral enzyme that catalyzes the transfer of glycans from lipid-linked oligosaccharides (LLOs) onto asparagine side chains, the first step in protein N-glycosylation. Here, we report the X-ray structure of a single-subunit OST, PglB from Campylobacter lari, trapped in an intermediate state bound to an acceptor peptide and a synthetic LLO analog. The structure reveals the role of the external loop EL5, present in all OST enzymes, in substrate recognition. Whereas the N-terminal half of EL5 binds LLO, the C-terminal half interacts with the acceptor peptide. The glycan moiety of LLO must thread under EL5 to access the active site. Reducing EL5 mobility decreases the catalytic rate of OST when full-size heptasaccharide LLO is provided, but not for a monosaccharide-containing LLO analog. Our results define the chemistry of a ternary complex state, assign functional roles to conserved OST motifs, and provide opportunities for glycoengineering by rational design of PglB.
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Affiliation(s)
- Maja Napiórkowska
- Institute of Molecular Biology and Biophysics, ETH Zurich, Zurich, Switzerland
| | - Jérémy Boilevin
- Department of Chemistry and Biochemistry, University of Berne, Berne, Switzerland
| | - Tina Sovdat
- Department of Chemistry and Biochemistry, University of Berne, Berne, Switzerland
| | - Tamis Darbre
- Department of Chemistry and Biochemistry, University of Berne, Berne, Switzerland
| | - Jean-Louis Reymond
- Department of Chemistry and Biochemistry, University of Berne, Berne, Switzerland
| | - Markus Aebi
- Institute of Microbiology, ETH Zurich, Zurich, Switzerland
| | - Kaspar P Locher
- Institute of Molecular Biology and Biophysics, ETH Zurich, Zurich, Switzerland
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38
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Shrimal S, Cherepanova NA, Gilmore R. DC2 and KCP2 mediate the interaction between the oligosaccharyltransferase and the ER translocon. J Cell Biol 2017; 216:3625-3638. [PMID: 28860277 PMCID: PMC5674889 DOI: 10.1083/jcb.201702159] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Revised: 06/29/2017] [Accepted: 07/27/2017] [Indexed: 12/21/2022] Open
Abstract
The STT3A isoform of the oligosaccharyltransferase is adjacent to the protein translocation channel to catalyze co-translational N-glycosylation of proteins in the endoplasmic reticulum. Shrimal et al. show that the DC2 and KCP2 subunits of the STT3A isoform of the oligosaccharyltransferase are responsible for mediating the interaction between the STT3A complex and the protein translocation channel to allow co-translational N-glycosylation of proteins. In metazoan organisms, the STT3A isoform of the oligosaccharyltransferase is localized adjacent to the protein translocation channel to catalyze co-translational N-linked glycosylation of proteins in the endoplasmic reticulum. The mechanism responsible for the interaction between the STT3A complex and the translocation channel has not been addressed. Using genetically modified human cells that are deficient in DC2 or KCP2 proteins, we show that loss of DC2 causes a defect in co-translational N-glycosylation of proteins that mimics an STT3A−/− phenotype. Biochemical analysis showed that DC2 and KCP2 are responsible for mediating the interaction between the protein translocation channel and the STT3A complex. Importantly, DC2- and KCP2-deficient STT3A complexes are stable and enzymatically active. Deletion mutagenesis revealed that a conserved motif in the C-terminal tail of DC2 is critical for assembly into the STT3A complex, whereas the lumenal loop and the N-terminal cytoplasmic segment are necessary for the functional interaction between the STT3A and Sec61 complexes.
