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Gu X, Kovacs AS, Myung Y, Ascher DB. Mutations in Glycosyltransferases and Glycosidases: Implications for Associated Diseases. Biomolecules 2024; 14:497. [PMID: 38672513 PMCID: PMC11048727 DOI: 10.3390/biom14040497] [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: 12/12/2023] [Revised: 03/20/2024] [Accepted: 03/22/2024] [Indexed: 04/28/2024] Open
Abstract
Glycosylation, a crucial and the most common post-translational modification, coordinates a multitude of biological functions through the attachment of glycans to proteins and lipids. This process, predominantly governed by glycosyltransferases (GTs) and glycoside hydrolases (GHs), decides not only biomolecular functionality but also protein stability and solubility. Mutations in these enzymes have been implicated in a spectrum of diseases, prompting critical research into the structural and functional consequences of such genetic variations. This study compiles an extensive dataset from ClinVar and UniProt, providing a nuanced analysis of 2603 variants within 343 GT and GH genes. We conduct thorough MTR score analyses for the proteins with the most documented variants using MTR3D-AF2 via AlphaFold2 (AlphaFold v2.2.4) predicted protein structure, with the analyses indicating that pathogenic mutations frequently correlate with Beta Bridge secondary structures. Further, the calculation of the solvent accessibility score and variant visualisation show that pathogenic mutations exhibit reduced solvent accessibility, suggesting the mutated residues are likely buried and their localisation is within protein cores. We also find that pathogenic variants are often found proximal to active and binding sites, which may interfere with substrate interactions. We also incorporate computational predictions to assess the impact of these mutations on protein function, utilising tools such as mCSM to predict the destabilisation effect of variants. By identifying these critical regions that are prone to disease-associated mutations, our study opens avenues for designing small molecules or biologics that can modulate enzyme function or compensate for the loss of stability due to these mutations.
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Affiliation(s)
- Xiaotong Gu
- School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, QLD 4000, Australia; (X.G.); (A.S.K.); (Y.M.)
- Computational Biology and Clinical Informatics, Baker Heart and Diabetes Institute, Melbourne, VIC 3004, Australia
| | - Aaron S. Kovacs
- School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, QLD 4000, Australia; (X.G.); (A.S.K.); (Y.M.)
- Computational Biology and Clinical Informatics, Baker Heart and Diabetes Institute, Melbourne, VIC 3004, Australia
| | - Yoochan Myung
- School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, QLD 4000, Australia; (X.G.); (A.S.K.); (Y.M.)
- Computational Biology and Clinical Informatics, Baker Heart and Diabetes Institute, Melbourne, VIC 3004, Australia
| | - David B. Ascher
- School of Chemistry and Molecular Biosciences, University of Queensland, Brisbane, QLD 4000, Australia; (X.G.); (A.S.K.); (Y.M.)
- Computational Biology and Clinical Informatics, Baker Heart and Diabetes Institute, Melbourne, VIC 3004, Australia
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2
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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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3
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Mei J, Li Z, Zhou S, Chen XL, Wilson RA, Liu W. Effector secretion and stability in the maize anthracnose pathogen Colletotrichum graminicola requires N-linked protein glycosylation and the ER chaperone pathway. THE NEW PHYTOLOGIST 2023; 240:1449-1466. [PMID: 37598305 DOI: 10.1111/nph.19213] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/07/2023] [Accepted: 08/01/2023] [Indexed: 08/21/2023]
Abstract
N-linked protein glycosylation is a conserved and essential modification mediating protein processing and quality control in the endoplasmic reticulum (ER), but how this contributes to the infection cycle of phytopathogenic fungi is largely unknown. In this study, we discovered that inhibition of protein N-glycosylation severely affected vegetative growth, hyphal tip development, conidial germination, appressorium formation, and, ultimately, the ability of the maize (Zea mays) anthracnose pathogen Colletotrichum graminicola to infect its host. Quantitative proteomics analysis showed that N-glycosylation can coordinate protein O-glycosylation, glycosylphosphatidylinositol anchor modification, and endoplasmic reticulum quality control (ERQC) by directly targeting the proteins from the corresponding pathway in the ER. We performed a functional study of the N-glycosylation pathway-related protein CgALG3 and of the ERQC pathway-related protein CgCNX1, which demonstrated that N-glycosylation of ER chaperone proteins is essential for effector stability, secretion, and pathogenicity of C. graminicola. Our study provides concrete evidence for the regulation of effector protein stability and secretion by N-glycosylation.
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Affiliation(s)
- Jie Mei
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, 100193, China
- Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, 518120, China
| | - Zhiqiang Li
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, 100193, China
| | - Shaoqun Zhou
- Shenzhen Branch, Guangdong Laboratory of Lingnan Modern Agriculture, Genome Analysis Laboratory of the Ministry of Agriculture and Rural Affairs, Agricultural Genomics Institute at Shenzhen, Chinese Academy of Agricultural Sciences, Shenzhen, 518120, China
| | - Xiao-Lin Chen
- State Key Laboratory of Agricultural Microbiology and Provincial Hubei Key Laboratory of Plant Pathology, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan, 430070, China
| | - Richard A Wilson
- Department of Plant Pathology, University of Nebraska-Lincoln, Lincoln, NE, 68583, USA
| | - Wende Liu
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, 100193, China
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4
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Wang CD, Xu S, Chen S, Chen ZH, Dean N, Wang N, Gao XD. An in vitro assay for enzymatic studies on human ALG13/14 heterodimeric UDP-N-acetylglucosamine transferase. Front Cell Dev Biol 2022; 10:1008078. [PMID: 36200043 PMCID: PMC9527342 DOI: 10.3389/fcell.2022.1008078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2022] [Accepted: 08/30/2022] [Indexed: 11/13/2022] Open
Abstract
The second step of eukaryotic lipid-linked oligosaccharide (LLO) biosynthesis is catalyzed by the conserved ALG13/ALG14 heterodimeric UDP-N-acetylglucosamine transferase (GnTase). In humans, mutations in ALG13 or ALG14 lead to severe neurological disorders with a multisystem phenotype, known as ALG13/14-CDG (congenital disorders of glycosylation). How these mutations relate to disease is unknown because to date, a reliable GnTase assay for studying the ALG13/14 complex is lacking. Here we describe the development of a liquid chromatography/mass spectrometry-based quantitative GnTase assay using chemically synthesized GlcNAc-pyrophosphate-dolichol as the acceptor and purified human ALG13/14 dimeric enzyme. This assay enabled us to demonstrate that in contrast to the literature, only the shorter human ALG13 isoform 2, but not the longer isoform 1 forms a functional complex with ALG14 that participates in LLO synthesis. The longer ALG13 isoform 1 does not form a complex with ALG14 and therefore lacks GnTase activity. Importantly, we further established a quantitative assay for GnTase activities of ALG13- and ALG14-CDG variant alleles, demonstrating that GnTase deficiency is the cause of ALG13/14-CDG phenotypes.
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Affiliation(s)
- Chun-Di Wang
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, China
| | - Si Xu
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, China
| | - Shuai Chen
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, China
| | - Zheng-Hui Chen
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, China
| | - Neta Dean
- Department of Biochemistry and Cell Biology, Stony Brook University, New York City, NY, United States
| | - Ning Wang
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, China
- *Correspondence: Xiao-Dong Gao, ; Ning Wang,
| | - Xiao-Dong Gao
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi, China
- State Key Laboratory of Biochemical Engineering, Institute of Process Engineering, Chinese Academy of Sciences, Beijing, China
- *Correspondence: Xiao-Dong Gao, ; Ning Wang,
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Meyer BH, Adam PS, Wagstaff BA, Kolyfetis GE, Probst AJ, Albers SV, Dorfmueller HC. Agl24 is an ancient archaeal homolog of the eukaryotic N-glycan chitobiose synthesis enzymes. eLife 2022; 11:e67448. [PMID: 35394422 PMCID: PMC8993221 DOI: 10.7554/elife.67448] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Accepted: 03/13/2022] [Indexed: 11/13/2022] Open
Abstract
Protein N-glycosylation is a post-translational modification found in organisms of all domains of life. The crenarchaeal N-glycosylation begins with the synthesis of a lipid-linked chitobiose core structure, identical to that in Eukaryotes, although the enzyme catalyzing this reaction remains unknown. Here, we report the identification of a thermostable archaeal β-1,4-N-acetylglucosaminyltransferase, named archaeal glycosylation enzyme 24 (Agl24), responsible for the synthesis of the N-glycan chitobiose core. Biochemical characterization confirmed its function as an inverting β-D-GlcNAc-(1→4)-α-D-GlcNAc-diphosphodolichol glycosyltransferase. Substitution of a conserved histidine residue, found also in the eukaryotic and bacterial homologs, demonstrated its functional importance for Agl24. Furthermore, bioinformatics and structural modeling revealed similarities of Agl24 to the eukaryotic Alg14/13 and a distant relation to the bacterial MurG, which are catalyzing the same or a similar reaction, respectively. Phylogenetic analysis of Alg14/13 homologs indicates that they are ancient in Eukaryotes, either as a lateral transfer or inherited through eukaryogenesis.
