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Zhou Z, Wang T, Du Y, Deng J, Gao G, Zhang J. Identification of a Novel Glycosyltransferase Prognostic Signature in Hepatocellular Carcinoma Based on LASSO Algorithm. Front Genet 2022; 13:823728. [PMID: 35356430 PMCID: PMC8959637 DOI: 10.3389/fgene.2022.823728] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2021] [Accepted: 02/23/2022] [Indexed: 01/10/2023] Open
Abstract
Although many prognostic models have been developed to help determine personalized prognoses and treatments, the predictive efficiency of these prognostic models in hepatocellular carcinoma (HCC), which is a highly heterogeneous malignancy, is less than ideal. Recently, aberrant glycosylation has been demonstrated to universally participate in tumour initiation and progression, suggesting that dysregulation of glycosyltransferases can serve as novel cancer biomarkers. In this study, a total of 568 RNA-sequencing datasets of HCC from the TCGA database and ICGC database were analysed and integrated via bioinformatic methods. LASSO regression analysis was applied to construct a prognostic signature. Kaplan-Meier survival, ROC curve, nomogram, and univariate and multivariate Cox regression analyses were performed to assess the predictive efficiency of the prognostic signature. GSEA and the "CIBERSORT" R package were utilized to further discover the potential biological mechanism of the prognostic signature. Meanwhile, the differential expression of the prognostic signature was verified by western blot, qRT-PCR and immunohistochemical staining derived from the HPA. Ultimately, we constructed a prognostic signature in HCC based on a combination of six glycosyltransferases, whose prognostic value was evaluated and validated successfully in the testing cohort and the validation cohort. The prognostic signature was identified as an independent unfavourable prognostic factor for OS, and a nomogram including the risk score was established and showed the good performance in predicting OS. Further analysis of the underlying mechanism revealed that the prognostic signature may be potentially associated with metabolic disorders and tumour-infiltrating immune cells.
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Affiliation(s)
- Zhiyang Zhou
- Department of General Surgery, The First Affiliated Hospital of Nanchang University, Nanchang, China
| | - Tao Wang
- Department of Day Ward, The First Affiliated Hospital of Nanchang University, Nanchang, China
| | - Yao Du
- Department of General Surgery, The First Affiliated Hospital of Nanchang University, Nanchang, China
| | - Junping Deng
- Department of General Surgery, The First Affiliated Hospital of Nanchang University, Nanchang, China
| | - Ge Gao
- Department of General Surgery, The First Affiliated Hospital of Nanchang University, Nanchang, China
| | - Jiangnan Zhang
- Department of General Surgery, The First Affiliated Hospital of Nanchang University, Nanchang, China
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Piłsyk S, Perlinska-Lenart U, Janik A, Gryz E, Ajchler-Adamska M, Kruszewska JS. Yil102c-A is a Functional Homologue of the DPMII Subunit of Dolichyl Phosphate Mannose Synthase in Saccharomyces cerevisiae. Int J Mol Sci 2020; 21:E8938. [PMID: 33255655 PMCID: PMC7728079 DOI: 10.3390/ijms21238938] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2020] [Revised: 11/20/2020] [Accepted: 11/23/2020] [Indexed: 11/30/2022] Open
Abstract
In a wide range of organisms, dolichyl phosphate mannose (DPM) synthase is a complex of tree proteins Dpm1, Dpm2, and Dpm3. However, in the yeast Saccharomyces cerevisiae, it is believed to be a single Dpm1 protein. The function of Dpm3 is performed in S. cerevisiae by the C-terminal transmembrane domain of the catalytic subunit Dpm1. Until present, the regulatory Dpm2 protein has not been found in S. cerevisiae. In this study, we show that, in fact, the Yil102c-A protein interacts directly with Dpm1 in S. cerevisiae and influences its DPM synthase activity. Deletion of the YIL102c-A gene is lethal, and this phenotype is reversed by the dpm2 gene from Trichoderma reesei. Functional analysis of Yil102c-A revealed that it also interacts with glucosylphosphatidylinositol-N-acetylglucosaminyl transferase (GPI-GnT), similar to DPM2 in human cells. Taken together, these results show that Yil102c-A is a functional homolog of DPMII from T. reesei and DPM2 from humans.
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Affiliation(s)
| | | | | | | | | | - Joanna S. Kruszewska
- Institute of Biochemistry and Biophysics Polish Academy of Sciences, 02-106 Warsaw, Poland; (S.P.); (U.P.-L.); (A.J.); (E.G.); (M.A.-A.)
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Li M, Xia S, Shi P. DPM1 expression as a potential prognostic tumor marker in hepatocellular carcinoma. PeerJ 2020; 8:e10307. [PMID: 33282554 PMCID: PMC7694566 DOI: 10.7717/peerj.10307] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2020] [Accepted: 10/15/2020] [Indexed: 12/21/2022] Open
Abstract
Background Altered glycosylation of proteins contributes to tumor progression. Dolichol phosphate mannose synthase (DPMS), an essential mannosyltransferase, plays a central role in post-translational modification of proteins, including N-linked glycoproteins, O-mannosylation, C-mannosylation and glycosylphosphatidylinositol anchors synthesis. Little is known about the function of DPMS in liver cancer. Methods The study explored the roles of DPMS in the prognosis of hepatocellular carcinoma using UALCAN, Human Protein Atlas, GEPIA, cBioPortal and Metascape databases. The mRNA expressions of DPM1/2/3 also were detected by quantitative real-time PCR experiments in vitro. Results The transcriptional and proteinic expressions of DPM1/2/3 were both over-expressed in patients with hepatocellular carcinoma. Over-expressions of DPMS were discovered to be dramatically associated with clinical cancer stages and pathological tumor grades in hepatocellular carcinoma patients. In addition, higher mRNA expressions of DPM1/2/3 were found to be significantly related to shorter overall survival in liver cancer patients. Futhermore, high genetic alteration rate of DPMS (41%) was also observed in patients with liver cancer, and genetic alteration in DPMS was associated with shorter overall survival in hepatocellular carcinoma patients. We also performed quantitative real-time PCR experiments in human normal hepatocytes and hepatoma cells to verify the expressions of DPM1/2/3 and results showed that the expression of DPM1 was significantly increased in hepatoma cells SMMC-7721 and HepG2. Conclusions Taken together, these results suggested that DPM1 could be a potential prognostic biomarker for survivals of hepatocellular carcinoma patients.
