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Gebhard LJ, Vershinin Z, Alarcón-Schumacher T, Eichler J, Erdmann S. Influence of N-Glycosylation on Virus-Host Interactions in Halorubrum lacusprofundi. Viruses 2023; 15:1469. [PMID: 37515157 PMCID: PMC10384203 DOI: 10.3390/v15071469] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2023] [Revised: 06/23/2023] [Accepted: 06/26/2023] [Indexed: 07/30/2023] Open
Abstract
N-glycosylation is a post-translational modification of proteins that occurs across all three domains of life. In Archaea, N-glycosylation is crucial for cell stability and motility, but importantly also has significant implications for virus-host interactions. While some archaeal viruses present glycosylated proteins or interact with glycosylated host proteins, the direct influence of N-glycosylation on archaeal virus-host interactions remains to be elucidated. In this study, we generated an N-glycosylation-deficient mutant of Halorubrum lacusprofundi, a halophilic archaeon commonly used to study cold adaptation, and examined the impact of compromised N-glycosylation on the infection dynamics of two very diverse viruses. While compromised N-glycosylation had no influence on the life cycle of the head-tailed virus HRTV-DL1, we observed a significant effect on membrane-containing virus HFPV-1. Both intracellular genome numbers and extracellular virus particle numbers of HFPV-1 were increased in the mutant strain, which we attribute to instability of the surface-layer which builds the protein envelope of the cell. When testing the impact of compromised N-glycosylation on the life cycle of plasmid vesicles, specialized membrane vesicles that transfer a plasmid between host cells, we determined that plasmid vesicle stability is strongly dependent on the host glycosylation machinery. Our study thus provides important insight into the role of N-glycosylation in virus-host interactions in Archaea, while pointing to how this influence strongly differs amongst various viruses and virus-like elements.
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Affiliation(s)
- L Johanna Gebhard
- Max Planck Institute for Marine Microbiology, Archaeal Virology, 28359 Bremen, Germany
| | - Zlata Vershinin
- Department of Life Sciences, Ben-Gurion University of the Negev, Beersheva 84105, Israel
| | | | - Jerry Eichler
- Department of Life Sciences, Ben-Gurion University of the Negev, Beersheva 84105, Israel
| | - Susanne Erdmann
- Max Planck Institute for Marine Microbiology, Archaeal Virology, 28359 Bremen, Germany
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2
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Distinct regions of the Haloferax volcanii dolichol phosphate-mannose synthase AglD mediate the assembly and subsequent processing of the lipid-linked mannose. J Bacteriol 2021; 204:e0044721. [PMID: 34633871 DOI: 10.1128/jb.00447-21] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Haloferax volcanii AglD is currently the only archaeal dolichol phosphate (DolP)-mannose synthase shown to participate in N-glycosylation. However, the relation between AglD and Pyrococcus furiosus PF0058, the only archaeal DolP-mannose synthase for which structural information is presently available, was unclear. In this report, similarities between the PF0058 and AglD catalytic domains were revealed. At the same time, AglD includes a transmembrane domain far longer than that of PF0058 or other DolP-mannose synthases. To determine whether this extension affords AglD functions in addition to generating mannose-charged DolP, a series of Hfx. volcanii strains expressing truncated versions of AglD was generated. Mass spectrometry revealed that a version of AglD comprising the catalytic domain and only two of the six to nine predicted membrane-spanning domains could mediate mannose addition to DolP. However, in cells expressing this or other truncated versions of AglD, mannose was not transferred from the lipid to the protein-bound tetrasaccharide precursor of the N-linked pentasaccharide normally decorating Hfx. volcanii glycoproteins. These results thus point to AglD as contributing to additional aspects of Hfx. volcanii N-glycosylation beyond charging DolP with mannose. Accordingly, the possibility that AglD, possibly in coordination with AglR, translocates DolP-mannose across the plasma membrane is discussed. Layman summary In the archaea Haloferax volcanii, the dolichol phosphate (DolP)-mannose synthase AglD charges the lipid DolP with mannose, which is delivered to a protein-bound tetrasaccharide to generate the pentasaccharide decorating glycoproteins in this organism. Structural studies demonstrated the similarity of AglD to Pyrococcus furiosus PF0058, the only archaeal DolP-mannose synthase with a solved 3D structure. Truncated AglD containing the catalytic domain and only two of the predicted six to nine membrane-spanning regions catalyzed mannose-charging of DolP. Yet, no mannose was delivered to protein-linked tetrasaccharide in cells expressing AglD mutants including only up to five membrane-spanning regions, pointing to a role for the extended C-terminal region in a subsequent step of Hfx. volcanii N-glycosylation, such as DolP-mannose translocation across the plasma membrane.
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3
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Makkay AM, Louyakis AS, Ram-Mohan N, Gophna U, Gogarten JP, Papke RT. Insights into gene expression changes under conditions that facilitate horizontal gene transfer (mating) of a model archaeon. Sci Rep 2020; 10:22297. [PMID: 33339886 PMCID: PMC7749143 DOI: 10.1038/s41598-020-79296-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Accepted: 11/19/2020] [Indexed: 12/16/2022] Open
Abstract
Horizontal gene transfer is a means by which bacteria, archaea, and eukaryotes are able to trade DNA within and between species. While there are a variety of mechanisms through which this genetic exchange can take place, one means prevalent in the archaeon Haloferax volcanii involves the transient formation of cytoplasmic bridges between cells and is referred to as mating. This process can result in the exchange of very large fragments of DNA between the participating cells. Genes governing the process of mating, including triggers to initiate mating, mechanisms of cell fusion, and DNA exchange, have yet to be characterized. We used a transcriptomic approach to gain a more detailed knowledge of how mating might transpire. By examining the differential expression of genes expressed in cells harvested from mating conditions on a filter over time and comparing them to those expressed in a shaking culture, we were able to identify genes and pathways potentially associated with mating. These analyses provide new insights into both the mechanisms and barriers of mating in Hfx. volcanii.