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Affiliation(s)
- Benjamin H Meyer
- Environmental Microbiology and Biotechnology (EMB), Aquatic Microbial Ecology, University of Duisburg-EssenEssenGermany
- Division of Molecular Microbiology, School of Life Sciences, University of DundeeDundeeUnited Kingdom
- Molecular Biology of Archaea, Faculty of Biology, University of FreiburgFreiburgGermany
| | - Panagiotis S Adam
- Group for Aquatic Microbial Ecology, Environmental Microbiology and Biotechnology, Faculty of Chemistry University Duisburg-EssenEssenGermany
| | - Ben A Wagstaff
- Division of Molecular Microbiology, School of Life Sciences, University of DundeeDundeeUnited Kingdom
| | - George E Kolyfetis
- Department of Biochemistry and Molecular Biology, Faculty of Biology, National and Kapodistrian University of AthensAthensGreece
| | - Alexander J Probst
- Centre of Water and Environmental Research (ZWU), University of Duisburg-EssenEssenGermany
| | - Sonja V Albers
- Molecular Biology of Archaea, Faculty of Biology, University of FreiburgFreiburgGermany
| | - Helge C Dorfmueller
- Division of Molecular Microbiology, School of Life Sciences, University of DundeeDundeeUnited Kingdom
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6
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Structural Analysis of the Effect of Asn107Ser Mutation on Alg13 Activity and Alg13-Alg14 Complex Formation and Expanding the Phenotypic Variability of ALG13-CDG. Biomolecules 2022; 12:biom12030398. [PMID: 35327592 PMCID: PMC8945535 DOI: 10.3390/biom12030398] [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: 10/16/2021] [Accepted: 03/02/2022] [Indexed: 11/16/2022] Open
Abstract
Congenital Disorders of Glycosylation (CDG) are multisystemic metabolic disorders showing highly heterogeneous clinical presentation, molecular etiology, and laboratory results. Here, we present different transferrin isoform patterns (obtained by isoelectric focusing) from three female patients harboring the ALG13 c.320A>G mutation. Contrary to other known variants of type I CDGs, where transferrin isoelectric focusing revealed notably increased asialo- and disialotransferrin fractions, a normal glycosylation pattern was observed in the probands. To verify this data and give novel insight into this variant, we modeled the human Alg13 protein and analyzed the dynamics of the apo structure and the complex with the UDP-GlcNAc substrate. We also modeled the Alg13-Alg14 heterodimer and ran multiple simulations of the complex in the presence of the substrate. Finally, we proposed a plausible complex formation mechanism.
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Alg mannosyltransferases: From functional and structural analyses to the lipid-linked oligosaccharide pathway reconstitution. Biochim Biophys Acta Gen Subj 2022; 1866:130112. [PMID: 35217128 DOI: 10.1016/j.bbagen.2022.130112] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2021] [Revised: 02/06/2022] [Accepted: 02/12/2022] [Indexed: 11/21/2022]
Abstract
BACKGROUND N-glycosylation is initiated from the biosynthesis of lipid-linked oligosaccharide (LLO) on the endoplasmic reticulum (ER), which is catalyzed by a series of Alg (asparagine-linked glycosylation) proteins. SCOPE OF REVIEW This review summarizes our recent studies on the enzymology of Alg mannosyltransferases (MTases). We also discuss the membrane topology and physiological importance of several ER cytosolic Alg proteins. MAJOR CONCLUSIONS Utilizing an efficient prokaryotic protein expression system and a new LC-MS quantitative activity assay, we overexpressed all Alg MTases and performed enzymology studies. Moreover, by reconstituting the LLO pathway, the high-yield chemoenzymatic synthesis of high-mannose-type N-glycans was accomplished using recombinant Alg MTases. GENERAL SIGNIFICANCE The analysis of the enzymology and topology of Alg MTases has provided valuable biochemical information in the LLO biosynthesis pathway. In addition, an efficient chemoenzymatic strategy that could prepare various oligomannose-type N-glycans in sufficient amounts was established for further biological assays.
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8
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Topological and enzymatic analysis of human Alg2 mannosyltransferase reveals its role in lipid-linked oligosaccharide biosynthetic pathway. Commun Biol 2022; 5:117. [PMID: 35136180 PMCID: PMC8827073 DOI: 10.1038/s42003-022-03066-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2021] [Accepted: 01/20/2022] [Indexed: 11/14/2022] Open
Abstract
N-glycosylation starts with the biosynthesis of lipid-linked oligosaccharide (LLO) on the endoplasmic reticulum (ER). Alg2 mannosyltransferase adds both the α1,3- and α1,6-mannose (Man) onto ManGlcNAc2-pyrophosphate-dolichol (M1Gn2-PDol) in either order to generate the branched M3Gn2-PDol product. The well-studied yeast Alg2 interacts with ER membrane through four hydrophobic domains. Unexpectedly, we show that Alg2 structure has diverged between yeast and humans. Human Alg2 (hAlg2) associates with the ER via a single membrane-binding domain and is markedly more stable in vitro. These properties were exploited to develop a liquid chromatography-mass spectrometry quantitative kinetics assay for studying purified hAlg2. Under physiological conditions, hAlg2 prefers to transfer α1,3-Man onto M1Gn2 before adding the α1,6-Man. However, this bias is altered by an excess of GDP-Man donor or an increased level of M1Gn2 substrate, both of which trigger production of the M2Gn2(α-1,6)-PDol. These results suggest that Alg2 may regulate the LLO biosynthetic pathway by controlling accumulation of M2Gn2 (α-1,6) intermediate. Despite the conservation of N-glycosylation, human and yeast Alg2 structures have diverged with distinct ER-binding topologies. The human enzyme is more stable than the yeast orthologue, and its activity is modulated by the concentration of donor or acceptor substrate.
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9
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Katata Y, Uneoka S, Saijyo N, Aihara Y, Miyazoe T, Koyamaishi S, Oikawa Y, Ito Y, Abe Y, Numata-Uematsu Y, Takayama J, Kikuchi A, Tamiya G, Uematsu M, Kure S. The longest reported sibling survivors of a severe form of congenital myasthenic syndrome with the ALG14 pathogenic variant. Am J Med Genet A 2021; 188:1293-1298. [PMID: 34971077 DOI: 10.1002/ajmg.a.62629] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Revised: 10/26/2021] [Accepted: 12/07/2021] [Indexed: 11/06/2022]
Abstract
Congenital myasthenic syndromes (CMS) is a group of diseases that causes abnormalities at the neuromuscular junction owing to genetic anomalies. The pathogenic variant in ALG14 results in a severe pathological form of CMS causing end-plate acetylcholine receptor deficiency. Here, we report the cases of two siblings with CMS associated with a novel variant in ALG14. Immediately after birth, they showed hypotonia and multiple joint contractures with low Apgar scores. Ptosis, low-set ears, and high-arched palate were noted. Deep tendon reflexes were symmetrical. They showed worsening swallowing and respiratory problems; hence, nasal feeding and tracheotomy were performed. Cranial magnetic resonance imaging scans revealed delayed myelination and cerebral atrophy. Exome sequencing indicated that the siblings had novel compound heterozygous missense variants, c.590T>G (p.Val197Gly) and c.433G>A (p.Gly145Arg), in exon 4 of ALG14. Repetitive nerve stimulation test showed an abnormal decrease in compound muscle action potential. After treatment with pyridostigmine, the time off the respirator increased. Their epileptic seizures were well controlled by anti-epileptic drugs. Their clinical course is stable even now at the ages of 5 and 2 years, making them the longest reported survivors of a severe form of CMS with the ALG14 variant thus far.
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Affiliation(s)
- Yu Katata
- Department of Pediatrics, Tohoku University School of Medicine, Sendai, Japan
| | - Saki Uneoka
- Department of Pediatrics, Tohoku University School of Medicine, Sendai, Japan
| | - Naoya Saijyo
- Department of Pediatrics, Tohoku University School of Medicine, Sendai, Japan
| | - Yu Aihara
- Department of Pediatrics, Tohoku University School of Medicine, Sendai, Japan
| | - Takamitsu Miyazoe
- Department of Pediatrics, Tohoku University School of Medicine, Sendai, Japan
| | - Shun Koyamaishi
- Department of Pediatrics, Hachinohe City Hospital, Hachinohe, Japan
| | - Yoshitsugu Oikawa
- Department of Pediatrics, Tohoku University School of Medicine, Sendai, Japan
| | - Yuya Ito
- Department of Pediatrics, Hachinohe City Hospital, Hachinohe, Japan.,Department of Neonatology, Aomori Prefectural Central Hospital, Hachinohe, Japan
| | - Yu Abe
- Department of Pediatrics, Tohoku University School of Medicine, Sendai, Japan.,Department of Pediatrics, Tsuruoka Municipal Shonai Hospital, Tsuruoka, Japan
| | | | - Jun Takayama
- Department of AI and Innovative Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan.,Tohoku Medical Megabank Organization, Tohoku University, Sendai, Japan.,Statistical Genetics Team, RIKEN Center for Advanced Intelligence Project, Tokyo, Japan
| | - Atsuo Kikuchi
- Department of Pediatrics, Tohoku University School of Medicine, Sendai, Japan
| | - Gen Tamiya
- Department of AI and Innovative Medicine, Tohoku University Graduate School of Medicine, Sendai, Japan.,Tohoku Medical Megabank Organization, Tohoku University, Sendai, Japan.,Statistical Genetics Team, RIKEN Center for Advanced Intelligence Project, Tokyo, Japan
| | - Mitsugu Uematsu
- Department of Pediatrics, Tohoku University School of Medicine, Sendai, Japan
| | - Shigeo Kure
- Department of Pediatrics, Tohoku University School of Medicine, Sendai, Japan
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Abstract
N-glycosylation is a highly conserved glycan modification, and more than 7000 proteins are N-glycosylated in humans. N-glycosylation has many biological functions such as protein folding, trafficking, and signal transduction. Thus, glycan modification to proteins is profoundly involved in numerous physiological and pathological processes. The N-glycan precursor is biosynthesized in the endoplasmic reticulum (ER) from dolichol phosphate by sequential enzymatic reactions to generate the dolichol-linked oligosaccharide composed of 14 sugar residues, Glc3Man9GlcNAc2. The oligosaccharide is then en bloc transferred to the consensus sequence N-X-S/T (X represents any amino acid except proline) of nascent proteins. Subsequently, the N-glycosylated nascent proteins enter the folding step, in which N-glycans contribute largely to attaining the correct protein fold by recruiting the lectin-like chaperones, calnexin, and calreticulin. Despite the N-glycan-dependent folding process, some glycoproteins do not fold correctly, and these misfolded glycoproteins are destined to degradation by proteasomes in the cytosol. Properly folded proteins are transported to the Golgi, and N-glycans undergo maturation by the sequential reactions of glycosidases and glycosyltransferases, generating complex-type N-glycans. N-Acetylglucosaminyltransferases (GnT-III, GnT-IV, and GnT-V) produce branched N-glycan structures, affording a higher complexity to N-glycans. In this chapter, we provide an overview of the biosynthetic pathway of N-glycans in the ER and Golgi.