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Affiliation(s)
- Shiteshu Shrimal
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA
| | - Natalia A Cherepanova
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA
| | - Reid Gilmore
- Department of Biochemistry and Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA
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Ramírez AS, Boilevin J, Lin CW, Ha Gan B, Janser D, Aebi M, Darbre T, Reymond JL, Locher KP. Chemo-enzymatic synthesis of lipid-linked GlcNAc2Man5 oligosaccharides using recombinant Alg1, Alg2 and Alg11 proteins. Glycobiology 2017; 27:726-733. [PMID: 28575298 PMCID: PMC5881667 DOI: 10.1093/glycob/cwx045] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2017] [Revised: 05/10/2017] [Accepted: 05/27/2017] [Indexed: 11/14/2022] Open
Abstract
The biosynthesis of eukaryotic lipid-linked oligosaccharides (LLOs) that act as donor substrates in eukaryotic protein N-glycosylation starts on the cytoplasmic side of the endoplasmic reticulum and includes the sequential addition of five mannose units to dolichol-pyrophosphate-GlcNAc2. These reactions are catalyzed by the Alg1, Alg2 and Alg11 gene products and yield Dol-PP-GlcNAc2Man5, an LLO intermediate that is subsequently flipped to the lumen of the endoplasmic reticulum. While the purification of active Alg1 has previously been described, Alg11 and Alg2 have been mostly studied in vivo. We here describe the expression and purification of functional, full length Alg2 protein. Along with the purified soluble domains Alg1 and Alg11, we used Alg2 to chemo-enzymatically generate Dol-PP-GlcNAc2Man5 analogs starting from synthetic LLOs containing a chitobiose moiety coupled to oligoprenyl carriers of distinct lengths (C10, C15, C20 and C25). We found that while the addition of the first mannose unit by Alg1 was successful with all of the LLO molecules, the Alg2-catalyzed reaction was only efficient if the acceptor LLOs contained a sufficiently long lipid tail of four or five isoprenyl units (C20 and C25). Following conversion with Alg11, the resulting C20 or C25 -containing GlcNAc2Man5 LLO analogs were successfully used as donor substrates of purified single-subunit oligosaccharyltransferase STT3A from Trypanosoma brucei. Our results provide a chemo-enzymatic method for the generation of eukaryotic LLO analogs and are the basis of subsequent mechanistic studies of the enigmatic Alg2 reaction mechanism.
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Affiliation(s)
- Ana S Ramírez
- Department of Biology, Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule (ETH), Schafmattstrasse 20, CH-8093 Zürich, Switzerland
| | - Jérémy Boilevin
- Department of Chemistry and Biochemistry, University of Berne, CH-3012 Berne, Switzerland
| | - Chia-Wei Lin
- Institute of Microbiology, Eidgenössische Technische Hochschule (ETH), CH-8093 Zürich, Switzerland
| | - Bee Ha Gan
- Department of Chemistry and Biochemistry, University of Berne, CH-3012 Berne, Switzerland
| | - Daniel Janser
- Department of Biology, Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule (ETH), Schafmattstrasse 20, CH-8093 Zürich, Switzerland
| | - Markus Aebi
- Institute of Microbiology, Eidgenössische Technische Hochschule (ETH), CH-8093 Zürich, Switzerland
| | - Tamis Darbre
- Department of Chemistry and Biochemistry, University of Berne, CH-3012 Berne, Switzerland
| | - Jean-Louis Reymond
- Department of Chemistry and Biochemistry, University of Berne, CH-3012 Berne, Switzerland
| | - Kaspar P Locher
- Department of Biology, Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule (ETH), Schafmattstrasse 20, CH-8093 Zürich, Switzerland
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Structural basis of inhibition of lipid-linked oligosaccharide flippase PglK by a conformational nanobody. Sci Rep 2017; 7:46641. [PMID: 28422165 PMCID: PMC5395944 DOI: 10.1038/srep46641] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2017] [Accepted: 03/21/2017] [Indexed: 12/16/2022] Open
Abstract
PglK is an ABC transporter that flips a lipid-linked oligosaccharide (LLO) that serves as a donor in protein N-glycosylation. Previous structures revealed two inward-facing conformations, both with very large separations of the nucleotide binding domains (NBDs), and a closed, ADP-bound state that featured an occluded cavity. To investigate additional states, we developed conformation-sensitive, single-domain camelid nanobodies (Nb) and studied their effect on PglK activity. Biochemical, structural, and mass spectrometric analyses revealed that one inhibitory Nb binds as a single copy to homodimeric PglK. The co-crystal structure of this Nb and ADP-bound PglK revealed a new, narrowly inward-open conformation. Rather than inducing asymmetry in the PglK homodimer, the binding of one Nb results in steric constraints that prevent a second Nb to access the symmetry-related site in PglK. The Nb performed its inhibitory role by a “sticky-doorstop” mechanism, where inhibition of ATP hydrolysis and LLO flipping activity occurs due to impaired closing of the NBD interface, which prevents PglK from converting to an outward-open conformation. This inhibitory mode suggests tight conformational coupling between the ATPase sites, which may apply to other ABC transporters.