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Affiliation(s)
- Andrea M Makkay
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT, USA
| | - Artemis S Louyakis
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT, USA
| | - Nikhil Ram-Mohan
- Department of Emergency Medicine, Stanford University School of Medicine, Stanford, CA, USA
| | - Uri Gophna
- The Shmunis School of Biomedicine and Cancer Research, Faculty of Life Sciences, Tel Aviv University, P.O. Box 39040, 6997801, Tel Aviv, Israel
| | - J Peter Gogarten
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT, USA.,Institute for Systems Genomics, University of Connecticut, Storrs, CT, USA
| | - R Thane Papke
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT, USA.
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4
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Lu H, Pei C, Zhou H, Lü Y, He Y, Li Y, Han J, Xiang H, Eichler J, Jin C. Agl22 and Agl23 are involved in the synthesis and utilization of the lipid‐linked intermediates in the glycosylation pathways of the halophilic archaeaonHaloarcula hispanica. Mol Microbiol 2020; 114:762-774. [DOI: 10.1111/mmi.14577] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Revised: 07/15/2020] [Accepted: 07/16/2020] [Indexed: 12/11/2022]
Affiliation(s)
- Hua Lu
- State Key Laboratory of Mycology Institute of Microbiology Chinese Academy of Sciences Beijing China
- University of Chinese Academy of Sciences Beijing China
| | - Caixia Pei
- State Key Laboratory of Mycology Institute of Microbiology Chinese Academy of Sciences Beijing China
- University of Chinese Academy of Sciences Beijing China
| | - Hui Zhou
- State Key Laboratory of Mycology Institute of Microbiology Chinese Academy of Sciences Beijing China
| | - Yang Lü
- State Key Laboratory of Mycology Institute of Microbiology Chinese Academy of Sciences Beijing China
| | - Yun He
- Laboratory of Cellular and Molecular Tumor Immunology Institutes of Biology and Medical Sciences Jiangsu Laboratory of Infection Immunity Soochow University Suzhou China
| | - Yunsen Li
- Laboratory of Cellular and Molecular Tumor Immunology Institutes of Biology and Medical Sciences Jiangsu Laboratory of Infection Immunity Soochow University Suzhou China
| | - Jing Han
- State Key Laboratory of Microbial Resources Institute of Microbiology Chinese Academy of Sciences Beijing China
| | - Hua Xiang
- State Key Laboratory of Microbial Resources Institute of Microbiology Chinese Academy of Sciences Beijing China
| | - Jerry Eichler
- Department of Life Sciences Ben Gurion University of the Negev Beersheva Israel
| | - Cheng Jin
- State Key Laboratory of Mycology Institute of Microbiology Chinese Academy of Sciences Beijing China
- University of Chinese Academy of Sciences Beijing China
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5
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Eichler J, Imperiali B. Biogenesis of Asparagine-Linked Glycoproteins Across Domains of Life-Similarities and Differences. ACS Chem Biol 2018; 13:833-837. [PMID: 29481041 DOI: 10.1021/acschembio.8b00163] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- Jerry Eichler
- Department of Life Sciences, Ben Gurion University of the Negev, Beersheva, Israel
| | - Barbara Imperiali
- Department of Biology and Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States
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6
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Shalev Y, Soucy SM, Papke RT, Gogarten JP, Eichler J, Gophna U. Comparative Analysis of Surface Layer Glycoproteins and Genes Involved in Protein Glycosylation in the Genus Haloferax. Genes (Basel) 2018; 9:genes9030172. [PMID: 29558455 PMCID: PMC5867893 DOI: 10.3390/genes9030172] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2018] [Revised: 03/01/2018] [Accepted: 03/09/2018] [Indexed: 11/16/2022] Open
Abstract
Within the Haloferax genus, both the surface (S)-layer protein, and the glycans that can decorate it, vary between species, which can potentially result in many different surface types, analogous to bacterial serotypes. This variation may mediate phenotypes, such as sensitivity to different viruses and mating preferences. Here, we describe S-layer glycoproteins found in multiple Haloferax strains and perform comparative genomics analyses of major and alternative glycosylation clusters of isolates from two coastal sites. We analyze the phylogeny of individual glycosylation genes and demonstrate that while the major glycosylation cluster tends to be conserved among closely related strains, the alternative cluster is highly variable. Thus, geographically- and genetically-related strains may exhibit diverse surface structures to such an extent that no two isolates present an identical surface profile.
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Affiliation(s)
- Yarden Shalev
- School of Molecular and Cell Biology and Biotechnology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel.
| | - Shannon M Soucy
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT 06269, USA.
| | - R Thane Papke
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT 06269, USA.
| | - J Peter Gogarten
- Institute for Systems Genomics, University of Connecticut, Storrs, CT 06269, USA.
| | - Jerry Eichler
- Department of Life Sciences, Ben Gurion University of the Negev, Beersheva 8410501, Israel.
| | - Uri Gophna
- School of Molecular and Cell Biology and Biotechnology, George S. Wise Faculty of Life Sciences, Tel Aviv University, Tel Aviv 69978, Israel.