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Ng BG, Eklund EA, Shiryaev SA, Dong YY, Abbott MA, Asteggiano C, Bamshad MJ, Barr E, Bernstein JA, Chelakkadan S, Christodoulou J, Chung WK, Ciliberto MA, Cousin J, Gardiner F, Ghosh S, Graf WD, Grunewald S, Hammond K, Hauser NS, Hoganson GE, Houck KM, Kohler JN, Morava E, Larson AA, Liu P, Madathil S, McCormack C, Meeks NJ, Miller R, Monaghan KG, Nickerson DA, Palculict TB, Papazoglu GM, Pletcher BA, Scheffer IE, Schenone AB, Schnur RE, Si Y, Rowe LJ, Serrano Russi AH, Russo RS, Thabet F, Tuite A, Mercedes Villanueva M, Wang RY, Webster RI, Wilson D, Zalan A, Wolfe LA, Rosenfeld JA, Rhodes L, Freeze HH. Predominant and novel de novo variants in 29 individuals with ALG13 deficiency: Clinical description, biomarker status, biochemical analysis, and treatment suggestions. J Inherit Metab Dis 2020; 43:1333-1348. [PMID: 32681751 PMCID: PMC7722193 DOI: 10.1002/jimd.12290] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/21/2020] [Revised: 07/03/2020] [Accepted: 07/09/2020] [Indexed: 12/14/2022]
Abstract
Asparagine-linked glycosylation 13 homolog (ALG13) encodes a nonredundant, highly conserved, X-linked uridine diphosphate (UDP)-N-acetylglucosaminyltransferase required for the synthesis of lipid linked oligosaccharide precursor and proper N-linked glycosylation. De novo variants in ALG13 underlie a form of early infantile epileptic encephalopathy known as EIEE36, but given its essential role in glycosylation, it is also considered a congenital disorder of glycosylation (CDG), ALG13-CDG. Twenty-four previously reported ALG13-CDG cases had de novo variants, but surprisingly, unlike most forms of CDG, ALG13-CDG did not show the anticipated glycosylation defects, typically detected by altered transferrin glycosylation. Structural homology modeling of two recurrent de novo variants, p.A81T and p.N107S, suggests both are likely to impact the function of ALG13. Using a corresponding ALG13-deficient yeast strain, we show that expressing yeast ALG13 with either of the highly conserved hotspot variants rescues the observed growth defect, but not its glycosylation abnormality. We present molecular and clinical data on 29 previously unreported individuals with de novo variants in ALG13. This more than doubles the number of known cases. A key finding is that a vast majority of the individuals presents with West syndrome, a feature shared with other CDG types. Among these, the initial epileptic spasms best responded to adrenocorticotropic hormone or prednisolone, while clobazam and felbamate showed promise for continued epilepsy treatment. A ketogenic diet seems to play an important role in the treatment of these individuals.
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Affiliation(s)
- Bobby G. Ng
- Human Genetics Program, Sanford Children’s Health Research Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California
| | - Erik A. Eklund
- Human Genetics Program, Sanford Children’s Health Research Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California
- Department of Clinical Sciences, Lund, Pediatrics, Lund University, Lund, Sweden
| | - Sergey A. Shiryaev
- Human Genetics Program, Sanford Children’s Health Research Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California
| | - Yin Y. Dong
- Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford, UK
| | - Mary-Alice Abbott
- Department of Pediatrics, Baystate Children’s Hospital, University of Massachusetts Medical School - Baystate, Springfield, Massachusetts
| | - Carla Asteggiano
- CEMECO—CONICET, Children Hospital, School of Medicine, National University of Cordoba, Cordoba, Argentina
- Chair of Pharmacology, Catholic University of Cordoba, Cordoba, Argentina
| | - Michael J. Bamshad
- Department of Pediatrics, University of Washington, Seattle, Washington
- Department of Genome Sciences, University of Washington, Seattle, Washington
| | - Eileen Barr
- Department of Human Genetics, Emory University, Atlanta, Georgia
| | - Jonathan A. Bernstein
- Stanford University School of Medicine, Stanford, California
- Stanford Center for Undiagnosed Diseases, Stanford University, Stanford, California
| | | | - John Christodoulou
- Brain and Mitochondrial Research Group, Murdoch Children’s Research Institute, Royal Children’s Hospital, Melbourne, Australia
- Department of Paediatrics, University of Melbourne, Melbourne, Australia
- Discipline of Child and Adolescent Health, Sydney Medical School, University of Sydney, Sydney, Australia
| | - Wendy K. Chung
- Department of Pediatrics, Columbia University, New York, New York
- Department of Medicine, Columbia University, New York, New York
| | - Michael A. Ciliberto
- Department of Pediatrics, University of Iowa Hospitals and Clinics, Iowa City, Iowa
| | - Janice Cousin
- Section of Human Biochemical Genetics, National Human Genome Research Institute, Bethesda, Maryland
| | - Fiona Gardiner
- University of Melbourne, Austin Health, Melbourne, Australia
| | - Suman Ghosh
- Department of Pediatrics Division of Pediatric Neurology, University of Florida College of Medicine, Gainesville, Florida
| | - William D. Graf
- Division of Pediatric Neurology, Department of Pediatrics, Connecticut Children’s; University of Connecticut, Farmington, Connecticut
| | - Stephanie Grunewald
- Metabolic Medicine Department, Great Ormond Street Hospital, Institute of Child Health University College London, NIHR Biomedical Research Center, London, UK
| | - Katherine Hammond
- Division of Pediatric Neurology, Department of Pediatrics, University of Alabama at Birmingham, Birmingham, Alabama
| | - Natalie S. Hauser
- Inova Translational Medicine Institute Division of Medical Genomics Inova Fairfax Hospital Falls Church, Virginia
| | - George E. Hoganson
- Department of Pediatrics, University of Illinois at Chicago, Chicago, Illinois
| | - Kimberly M. Houck
- Department of Pediatrics, Section of Neurology and Developmental Neuroscience, Baylor College of Medicine, Houston, Texas
| | - Jennefer N. Kohler
- Stanford University School of Medicine, Stanford, California
- Division of Cardiovascular Medicine, Department of Medicine, Stanford University School of Medicine, Stanford, California
| | - Eva Morava
- Department of Clinical Genomics, Mayo Clinic, Rochester, Minnesota
| | - Austin A. Larson
- Section of Clinical Genetics and Metabolism, Department of Pediatrics, University of Colorado, Anschutz Medical Campus, Aurora, Colorado
| | - Pengfei Liu
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas
- Baylor Genetics Laboratories, Houston, Texas
| | - Sujana Madathil
- Department of Pediatrics, University of Iowa Hospitals and Clinics, Iowa City, Iowa
| | - Colleen McCormack
- Stanford University School of Medicine, Stanford, California
- Division of Cardiovascular Medicine, Department of Medicine, Stanford University School of Medicine, Stanford, California
| | - Naomi J.L. Meeks
- Section of Clinical Genetics and Metabolism, Department of Pediatrics, University of Colorado, Anschutz Medical Campus, Aurora, Colorado
| | - Rebecca Miller
- Inova Translational Medicine Institute Division of Medical Genomics Inova Fairfax Hospital Falls Church, Virginia
| | | | | | | | - Gabriela Magali Papazoglu
- CEMECO—CONICET, Children Hospital, School of Medicine, National University of Cordoba, Cordoba, Argentina
| | - Beth A. Pletcher
- Department of Pediatrics, Rutgers New Jersey Medical School, Newark, New Jersey
| | - Ingrid E. Scheffer
- University of Melbourne, Austin Health, Melbourne, Australia
- University of Melbourne, Royal Children’s Hospital, Florey and Murdoch Institutes, Melbourne, Australia
| | | | | | - Yue Si
- GeneDx, Inc. Laboratory, Gaithersburg, Maryland
| | - Leah J. Rowe
- Section of Clinical Genetics and Metabolism, Department of Pediatrics, University of Colorado, Anschutz Medical Campus, Aurora, Colorado
| | - Alvaro H. Serrano Russi
- Division of Medical Genetics Children’s Hospital Los Angeles, University of Southern California, Los Angeles, California
- Keck School of Medicine, University of Southern California, Los Angeles, California
| | | | | | - Allysa Tuite
- Department of Pediatrics, Rutgers New Jersey Medical School, Newark, New Jersey