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Affiliation(s)
- Ming Li
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China
| | - Shengli Xia
- Department of Orthopedics, Shanghai University of Medicine & Health Sciences Affiliated Zhoupu Hospital, Shanghai, China
| | - Ping Shi
- State Key Laboratory of Bioreactor Engineering, East China University of Science and Technology, Shanghai, China
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Dolichol phosphate mannose synthase: a Glycosyltransferase with Unity in molecular diversities. Glycoconj J 2017; 34:467-479. [PMID: 28616799 DOI: 10.1007/s10719-017-9777-4] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2016] [Revised: 04/20/2017] [Accepted: 05/18/2017] [Indexed: 10/19/2022]
Abstract
N-glycans provide structural and functional stability to asparagine-linked (N-linked) glycoproteins, and add flexibility. Glycan biosynthesis is elaborative, multi-compartmental and involves many glycosyltransferases. Failure to assemble N-glycans leads to phenotypic changes developing infection, cancer, congenital disorders of glycosylation (CDGs) among others. Biosynthesis of N-glycans begins at the endoplasmic reticulum (ER) with the assembly of dolichol-linked tetra-decasaccharide (Glc3Man9GlcNAc2-PP-Dol) where dolichol phosphate mannose synthase (DPMS) plays a central role. DPMS is also essential for GPI anchor biosynthesis as well as for O- and C-mannosylation of proteins in yeast and in mammalian cells. DPMS has been purified from several sources and its gene has been cloned from 39 species (e.g., from protozoan parasite to human). It is an inverting GT-A folded enzyme and classified as GT2 by CAZy (carbohydrate active enZyme; http://www.cazy.org ). The sequence alignment detects the presence of a metal binding DAD signature in DPMS from all 39 species but finds cAMP-dependent protein phosphorylation motif (PKA motif) in only 38 species. DPMS also has hydrophobic region(s). Hydropathy analysis of amino acid sequences from bovine, human, S. crevisiae and A. thaliana DPMS show PKA motif is present between the hydrophobic domains. The location of PKA motif as well as the hydrophobic domain(s) in the DPMS sequence vary from species to species. For example, the domain(s) could be located at the center or more towards the C-terminus. Irrespective of their catalytic similarity, the DNA sequence, the amino acid identity, and the lack of a stretch of hydrophobic amino acid residues at the C-terminus, DPMS is still classified as Type I and Type II enzyme. Because of an apparent bio-sensing ability, extracellular signaling and microenvironment regulate DPMS catalytic activity. In this review, we highlight some important features and the molecular diversities of DPMS.
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Hedberg-Oldfors C, Glamuzina E, Ruygrok P, Anderson LJ, Elliott P, Watkinson O, Occleshaw C, Abernathy M, Turner C, Kingston N, Murphy E, Oldfors A. Cardiomyopathy as presenting sign of glycogenin-1 deficiency-report of three cases and review of the literature. J Inherit Metab Dis 2017; 40:139-149. [PMID: 27718144 PMCID: PMC5203857 DOI: 10.1007/s10545-016-9978-1] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/24/2016] [Revised: 09/01/2016] [Accepted: 09/12/2016] [Indexed: 01/19/2023]
Abstract
We describe a new type of cardiomyopathy caused by a mutation in the glycogenin-1 gene (GYG1). Three unrelated male patients aged 34 to 52 years with cardiomyopathy and abnormal glycogen storage on endomyocardial biopsy were homozygous for the missense mutation p.Asp102His in GYG1. The mutated glycogenin-1 protein was expressed in cardiac tissue but had lost its ability to autoglucosylate as demonstrated by an in vitro assay and western blot analysis. It was therefore unable to form the primer for normal glycogen synthesis. Two of the patients showed similar patterns of heart dilatation, reduced ejection fraction and extensive late gadolinium enhancement on cardiac magnetic resonance imaging. These two patients were severely affected, necessitating cardiac transplantation. The cardiomyocyte storage material was characterized by large inclusions of periodic acid and Schiff positive material that was partly resistant to alpha-amylase treatment consistent with polyglucosan. The storage material had, unlike normal glycogen, a partly fibrillar structure by electron microscopy. None of the patients showed signs or symptoms of muscle weakness but a skeletal muscle biopsy in one case revealed muscle fibres with abnormal glycogen storage. Glycogenin-1 deficiency is known as a rare cause of skeletal muscle glycogen storage disease, usually without cardiomyopathy. We demonstrate that it may also be the cause of severe cardiomyopathy and cardiac failure without skeletal muscle weakness. GYG1 should be included in cardiomyopathy gene panels.
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Affiliation(s)
| | - Emma Glamuzina
- National Metabolic Service, Starship Children’s Hospital, Auckland, New Zealand
| | - Peter Ruygrok
- Green Lane Cardiovascular Service, Auckland City Hospital, Auckland, New Zealand
| | | | | | | | - Chris Occleshaw
- Green Lane Cardiovascular Service, Auckland City Hospital, Auckland, New Zealand
| | | | - Clinton Turner
- Anatomical Pathology, LabPlus, Auckland City Hospital, Auckland, New Zealand
| | - Nicola Kingston
- Anatomical Pathology, LabPlus, Auckland City Hospital, Auckland, New Zealand
| | - Elaine Murphy
- Charles Dent Metabolic Unit, National Hospital for Neurology and Neurosurgery, London, UK
| | - Anders Oldfors
- Department of Pathology and Genetics, University of Gothenburg, Gothenburg, Sweden
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Kellokumpu S, Hassinen A, Glumoff T. Glycosyltransferase complexes in eukaryotes: long-known, prevalent but still unrecognized. Cell Mol Life Sci 2016; 73:305-25. [PMID: 26474840 PMCID: PMC7079781 DOI: 10.1007/s00018-015-2066-0] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2015] [Revised: 09/28/2015] [Accepted: 10/08/2015] [Indexed: 01/08/2023]
Abstract
Glycosylation is the most common and complex cellular modification of proteins and lipids. It is critical for multicellular life and its abrogation often leads to a devastating disease. Yet, the underlying mechanistic details of glycosylation in both health and disease remain unclear. Partly, this is due to the complexity and dynamicity of glycan modifications, and the fact that not all the players are taken into account. Since late 1960s, a vast number of studies have demonstrated that glycosyltransferases typically form homomeric and heteromeric complexes with each other in yeast, plant and animal cells. To propagate their acceptance, we will summarize here accumulated data for their prevalence and potential functional importance for glycosylation focusing mainly on their mutual interactions, the protein domains mediating these interactions, and enzymatic activity changes that occur upon complex formation. Finally, we will highlight the few existing 3D structures of these enzyme complexes to pinpoint their individual nature and to emphasize that their lack is the main obstacle for more detailed understanding of how these enzyme complexes interact and function in a eukaryotic cell.