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7
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Rodrigues-Oliveira T, Belmok A, Vasconcellos D, Schuster B, Kyaw CM. Archaeal S-Layers: Overview and Current State of the Art. Front Microbiol 2017; 8:2597. [PMID: 29312266 PMCID: PMC5744192 DOI: 10.3389/fmicb.2017.02597] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2017] [Accepted: 12/12/2017] [Indexed: 01/01/2023] Open
Abstract
In contrast to bacteria, all archaea possess cell walls lacking peptidoglycan and a number of different cell envelope components have also been described. A paracrystalline protein surface layer, commonly referred to as S-layer, is present in nearly all archaea described to date. S-layers are composed of only one or two proteins and form different lattice structures. In this review, we summarize current understanding of archaeal S-layer proteins, discussing topics such as structure, lattice type distribution among archaeal phyla and glycosylation. The hexagonal lattice type is dominant within the phylum Euryarchaeota, while in the Crenarchaeota this feature is mainly associated with specific orders. S-layers exclusive to the Crenarchaeota have also been described, which are composed of two proteins. Information regarding S-layers in the remaining archaeal phyla is limited, mainly due to organism description through only culture-independent methods. Despite the numerous applied studies using bacterial S-layers, few reports have employed archaea as a study model. As such, archaeal S-layers represent an area for exploration in both basic and applied research.
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Affiliation(s)
- Thiago Rodrigues-Oliveira
- Department of Cell Biology, Institute of Biological Sciences, University of Brasília, Brasília, Brazil
| | - Aline Belmok
- Department of Cell Biology, Institute of Biological Sciences, University of Brasília, Brasília, Brazil
| | - Deborah Vasconcellos
- Department of Cell Biology, Institute of Biological Sciences, University of Brasília, Brasília, Brazil
| | - Bernhard Schuster
- Department of NanoBiotechnology, Institute for Synthetic Bioarchitectures, University of Natural Resources and Life Sciences, Vienna, Austria
| | - Cynthia M. Kyaw
- Department of Cell Biology, Institute of Biological Sciences, University of Brasília, Brasília, Brazil
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8
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Elharar Y, Podilapu AR, Guan Z, Kulkarni SS, Eichler J. Assembling Glycan-Charged Dolichol Phosphates: Chemoenzymatic Synthesis of a Haloferax volcanii N-Glycosylation Pathway Intermediate. Bioconjug Chem 2017; 28:2461-2470. [PMID: 28809486 DOI: 10.1021/acs.bioconjchem.7b00436] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
N-glycosylation, the covalent attachment of glycans to select protein target Asn residues, is a post-translational modification performed by all three domains of life. In the halophilic archaea Haloferax volcanii, in which understanding of this universal protein-processing event is relatively well-advanced, genes encoding the components of the archaeal glycosylation (Agl) pathway responsible for the assembly and attachment of an N-linked pentasaccharide have been identified. As elsewhere, the N-linked glycan is assembled on phosphodolichol carriers before transfer to target Asn residues. However, as little is presently known of the Hfx. volcanii Agl pathway at the protein level, the seemingly unique ability of Archaea to use dolichol phosphate (DolP) as the glycan lipid carrier, rather than dolichol pyrophosphate used by eukaryotes, remains poorly understood. With this in mind, a chemoenzymatic approach was taken to biochemically study AglG, one of the five glycosyltransferases of the pathway. Accordingly, a novel regio- and stereoselective reduction of naturally isolated polyprenol gave facile access to S-dolichol via asymmetric transfer hydrogenation under very mild conditions. This compound was used to generate glucose-charged DolP, a precursor of the N-linked pentasaccharide, as well as DolP-glucose-glucuronic acid and DolP-glucuronic acid. AglG, purified from Hfx. volcanii membranes in hypersaline conditions, like those encountered in situ, was subsequently combined with uridine diphosphate (UDP)-glucuronic acid and DolP-glucose to yield DolP-glucose-glucuronic acid. The in vitro system for the study of AglG activity developed here represents the first such tool for studying halophilic glycosyltransferases and will allow for a detailed understanding of archaeal N-glycosylation.
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Affiliation(s)
- Yifat Elharar
- Department of Life Sciences, Ben Gurion University of the Negev , Beersheva 8410501, Israel
| | - Ananda Rao Podilapu
- Department of Chemistry, Indian Institute of Technology Bombay , Powai, Mumbai 400076, India
| | - Ziqiang Guan
- Department of Biochemistry, Duke University Medical Center , Durham, North Carolina 27710, United States
| | - Suvarn S Kulkarni
- Department of Chemistry, Indian Institute of Technology Bombay , Powai, Mumbai 400076, India
| | - Jerry Eichler
- Department of Life Sciences, Ben Gurion University of the Negev , Beersheva 8410501, Israel
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Eichler J, Guan Z. Lipid sugar carriers at the extremes: The phosphodolichols Archaea use in N-glycosylation. Biochim Biophys Acta Mol Cell Biol Lipids 2017; 1862:589-599. [PMID: 28330764 DOI: 10.1016/j.bbalip.2017.03.005] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2016] [Revised: 03/15/2017] [Accepted: 03/17/2017] [Indexed: 11/28/2022]
Abstract
N-glycosylation, a post-translational modification whereby glycans are covalently linked to select Asn residues of target proteins, occurs in all three domains of life. Across evolution, the N-linked glycans are initially assembled on phosphorylated cytoplasmically-oriented polyisoprenoids, with polyprenol (mainly C55 undecaprenol) fulfilling this role in Bacteria and dolichol assuming this function in Eukarya and Archaea. The eukaryal and archaeal versions of dolichol can, however, be distinguished on the basis of their length, degree of saturation and by other traits. As is true for many facets of their biology, Archaea, best known in their capacity as extremophiles, present unique approaches for synthesizing phosphodolichols. At the same time, general insight into the assembly and processing of glycan-bearing phosphodolichols has come from studies of the archaeal enzymes responsible. In this review, these and other aspects of archaeal phosphodolichol biology are addressed.