| | | | - Raymond Y. Wang
- Division of Metabolic Disorders, Children’s Hospital of Orange County, Orange, California
- Department of Pediatrics, University of California-Irvine, Orange, California
| | - Richard I. Webster
- T.Y. Nelson Department of Neurology and Neurosurgery, The Children’s Hospital, Westmead, Australia
- Kids Neuroscience Centre, The Children’s Hospital, Westmead, Australia
| | - Dorcas Wilson
- Netcare Sunninghill Hospital, Sandton, South Africa
- Nelson Mandela Children’s Hospital, Johannesburg, South Africa
| | - Alice Zalan
- Department of Pediatrics, University of Illinois at Chicago, Chicago, Illinois
| | | | - Lynne A. Wolfe
- Undiagnosed Diseases Program, Common Fund, National Institutes of Health, Bethesda, Maryland
| | - Jill A. Rosenfeld
- Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas
- Baylor Genetics Laboratories, Houston, Texas
| | | | - Hudson H. Freeze
- Human Genetics Program, Sanford Children’s Health Research Center, Sanford Burnham Prebys Medical Discovery Institute, La Jolla, California
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12
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Huo J, Ren S, Gao P, Wan D, Rong S, Li X, Liu S, Xu S, Sun K, Guo B, Wang P, Yu B, Wu J, Wang F, Sun T. ALG13 participates in epileptogenesis via regulation of GABA A receptors in mouse models. Cell Death Discov 2020; 6:87. [PMID: 33014431 PMCID: PMC7499177 DOI: 10.1038/s41420-020-00319-6] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2020] [Revised: 08/09/2020] [Accepted: 09/01/2020] [Indexed: 12/23/2022] Open
Abstract
ALG13 (asparagine-linked glycosylation 13) plays crucial roles in the process of N-linked glycosylation. Mutations of the ALG13 gene underlie congenital disorders of glycosylation type I (CDG-I), a rare human genetic disorder with defective glycosylation. Epilepsy is commonly observed in congenital disorders of glycosylation type I (CDG-I). In our study, we found that about 20% of adult ALG13KO knockout mice display spontaneous seizures, which were identified in a simultaneous video and intracranial EEG recording. However, the mechanisms of ALG13 by which deficiency leads to epilepsy are unknown. Whole-cell patch-clamp recordings demonstrated that ALG13KO mice show a marked decrease in gamma-aminobutyric acid A receptor (GABAAR)-mediated inhibitory synaptic transmission. Furthermore, treatment with low-dose diazepam (a positive allosteric modulator of GABAA receptors), which enhances GABAAR function, also markedly ameliorates severity of epileptic seizures in ALG13KO mice. Moreover, ALG13 may influenced the expression of GABAARα2 membrane and total protein by changing transcription level of GABAARα2. Furthermore, protein interactions between ALG13 and GABAARα2 were observed in the cortex of wild-type mice. Overall, these results reveal that ALG13 may be involved in the occurrence of epilepsy through the regulation of GABAAR function, and may provide new insight into epilepsy prevention and treatment.
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Affiliation(s)
- Junming Huo
- Ningxia Key Laboratory of Cerebrocranial Diseases, Ningxia Medical University, 1160 Shengli Street, Yinchuan, 750001 Ningxia China
| | - Shuanglai Ren
- Ningxia Key Laboratory of Cerebrocranial Diseases, Ningxia Medical University, 1160 Shengli Street, Yinchuan, 750001 Ningxia China
| | - Peng Gao
- Ningxia Key Laboratory of Cerebrocranial Diseases, Ningxia Medical University, 1160 Shengli Street, Yinchuan, 750001 Ningxia China
- Department of Neurosurgery, General Hospital of Ningxia Medical University, 804 Shengli Street, Yinchuan, 750001 Ningxia China
| | - Ding Wan
- Ningxia Key Laboratory of Cerebrocranial Diseases, Ningxia Medical University, 1160 Shengli Street, Yinchuan, 750001 Ningxia China
- Department of Neurosurgery, General Hospital of Ningxia Medical University, 804 Shengli Street, Yinchuan, 750001 Ningxia China
| | - Shikuo Rong
- Ningxia Key Laboratory of Cerebrocranial Diseases, Ningxia Medical University, 1160 Shengli Street, Yinchuan, 750001 Ningxia China
| | - Xinxiao Li
- Ningxia Key Laboratory of Cerebrocranial Diseases, Ningxia Medical University, 1160 Shengli Street, Yinchuan, 750001 Ningxia China
| | - Shenhai Liu
- Ningxia Key Laboratory of Cerebrocranial Diseases, Ningxia Medical University, 1160 Shengli Street, Yinchuan, 750001 Ningxia China
| | - Siying Xu
- Ningxia Key Laboratory of Cerebrocranial Diseases, Ningxia Medical University, 1160 Shengli Street, Yinchuan, 750001 Ningxia China
| | - Kuisheng Sun
- Ningxia Key Laboratory of Cerebrocranial Diseases, Ningxia Medical University, 1160 Shengli Street, Yinchuan, 750001 Ningxia China
| | - Baorui Guo
- Ningxia Key Laboratory of Cerebrocranial Diseases, Ningxia Medical University, 1160 Shengli Street, Yinchuan, 750001 Ningxia China
| | - Peng Wang
- Ningxia Key Laboratory of Cerebrocranial Diseases, Ningxia Medical University, 1160 Shengli Street, Yinchuan, 750001 Ningxia China
| | - Baoli Yu
- Renji Hospital Shanghai Jiaotong University School of Medicine, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders (Ministry of Education), Bio-X Institutes, Shanghai Jiao Tong University, Shanghai, 200240 China
| | - Ji Wu
- Renji Hospital Shanghai Jiaotong University School of Medicine, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders (Ministry of Education), Bio-X Institutes, Shanghai Jiao Tong University, Shanghai, 200240 China
- Ningxia Key Laboratory of Reproduction and Genetics, Ningxia Medical University, 1160 Shengli Street, Yinchuan, 750001 Ningxia China
| | - Feng Wang
- Ningxia Key Laboratory of Cerebrocranial Diseases, Ningxia Medical University, 1160 Shengli Street, Yinchuan, 750001 Ningxia China
- Department of Neurosurgery, General Hospital of Ningxia Medical University, 804 Shengli Street, Yinchuan, 750001 Ningxia China
| | - Tao Sun
- Ningxia Key Laboratory of Cerebrocranial Diseases, Ningxia Medical University, 1160 Shengli Street, Yinchuan, 750001 Ningxia China
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13
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CRISPR/Cas9-mediated mutation of asparagine-linked glycosylation 13 transcript variant 1 causes epilepsy in mice. JOURNAL OF BIO-X RESEARCH 2020. [DOI: 10.1097/jbr.0000000000000059] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
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14
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Inhibition of Dephosphorylation of Dolichyl Diphosphate Alters the Synthesis of Dolichol and Hinders Protein N-Glycosylation and Morphological Transitions in Candida albicans. Int J Mol Sci 2019; 20:ijms20205067. [PMID: 31614738 PMCID: PMC6829516 DOI: 10.3390/ijms20205067] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Revised: 10/11/2019] [Accepted: 10/11/2019] [Indexed: 11/17/2022] Open
Abstract
The essential role of dolichyl phosphate (DolP) as a carbohydrate carrier during protein N-glycosylation is well established. The cellular pool of DolP is derived from de novo synthesis in the dolichol branch of the mevalonate pathway and from recycling of DolPP after each cycle of N-glycosylation, when the oligosaccharide is transferred from the lipid carrier to the protein and DolPP is released and then dephosphorylated. In Saccharomyces cerevisiae, the dephosphorylation of DolPP is known to be catalyzed by the Cwh8p protein. To establish the role of the Cwh8p orthologue in another distantly related yeast species, Candida albicans, we studied its mutant devoid of the CaCWH8 gene. A double Cacwh8∆/Cacwh8∆ strain was constructed by the URA-blaster method. As in S. cerevisiae, the mutant was impaired in DolPP recycling. This defect, however, was accompanied by an elevation of cis-prenyltransferase activity and higher de novo production of dolichols. Despite these compensatory changes, protein glycosylation, cell wall integrity, filamentous growth, and biofilm formation were impaired in the mutant. These results suggest that the defects are not due to the lack of DolP for the protein N-glycosylation but rather that the activity of oligosacharyltransferase could be inhibited by the excess DolPP accumulating in the mutant.