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Affiliation(s)
- Sakari Kellokumpu
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, Aapistie 7, 90220, Oulu, Finland.
| | - Antti Hassinen
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, Aapistie 7, 90220, Oulu, Finland
| | - Tuomo Glumoff
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, Aapistie 7, 90220, Oulu, Finland
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Juchimiuk M, Kruszewska J, Palamarczyk G. Dolichol phosphate mannose synthase from the pathogenic yeast Candida albicans is a multimeric enzyme. Biochim Biophys Acta Gen Subj 2015; 1850:2265-75. [DOI: 10.1016/j.bbagen.2015.08.012] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2015] [Accepted: 08/12/2015] [Indexed: 11/29/2022]
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Rapid identification of sequences for orphan enzymes to power accurate protein annotation. PLoS One 2013; 8:e84508. [PMID: 24386392 PMCID: PMC3875567 DOI: 10.1371/journal.pone.0084508] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2013] [Accepted: 11/21/2013] [Indexed: 11/19/2022] Open
Abstract
The power of genome sequencing depends on the ability to understand what those genes and their proteins products actually do. The automated methods used to assign functions to putative proteins in newly sequenced organisms are limited by the size of our library of proteins with both known function and sequence. Unfortunately this library grows slowly, lagging well behind the rapid increase in novel protein sequences produced by modern genome sequencing methods. One potential source for rapidly expanding this functional library is the "back catalog" of enzymology--"orphan enzymes," those enzymes that have been characterized and yet lack any associated sequence. There are hundreds of orphan enzymes in the Enzyme Commission (EC) database alone. In this study, we demonstrate how this orphan enzyme "back catalog" is a fertile source for rapidly advancing the state of protein annotation. Starting from three orphan enzyme samples, we applied mass-spectrometry based analysis and computational methods (including sequence similarity networks, sequence and structural alignments, and operon context analysis) to rapidly identify the specific sequence for each orphan while avoiding the most time- and labor-intensive aspects of typical sequence identifications. We then used these three new sequences to more accurately predict the catalytic function of 385 previously uncharacterized or misannotated proteins. We expect that this kind of rapid sequence identification could be efficiently applied on a larger scale to make enzymology's "back catalog" another powerful tool to drive accurate genome annotation.
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Identification and functional analysis of Trypanosoma cruzi genes that encode proteins of the glycosylphosphatidylinositol biosynthetic pathway. PLoS Negl Trop Dis 2013; 7:e2369. [PMID: 23951384 PMCID: PMC3738449 DOI: 10.1371/journal.pntd.0002369] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2013] [Accepted: 07/01/2013] [Indexed: 12/03/2022] Open
Abstract
Background Trypanosoma cruzi is a protist parasite that causes Chagas disease. Several proteins that are essential for parasite virulence and involved in host immune responses are anchored to the membrane through glycosylphosphatidylinositol (GPI) molecules. In addition, T. cruzi GPI anchors have immunostimulatory activities, including the ability to stimulate the synthesis of cytokines by innate immune cells. Therefore, T. cruzi genes related to GPI anchor biosynthesis constitute potential new targets for the development of better therapies against Chagas disease. Methodology/Principal Findings In silico analysis of the T. cruzi genome resulted in the identification of 18 genes encoding proteins of the GPI biosynthetic pathway as well as the inositolphosphorylceramide (IPC) synthase gene. Expression of GFP fusions of some of these proteins in T. cruzi epimastigotes showed that they localize in the endoplasmic reticulum (ER). Expression analyses of two genes indicated that they are constitutively expressed in all stages of the parasite life cycle. T. cruzi genes TcDPM1, TcGPI10 and TcGPI12 complement conditional yeast mutants in GPI biosynthesis. Attempts to generate T. cruzi knockouts for three genes were unsuccessful, suggesting that GPI may be an essential component of the parasite. Regarding TcGPI8, which encodes the catalytic subunit of the transamidase complex, although we were able to generate single allele knockout mutants, attempts to disrupt both alleles failed, resulting instead in parasites that have undergone genomic recombination and maintained at least one active copy of the gene. Conclusions/Significance Analyses of T. cruzi sequences encoding components of the GPI biosynthetic pathway indicated that they are essential genes involved in key aspects of host-parasite interactions. Complementation assays of yeast mutants with these T. cruzi genes resulted in yeast cell lines that can now be employed in high throughput screenings of drugs against this parasite. Chagas disease, considered one of the most neglected tropical diseases, is caused by the blood-borne parasite Trypanosoma cruzi and currently affects about 8 million people in Latin America. T. cruzi can be transmitted by insect vectors, blood transfusion, organ transplantation and mother-to-baby as well as through ingestion of contaminated food. Although T. cruzi causes life-long infections that can result in serious damage to the heart, the two drugs currently available to treat Chagas disease, benznidazole and nifurtimox, which have been used for more than 40 years, have proven efficacy only during the acute phase of the disease. Thus, there is an urgent need to develop new drugs that are more targeted, less toxic, and more effective against this parasite. Here we described the characterization of T. cruzi genes involved in the biosynthesis of GPI anchors, a molecule responsible for holding different types of glycoproteins on the parasite membrane. Since GPI anchored proteins are essential molecules T. cruzi uses during infection, besides helping understand how this parasite interacts with its host, this work may contribute to the development of better therapies against Chagas disease.
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Barone R, Aiello C, Race V, Morava E, Foulquier F, Riemersma M, Passarelli C, Concolino D, Carella M, Santorelli F, Vleugels W, Mercuri E, Garozzo D, Sturiale L, Messina S, Jaeken J, Fiumara A, Wevers RA, Bertini E, Matthijs G, Lefeber DJ. DPM2-CDG: a muscular dystrophy-dystroglycanopathy syndrome with severe epilepsy. Ann Neurol 2013; 72:550-8. [PMID: 23109149 DOI: 10.1002/ana.23632] [Citation(s) in RCA: 106] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
OBJECTIVE Congenital disorders of glycosylation (CDG) are a group of metabolic diseases due to defects in protein and lipid glycosylation. We searched for the primary defect in 3 children from 2 families with a severe neurological phenotype, including profound developmental delay, intractable epilepsy, progressive microcephaly, severe hypotonia with elevated blood creatine kinase levels, and early fatal outcome. There was clinical evidence of a muscular dystrophy-dystroglycanopathy syndrome, supported by deficient O-mannosylation by muscle immunohistochemistry. METHODS Biochemical and molecular methods were combined to pinpoint the defect in the glycosylation pathway in the endoplasmic reticulum. RESULTS Metabolic investigations revealed CDG-I, pointing to a defect in protein N-glycosylation in the endoplasmic reticulum. Analysis of lipid-linked oligosaccharides in fibroblasts showed accumulation of Dol-PP-GlcNAc(2) -Man(5) . DNA analysis revealed mutations in DPM2, 1 of the subunits of the dolichol-phosphate-mannose (DPM) synthase; the patient in the first family is compound heterozygous for 2 mutations (c.68A>G, predicting a missense mutation p.Y23C and c.4-1G>C, a splice mutation), whereas the patients in the second family are homozygous for the same missense mutation (c.68A>G, p.Y23C). INTERPRETATION We describe a new CDG, due to a deficiency of DPM2. Hence, mutations have now been described in the genes for the 3 subunits of DPM: DPM1, DPM2, and DPM3, whereby DPM2-CDG links the congenital disorders of glycosylation to the congenital muscular dystrophies.