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Affiliation(s)
- Jerry Eichler
- Department of Life Sciences, Ben Gurion University of the Negev, Beersheva 84105, Israel.
| | - Ziqiang Guan
- Department of Biochemistry, Duke University Medical Center, Durham, NC 27710, USA
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10
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N-Glycosylation Is Important for Proper Haloferax volcanii S-Layer Stability and Function. Appl Environ Microbiol 2017; 83:AEM.03152-16. [PMID: 28039139 DOI: 10.1128/aem.03152-16] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2016] [Accepted: 12/28/2016] [Indexed: 12/13/2022] Open
Abstract
N-Glycosylation, the covalent linkage of glycans to select Asn residues of target proteins, is an almost universal posttranslational modification in archaea. However, whereas roles for N-glycosylation have been defined in eukarya and bacteria, the function of archaeal N-glycosylation remains unclear. Here, the impact of perturbed N-glycosylation on the structure and physiology of the haloarchaeon Haloferax volcanii was considered. Cryo-electron microscopy was used to examine right-side-out membrane vesicles prepared from cells of a parent strain and from strains lacking genes encoding glycosyltransferases involved in assembling the N-linked pentasaccharide decorating the surface layer (S-layer) glycoprotein, the sole component of the S-layer surrounding H. volcanii cells. Whereas a regularly repeating S-layer covered the entire surface of vesicles prepared from parent strain cells, vesicles from the mutant cells were only partially covered. To determine whether such N-glycosylation-related effects on S-layer assembly also affected cell function, the secretion of a reporter protein was addressed in the parent and N-glycosylation mutant strains. Compromised S-layer glycoprotein N-glycosylation resulted in impaired transfer of the reporter past the S-layer and into the growth medium. Finally, an assessment of S-layer glycoprotein susceptibility to added proteases in the mutants revealed that in cells lacking AglD, which is involved in adding the final pentasaccharide sugar, a distinct S-layer glycoprotein conformation was assumed in which the N-terminal region was readily degraded. Perturbed N-glycosylation thus affects S-layer glycoprotein folding. These findings suggest that H. volcanii could adapt to changes in its surroundings by modulating N-glycosylation so as to affect S-layer architecture and function.IMPORTANCE Long held to be a process unique to eukaryotes, it is now accepted that bacteria and archaea also perform N-glycosylation, namely, the covalent attachment of sugars to select asparagine residues of target proteins. Yet, while information on the importance of N-glycosylation in eukaryotes and bacteria is available, the role of this posttranslational modification in archaea remains unclear. Here, insight into the purpose of archaeal N-glycosylation was gained by addressing the surface layer (S-layer) surrounding cells of the halophilic species Haloferax volcanii Relying on mutant strains defective in N-glycosylation, such efforts revealed that compromised N-glycosylation affected S-layer integrity and the transfer of a secreted reporter protein across the S-layer into the growth medium, as well as the conformation of the S-layer glycoprotein, the sole component of the S-layer. Thus, by modifying N-glycosylation, H. volcanii cells can change how they interact with their surroundings.
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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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12
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Kandiba L, Lin CW, Aebi M, Eichler J, Guerardel Y. Structural characterization of the N-linked pentasaccharide decorating glycoproteins of the halophilic archaeon Haloferax volcanii. Glycobiology 2016; 26:745-756. [PMID: 26863921 DOI: 10.1093/glycob/cww014] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2016] [Accepted: 02/03/2016] [Indexed: 12/30/2022] Open
Abstract
N-Glycosylation is a post-translational modification performed in all three domains of life. In the halophilic archaea Haloferax volcanii, glycoproteins such as the S-layer glycoprotein are modified by an N-linked pentasaccharide assembled by a series of Agl (archaeal glycosylation) proteins. In the present study, mass spectrometry (MS) and nuclear magnetic resonance spectroscopy were used to define the structure of this glycan attached to at least four of the seven putative S-layer glycoprotein N-glycosylation sites, namely Asn-13, Asn-83, Asn-274 and Asn-279. Such approaches detected a trisaccharide corresponding to glucuronic acid (GlcA)-β1,4-GlcA-β1,4-glucose-β1-Asn, a tetrasaccharide corresponding to methyl-O-4-GlcA-β-1,4-galacturonic acid-α1,4-GlcA-β1,4-glucose-β1-Asn, and a pentasaccharide corresponding to hexose-1,2-[methyl-O-4-]GlcA-β-1,4-galacturonic acid-α1,4-GlcA-β1,4-glucose-β1-Asn, with previous MS and radiolabeling experiments showing the hexose at the non-reducing end of the pentasaccharide to be mannose. The present analysis thus corrects the earlier assignment of the penultimate sugar as a methyl ester of a hexuronic acid, instead revealing this sugar to be a methylated GlcA. The assignments made here are in good agreement with what was already known of the Hfx. volcanii N-glycosylation pathway from previous genetic and biochemical efforts while providing new insight into the process.