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15
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SNV discovery and functional candidate gene identification for milk composition based on whole genome resequencing of Holstein bulls with extremely high and low breeding values. PLoS One 2019; 14:e0220629. [PMID: 31369641 PMCID: PMC6675115 DOI: 10.1371/journal.pone.0220629] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2019] [Accepted: 07/19/2019] [Indexed: 02/06/2023] Open
Abstract
We have sequenced the whole genomes of eight proven Holstein bulls from the four half-sib or full-sib families with extremely high and low estimated breeding values (EBV) for milk protein percentage (PP) and fat percentage (FP) using Illumina re-sequencing technology. Consequently, 2.3 billion raw reads were obtained with an average effective depth of 8.1×. After single nucleotide variant (SNV) calling, total 10,961,243 SNVs were identified, and 57,451 of them showed opposite fixed sites between the bulls with high and low EBVs within each family (called as common differential SNVs). Next, we annotated the common differential SNVs based on the bovine reference genome, and observed that 45,188 SNVs (78.70%) were located in the intergenic region of genes and merely 11,871 SNVs (20.67%) located within the protein-coding genes. Of them, 13,099 common differential SNVs that were within or close to protein-coding genes with less than 5 kb were chosen for identification of candidate genes for milk compositions in dairy cattle. By integrated analysis of the 2,657 genes with the GO terms and pathways related to protein and fat metabolism, and the known quantitative trait loci (QTLs) for milk protein and fat traits, we identified 17 promising candidate genes: ALG14, ATP2C1, PLD1, C3H1orf85, SNX7, MTHFD2L, CDKN2D, COL5A3, FDX1L, PIN1, FIG4, EXOC7, LASP1, PGS1, SAO, GPLD1 and MGEA5. Our findings provided an important foundation for further study and a prompt for molecular breeding of dairy cattle.
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16
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Li ST, Lu TT, Xu XX, Ding Y, Li Z, Kitajima T, Dean N, Wang N, Gao XD. Reconstitution of the lipid-linked oligosaccharide pathway for assembly of high-mannose N-glycans. Nat Commun 2019; 10:1813. [PMID: 31000718 PMCID: PMC6472349 DOI: 10.1038/s41467-019-09752-3] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2018] [Accepted: 03/29/2019] [Indexed: 11/11/2022] Open
Abstract
The asparagine (N)-linked Man9GlcNAc2 is required for glycoprotein folding and secretion. Understanding how its structure contributes to these functions has been stymied by our inability to produce this glycan as a homogenous structure of sufficient quantities for study. Here, we report the high yield chemoenzymatic synthesis of Man9GlcNAc2 and its biosynthetic intermediates by reconstituting the eukaryotic lipid-linked oligosaccharide (LLO) pathway. Endoplasmic reticulum mannosyltransferases (MTases) are expressed in E. coli and used for mannosylation of the dolichol mimic, phytanyl pyrophosphate GlcNAc2. These recombinant MTases recognize unique substrates and when combined, synthesize end products that precisely mimic those in vivo, demonstrating that ordered assembly of LLO is due to the strict enzyme substrate specificity. Indeed, non-physiological glycans are produced only when the luminal MTases are challenged with cytosolic substrates. Reconstitution of the LLO pathway to synthesize Man9GlcNAc2 in vitro provides an important tool for functional studies of the N-linked glycoprotein biosynthesis pathway. Attachment of the oligosaccharide Man9GlcNAc2 is required for glycoprotein folding and secretion but synthesizing this compound for structural and functional studies has remained challenging. Here, the authors achieve efficient Man9GlcNAc2 synthesis by reconstituting its biosynthetic pathway in vitro.
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Affiliation(s)
- Sheng-Tao Li
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 214122, Wuxi, China
| | - Tian-Tian Lu
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 214122, Wuxi, China
| | - Xin-Xin Xu
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 214122, Wuxi, China
| | - Yi Ding
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 214122, Wuxi, China
| | - Zijie Li
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 214122, Wuxi, China
| | - Toshihiko Kitajima
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 214122, Wuxi, China
| | - Neta Dean
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY, 11794-5215, USA
| | - Ning Wang
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 214122, Wuxi, China.
| | - Xiao-Dong Gao
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 214122, Wuxi, China.
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17
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Xu XX, Li ST, Wang N, Kitajima T, Yoko-O T, Fujita M, Nakanishi H, Gao XD. Structural and functional analysis of Alg1 beta-1,4 mannosyltransferase reveals the physiological importance of its membrane topology. Glycobiology 2019; 28:741-753. [PMID: 29939232 DOI: 10.1093/glycob/cwy060] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Accepted: 06/24/2018] [Indexed: 12/20/2022] Open
Abstract
In eukaryotes, the biosynthesis of a highly conserved dolichol-linked oligosaccharide (DLO) precursor Glc3Man9GlcNAc2-pyrophosphate-dolichol (PP-Dol) begins on the cytoplasmic face of the endoplasmic reticulum (ER) and ends within the lumen. Two functionally distinguished heteromeric glycosyltransferase (GTase) complexes are responsible for the cytosolic DLO assembly. Alg1, a β-1, 4 mannosyltransferase (MTase) physically interacts with Alg2 and Alg11 proteins to form the multienzyme complex which catalyzes the addition of all five mannose to generate the Man5GlcNAc2-PP-Dol intermediate. Despite the fact that Alg1 plays a central role in the formation of the multi-MTase has been confirmed, the topological information of Alg1 including the molecular mechanism of membrane association are still poorly understood. Using a combination of bioinformatics and biological approaches, we have undertaken a structural and functional study on Alg1 protein, in which the enzymatic activities of Alg1 and its variants were monitored by a complementation assay using the GALpr-ALG1 yeast strain, and further confirmed by a liquid chromatography-mass spectrometry-based in vitro quantitative assay. Computational and experimental evidence confirmed Alg1 shares structure similarity with Alg13/14 complex, which has been defined as a membrane-associated GT-B GTase. Particularly, we provide clear evidence that the N-terminal transmembrane domain including the following positively charged amino acids and an N-terminal amphiphilic-like α helix domain exposed on the protein surface strictly coordinate the Alg1 orientation on the ER membrane. This work provides detailed membrane topology of Alg1 and further reveals its biological importance at the spatial aspect in coordination of cytosolic DLO biosynthesis.
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Affiliation(s)
- Xin-Xin Xu
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 1800 Lihu Avenue, Wuxi, China
| | - Sheng-Tao Li
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 1800 Lihu Avenue, Wuxi, China
| | - Ning Wang
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 1800 Lihu Avenue, Wuxi, China
| | - Toshihiko Kitajima
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 1800 Lihu Avenue, Wuxi, China
| | - Takehiko Yoko-O
- Biotechnology Research Institute for Drug Discovery, National Institute of Advanced Industrial Science and Technology (AIST), AIST Tsukuba Central 6, Higashi, Tsukuba, Japan
| | - Morihisa Fujita
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 1800 Lihu Avenue, Wuxi, China
| | - Hideki Nakanishi
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 1800 Lihu Avenue, Wuxi, China
| | - Xiao-Dong Gao
- Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, 1800 Lihu Avenue, Wuxi, China
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18
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Schmid-Hempel P, Aebi M, Barribeau S, Kitajima T, du Plessis L, Schmid-Hempel R, Zoller S. The genomes of Crithidia bombi and C. expoeki, common parasites of bumblebees. PLoS One 2018; 13:e0189738. [PMID: 29304093 PMCID: PMC5755769 DOI: 10.1371/journal.pone.0189738] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2017] [Accepted: 11/30/2017] [Indexed: 11/19/2022] Open
Abstract
Trypanosomatids (Trypanosomatidae, Kinetoplastida) are flagellated protozoa containing many parasites of medical or agricultural importance. Among those, Crithidia bombi and C. expoeki, are common parasites in bumble bees around the world, and phylogenetically close to Leishmania and Leptomonas. They have a simple and direct life cycle with one host, and partially castrate the founding queens greatly reducing their fitness. Here, we report the nuclear genome sequences of one clone of each species, extracted from a field-collected infection. Using a combination of Roche 454 FLX Titanium, Pacific Biosciences PacBio RS, and Illumina GA2 instruments for C. bombi, and PacBio for C. expoeki, we could produce high-quality and well resolved sequences. We find that these genomes are around 32 and 34 MB, with 7,808 and 7,851 annotated genes for C. bombi and C. expoeki, respectively-which is somewhat less than reported from other trypanosomatids, with few introns, and organized in polycistronic units. A large fraction of genes received plausible functional support in comparison primarily with Leishmania and Trypanosoma. Comparing the annotated genes of the two species with those of six other trypanosomatids (C. fasciculata, L. pyrrhocoris, L. seymouri, B. ayalai, L. major, and T. brucei) shows similar gene repertoires and many orthologs. Similar to other trypanosomatids, we also find signs of concerted evolution in genes putatively involved in the interaction with the host, a high degree of synteny between C. bombi and C. expoeki, and considerable overlap with several other species in the set. A total of 86 orthologous gene groups show signatures of positive selection in the branch leading to the two Crithidia under study, mostly of unknown function. As an example, we examined the initiating glycosylation pathway of surface components in C. bombi, finding it deviates from most other eukaryotes and also from other kinetoplastids, which may indicate rapid evolution in the extracellular matrix that is involved in interactions with the host. Bumble bees are important pollinators and Crithidia-infections are suspected to cause substantial selection pressure on their host populations. These newly sequenced genomes provide tools that should help better understand host-parasite interactions in these pollinator pathogens.