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Affiliation(s)
- Rita Barone
- Pediatric Neurology, Department of Pediatrics, University of Catania, Catania, Italy
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Banerjee DK. N-glycans in cell survival and death: cross-talk between glycosyltransferases. BIOCHIMICA ET BIOPHYSICA ACTA 2012; 1820:1338-46. [PMID: 22326428 PMCID: PMC3499948 DOI: 10.1016/j.bbagen.2012.01.013] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2011] [Revised: 01/12/2012] [Accepted: 01/27/2012] [Indexed: 11/25/2022]
Abstract
Asparagine-linked (N-linked) protein glycosylation is one of the most important protein modifications. N-glycans with "high mannose", "hybrid", or "complex" type sugar chains participate in a multitude of cellular processes. These include cell-cell/cell-matrix/receptor-ligand interaction, cell signaling/growth and differentiation, to name a few. Many diseases such as disorders of blood clotting, congenital disorder of glycosylation, diseases of blood vessels, cancer, neo-vascularization, i.e., angiogenesis essential for breast and other solid tumor progression and metastasis are associated with N-glycan expression. Biosynthesis of N-glycans requires multiple steps and multiple cellular compartments. Following transcription and translation the proteins migrate to the endoplasmic reticulum (ER) lumen to acquire glycan chain(s) with a defined glycoform, i.e., a tetradecasaccharide. These are further modified, i.e., edited in ER lumen and in Golgi prior to moving to their respective destinations. The tetradecasaccharide is pre-assembled on a poly-isoprenoid lipid called dolichol, and becomes an essential component of the supply chain. Therefore, dolichol cycle synthesizing the lipid-linked oligosaccharide (LLO) is a hallmark for all N-linked glycoproteins. It is expected that there is a great deal of cross-talk between the participating glycosyltransferases and any missed step would express defective N-glycans that could have fatal consequences. The positive impact of the structurally altered N-glycans could lead to discovery of an N-glycan signature for a disease and/or help developing glycotherapeutic treating cancer or other human diseases. The purpose of this review is to identify the gaps of N-glycan biology and help developing appropriate technology for biomedical applications. This article is part of a Special Issue entitled Glycoproteomics.
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Affiliation(s)
- Dipak K Banerjee
- Department of Biochemistry, School of Medicine, University of Puerto Rico, Medical Sciences Campus, San Juan, PR 00936-5067.
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Zembek P, Perlińska-Lenart U, Rawa K, Górka-Nieć W, Palamarczyk G, Kruszewska JS. Cloning and functional analysis of the dpm2 and dpm3 genes from Trichoderma reesei expressed in a Saccharomyces cerevisiae dpm1Δ mutant strain. Biol Chem 2011; 392:517-27. [DOI: 10.1515/bc.2011.058] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
AbstractInTrichoderma reesei, dolichyl phosphate mannose (dpm) synthase, a key enzyme in the O-glycosylation process, requires three proteins for full activity. In this study, thedpm2anddpm3genes coding for the DPMII and DPMIII subunits ofT. reeseiDPM synthase were cloned and functionally analyzed after expression in theSaccharomyces cerevisiae dpm1Δ[genotype (BY4743;his3Δ1; /leu2Δ0; lys2Δ0; /ura3Δ0; YPR183w::kanMX4] mutant. It was found that apart from the catalytic subunit DPMI, the DPMIII subunit is also essential to form an active DPM synthase in yeast. Additional expression of the DPMII protein, considered to be a regulatory subunit of DPM synthase, decreased the enzymatic activity. We also characterizedS. cerevisiaestrains expressing thedpm1,2,3ordpm1, 3genes and analyzed the consequences ofdpmexpression on protein O-glycosylationin vivoand on the cell wall composition.
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Jadid N, Mialoundama AS, Heintz D, Ayoub D, Erhardt M, Mutterer J, Meyer D, Alioua A, Van Dorsselaer A, Rahier A, Camara B, Bouvier F. DOLICHOL PHOSPHATE MANNOSE SYNTHASE1 mediates the biogenesis of isoprenyl-linked glycans and influences development, stress response, and ammonium hypersensitivity in Arabidopsis. THE PLANT CELL 2011; 23:1985-2005. [PMID: 21558543 PMCID: PMC3123950 DOI: 10.1105/tpc.111.083634] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/25/2011] [Revised: 04/19/2011] [Accepted: 05/01/2011] [Indexed: 05/17/2023]
Abstract
The most abundant posttranslational modification in nature is the attachment of preassembled high-mannose-type glycans, which determines the fate and localization of the modified protein and modulates the biological functions of glycosylphosphatidylinositol-anchored and N-glycosylated proteins. In eukaryotes, all mannose residues attached to glycoproteins from the luminal side of the endoplasmic reticulum (ER) derive from the polyprenyl monosaccharide carrier, dolichol P-mannose (Dol-P-Man), which is flipped across the ER membrane to the lumen. We show that in plants, Dol-P-Man is synthesized when Dol-P-Man synthase1 (DPMS1), the catalytic core, interacts with two binding proteins, DPMS2 and DPMS3, that may serve as membrane anchors for DPMS1 or provide catalytic assistance. This configuration is reminiscent of that observed in mammals but is distinct from the single DPMS protein catalyzing Dol-P-Man biosynthesis in bakers' yeast and protozoan parasites. Overexpression of DPMS1 in Arabidopsis thaliana results in disorganized stem morphology and vascular bundle arrangements, wrinkled seed coat, and constitutive ER stress response. Loss-of-function mutations and RNA interference-mediated reduction of DPMS1 expression in Arabidopsis also caused a wrinkled seed coat phenotype and most remarkably enhanced hypersensitivity to ammonium that was manifested by extensive chlorosis and a strong reduction of root growth. Collectively, these data reveal a previously unsuspected role of the prenyl-linked carrier pathway for plant development and physiology that may help integrate several aspects of candidate susceptibility genes to ammonium stress.