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Affiliation(s)
- Lina Kandiba
- Department of Life Sciences, Ben Gurion University of the Negev, PO Box 653, Beersheva 84105, Israel
| | - Chia-Wei Lin
- Institute of Microbiology, ETH Zurich, CH-8093 Zurich, Switzerland
| | - Markus Aebi
- Institute of Microbiology, ETH Zurich, CH-8093 Zurich, Switzerland
| | - Jerry Eichler
- Department of Life Sciences, Ben Gurion University of the Negev, PO Box 653, Beersheva 84105, Israel
| | - Yann Guerardel
- Université de Lille, CNRS, UMR 8576-UGSF-Unité de Glycobiologie Structurale et Fonctionnelle, F 59000 Lille, France
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13
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Ding Y, Jones GM, Brimacombe C, Uchida K, Aizawa SI, Logan SM, Kelly JF, Jarrell KF. Identification of a gene involved in the biosynthesis pathway of the terminal sugar of the archaellin N-linked tetrasaccharide in Methanococcus maripaludis. Antonie van Leeuwenhoek 2015; 109:131-48. [PMID: 26590834 DOI: 10.1007/s10482-015-0615-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Accepted: 10/28/2015] [Indexed: 10/22/2022]
Abstract
In Methanococcus maripaludis, the three archaellins which comprise the archaellum are modified at multiple sites with an N-linked tetrasaccharide with the structure of Sug-4-β-ManNAc3NAmA6Thr-4-β-GlcNAc3NAcA-3-β-GalNAc, where Sug is a unique sugar (5S)-2-acetamido-2,4-dideoxy-5-O-methyl-L-erythro-hexos-5-ulo-1,5-pyranose, so far found exclusively in this species. In this study, a six-gene cluster mmp1089-1094, neighboring one of the genomic regions already known to contain genes involved with the archaellin N-glycosylation pathway, was examined for its potential involvement in the archaellin N-glycosylation or sugar biosynthesis pathway. The co-transcription of these six genes was demonstrated by RT-PCR. Mutants carrying an in-frame deletion in mmp1090, mmp1091 or mmp1092 were successfully generated. The Δmmp1090 deletion mutant was archaellated when examined by electron microscopy and mass spectrometry analysis of purified archaella showed that the archaellins were modified with a truncated N-glycan in which the terminal sugar residue and the threonine linked to the third sugar residue were missing. Both gene annotation and bioinformatic analyses indicate that MMP1090 is a UDP-glucose 4-epimerase, suggesting that the unique terminal sugar of the archaellin N-glycan might be synthesised from UDP-glucose or UDP-N-acetylglucosamine with an essential early step in synthesis catalysed by MMP1090. In contrast, no detectable phenotype related to archaellin glycosylation was observed in mutants deleted for either mmp1091 or mmp1092 while attempts to delete mmp1089, mmp1093 and mmp1094 were unsuccessful. Based on its demonstrated involvement in the archaellin N-glycosylation pathway, we designated mmp1090 as aglW.
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Affiliation(s)
- Yan Ding
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, K7L 3N6, Canada
| | - Gareth M Jones
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, K7L 3N6, Canada
| | - Cedric Brimacombe
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, K7L 3N6, Canada
| | - Kaoru Uchida
- Department of Life Sciences, Prefectural University of Hiroshima, Shobara, Hiroshima, 727-0023, Japan
| | - Shin-Ichi Aizawa
- Department of Life Sciences, Prefectural University of Hiroshima, Shobara, Hiroshima, 727-0023, Japan
| | - Susan M Logan
- Human Health Therapeutics Portfolio, National Research Council, Ottawa, K1A 0R6, Canada
| | - John F Kelly
- Human Health Therapeutics Portfolio, National Research Council, Ottawa, K1A 0R6, Canada.
| | - Ken F Jarrell
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, K7L 3N6, Canada.
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14
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Evidence that biosynthesis of the second and third sugars of the archaellin Tetrasaccharide in the archaeon Methanococcus maripaludis occurs by the same pathway used by Pseudomonas aeruginosa to make a di-N-acetylated sugar. J Bacteriol 2015; 197:1668-80. [PMID: 25733616 DOI: 10.1128/jb.00040-15] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2015] [Accepted: 02/24/2015] [Indexed: 01/09/2023] Open
Abstract
UNLABELLED Methanococcus maripaludis has two surface appendages, archaella and type IV pili, which are composed of glycoprotein subunits. Archaellins are modified with an N-linked tetrasaccharide with the structure Sug-1,4-β-ManNAc3NAmA6Thr-1,4-β-GlcNAc3NAcA-1,3-β-GalNAc, where Sug is (5S)-2-acetamido-2,4-dideoxy-5-O-methyl-α-L-erythro-hexos-5-ulo-1,5-pyranose. The pilin glycan has an additional hexose attached to GalNAc. In this study, genes located in two adjacent, divergently transcribed operons (mmp0350-mmp0354 and mmp0359-mmp0355) were targeted for study based on annotations suggesting their involvement in biosynthesis of N-glycan sugars. Mutants carrying deletions in mmp0350, mmp0351, mmp0352, or mmp0353 were nonarchaellated and synthesized archaellins modified with a 1-sugar glycan, as estimated from Western blots. Mass spectroscopy analysis of pili purified from the Δmmp0352 strain confirmed a glycan with only GalNAc, suggesting mmp0350 to mmp0353 were all involved in biosynthesis of the second sugar (GlcNAc3NAcA). The Δmmp0357 mutant was archaellated and had archaellins with a 2-sugar glycan, as confirmed by mass spectroscopy of purified archaella, indicating a role for MMP0357 in biosynthesis of the third sugar (ManNAc3NAmA6Thr). M. maripaludis mmp0350, mmp0351, mmp0352, mmp0353, and mmp0357 are proposed to be functionally equivalent to Pseudomonas aeruginosa wbpABEDI, involved in converting UDP-N-acetylglucosamine to UDP-2,3-diacetamido-2,3-dideoxy-d-mannuronic acid, an O5-specific antigen sugar. Cross-domain complementation of the final step of the P. aeruginosa pathway with mmp0357 supports this hypothesis. IMPORTANCE This work identifies a series of genes in adjacent operons that are shown to encode the enzymes that complete the entire pathway for generation of the second and third sugars of the N-linked tetrasaccharide that modifies archaellins of Methanococcus maripaludis. This posttranslational modification of archaellins is important, as it is necessary for archaellum assembly. Pilins are modified with a different N-glycan consisting of the archaellin tetrasaccharide but with an additional hexose attached to the linking sugar. Mass spectrometry analysis of the pili of one mutant strain provided insight into how this different glycan might ultimately be assembled. This study includes a rare example of an archaeal gene functionally replacing a bacterial gene in a complex sugar biosynthesis pathway.