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41
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Song Q, Wu Z, Fan Y, Song W, Zhang P, Wang L, Wang F, Xu Y, Wang PG, Cheng J. Production of homogeneous glycoprotein with multisite modifications by an engineered N-glycosyltransferase mutant. J Biol Chem 2017; 292:8856-8863. [PMID: 28381551 DOI: 10.1074/jbc.m117.777383] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2017] [Revised: 04/04/2017] [Indexed: 12/26/2022] Open
Abstract
Naturally occurring N-glycoproteins exhibit glycoform heterogeneity with respect to N-glycan sequon occupancy (macroheterogeneity) and glycan structure (microheterogeneity). However, access to well-defined glycoproteins is always important for both basic research and therapeutic purposes. As a result, there has been a substantial effort to identify and understand the catalytic properties of N-glycosyltransferases, enzymes that install the first glycan on the protein chain. In this study we found that ApNGT, a newly discovered cytoplasmic N-glycosyltransferase from Actinobacillus pleuropneumoniae, has strict selectivity toward the residues around the Asn of N-glycosylation sequon by screening a small library of synthetic peptides. The inherent stringency was subsequently demonstrated to be closely associated with a critical residue (Gln-469) of ApNGT which we propose hinders the access of bulky residues surrounding the occupied Asn into the active site. Site-saturated mutagenesis revealed that the introduction of small hydrophobic residues at the site cannot only weaken the stringency of ApNGT but can also contribute to enormous improvement of glycosylation efficiency against both short peptides and proteins. We then employed the most efficient mutant (Q469A) other than the wild-type ApNGT to produce a homogeneous glycoprotein carrying multiple (up to 10) N-glycans, demonstrating that this construct is a promising biocatalyst for potentially addressing the issue of macroheterogeneity in glycoprotein preparation.
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Affiliation(s)
- Qitao Song
- From the State Key Laboratory of Medicinal Chemical Biology and College of Pharmacy, Nankai University, Haihe Education Park, 38 Tongyan Road, Tianjin 300353, China and
| | - Zhigang Wu
- the Department of Chemistry, Georgia State University, Atlanta, Georgia 30303
| | - Yueyuan Fan
- From the State Key Laboratory of Medicinal Chemical Biology and College of Pharmacy, Nankai University, Haihe Education Park, 38 Tongyan Road, Tianjin 300353, China and
| | - Woran Song
- From the State Key Laboratory of Medicinal Chemical Biology and College of Pharmacy, Nankai University, Haihe Education Park, 38 Tongyan Road, Tianjin 300353, China and
| | - Peiru Zhang
- From the State Key Laboratory of Medicinal Chemical Biology and College of Pharmacy, Nankai University, Haihe Education Park, 38 Tongyan Road, Tianjin 300353, China and
| | - Li Wang
- From the State Key Laboratory of Medicinal Chemical Biology and College of Pharmacy, Nankai University, Haihe Education Park, 38 Tongyan Road, Tianjin 300353, China and
| | - Faxing Wang
- From the State Key Laboratory of Medicinal Chemical Biology and College of Pharmacy, Nankai University, Haihe Education Park, 38 Tongyan Road, Tianjin 300353, China and
| | - Yangyang Xu
- From the State Key Laboratory of Medicinal Chemical Biology and College of Pharmacy, Nankai University, Haihe Education Park, 38 Tongyan Road, Tianjin 300353, China and
| | - Peng G Wang
- From the State Key Laboratory of Medicinal Chemical Biology and College of Pharmacy, Nankai University, Haihe Education Park, 38 Tongyan Road, Tianjin 300353, China and
| | - Jiansong Cheng
- From the State Key Laboratory of Medicinal Chemical Biology and College of Pharmacy, Nankai University, Haihe Education Park, 38 Tongyan Road, Tianjin 300353, China and
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Increased glycosylation efficiency of recombinant proteins in Escherichia coli by auto-induction. Biochem Biophys Res Commun 2017; 485:138-143. [DOI: 10.1016/j.bbrc.2017.02.037] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Accepted: 02/07/2017] [Indexed: 01/30/2023]
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43