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Affiliation(s)
- Nurul Jadid
- Institut de Biologie Moléculaire des Plantes du Centre National de la Recherche Scientifique, Université de Strasbourg, 67084 Strasbourg Cedex, France
- Department of Biology, Botanical and Plant Tissue Culture Laboratory, Sepuluh Nopember Institut of Technology (Its), Gedung H Kampus Its Sukolilo, Surabaya 60111, East-Java, Indonesia
| | - Alexis Samba Mialoundama
- Institut de Biologie Moléculaire des Plantes du Centre National de la Recherche Scientifique, Université de Strasbourg, 67084 Strasbourg Cedex, France
| | - Dimitri Heintz
- Institut de Biologie Moléculaire des Plantes du Centre National de la Recherche Scientifique, Université de Strasbourg, 67084 Strasbourg Cedex, France
| | - Daniel Ayoub
- Laboratoire de Spectrométrie de Masse Bio-Organique, Département des Sciences Analytiques, Institut Pluridisciplinaire Hubert Curien du Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7178, Université de Strasbourg, 67087 Strasbourg Cedex, France
| | - Mathieu Erhardt
- Institut de Biologie Moléculaire des Plantes du Centre National de la Recherche Scientifique, Université de Strasbourg, 67084 Strasbourg Cedex, France
| | - Jérôme Mutterer
- Institut de Biologie Moléculaire des Plantes du Centre National de la Recherche Scientifique, Université de Strasbourg, 67084 Strasbourg Cedex, France
| | - Denise Meyer
- Institut de Biologie Moléculaire des Plantes du Centre National de la Recherche Scientifique, Université de Strasbourg, 67084 Strasbourg Cedex, France
| | - Abdelmalek Alioua
- Institut de Biologie Moléculaire des Plantes du Centre National de la Recherche Scientifique, Université de Strasbourg, 67084 Strasbourg Cedex, France
| | - Alain Van Dorsselaer
- Laboratoire de Spectrométrie de Masse Bio-Organique, Département des Sciences Analytiques, Institut Pluridisciplinaire Hubert Curien du Centre National de la Recherche Scientifique, Unité Mixte de Recherche 7178, Université de Strasbourg, 67087 Strasbourg Cedex, France
| | - Alain Rahier
- Institut de Biologie Moléculaire des Plantes du Centre National de la Recherche Scientifique, Université de Strasbourg, 67084 Strasbourg Cedex, France
| | - Bilal Camara
- Institut de Biologie Moléculaire des Plantes du Centre National de la Recherche Scientifique, Université de Strasbourg, 67084 Strasbourg Cedex, France
| | - Florence Bouvier
- Institut de Biologie Moléculaire des Plantes du Centre National de la Recherche Scientifique, Université de Strasbourg, 67084 Strasbourg Cedex, France
- Address correspondence to
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14
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Mora-Montes HM, Ponce-Noyola P, Villagómez-Castro JC, Gow NA, Flores-Carreón A, López-Romero E. Protein glycosylation in Candida. Future Microbiol 2010; 4:1167-83. [PMID: 19895219 DOI: 10.2217/fmb.09.88] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Candidiasis is a significant cause of invasive human mycosis with associated mortality rates that are equivalent to, or worse than, those cited for most cases of bacterial septicemia. As a result, considerable efforts are being made to understand how the fungus invades host cells and to identify new targets for fungal chemotherapy. This has led to an increasing interest in Candida glycobiology, with an emphasis on the identification of enzymes essential for glycoprotein and adhesion metabolism, and the role of N- and O-linked glycans in host recognition and virulence. Here, we refer to studies dealing with the identification and characterization of enzymes such as dolichol phosphate mannose synthase, dolichol phosphate glucose synthase and processing glycosidases and synthesis, structure and recognition of mannans and discuss recent findings in the context of Candida albicans pathogenesis.
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Yamamoto A, Nakatsu S, Kondo A, Asato T, Okabe M, Fukuzawa M, Miyagawa S. A newly cloned pig dolichyl-phosphate mannosyl-transferase for preventing the transmission of porcine endogenous retrovirus to human cells. Transpl Int 2009; 23:424-31. [PMID: 19912589 DOI: 10.1111/j.1432-2277.2009.00999.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Porcine endogenous retrovirus (PERV) is a major problem associated with successful clinical xenotransplantation. In our previous study, reducing the high mannose type of N-glycan content proved to be very effective in downregulating PERV infectivity. In this study, dolichyl-phosphate mannosyltransferase (D-P-M), an enzyme related to the early stages of N-linked sugar synthesis was studied. The pig cDNA of the encoding D-P-M was newly isolated. The RNA interference (siRNA) for the D-P-M was applied and transfected to PEC(Z)/PB cells, a pig endothelial cell line with the Lac Z gene and PERV-B, to reduce the levels of high mannose type N-glycans. Compared with the mock line, the temporary PEC(Z)/PB lines showed a decreased mRNA expression for pig D-P-M, and each line then showed a clear destruction of PERV infectivity to human cells in the Lac Z pseudotype assay. The PEC(Z)/PB was next transfected with pSXGH-siRNA, H1-RNA gene promoter. The established PEC(Z)/PB clones with pSXGH-siRNA clearly led to the downregulation of PERV infectivity, as evidenced by the decreased levels of the mRNA for pig D-P-M. Reducing D-P-M enzyme activity represents a potentially useful approach to address the problem of PERV infections in clinical xenotransplantations.
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Affiliation(s)
- Aki Yamamoto
- Division of Organ Transplantation, Department of Surgery, and Osaka University Graduate School of Medicine, Japan
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16
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Lefeber DJ, Schönberger J, Morava E, Guillard M, Huyben KM, Verrijp K, Grafakou O, Evangeliou A, Preijers FW, Manta P, Yildiz J, Grünewald S, Spilioti M, van den Elzen C, Klein D, Hess D, Ashida H, Hofsteenge J, Maeda Y, van den Heuvel L, Lammens M, Lehle L, Wevers RA. Deficiency of Dol-P-Man synthase subunit DPM3 bridges the congenital disorders of glycosylation with the dystroglycanopathies. Am J Hum Genet 2009; 85:76-86. [PMID: 19576565 DOI: 10.1016/j.ajhg.2009.06.006] [Citation(s) in RCA: 163] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2009] [Revised: 06/04/2009] [Accepted: 06/12/2009] [Indexed: 11/28/2022] Open
Abstract
Alpha-dystroglycanopathies such as Walker Warburg syndrome represent an important subgroup of the muscular dystrophies that have been related to defective O-mannosylation of alpha-dystroglycan. In many patients, the underlying genetic etiology remains unsolved. Isolated muscular dystrophy has not been described in the congenital disorders of glycosylation (CDG) caused by N-linked protein glycosylation defects. Here, we present a genetic N-glycosylation disorder with muscular dystrophy in the group of CDG type I. Extensive biochemical investigations revealed a strongly reduced dolichol-phosphate-mannose (Dol-P-Man) synthase activity. Sequencing of the three DPM subunits and complementation of DPM3-deficient CHO2.38 cells showed a pathogenic p.L85S missense mutation in the strongly conserved coiled-coil domain of DPM3 that tethers catalytic DPM1 to the ER membrane. Cotransfection experiments in CHO cells showed a reduced binding capacity of DPM3(L85S) for DPM1. Investigation of the four Dol-P-Man-dependent glycosylation pathways in the ER revealed strongly reduced O-mannosylation of alpha-dystroglycan in a muscle biopsy, thereby explaining the clinical phenotype of muscular dystrophy. This mild Dol-P-Man biosynthesis defect due to DPM3 mutations is a cause for alpha-dystroglycanopathy, thereby bridging the congenital disorders of glycosylation with the dystroglycanopathies.