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15
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Kandiba L, Eichler J. Deciphering a pathway of Halobacterium salinarum N-glycosylation. Microbiologyopen 2014; 4:28-40. [PMID: 25461760 PMCID: PMC4335974 DOI: 10.1002/mbo3.215] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/04/2014] [Revised: 08/15/2014] [Accepted: 08/20/2014] [Indexed: 12/14/2022] Open
Abstract
Genomic analysis points to N-glycosylation as being a common posttranslational modification in Archaea. To date, however, pathways of archaeal N-glycosylation have only been described for few species. With this in mind, the similarities of N-linked glycans decorating glycoproteins in the haloarchaea Haloferax volcanii and Halobacterium salinarum directed a series of bioinformatics, genetic, and biochemical experiments designed to describe that Hbt. salinarum pathway responsible for biogenesis of one of the two N-linked oligosaccharides described in this species. As in Hfx. volcanii, where agl (archaeal glycosylation) genes that encode proteins responsible for the assembly and attachment of a pentasaccharide to target protein Asn residues are clustered in the genome, Hbt. salinarum also contains a group of clustered homologous genes (VNG1048G-VNG1068G). Introduction of these Hbt. salinarum genes into Hfx. volcanii mutant strains deleted of the homologous sequence restored the lost activity. Moreover, transcription of the Hbt. salinarum genes in the native host, as well as in vitro biochemical confirmation of the predicted functions of several of the products of these genes provided further support for assignments made following bioinformatics and genetic experiments. Based on the results obtained in this study, the first description of an N-glycosylation pathway in Hbt. salinarum is offered.
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Affiliation(s)
- Lina Kandiba
- Department of Life Sciences, Ben Gurion University of the Negev, Beersheva, Israel
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16
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Abstract
Prokaryotic glycosylation fulfills an important role in maintaining and protecting the structural integrity and function of the bacterial cell wall, as well as serving as a flexible adaption mechanism to evade environmental and host-induced pressure. The scope of bacterial and archaeal protein glycosylation has considerably expanded over the past decade(s), with numerous examples covering the glycosylation of flagella, pili, glycosylated enzymes, as well as surface-layer proteins. This article addresses structure, analysis, function, genetic basis, biosynthesis, and biomedical and biotechnological applications of cell-envelope glycoconjugates, S-layer glycoprotein glycans, and "nonclassical" secondary-cell wall polysaccharides. The latter group of polymers mediates the important attachment and regular orientation of the S-layer to the cell wall. The structures of these glycopolymers reveal an enormous diversity, resembling the structural variability of bacterial lipopolysaccharides and capsular polysaccharides. While most examples are presented for Gram-positive bacteria, the S-layer glycan of the Gram-negative pathogen Tannerella forsythia is also discussed. In addition, archaeal S-layer glycoproteins are briefly summarized.
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Affiliation(s)
- Paul Messner
- Department of NanoBiotechnology, NanoGlycobiology Unit, University of Natural Resources and Life Sciences, Vienna, Austria
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17
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Jarrell KF, Ding Y, Meyer BH, Albers SV, Kaminski L, Eichler J. N-linked glycosylation in Archaea: a structural, functional, and genetic analysis. Microbiol Mol Biol Rev 2014; 78:304-41. [PMID: 24847024 PMCID: PMC4054257 DOI: 10.1128/mmbr.00052-13] [Citation(s) in RCA: 145] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
N-glycosylation of proteins is one of the most prevalent posttranslational modifications in nature. Accordingly, a pathway with shared commonalities is found in all three domains of life. While excellent model systems have been developed for studying N-glycosylation in both Eukarya and Bacteria, an understanding of this process in Archaea was hampered until recently by a lack of effective molecular tools. However, within the last decade, impressive advances in the study of the archaeal version of this important pathway have been made for halophiles, methanogens, and thermoacidophiles, combining glycan structural information obtained by mass spectrometry with bioinformatic, genetic, biochemical, and enzymatic data. These studies reveal both features shared with the eukaryal and bacterial domains and novel archaeon-specific aspects. Unique features of N-glycosylation in Archaea include the presence of unusual dolichol lipid carriers, the use of a variety of linking sugars that connect the glycan to proteins, the presence of novel sugars as glycan constituents, the presence of two very different N-linked glycans attached to the same protein, and the ability to vary the N-glycan composition under different growth conditions. These advances are the focus of this review, with an emphasis on N-glycosylation pathways in Haloferax, Methanococcus, and Sulfolobus.