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Affiliation(s)
| | - Markus Aebi
- Institute of Microbiology, ETH Zurich, Zürich, Switzerland
| | - Seth Barribeau
- Institute of Integrative Biology (IBZ), ETH Zurich, Zürich, Switzerland
| | | | - Louis du Plessis
- Institute of Integrative Biology (IBZ), ETH Zurich, Zürich, Switzerland
| | | | - Stefan Zoller
- Genetic Diversity Centre (GDC), ETH Zurich, Zürich, Switzerland
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19
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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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20
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Niewiadomska M, Janik A, Perlińska-Lenart U, Piłsyk S, Palamarczyk G, Kruszewska JS. The role of Alg13 N-acetylglucosaminyl transferase in the expression of pathogenic features of Candida albicans. Biochim Biophys Acta Gen Subj 2017; 1861:789-801. [DOI: 10.1016/j.bbagen.2017.01.019] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Revised: 01/16/2017] [Accepted: 01/21/2017] [Indexed: 01/09/2023]
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21
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Harada Y. Biosynthesis and Degradation of Dolichol-Linked Oligosaccharides. TRENDS GLYCOSCI GLYC 2016. [DOI: 10.4052/tigg.1512.1j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Affiliation(s)
- Yoichiro Harada
- Department of Systems Biology in Thromboregulation, Kagoshima University
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22
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Affiliation(s)
- Yoichiro Harada
- Department of Systems Biology in Thromboregulation, Kagoshima University
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23
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Cova M, Rodrigues JA, Smith TK, Izquierdo L. Sugar activation and glycosylation in Plasmodium. Malar J 2015; 14:427. [PMID: 26520586 PMCID: PMC4628283 DOI: 10.1186/s12936-015-0949-z] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Accepted: 10/21/2015] [Indexed: 11/24/2022] Open
Abstract
Glycoconjugates are important mediators of host-pathogen interactions and are usually very abundant in the surface of many protozoan parasites. However, in the particular case of Plasmodium species, previous works show that glycosylphosphatidylinositol anchor modifications, and to an unknown extent, a severely truncated N-glycosylation are the only glycosylation processes taking place in the parasite. Nevertheless, a detailed analysis of the parasite genome and the recent identification of the sugar nucleotide precursors biosynthesized by Plasmodium falciparum support a picture in which several overlooked, albeit not very prominent glycosylations may be occurring during the parasite life cycle. In this work,
the authors review recent developments in the characterization of the biosynthesis of glycosylation precursors in the parasite, focusing on the outline of the possible fates of these precursors.
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Affiliation(s)
- Marta Cova
- ISGlobal, Barcelona Ctr. Int. Health Res. (CRESIB), Hospital Clínic, Universitat de Barcelona, Barcelona, Spain.
| | - João A Rodrigues
- Instituto de Medicina Molecular, Faculdade de Medicina da Universidade de Lisboa, Av. Prof. Egas Moniz, Edificio Egas Moniz, 1649-028, Lisbon, Portugal.
| | - Terry K Smith
- Biomedical Sciences Research Complex, University of St Andrews, North Haugh, St Andrews, Fife, KY16 9ST, UK.
| | - Luis Izquierdo
- ISGlobal, Barcelona Ctr. Int. Health Res. (CRESIB), Hospital Clínic, Universitat de Barcelona, Barcelona, Spain.
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24
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Dimassi S, Labalme A, Ville D, Calender A, Mignot C, Boutry-Kryza N, de Bellescize J, Rivier-Ringenbach C, Bourel-Ponchel E, Cheillan D, Simonet T, Maincent K, Rossi M, Till M, Mougou-Zerelli S, Edery P, Saad A, Heron D, des Portes V, Sanlaville D, Lesca G. Whole-exome sequencing improves the diagnosis yield in sporadic infantile spasm syndrome. Clin Genet 2015; 89:198-204. [PMID: 26138355 DOI: 10.1111/cge.12636] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2015] [Revised: 06/13/2015] [Accepted: 06/29/2015] [Indexed: 12/25/2022]
Abstract
Infantile spasms syndrome (ISs) is characterized by clinical spasms with ictal electrodecrement, usually occurring before the age of 1 year and frequently associated with cognitive impairment. Etiology is widely heterogeneous, the cause remaining elusive in 40% of patients. We searched for de novo mutations in 10 probands with ISs and their parents using whole-exome sequencing (WES). Patients had neither consanguinity nor family history of epilepsy. Common causes of ISs were excluded by brain magnetic resonance imaging (MRI), metabolic screening, array-comparative genomic hybridization (CGH) and testing for mutations in CDKL5, STXBP1, and for ARX duplications. We found a probably pathogenic mutation in four patients. Missense mutations in SCN2A (p.Leu1342Pro) and KCNQ2 (p.Ala306Thr) were found in two patients with no history of epilepsy before the onset of ISs. The p.Asn107Ser missense mutation of ALG13 had been previously reported in four females with ISs. The fourth mutation was an in-frame deletion (p.Phe110del) in NR2F1, a gene whose mutations cause intellectual disability, epilepsy, and optic atrophy. In addition, we found a possibly pathogenic variant in KIF3C that encodes a kinesin expressed during neural development. Our results confirm that WES improves significantly the diagnosis yield in patients with sporadic ISs.
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Affiliation(s)
- S Dimassi
- Department of Medical Genetics, Lyon University Hospital, Lyon, France.,CNRS UMR 5292, INSERM U1028, CNRL, Lyon, France.,Claude Bernard Lyon I University, University of Lyon, Lyon, France.,Cytogenetics and Reproductive Biology Department, Farhat Hached University Teaching Hospital, Sousse, Tunisia.,Common Service Units for Research in Genetics, Faculty of Medicine of Sousse, Avenue Mohamed Karoui, University of Sousse, Tunisia
| | - A Labalme
- Department of Medical Genetics, Lyon University Hospital, Lyon, France
| | - D Ville
- Department of Neuropediatrics, Lyon University Hospital, Lyon, France
| | - A Calender
- Claude Bernard Lyon I University, University of Lyon, Lyon, France.,Department of Molecular Genetics, Lyon University Hospital, Lyon, France
| | - C Mignot
- Département de Génétique et Centre de Référence "Déficiences intellectuelles de causes rares", AP-HP, Groupe Hospitalier Pitié-Salpêtrière, Paris, France.,Department of Pediatric Neurophysiology, Amiens University Hospital, Amiens, France
| | - N Boutry-Kryza
- CNRS UMR 5292, INSERM U1028, CNRL, Lyon, France.,Claude Bernard Lyon I University, University of Lyon, Lyon, France.,Department of Molecular Genetics, Lyon University Hospital, Lyon, France
| | - J de Bellescize
- Epilepsy, Sleep and Pediatric Neurophysiology Department, Lyon University Hospital, Lyon, France
| | - C Rivier-Ringenbach
- Department of Pediatrics, Nord-Ouest Hospital, Villefranche-sur-Saone, France
| | - E Bourel-Ponchel
- Department of Pediatric Neurophysiology, Amiens University Hospital, Amiens, France
| | - D Cheillan
- Claude Bernard Lyon I University, University of Lyon, Lyon, France.,Service des Maladies Héréditaires du métabolisme, INSERM U1060, Lyon University Hospital, Lyon, France
| | - T Simonet
- Department of Cell Biotechnology, ENS Lyon, Lyon University Hospital, Lyon, France
| | - K Maincent
- Department of Pediatric Neurology, Hôpital Trousseau, Assistance Publique des Hôpitaux de Paris, Paris, France
| | - M Rossi
- Department of Medical Genetics, Lyon University Hospital, Lyon, France.,CNRS UMR 5292, INSERM U1028, CNRL, Lyon, France
| | - M Till
- Department of Medical Genetics, Lyon University Hospital, Lyon, France
| | - S Mougou-Zerelli
- Cytogenetics and Reproductive Biology Department, Farhat Hached University Teaching Hospital, Sousse, Tunisia.,Common Service Units for Research in Genetics, Faculty of Medicine of Sousse, Avenue Mohamed Karoui, University of Sousse, Tunisia
| | - P Edery
- Department of Medical Genetics, Lyon University Hospital, Lyon, France.,CNRS UMR 5292, INSERM U1028, CNRL, Lyon, France.,Claude Bernard Lyon I University, University of Lyon, Lyon, France
| | - A Saad
- Cytogenetics and Reproductive Biology Department, Farhat Hached University Teaching Hospital, Sousse, Tunisia.,Common Service Units for Research in Genetics, Faculty of Medicine of Sousse, Avenue Mohamed Karoui, University of Sousse, Tunisia
| | - D Heron
- Département de Génétique et Centre de Référence "Déficiences intellectuelles de causes rares", AP-HP, Groupe Hospitalier Pitié-Salpêtrière, Paris, France.,GRC-Génétique des Déficiences Intellectuelles de Causes rares, Université Pierre et Marie Curie, Paris, France
| | - V des Portes
- Department of Neuropediatrics, Lyon University Hospital, Lyon, France.,Department of Molecular Genetics, Lyon University Hospital, Lyon, France.,Reference Center for Tuberous Sclerosis and Rare Epileptic Syndromes, Lyon University Hospital, Lyon, France
| | - D Sanlaville
- Department of Medical Genetics, Lyon University Hospital, Lyon, France.,CNRS UMR 5292, INSERM U1028, CNRL, Lyon, France.,Claude Bernard Lyon I University, University of Lyon, Lyon, France
| | - G Lesca
- Department of Medical Genetics, Lyon University Hospital, Lyon, France.,CNRS UMR 5292, INSERM U1028, CNRL, Lyon, France.,Claude Bernard Lyon I University, University of Lyon, Lyon, France
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25
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Harada Y, Hirayama H, Suzuki T. Generation and degradation of free asparagine-linked glycans. Cell Mol Life Sci 2015; 72:2509-33. [PMID: 25772500 PMCID: PMC11113800 DOI: 10.1007/s00018-015-1881-7] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2014] [Revised: 02/19/2015] [Accepted: 03/05/2015] [Indexed: 10/23/2022]
Abstract
Asparagine (N)-linked protein glycosylation, which takes place in the eukaryotic endoplasmic reticulum (ER), is important for protein folding, quality control and the intracellular trafficking of secretory and membrane proteins. It is known that, during N-glycosylation, considerable amounts of lipid-linked oligosaccharides (LLOs), the glycan donor substrates for N-glycosylation, are hydrolyzed to form free N-glycans (FNGs) by unidentified mechanisms. FNGs are also generated in the cytosol by the enzymatic deglycosylation of misfolded glycoproteins during ER-associated degradation. FNGs derived from LLOs and misfolded glycoproteins are eventually merged into one pool in the cytosol and the various glycan structures are processed to a near homogenous glycoform. This article summarizes the current state of our knowledge concerning the formation and catabolism of FNGs.