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Affiliation(s)
- Dirk J Lefeber
- Laboratory of Pediatrics & Neurology, Institute for Genetic and Metabolic Disease, Radboud University Nijmegen Medical Centre, 6500 HB Nijmegen, The Netherlands.
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17
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Baksi K, Zhang Z, Banerjee A, Banerjee DK. Cloning and expression of mannosylphospho dolichol synthase from bovine adrenal medullary capillary endothelial cells. Glycoconj J 2009; 26:635-45. [PMID: 19214747 DOI: 10.1007/s10719-008-9214-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2008] [Revised: 10/21/2008] [Accepted: 10/28/2008] [Indexed: 10/21/2022]
Abstract
Mannosylphospho dolichol synthase (DPMS) is a critical enzyme in the biosynthesis of lipid-linked oligosaccharide (LLO; Glc(3)Man(9)GlcNAc(2)-PP-Dol), a pre-requisite for asparagine-linked (N-linked) protein glycosylation. We have shown earlier that DPMS is important for angiogenesis, i.e., endothelial cell proliferation. This is true when cAMP is used for intracellular signaling. During cAMP signaling, DPMS is activated and ER stress is reduced. To understand the activation of DPMS at the molecular level we have isolated a cDNA clone for the DPMS gene (bDPMS) from the capillary endothelial cells of bovine adrenal medulla. DNA sequencing and the deduced amino acid sequence have established that bDPMS has a motif to be phosphorylated by cAMP-dependent protein kinase (PKA). Based on the sequence information Serine 165 has been found to be the phosphorylation target in bDPMS. Hydropathy Index when plotted against amino acid number indicates the presence of a hydrophobic region around the amino acid residues 120-160, supporting that bDPMS has one membrane spanning region. The recombinant bDPMS has now been purified as His-tag protein with an apparent molecular weight of M (r) 33 kDa. Additionally, we show here that overexpression of DPMS is indeed angiogenic. The capillary endothelial cells proliferate at a higher rate carrying the DPMS overexpression plasmid over the parental cells or the vector.
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Affiliation(s)
- Krishna Baksi
- Department of Anatomy and Cell Biology, School of Medicine, Universidad Central del Caribe, Bayamón, PR 00930-3100, USA
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18
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Maeda Y, Kinoshita T. Dolichol-phosphate mannose synthase: Structure, function and regulation. Biochim Biophys Acta Gen Subj 2008; 1780:861-8. [DOI: 10.1016/j.bbagen.2008.03.005] [Citation(s) in RCA: 83] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2007] [Revised: 02/11/2008] [Accepted: 03/06/2008] [Indexed: 11/30/2022]
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19
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Shams-Eldin H, de Macedo CS, Niehus S, Dorn C, Kimmel J, Azzouz N, Schwarz RT. Plasmodium falciparum dolichol phosphate mannose synthase represents a novel clade. Biochem Biophys Res Commun 2008; 370:388-93. [DOI: 10.1016/j.bbrc.2008.03.033] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2008] [Accepted: 03/05/2008] [Indexed: 11/16/2022]
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Heinicke S, Livstone MS, Lu C, Oughtred R, Kang F, Angiuoli SV, White O, Botstein D, Dolinski K. The Princeton Protein Orthology Database (P-POD): a comparative genomics analysis tool for biologists. PLoS One 2007; 2:e766. [PMID: 17712414 PMCID: PMC1942082 DOI: 10.1371/journal.pone.0000766] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2007] [Accepted: 07/18/2007] [Indexed: 02/07/2023] Open
Abstract
Many biological databases that provide comparative genomics information and tools are now available on the internet. While certainly quite useful, to our knowledge none of the existing databases combine results from multiple comparative genomics methods with manually curated information from the literature. Here we describe the Princeton Protein Orthology Database (P-POD, http://ortholog.princeton.edu), a user-friendly database system that allows users to find and visualize the phylogenetic relationships among predicted orthologs (based on the OrthoMCL method) to a query gene from any of eight eukaryotic organisms, and to see the orthologs in a wider evolutionary context (based on the Jaccard clustering method). In addition to the phylogenetic information, the database contains experimental results manually collected from the literature that can be compared to the computational analyses, as well as links to relevant human disease and gene information via the OMIM, model organism, and sequence databases. Our aim is for the P-POD resource to be extremely useful to typical experimental biologists wanting to learn more about the evolutionary context of their favorite genes. P-POD is based on the commonly used Generic Model Organism Database (GMOD) schema and can be downloaded in its entirety for installation on one's own system. Thus, bioinformaticians and software developers may also find P-POD useful because they can use the P-POD database infrastructure when developing their own comparative genomics resources and database tools.