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Matsumoto S, Taguchi Y, Shimada A, Igura M, Kohda D. Tethering an N-Glycosylation Sequon-Containing Peptide Creates a Catalytically Competent Oligosaccharyltransferase Complex. Biochemistry 2017; 56:602-611. [PMID: 27997792 DOI: 10.1021/acs.biochem.6b01089] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
Oligosaccharyltransferase (OST) transfers an oligosaccharide chain to the Asn residue in the Asn-X-Ser/Thr sequon in proteins, where X is not proline. A sequon was tethered to an archaeal OST enzyme via a disulfide bond. The positions of the cysteine residues in the OST protein and the sequon-containing acceptor peptide were selected by reference to the eubacterial OST structure in a noncovalent complex with an acceptor peptide. We determined the crystal structure of the cross-linked OST-sequon complex. The Ser/Thr-binding pocket recognizes the Thr residue in the sequon, and the catalytic structure termed the "carboxylate dyad" interacted with the Asn residue. Thus, the recognition and the catalytic mechanism of the sequon are conserved between the archaeal and eubacterial OSTs. We found that the tethered peptides in the complex were efficiently glycosylated in the presence of the oligosaccharide donor. The stringent requirements are greatly relaxed in the cross-linked state. The two conserved acidic residues in the catalytic structure were each dispensable, although the double mutation abolished the activity. A Gln residue at the Asn position in the sequon functioned as an acceptor, and the hydroxy group at position +2 was not required. In the standard assay using short free peptides, strong amino acid preferences were observed at the X position, but the preferences, except for Pro, completely disappeared in the cross-linked state. By skipping the initial binding process and stabilizing the complex state, the catalytically competent cross-linked complex offers a unique system for studying the oligosaccharyl transfer reaction.
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Affiliation(s)
- Shunsuke Matsumoto
- Division of Structural Biology, Medical Institute of Bioregulation, ‡Research Center for Advanced Immunology, and §Research Center for Live-Protein Dynamics, Kyushu University , Maidashi 3-1-1, Higashi-ku, Fukuoka 812-8582, Japan
| | - Yuya Taguchi
- Division of Structural Biology, Medical Institute of Bioregulation, ‡Research Center for Advanced Immunology, and §Research Center for Live-Protein Dynamics, Kyushu University , Maidashi 3-1-1, Higashi-ku, Fukuoka 812-8582, Japan
| | - Atsushi Shimada
- Division of Structural Biology, Medical Institute of Bioregulation, ‡Research Center for Advanced Immunology, and §Research Center for Live-Protein Dynamics, Kyushu University , Maidashi 3-1-1, Higashi-ku, Fukuoka 812-8582, Japan
| | - Mayumi Igura
- Division of Structural Biology, Medical Institute of Bioregulation, ‡Research Center for Advanced Immunology, and §Research Center for Live-Protein Dynamics, Kyushu University , Maidashi 3-1-1, Higashi-ku, Fukuoka 812-8582, Japan
| | - Daisuke Kohda
- Division of Structural Biology, Medical Institute of Bioregulation, ‡Research Center for Advanced Immunology, and §Research Center for Live-Protein Dynamics, Kyushu University , Maidashi 3-1-1, Higashi-ku, Fukuoka 812-8582, Japan
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44
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Abstract
The glycosylation systems of Campylobacter jejuni (C. jejuni) are considered archetypal examples of both N- and O-linked glycosylations in the field of bacterial glycosylation. The discovery and characterization of these systems both have revealed important biological insight into C. jejuni and have led to the refinement and enhancement of methodologies to characterize bacterial glycosylation. In general, mass spectrometry-based characterization has become the preferred methodology for the study of C. jejuni glycosylation because of its speed, sensitivity, and ability to enable both qualitative and quantitative assessments of glycosylation events. In these experiments the generation of insightful data requires the careful selection of experimental approaches and mass spectrometry (MS) instrumentation. As such, it is essential to have a deep understanding of the technologies and approaches used for characterization of glycosylation events. Here we describe protocols for the initial characterization of C. jejuni glycoproteins using protein-/peptide-centric approaches and discuss considerations that can enhance the generation of insightful data.