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Affiliation(s)
- Yoichiro Harada
- Glycometabolome Team, Systems Glycobiology Research Group, RIKEN-Max Planck Joint Research Center, Global Research Cluster, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 Japan
| | - Hiroto Hirayama
- Glycometabolome Team, Systems Glycobiology Research Group, RIKEN-Max Planck Joint Research Center, Global Research Cluster, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 Japan
| | - Tadashi Suzuki
- Glycometabolome Team, Systems Glycobiology Research Group, RIKEN-Max Planck Joint Research Center, Global Research Cluster, RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 Japan
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26
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Rush JS, Subramanian T, Subramanian KL, Onono FO, Waechter CJ, Spielmann HP. Novel Citronellyl-Based Photoprobes Designed to Identify ER Proteins Interacting with Dolichyl Phosphate in Yeast and Mammalian Cells. ACTA ACUST UNITED AC 2015; 9:123-141. [PMID: 27099830 DOI: 10.2174/2212796810666160216221610] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
BACKGROUND Dolichyl phosphate-linked mono- and oligosaccharides (DLO) are essential intermediates in protein N-glycosylation, C- and O-mannosylation and GPI anchor biosynthesis. While many membrane proteins in the endoplasmic reticulum (ER) involved in the assembly of DLOs are known, essential proteins believed to be required for the transbilayer movement (flip-flopping) and proteins potentially involved in the regulation of DLO synthesis remain to be identified. METHODS The synthesis of a series of Dol-P derivatives composed of citronellyl-based photoprobes with benzophenone groups equipped with alkyne moieties for Huisgen "click" chemistry is now described to utilize as tools for identifying ER proteins involved in regulating the biosynthesis and transbilayer movement of lipid intermediates. In vitro enzymatic assays were used to establish that the photoprobes contain the critical structural features recognized by pertinent enzymes in the dolichol pathway. ER proteins that photoreacted with the novel probes were identified by MS. RESULTS The potential of the newly designed photoprobes, m-PAL-Cit-P and p-PAL-Cit-P, for identifying previously unidentified Dol-P-interacting proteins is supported by the observation that they are enzymatically mannosylated by Man-P-Dol synthase (MPDS) from Chinese Hamster Ovary (CHO) cells at an enzymatic rate similar to that for Dol-P. MS analyses reveal that DPM1, ALG14 and several other yeast ER proteins involved in DLO biosynthesis and lipid-mediated protein O-mannosylation photoreacted with the novel probes. CONCLUSION The newly-designed photoprobes described in this paper provide promising new tools for the identification of yet to be identified Dol-P interacting ER proteins in yeast and mammalian cells, including the Dol-P flippase required for the "re-cycling" of the glycosyl carrier lipid from the lumenal monolayer of the ER to the cytoplasmic leaflet for new rounds of DLO synthesis.
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Affiliation(s)
- Jeffrey S Rush
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky 40536, USA
| | - Thangaiah Subramanian
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky 40536, USA
| | - Karunai Leela Subramanian
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky 40536, USA
| | - Fredrick O Onono
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky 40536, USA
| | - Charles J Waechter
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky 40536, USA
| | - H Peter Spielmann
- Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, Kentucky 40536, USA; University of Kentucky College of Medicine, Markey Cancer Center, University of Kentucky, Lexington, Kentucky 40536, USA; Kentucky Center for Structural Biology, University of Kentucky, Lexington, Kentucky 40536, USA; Department of Chemistry, University of Kentucky, Lexington, Kentucky 40536, USA
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27
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Srichaisupakit A, Ohashi T, Misaki R, Fujiyama K. Production of initial-stage eukaryotic N-glycan and its protein glycosylation in Escherichia coli. J Biosci Bioeng 2014; 119:399-405. [PMID: 25449758 DOI: 10.1016/j.jbiosc.2014.09.016] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2014] [Revised: 09/13/2014] [Accepted: 09/17/2014] [Indexed: 11/20/2022]
Abstract
N-Glycosylation is a ubiquitous protein post-translational modification mechanism in eukaryotes. In this work, a synthetic pathway containing glycosyltransferases from Saccharomyces cerevisiae was introduced to Escherichia coli to synthesize lipid-linked mannosyl-chitobiose (Man-GlcNAc2) and trimannosyl-chitobiose (Man3-GlcNAc2). Transfer of Man3-GlcNAc2 onto a model periplasmic protein occurred in the engineered E. coli cell using oligosaccharyltransferase PglB from Campylobacter jejuni. Mass spectrometric analysis of the fluorescently labeled N-glycan indicated a glycan signal composed of 2 HexNAc and 3 Hex residues. The reversed-phase HPLC analysis suggested that the Hex residues were α1,3-, α1,6- and β1,4-linked mannoses. These results indicated that the constructed system synthesizes a Man3-GlcNAc2, identical to that observed in an early eukaryotic dolichol pathway. Finally, glycopeptide mass spectrometry confirmed the transfer of the assembled glycan moiety onto an engineered glycosylation motif of recombinant maltose binding protein. Surprisingly, the Man3-GlcNAc2 structure but not Man-GlcNAc2 was transferred onto maltose binding protein. This work showed that PglB protein might be able to accommodate the transfer of the further engineered glycan with greater complexity.
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Affiliation(s)
| | - Takao Ohashi
- International Center for Biotechnology, Osaka University, Suita, Osaka 565-0871, Japan
| | - Ryo Misaki
- International Center for Biotechnology, Osaka University, Suita, Osaka 565-0871, Japan
| | - Kazuhito Fujiyama
- International Center for Biotechnology, Osaka University, Suita, Osaka 565-0871, Japan.
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28
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Vanholme B, Vanholme R, Turumtay H, Goeminne G, Cesarino I, Goubet F, Morreel K, Rencoret J, Bulone V, Hooijmaijers C, De Rycke R, Gheysen G, Ralph J, De Block M, Meulewaeter F, Boerjan W. Accumulation of N-acetylglucosamine oligomers in the plant cell wall affects plant architecture in a dose-dependent and conditional manner. PLANT PHYSIOLOGY 2014; 165:290-308. [PMID: 24664205 PMCID: PMC4012587 DOI: 10.1104/pp.113.233742] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2013] [Accepted: 03/21/2014] [Indexed: 05/18/2023]
Abstract
To study the effect of short N-acetylglucosamine (GlcNAc) oligosaccharides on the physiology of plants, N-ACETYLGLUCOSAMINYLTRANSFERASE (NodC) of Azorhizobium caulinodans was expressed in Arabidopsis (Arabidopsis thaliana). The corresponding enzyme catalyzes the polymerization of GlcNAc and, accordingly, β-1,4-GlcNAc oligomers accumulated in the plant. A phenotype characterized by difficulties in developing an inflorescence stem was visible when plants were grown for several weeks under short-day conditions before transfer to long-day conditions. In addition, a positive correlation between the oligomer concentration and the penetrance of the phenotype was demonstrated. Although NodC overexpression lines produced less cell wall compared with wild-type plants under nonpermissive conditions, no indications were found for changes in the amount of the major cell wall polymers. The effect on the cell wall was reflected at the transcriptome level. In addition to genes encoding cell wall-modifying enzymes, a whole set of genes encoding membrane-coupled receptor-like kinases were differentially expressed upon GlcNAc accumulation, many of which encoded proteins with an extracellular Domain of Unknown Function26. Although stress-related genes were also differentially expressed, the observed response differed from that of a classical chitin response. This is in line with the fact that the produced chitin oligomers were too small to activate the chitin receptor-mediated signal cascade. Based on our observations, we propose a model in which the oligosaccharides modify the architecture of the cell wall by acting as competitors in carbohydrate-carbohydrate or carbohydrate-protein interactions, thereby affecting noncovalent interactions in the cell wall or at the interface between the cell wall and the plasma membrane.