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Affiliation(s)
- Sven Heinicke
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey, United States of America
| | - Michael S. Livstone
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey, United States of America
| | - Charles Lu
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey, United States of America
| | - Rose Oughtred
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey, United States of America
| | - Fan Kang
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey, United States of America
| | - Samuel V. Angiuoli
- The Institute for Genomic Research, Rockville, Maryland, United States of America
- Center for Bioinformatics and Computational Biology, University of Maryland, College Park, Maryland, United States of America
| | - Owen White
- The Institute for Genomic Research, Rockville, Maryland, United States of America
| | - David Botstein
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey, United States of America
| | - Kara Dolinski
- Lewis-Sigler Institute for Integrative Genomics, Princeton University, Princeton, New Jersey, United States of America
- * To whom correspondence should be addressed. E-mail:
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Shin DJ, Cho D, Kim YR, Rhee JH, Choy HE, Lee JJ, Hong Y. Diagnosis of paroxysmal nocturnal hemoglobinuria by fluorescent clostridium septicum alpha toxin. J Mol Microbiol Biotechnol 2006; 11:20-7. [PMID: 16825787 DOI: 10.1159/000092816] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Paroxysmal nocturnal hemoglobinuria (PNH), a hematopoietic stem cell disorder, is caused by the loss of glycosylphosphatidylinositol (GPI)-anchored proteins on the cell membrane. PNH can be simply diagnosed by flow cytometry using monoclonal antibodies against GPI-anchored proteins or fluorescent-tagged aerolysin, a bacterial toxin that binds GPI anchored proteins. Clostridium septicum alpha toxin is homologous to aerolysin and specifically binds GPI-anchored proteins. Previously, we found that an alpha toxin m45 mutant with two amino acid changes, S189C/S238C, lost cytotoxicity but still possessed binding activity for GPI-anchored proteins. To use this mutant toxin as a diagnostic probe in flow cytometry, we constructed the EGFP-AT(m45) expression vector, comprising a S189C/S238C alpha toxin mutant with EGFP and His tags at the N and C termini, respectively. The recombinant EGFP-AT(m45) was easily purified using single-step affinity chromatography against His tag from Escherichia coli. EGFP-AT(m45) bound to CHO and HeLa cells in a similar manner to monoclonal antibodies against GPI-anchored proteins or aerolysin. In whole blood from a PNH patient, GPI-deficient granulocytes could be differentiated by EGFP-AT(m45) using the same procedure as that employed with commercially available monoclonal antibodies. Therefore, nontoxic EGFP-conjugated C. septicum alpha toxin could be used clinically for PNH diagnosis.
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Affiliation(s)
- Dong-Jun Shin
- Genomic Research Center for Enteropathogenic Bacteria and Department of Microbiology, Chonnam National University Medical School, Gwangju, Korea
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22
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Lamani E, Mewbourne RB, Fletcher DS, Maltsev SD, Danilov LL, Veselovsky VV, Lozanova AV, Grigorieva NY, Pinsker OA, Xing J, Forsee WT, Cheung HC, Schutzbach JS, Shibaev VN, Jedrzejas MJ. Structural studies and mechanism of Saccharomyces cerevisiae dolichyl-phosphate-mannose synthase: insights into the initial step of synthesis of dolichyl-phosphate-linked oligosaccharide chains in membranes of endoplasmic reticulum. Glycobiology 2006; 16:666-78. [PMID: 16549409 DOI: 10.1093/glycob/cwj104] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Dolichyl-phosphate-mannose (Dol-P-Man) synthase catalyzes the reversible formation of a key intermediate that is involved as a mannosyl donor in at least three different pathways for the synthesis of glycoconjugates important for eukaryotic development and viability. The enzyme is found associated with membranes of the endoplasmic reticulum (ER), where it transfers mannose from the water soluble cytoplasmic donor, guanosine 5'-diphosphate (GDP)-Man, to the membrane-bound, extremely hydrophobic, and long-chain polyisoprenoid acceptor, dolichyl-phosphate (Dol-P). The enzyme from Saccharomyces cerevisiae has been utilized to investigate the structure and activity of the protein and interactions of the enzyme with Dol-P and synthetic Dol-P analogs containing fluorescent probes. These interactions have been explored utilizing fluorescence resonance energy transfer (FRET) to establish intramolecular distances within the protein molecule as well as intermolecular distances to determine the localization of the active site and the hydrophobic substrate on the enzyme's surface. A three-dimensional (3D) model of the enzyme was produced with bound substrates, Dol-P, GDP-Man, and divalent cations to delineate the binding sites for these substrates as well as the catalytic site. The FRET analysis was used to characterize the functional properties of the enzyme and to evaluate its modeled structure. The data allowed for proposing a molecular mechanism of catalysis as an inverting mechanism of mannosyl residue transfer.
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Affiliation(s)
- Ejvis Lamani
- Children's Hospital Oakland Research Institute, CA 94609, USA
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Abstract
Glycosylphosphatidylinositol (GPI) is used for anchoring many cell surface proteins to the plasma membrane. Biosynthesis of GPI anchor, its attachment to proteins, and modification of GPI-anchored proteins (GPI-APs) en route to the plasma membrane are complex processes (Ferguson, 1999; Kinoshita and Inoue, 2000). GPI-AP-defective mutant cell lines derived from CHO and other cells have been very useful in elucidating GPI biosynthetic pathway and cloning genes involved in these processes. In this chapter, we overview GPI-AP biosynthesis, establishment and characterization of GPI-AP-defective mutant cell lines, expression cloning using those mutant cells, and characteristics of GPI-AP-defective mutant cell lines.
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Affiliation(s)
- Yusuke Maeda
- Department of Immunoregulation, Research Institute for Microbial Diseases, Osaka University, Japan
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Ashida H, Maeda Y, Kinoshita T. DPM1, the catalytic subunit of dolichol-phosphate mannose synthase, is tethered to and stabilized on the endoplasmic reticulum membrane by DPM3. J Biol Chem 2005; 281:896-904. [PMID: 16280320 DOI: 10.1074/jbc.m511311200] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Dolichol-phosphate mannose (DPM) synthase is required for synthesis of the glycosylphosphatidylinositol (GPI) anchor, N-glycan precursor, protein O-mannose, and C-mannose. We previously identified DPM3, the third component of this enzyme, which was co-purified with DPM1 and DPM2. Here, we have established mutant Chinese hamster ovary (CHO) 2.38 cells that were defective in DPM3. CHO2.38 cells were negative for GPI-anchored proteins, and microsomes from these cells showed no detectable DPM synthase activity, indicating that DPM3 is an essential component of this enzyme. A coiled-coil domain near the C terminus of DPM3 was important for tethering DPM1, the catalytic subunit of the enzyme, to the endoplasmic reticulum membrane and, therefore, was critical for enzyme activity. On the other hand, two transmembrane regions in the N-terminal portion of DPM3 showed no specific functions. DPM1 was rapidly degraded by the proteasome in the absence of DPM3. Free DPM1 was strongly associated with the C terminus of Hsc70-interacting protein (CHIP), a chaperone-dependent E3 ubiquitin ligase, suggesting that DPM1 is ubiquitinated, at least in part, by CHIP.