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Affiliation(s)
- Nichollas E Scott
- Department of Microbiology and Immunology, Doherty Institute, The University of Melbourne, 792 Elizabeth St., Melbourne, Victoria, 3001, Australia.
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45
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Diversification in the HIV-1 Envelope Hyper-variable Domains V2, V4, and V5 and Higher Probability of Transmitted/Founder Envelope Glycosylation Favor the Development of Heterologous Neutralization Breadth. PLoS Pathog 2016; 12:e1005989. [PMID: 27851829 PMCID: PMC5112890 DOI: 10.1371/journal.ppat.1005989] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Accepted: 10/11/2016] [Indexed: 11/19/2022] Open
Abstract
A recent study of plasma neutralization breadth in HIV-1 infected individuals at nine International AIDS Vaccine Initiative (IAVI) sites reported that viral load, HLA-A*03 genotype, and subtype C infection were strongly associated with the development of neutralization breadth. Here, we refine the findings of that study by analyzing the impact of the transmitted/founder (T/F) envelope (Env), early Env diversification, and autologous neutralization on the development of plasma neutralization breadth in 21 participants identified during recent infection at two of those sites: Kigali, Rwanda (n = 9) and Lusaka, Zambia (n = 12). Single-genome analysis of full-length T/F Env sequences revealed that all 21 individuals were infected with a highly homogeneous population of viral variants, which were categorized as subtype C (n = 12), A1 (n = 7), or recombinant AC (n = 2). An extensive amino acid sequence-based analysis of variable loop lengths and glycosylation patterns in the T/F Envs revealed that a lower ratio of NXS to NXT-encoded glycan motifs correlated with neutralization breadth. Further analysis comparing amino acid sequence changes, insertions/deletions, and glycan motif alterations between the T/F Env and autologous early Env variants revealed that extensive diversification focused in the V2, V4, and V5 regions of gp120, accompanied by contemporaneous viral escape, significantly favored the development of breadth. These results suggest that more efficient glycosylation of subtype A and C T/F Envs through fewer NXS-encoded glycan sites is more likely to elicit antibodies that can transition from autologous to heterologous neutralizing activity following exposure to gp120 diversification. This initiates an Env-antibody co-evolution cycle that increases neutralization breadth, and is further augmented over time by additional viral and host factors. These findings suggest that understanding how variation in the efficiency of site-specific glycosylation influences neutralizing antibody elicitation and targeting could advance the design of immunogens aimed at inducing antibodies that can transition from autologous to heterologous neutralizing activity.
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46
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Schäffer C, Messner P. Emerging facets of prokaryotic glycosylation. FEMS Microbiol Rev 2016; 41:49-91. [PMID: 27566466 DOI: 10.1093/femsre/fuw036] [Citation(s) in RCA: 92] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 02/17/2016] [Accepted: 08/01/2016] [Indexed: 12/16/2022] Open
Abstract
Glycosylation of proteins is one of the most prevalent post-translational modifications occurring in nature, with a wide repertoire of biological implications. Pathways for the main types of this modification, the N- and O-glycosylation, can be found in all three domains of life-the Eukarya, Bacteria and Archaea-thereby following common principles, which are valid also for lipopolysaccharides, lipooligosaccharides and glycopolymers. Thus, studies on any glycoconjugate can unravel novel facets of the still incompletely understood fundamentals of protein N- and O-glycosylation. While it is estimated that more than two-thirds of all eukaryotic proteins would be glycosylated, no such estimate is available for prokaryotic glycoproteins, whose understanding is lagging behind, mainly due to the enormous variability of their glycan structures and variations in the underlying glycosylation processes. Combining glycan structural information with bioinformatic, genetic, biochemical and enzymatic data has opened up an avenue for in-depth analyses of glycosylation processes as a basis for glycoengineering endeavours. Here, the common themes of glycosylation are conceptualised for the major classes of prokaryotic (i.e. bacterial and archaeal) glycoconjugates, with a special focus on glycosylated cell-surface proteins. We describe the current knowledge of biosynthesis and importance of these glycoconjugates in selected pathogenic and beneficial microbes.