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29
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Monies DM, Al-Hindi HN, Al-Muhaizea MA, Jaroudi DJ, Al-Younes B, Naim EA, Wakil SM, Meyer BF, Bohlega S. Clinical and pathological heterogeneity of a congenital disorder of glycosylation manifesting as a myasthenic/myopathic syndrome. Neuromuscul Disord 2014; 24:353-9. [DOI: 10.1016/j.nmd.2013.12.010] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2013] [Revised: 12/07/2013] [Accepted: 12/24/2013] [Indexed: 01/05/2023]
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30
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Aebi M. N-linked protein glycosylation in the ER. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2013; 1833:2430-7. [PMID: 23583305 DOI: 10.1016/j.bbamcr.2013.04.001] [Citation(s) in RCA: 484] [Impact Index Per Article: 44.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 01/10/2013] [Revised: 03/25/2013] [Accepted: 04/01/2013] [Indexed: 01/18/2023]
Abstract
N-linked protein glycosylation in the endoplasmic reticulum (ER) is a conserved two phase process in eukaryotic cells. It involves the assembly of an oligosaccharide on a lipid carrier, dolichylpyrophosphate and the transfer of the oligosaccharide to selected asparagine residues of polypeptides that have entered the lumen of the ER. The assembly of the oligosaccharide (LLO) takes place at the ER membrane and requires the activity of several specific glycosyltransferases. The biosynthesis of the LLO initiates at the cytoplasmic side of the ER membrane and terminates in the lumen where oligosaccharyltransferase (OST) selects N-X-S/T sequons of polypeptide and generates the N-glycosidic linkage between the side chain amide of asparagine and the oligosaccharide. The N-glycosylation pathway in the ER modifies a multitude of proteins at one or more asparagine residues with a unique carbohydrate structure that is used as a signalling molecule in their folding pathway. In a later stage of glycoprotein processing, the same systemic modification is used in the Golgi compartment, but in this process, remodelling of the N-linked glycans in a protein-, cell-type and species specific manner generates the high structural diversity of N-linked glycans observed in eukaryotic organisms. This article summarizes the current knowledge of the N-glycosylation pathway in the ER that results in the covalent attachment of an oligosaccharide to asparagine residues of polypeptide chains and focuses on the model organism Saccharomyces cerevisiae. This article is part of a Special Issue entitled: Functional and structural diversity of endoplasmic reticulum.
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Affiliation(s)
- Markus Aebi
- Department of Biology, Institute of Microbiology, Zurich, Switzerland.
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31
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Cossins J, Belaya K, Hicks D, Salih MA, Finlayson S, Carboni N, Liu WW, Maxwell S, Zoltowska K, Farsani GT, Laval S, Seidhamed MZ, Donnelly P, Bentley D, McGowan SJ, Müller J, Palace J, Lochmüller H, Beeson D. Congenital myasthenic syndromes due to mutations in ALG2 and ALG14. Brain 2013; 136:944-56. [PMID: 23404334 PMCID: PMC3580273 DOI: 10.1093/brain/awt010] [Citation(s) in RCA: 96] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2012] [Revised: 12/13/2012] [Accepted: 12/19/2012] [Indexed: 01/22/2023] Open
Abstract
Congenital myasthenic syndromes are a heterogeneous group of inherited disorders that arise from impaired signal transmission at the neuromuscular synapse. They are characterized by fatigable muscle weakness. We performed linkage analysis, whole-exome and whole-genome sequencing to determine the underlying defect in patients with an inherited limb-girdle pattern of myasthenic weakness. We identify ALG14 and ALG2 as novel genes in which mutations cause a congenital myasthenic syndrome. Through analogy with yeast, ALG14 is thought to form a multiglycosyltransferase complex with ALG13 and DPAGT1 that catalyses the first two committed steps of asparagine-linked protein glycosylation. We show that ALG14 is concentrated at the muscle motor endplates and small interfering RNA silencing of ALG14 results in reduced cell-surface expression of muscle acetylcholine receptor expressed in human embryonic kidney 293 cells. ALG2 is an alpha-1,3-mannosyltransferase that also catalyses early steps in the asparagine-linked glycosylation pathway. Mutations were identified in two kinships, with mutation ALG2p.Val68Gly found to severely reduce ALG2 expression both in patient muscle, and in cell cultures. Identification of DPAGT1, ALG14 and ALG2 mutations as a cause of congenital myasthenic syndrome underscores the importance of asparagine-linked protein glycosylation for proper functioning of the neuromuscular junction. These syndromes form part of the wider spectrum of congenital disorders of glycosylation caused by impaired asparagine-linked glycosylation. It is likely that further genes encoding components of this pathway will be associated with congenital myasthenic syndromes or impaired neuromuscular transmission as part of a more severe multisystem disorder. Our findings suggest that treatment with cholinesterase inhibitors may improve muscle function in many of the congenital disorders of glycosylation.
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Affiliation(s)
- Judith Cossins
- Neurosciences Group, Weatherall Institute of Molecular Medicine, The John Radcliffe, Oxford OX3 9DS, UK.
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32
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Lu J, Takahashi T, Ohoka A, Nakajima KI, Hashimoto R, Miura N, Tachikawa H, Gao XD. Alg14 organizes the formation of a multiglycosyltransferase complex involved in initiation of lipid-linked oligosaccharide biosynthesis. Glycobiology 2011; 22:504-16. [PMID: 22061998 DOI: 10.1093/glycob/cwr162] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Protein N-glycosylation begins with the assembly of a lipid-linked oligosaccharide (LLO) on the endoplasmic reticulum (ER) membrane. The first two steps of LLO biosynthesis are catalyzed by a functional multienzyme complex comprised of the Alg7 GlcNAc phosphotransferase and the heterodimeric Alg13/Alg14 UDP-GlcNAc transferase on the cytosolic face of the ER. In the Alg13/14 glycosyltransferase, Alg14 recruits cytosolic Alg13 to the ER membrane through interaction between their C-termini. Bioinformatic analysis revealed that eukaryotic Alg14 contains an evolved N-terminal region that is missing in bacterial orthologs. Here, we show that this N-terminal region of Saccharomyces cerevisiae Alg14 localize its green fluorescent protein fusion to the ER membrane. Deletion of this region causes defective growth at 38.5°C that can be partially complemented by overexpression of Alg7. Coimmunoprecipitation demonstrated that the N-terminal region of Alg14 is required for direct interaction with Alg7. Our data also show that Alg14 lacking the N-terminal region remains on the ER membrane through a nonperipheral association, suggesting the existence of another membrane-binding site. Mutational studies guided by the 3D structure of Alg14 identified a conserved α-helix involved in the second membrane association site that contributes to an integral interaction and protein stability. We propose a model in which the N- and C-termini of Alg14 coordinate recruitment of catalytic Alg7 and Alg13 to the ER membrane for initiating LLO biosynthesis.
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Affiliation(s)
- Jishun Lu
- Graduate School of Life Science, Hokkaido University, N8, W5, Kita-Ku, Sapporo 060-0808, Japan
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33
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Larkin A, Imperiali B. The expanding horizons of asparagine-linked glycosylation. Biochemistry 2011; 50:4411-26. [PMID: 21506607 DOI: 10.1021/bi200346n] [Citation(s) in RCA: 176] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Asparagine-linked glycosylation involves the sequential assembly of an oligosaccharide onto a polyisoprenyl donor, followed by the en bloc transfer of the glycan to particular asparagine residues within acceptor proteins. These N-linked glycans play a critical role in a wide variety of biological processes, such as protein folding, cellular targeting and motility, and the immune response. In the past decade, research in the field of N-linked glycosylation has achieved major advances, including the discovery of new carbohydrate modifications, the biochemical characterization of the enzymes involved in glycan assembly, and the determination of the biological impact of these glycans on target proteins. It is now firmly established that this enzyme-catalyzed modification occurs in all three domains of life. However, despite similarities in the overall logic of N-linked glycoprotein biosynthesis among the three kingdoms, the structures of the appended glycans are markedly different and thus influence the functions of elaborated proteins in various ways. Though nearly all eukaryotes produce the same nascent tetradecasaccharide (Glc(3)Man(9)GlcNAc(2)), heterogeneity is introduced into this glycan structure after it is transferred to the protein through a complex series of glycosyl trimming and addition steps. In contrast, bacteria and archaea display diversity within their N-linked glycan structures through the use of unique monosaccharide building blocks during the assembly process. In this review, recent progress toward gaining a deeper biochemical understanding of this modification across all three kingdoms will be summarized. In addition, a brief overview of the role of N-linked glycosylation in viruses will also be presented.
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Affiliation(s)
- Angelyn Larkin
- Department of Chemistry Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
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34
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Noffz C, Keppler-Ross S, Dean N. Hetero-oligomeric interactions between early glycosyltransferases of the dolichol cycle. Glycobiology 2009; 19:472-8. [PMID: 19129246 PMCID: PMC2667158 DOI: 10.1093/glycob/cwp001] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2008] [Revised: 01/02/2009] [Accepted: 01/03/2009] [Indexed: 11/14/2022] Open
Abstract
N-Linked glycosylation begins with the formation of a dolichol-linked oligosaccharide in the endoplasmic reticulum (ER). The first two steps of this pathway lead to the formation of GlcNAc(2)-PP-dolichol, whose synthesis is sequentially catalyzed by the Alg7p GlcNAc phosphotransferase and by the dimeric Alg13p/Alg14p UDP-GlcNAc transferase on the cytosolic face of the endoplasmic reticulum. Here, we show that the Alg7p, Alg13p, and Alg14p glycosyltransferases form a functional multienzyme complex. Coimmunoprecipitation and gel filtration assays demonstrate that the Alg7p/Alg13p/Alg14p complex is a hexamer with a native molecular weight of approximately 200 kDa and an Alg7p:Alg13:Alg14p stoichiometry of 1:1:1. These results highlight and extend the striking parallels that exist between these eukaryotic UDP-GlcNAc transferases and their bacterial MraY and MurG homologs that catalyze the first two steps of the lipid-linked peptidoglycan precursor. In addition to their preferred substrate and lipid acceptors, these enzymes are similar in their structure, chemistry, temporal, and spatial organization. These similarities point to an evolutionary link between the early steps of N-linked glycosylation and those of peptidoglycan synthesis.
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Affiliation(s)
- Christine Noffz
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794-5215, USA
| | - Sabine Keppler-Ross
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794-5215, USA
| | - Neta Dean
- Department of Biochemistry and Cell Biology, Stony Brook University, Stony Brook, NY 11794-5215, USA
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