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Affiliation(s)
- Ken F Jarrell
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Yan Ding
- Department of Biomedical and Molecular Sciences, Queen's University, Kingston, Ontario, Canada
| | - Benjamin H Meyer
- Molecular Biology of Archaea, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Sonja-Verena Albers
- Molecular Biology of Archaea, Max Planck Institute for Terrestrial Microbiology, Marburg, Germany
| | - Lina Kaminski
- Department of Life Sciences, Ben Gurion University, Beersheva, Israel
| | - Jerry Eichler
- Department of Life Sciences, Ben Gurion University, Beersheva, Israel
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18
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Eichler J, Arbiv A, Cohen-Rosenzweig C, Kaminski L, Kandiba L, Konrad Z. N-glycosylation in Haloferax volcanii: adjusting the sweetness. Front Microbiol 2013; 4:403. [PMID: 24399998 PMCID: PMC3871713 DOI: 10.3389/fmicb.2013.00403] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2013] [Accepted: 12/06/2013] [Indexed: 12/23/2022] Open
Abstract
Long believed to be restricted to Eukarya, it is now known that cells of all three domains of life perform N-glycosylation, the covalent attachment of glycans to select target protein asparagine residues. Still, it is only in the last decade that pathways of N-glycosylation in Archaea have been delineated. In the haloarchaeon Haloferax volcanii, a series of Agl (archaeal glycosylation) proteins is responsible for the addition of an N-linked pentasaccharide to modified proteins, including the surface (S)-layer glycoprotein, the sole component of the surface layer surrounding the cell. The S-layer glycoprotein N-linked glycosylation profile changes, however, as a function of surrounding salinity. Upon growth at different salt concentrations, the S-layer glycoprotein is either decorated by the N-linked pentasaccharide introduced above or by both this pentasaccharide as well as a tetrasaccharide of distinct composition. Recent efforts have identified Agl5–Agl15 as components of a second Hfx. volcanii N-glycosylation pathway responsible for generating the tetrasaccharide attached to S-layer glycoprotein when growth occurs in 1.75 M but not 3.4 M NaCl-containing medium.
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Affiliation(s)
- Jerry Eichler
- Department of Life Sciences, Ben Gurion University of the Negev Beersheva, Israel
| | - Adi Arbiv
- Department of Life Sciences, Ben Gurion University of the Negev Beersheva, Israel
| | | | - Lina Kaminski
- Department of Life Sciences, Ben Gurion University of the Negev Beersheva, Israel
| | - Lina Kandiba
- Department of Life Sciences, Ben Gurion University of the Negev Beersheva, Israel
| | - Zvia Konrad
- Department of Life Sciences, Ben Gurion University of the Negev Beersheva, Israel
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Arbiv A, Yurist-Doutsch S, Guan Z, Eichler J. AglQ is a novel component of the Haloferax volcanii N-glycosylation pathway. PLoS One 2013; 8:e81782. [PMID: 24236216 PMCID: PMC3827465 DOI: 10.1371/journal.pone.0081782] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2013] [Accepted: 10/23/2013] [Indexed: 11/19/2022] Open
Abstract
N-glycosylation is a post-translational modification performed by members of all three domains of life. Studies on the halophile Haloferax volcanii have offered insight into the archaeal version of this universal protein-processing event. In the present study, AglQ was identified as a novel component of the pathway responsible for the assembly and addition of a pentasaccharide to select Asn residues of Hfx. volcanii glycoproteins, such as the S-layer glycoprotein. In cells deleted of aglQ, both dolichol phosphate, the lipid carrier used in Hfx. volcanii N-glycosylation, and modified S-layer glycoprotein Asn residues only presented the first three pentasaccharide subunits, pointing to a role for AglQ in either preparing the third sugar for attachment of the fourth pentasaccharide subunit or processing the fourth sugar prior to its addition to the lipid-linked trisaccharide. To better define the precise role of AglQ, shown to be a soluble protein, bioinformatics tools were recruited to identify sequence or structural homologs of known function. Site-directed mutagenesis experiments guided by these predictions identified residues important for AglQ function. The results obtained point to AglQ acting as an isomerase in Hfx. volcanii N-glycosylation.
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Affiliation(s)
- Adi Arbiv
- Department of Life Sciences, Ben Gurion University, Beersheva, Israel
| | | | - Ziqiang Guan
- Department of Biochemistry, Duke University Medical Center, Durham, North Carolina, United States of America
| | - Jerry Eichler
- Department of Life Sciences, Ben Gurion University, Beersheva, Israel
- * E-mail:
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20
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Two distinct N-glycosylation pathways process the Haloferax volcanii S-layer glycoprotein upon changes in environmental salinity. mBio 2013; 4:e00716-13. [PMID: 24194539 PMCID: PMC3892788 DOI: 10.1128/mbio.00716-13] [Citation(s) in RCA: 58] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
N-glycosylation in Archaea presents aspects of this posttranslational modification not seen in either Eukarya or Bacteria. In the haloarchaeon Haloferax volcanii, the surface (S)-layer glycoprotein can be simultaneously modified by two different N-glycans. Asn-13 and Asn-83 are modified by a pentasaccharide, whereas Asn-498 is modified by a tetrasaccharide of distinct composition, with N-glycosylation at this position being related to environmental conditions. Specifically, N-glycosylation of Asn-498 is detected when cells are grown in the presence of 1.75 but not 3.4 M NaCl. While deletion of genes encoding components of the pentasaccharide assembly pathway had no effect on the biosynthesis of the tetrasaccharide bound to Asn-498, deletion of genes within the cluster spanning HVO_2046 to HVO_2061 interfered with the assembly and attachment of the Asn-498-linked tetrasaccharide. Transfer of the “low-salt” tetrasaccharide from the dolichol phosphate carrier upon which it is assembled to S-layer glycoprotein Asn-498 did not require AglB, the oligosaccharyltransferase responsible for pentasaccharide attachment to Asn-13 and Asn-83. Finally, although biogenesis of the low-salt tetrasaccharide is barely discernible upon growth at the elevated salinity, this glycan was readily detected under such conditions in strains deleted of pentasaccharide biosynthesis pathway genes, indicative of cross talk between the two N-glycosylation pathways. In the haloarchaeon Haloferax volcanii, originally from the Dead Sea, the pathway responsible for the assembly and attachment of a pentasaccharide to the S-layer glycoprotein, a well-studied glycoprotein in this species, has been described. More recently, it was shown that in response to growth in low salinity, the same glycoprotein is modified by a novel tetrasaccharide. In the present study, numerous components of the pathway used to synthesize this “low-salt” tetrasaccharide are described. As such, this represents the first report of two N-glycosylation pathways able to simultaneously modify a single protein as a function of environmental salinity. Moreover, and to the best of our knowledge, the ability to N-glycosylate the same protein with different and unrelated glycans has not been observed in either Eukarya or Bacteria or indeed beyond the halophilic archaea, for which similar dual modification of the Halobacterium salinarum S-layer glycoprotein was reported.