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Affiliation(s)
- Christina Schäffer
- Department of NanoBiotechnology, Institute of Biologically Inspired Materials, NanoGlycobiology unit, Universität für Bodenkultur Wien, A-1180 Vienna, Austria
| | - Paul Messner
- Department of NanoBiotechnology, Institute of Biologically Inspired Materials, NanoGlycobiology unit, Universität für Bodenkultur Wien, A-1180 Vienna, Austria
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47
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Sugar and Spice Make Bacteria Not Nice: Protein Glycosylation and Its Influence in Pathogenesis. J Mol Biol 2016; 428:3206-3220. [DOI: 10.1016/j.jmb.2016.04.013] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2016] [Revised: 04/04/2016] [Accepted: 04/08/2016] [Indexed: 01/08/2023]
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48
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Musial-Siwek M, Jaffee MB, Imperiali B. Probing Polytopic Membrane Protein-Substrate Interactions by Luminescence Resonance Energy Transfer. J Am Chem Soc 2016; 138:3806-12. [PMID: 26918528 DOI: 10.1021/jacs.5b13426] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Integral membrane proteins play essential roles in all living systems; however, major technical hurdles challenge analyses of this class of proteins. Biophysical approaches that provide structural information to complement and leverage experimentally determined and computationally predicted structures are urgently needed. Herein we present the application of luminescence resonance energy transfer (LRET) for investigating the interactions of the polytopic membrane-bound oligosaccharyl transferases (OTases) with partner substrates. Monomeric OTases, such as the PglBs from Campylobacter jejuni and Campylobacter lari, catalyze transfer of glycans from membrane-associated undecaprenol diphosphate-linked substrates to proteins in the bacterial periplasm. LRET-based distance measurements are enabled by the inclusion of an encoded N-terminal lanthanide-binding tag (LBT), and LRET between the luminescent (LBT)-Tb(3+) donor complex and fluorescently labeled peptide and glycan substrates provides discrete distance measurements across the span of the membrane. LRET-based measurements of detergent-solubilized PglB from C. lari allowed direct comparison with the distances based on the previously reported the C. lari PglB crystal structure, thereby validating the approach in a defined system. Distance measurements between peptide and glycan substrates and the C. jejuni PglB offer new experimental information on substrate binding to the related, but structurally uncharacterized, eukaryotic OTase.
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Affiliation(s)
- Monika Musial-Siwek
- Departments of Biology and Chemistry, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - Marcie B Jaffee
- Departments of Biology and Chemistry, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
| | - Barbara Imperiali
- Departments of Biology and Chemistry, Massachusetts Institute of Technology , Cambridge, Massachusetts 02139, United States
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49
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Mills DC, Jervis AJ, Abouelhadid S, Yates LE, Cuccui J, Linton D, Wren BW. Functional analysis of N-linking oligosaccharyl transferase enzymes encoded by deep-sea vent proteobacteria. Glycobiology 2015; 26:398-409. [PMID: 26610891 DOI: 10.1093/glycob/cwv111] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Accepted: 11/20/2015] [Indexed: 01/04/2023] Open
Abstract
Bacterial N-linking oligosaccharyl transferases (OTase enzymes) transfer lipid-linked glycans to selected proteins in the periplasm and were first described in the intestinal pathogen Campylobacter jejuni, a member of the ε-proteobacteria-subdivision of bacteria. More recently, orthologues from other ε-proteobacterial Campylobacter and Helicobacter species and a δ-proteobacterium, Desulfovibrio desulfuricans, have been described, suggesting that these two subdivisions of bacteria may be a source of further N-linked protein glycosylation systems. Whole-genome sequencing of both ε- and δ-proteobacteria from deep-sea vent habitats, a rich source of species from these subdivisions, revealed putative ORFs encoding OTase enzymes and associated adjacent glycosyltransferases similar to the C. jejuni N-linked glycosylation locus. We expressed putative OTase ORFs from the deep-sea vent species Nitratiruptor tergarcus, Sulfurovum lithotrophicum and Deferribacter desulfuricans in Escherichia coli and showed that they were able to functionally complement the C. jejuni OTase, CjPglB. The enzymes were shown to possess relaxed glycan specificity, transferring diverse glycan structures and demonstrated different glycosylation sequon specificities. Additionally, a permissive D. desulfuricans acceptor protein was identified, and we provide evidence that the N-linked glycan synthesized by N. tergarcus and S. lithotrophicum contains an acetylated sugar at the reducing end. This work demonstrates that deep-sea vent bacteria encode functional N-glycosylation machineries and are a potential source of biotechnologically important OTase enzymes.
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Affiliation(s)
- Dominic C Mills
- Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, University of London, Keppel Street, London WC1E 7HT, UK
| | - Adrian J Jervis
- Faculty of Life Sciences, University of Manchester, Michael Smith Building, Manchester M13 9PT, UK
| | - Sherif Abouelhadid
- Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, University of London, Keppel Street, London WC1E 7HT, UK
| | - Laura E Yates
- Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, University of London, Keppel Street, London WC1E 7HT, UK
| | - Jon Cuccui
- Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, University of London, Keppel Street, London WC1E 7HT, UK
| | - Dennis Linton
- Faculty of Life Sciences, University of Manchester, Michael Smith Building, Manchester M13 9PT, UK
| | - Brendan W Wren
- Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, University of London, Keppel Street, London WC1E 7HT, UK
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50
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Faid V, Denguir N, Chapuis V, Bihoreau N, Chevreux G. Site-specific N-glycosylation analysis of human factor XI: Identification of a noncanonical NXC glycosite. Proteomics 2015; 14:2460-70. [PMID: 25092234 DOI: 10.1002/pmic.201400038] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2014] [Revised: 05/07/2014] [Accepted: 07/31/2014] [Indexed: 01/13/2023]
Abstract
Human factor XI (hFXI) is a 160-kDa disulphide-linked homodimer zymogen involved in the coagulation cascade. Its deficiency results in bleeding diathesis referred to as hemophilia C. hFXI bears five N-glycosylation consensus sites per monomer, N72 , N108 , N335 on the heavy chain and N432 , N473 on the light chain. This study reports the first in-depth glycosylation analysis of hFXI based on advanced MS approaches. Hydrophilic interaction LC and MS characterization and quantification of the N-glycans showed that the two major forms are complex biantennary mono-α2,6-sialylated (A2 S1 , 20%) and bis-α2,6-sialylated structures (A2 S2 , 66%). Minor triantennary structures (A3 S3 F, ∼1.5%; A3 S3 , ∼2%) were also identified. MS analyses of intact hFXI revealed full occupation of two of the three heavy-chain glycosites and almost full-site occupancy of the light chain. Analysis of hFXI glycopeptides by LC-MS/MS enabled site-specific glycan profiling and occupancy. It was evidenced that N335 was not glycosylated and that N72 and N108 were fully occupied, whereas N432 and N473 were occupied at about 92 and 95%, respectively. We also identified a new glycosite of the noncanonical format NXC at N145 , occupied at around 5%. These data provide valuable structural information useful to understand the potential roles of N-glycosylation on hFXI function and could serve as a structural reference.
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Affiliation(s)
- Valegh Faid
- Analytical Department, LFB Biotechnologies, Courtaboeuf, France
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