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21
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Phylogenetic- and genome-derived insight into the evolution of N-glycosylation in Archaea. Mol Phylogenet Evol 2013; 68:327-39. [DOI: 10.1016/j.ympev.2013.03.024] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Revised: 03/23/2013] [Accepted: 03/26/2013] [Indexed: 11/21/2022]
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22
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Identification of genes involved in the biosynthesis of the third and fourth sugars of the Methanococcus maripaludis archaellin N-linked tetrasaccharide. J Bacteriol 2013; 195:4094-104. [PMID: 23836872 DOI: 10.1128/jb.00668-13] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
N-glycosylation is a protein posttranslational modification found in all three domains of life. Many surface proteins in Archaea, including S-layer proteins, pilins, and archaellins (archaeal flagellins) are known to contain N-linked glycans. In Methanococcus maripaludis, the archaellins are modified at multiple sites with an N-linked tetrasaccharide with the structure Sug-1,4-β-ManNAc3NAmA6Thr-1,4-β-GlcNAc3NAcA-1,3-β-GalNAc, where Sug is the unique sugar (5S)-2-acetamido-2,4-dideoxy-5-O-methyl-α-l-erythro-hexos-5-ulo-1,5-pyranose. In this study, four genes--mmp1084, mmp1085, mmp1086, and mmp1087--were targeted to determine their potential involvement of the biosynthesis of the sugar components in the N-glycan, based on bioinformatics analysis and proximity to a number of genes which have been previously demonstrated to be involved in the N-glycosylation pathway. The genes mmp1084 to mmp1087 were shown to be cotranscribed, and in-frame deletions of each gene as well as a Δmmp1086Δmmp1087 double mutant were successfully generated. All mutants were archaellated and motile. Mass spectrometry examination of purified archaella revealed that in Δmmp1084 mutant cells, the threonine linked to the third sugar of the glycan was missing, indicating a putative threonine transferase function of MMP1084. Similar analysis of the archaella of the Δmmp1085 mutant cells demonstrated that the glycan lacked the methyl group at the C-5 position of the terminal sugar, indicating that MMP1085 is a methyltransferase involved in the biosynthesis of this unique sugar. Deletion of the remaining two genes, mmp1086 and mmp1087, either singularly or together, had no effect on the structure of the archaellin N-glycan. Because of their demonstrated involvement in the N-glycosylation pathway, we designated mmp1084 as aglU and mmp1085 as aglV.
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24
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Eichler J, Maupin-Furlow J. Post-translation modification in Archaea: lessons from Haloferax volcanii and other haloarchaea. FEMS Microbiol Rev 2012; 37:583-606. [PMID: 23167813 DOI: 10.1111/1574-6976.12012] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2012] [Revised: 11/13/2012] [Accepted: 11/13/2012] [Indexed: 01/11/2023] Open
Abstract
As an ever-growing number of genome sequences appear, it is becoming increasingly clear that factors other than genome sequence impart complexity to the proteome. Of the various sources of proteomic variability, post-translational modifications (PTMs) most greatly serve to expand the variety of proteins found in the cell. Likewise, modulating the rates at which different proteins are degraded also results in a constantly changing cellular protein profile. While both strategies for generating proteomic diversity are adopted by organisms across evolution, the responsible pathways and enzymes in Archaea are often less well described than are their eukaryotic and bacterial counterparts. Studies on halophilic archaea, in particular Haloferax volcanii, originally isolated from the Dead Sea, are helping to fill the void. In this review, recent developments concerning PTMs and protein degradation in the haloarchaea are discussed.
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Affiliation(s)
- Jerry Eichler
- Department of Life Sciences, Ben Gurion University, Beersheva, Israel.
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25
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AglS, a novel component of the Haloferax volcanii N-glycosylation pathway, is a dolichol phosphate-mannose mannosyltransferase. J Bacteriol 2012; 194:6909-16. [PMID: 23086206 DOI: 10.1128/jb.01716-12] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
In Haloferax volcanii, a series of Agl proteins mediates protein N-glycosylation. The genes encoding all but one of the Agl proteins are sequestered into a single gene island. The same region of the genome includes sequences also suspected but not yet verified as serving N-glycosylation roles, such as HVO_1526. In the following, HVO_1526, renamed AglS, is shown to be necessary for the addition of the final mannose subunit of the pentasaccharide N-linked to the surface (S)-layer glycoprotein, a convenient reporter of N-glycosylation in Hfx. volcanii. Relying on bioinformatics, topological analysis, gene deletion, mass spectrometry, and biochemical assays, AglS was shown to act as a dolichol phosphate-mannose mannosyltransferase, mediating the transfer of mannose from dolichol phosphate to the tetrasaccharide corresponding to the first four subunits of the pentasaccharide N-linked to the S-layer glycoprotein.
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