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Affiliation(s)
- Hisashi Ashida
- Department of Immunoregulation, Research Institute for Microbial Diseases, Osaka University, Japan
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Banerjee DK, Carrasquillo EA, Hughey P, Schutzbach JS, Martínez JA, Baksi K. In vitro phosphorylation by cAMP-dependent protein kinase up-regulates recombinant Saccharomyces cerevisiae mannosylphosphodolichol synthase. J Biol Chem 2004; 280:4174-81. [PMID: 15548536 DOI: 10.1074/jbc.m406962200] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
DPM1 is the structural gene for mannosylphosphodolichol synthase (i.e. Dol-P-Man synthase, DPMS) in Saccharomyces cerevisiae. Earlier studies with cDNA cloning and sequence analysis have established that 31-kDa DPMS of S. cerevisiae contains a consensus sequence (YRRVIS141) that can be phosphorylated by cAMP-dependent protein kinase (PKA). We have been studying the up-regulation of DPMS activity by protein kinase A-mediated phosphorylation in higher eukaryotes, and used the recombinant DPMS from S. cerevisiae in this study to advance our knowledge further. DPMS catalytic activity was indeed enhanced severalfold when the recombinant protein was phosphorylated in vitro. The rate as well as the magnitude of catalysis was higher with the phosphorylated enzyme. A similar increase in the catalytic activity was also observed when the in vitro phosphorylated recombinant DPMS was assayed as a function of increasing concentrations of exogenous dolichylmonophosphate (Dol-P). Kinetic studies indicated that there was no change in the Km for GDP-mannose between the in vitro phosphorylated and control recombinant DPMS, but the Vmax was increased by 6-fold with the phosphorylated enzyme. In vitro phosphorylated recombinant DPMS also exhibited higher enzyme turnover (kcat) and enzyme efficiency (kcat/Km). SDS-PAGE followed by autoradiography of the 32P-labeled DPMS detected a 31-kDa phosphoprotein, and immunoblotting with anti-phosphoserine antibody established the presence of a phosphoserine residue in in vitro phosphorylated recombinant DPMS. To confirm the phosphorylation activation of recombinant DPMS, serine 141 in the consensus sequence was replaced with alanine by PCR site-directed mutagenesis. The S141A DPMS mutant exhibited more than half-a-fold reduction in catalytic activity compared with the wild type when both were analyzed after in vitro phosphorylation. Thus, confirming that S. cerevisiae DPMS activity is indeed regulated by the cAMP-dependent protein phosphorylation signal, and the phosphorylation target is serine 141.
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Affiliation(s)
- Dipak K Banerjee
- Department of Biochemistry, School of Medicine, University of Puerto Rico, San Juan, Puerto Rico 00936-5067.
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Pu L, Scocca JR, Walker BK, Krag SS. The divergent 5' ends of DPM2 mRNAs originate from the alternative splicing of two adjacent introns: characterization of the hamster DPM2 gene. Biochem Biophys Res Commun 2004; 312:817-24. [PMID: 14680839 DOI: 10.1016/j.bbrc.2003.10.192] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2003] [Indexed: 11/18/2022]
Abstract
Mammalian dolichol-phosphate-mannose (DPM) synthase has three subunits, DPM1, DPM2, and DPM3. In this report, an analysis of the gene and cDNAs of hamster DPM2 is presented. The CHO DPM2 gene has two special features. First, the initiation codon ATG is separated from the remainder of the coding region by intron sequences. Second, within these intron sequences the DPM2 gene contains an adjacent 3' splice site (acceptor) and a 5' splice site (donor), suggestive of a deleted exon between the first and second codons. In fact, these sites overlap by four nucleotides (nt) of AGGT. Splicing intermediates using both of these alternative splice sites were observed. This latter feature appears unique and is particularly unusual considering the relatively small size of the gene (2.7 kb) and of introns a (123 bp) and b (152 bp).
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Affiliation(s)
- Lixia Pu
- Department of Biochemistry and Molecular Biology, Johns Hopkins Bloomberg School of Public Health, 615 N. Wolfe Street, Baltimore, MD 21205, USA.
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Pu L, Scocca JR, Walker BK, Krag SS. A single point mutation resulting in an adversely reduced expression of DPM2 in the Lec15.1 cells. Biochem Biophys Res Commun 2003; 312:555-61. [PMID: 14680801 DOI: 10.1016/j.bbrc.2003.10.152] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2003] [Indexed: 12/01/2022]
Abstract
Mammalian dolichol-phosphate-mannose (DPM) synthase consists of three subunits, DPM1, DPM2, and DPM3. Lec15.1 Chinese hamster ovary cells are deficient in DPM synthase activity. The present paper reports that DPM1 cDNA from wild type and Lec15.1 CHO cells were found to be identical, and transfection with CHO DPM1 cDNA did not reverse the Lec15.1 phenotype. Neither did a chimeric cDNA containing the complete hamster DPM1 open reading frame fused to the Saccharomyces cerevisiae DPM1 C-terminal transmembrane domain. In contrast, Lec15.1 cells were found to have a single point mutation G29A within the coding region of the DPM2 gene, resulting in a glycine to glutamic acid change in amino acid residue 10 of the peptide. Moreover, mutant DPM2 cDNA expressed a drastically reduced amount of DPM2 protein and poorly corrects the Lec15.1 cell phenotype when compared with wild type CHO DPM2 cDNA (G(29) form).
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Affiliation(s)
- Lixia Pu
- Department of Biochemistry and Molecular Biology, The Johns Hopkins Bloomberg School of Public Health, 615 N. Wolfe Street, Baltimore, MD 21205, USA.
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Murakami Y, Siripanyapinyo U, Hong Y, Kang JY, Ishihara S, Nakakuma H, Maeda Y, Kinoshita T. PIG-W is critical for inositol acylation but not for flipping of glycosylphosphatidylinositol-anchor. Mol Biol Cell 2003; 14:4285-95. [PMID: 14517336 PMCID: PMC207019 DOI: 10.1091/mbc.e03-03-0193] [Citation(s) in RCA: 73] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
Many cell surface proteins are anchored to a membrane via a glycosylphosphatidylinositol (GPI), which is attached to the C termini in the endoplasmic reticulum. The inositol ring of phosphatidylinositol is acylated during biosynthesis of GPI. In mammalian cells, the acyl chain is added to glucosaminyl phosphatidylinositol at the third step in the GPI biosynthetic pathway and then is usually removed soon after the attachment of GPIs to proteins. The mechanisms and roles of the inositol acylation and deacylation have not been well clarified. Herein, we report derivation of human and Chinese hamster mutant cells defective in inositol acylation and the gene responsible, PIG-W. The surface expressions of GPI-anchored proteins on these mutant cells were greatly diminished, indicating the critical role of inositol acylation. PIG-W encodes a 504-amino acid protein expressed in the endoplasmic reticulum. PIG-W is most likely inositol acyltransferase itself because the tagged PIG-W affinity purified from transfected human cells had inositol acyltransferase activity and because both mutant cells were complemented with PIG-W homologs of Saccharomyces cerevisiae and Schizosaccharomyces pombe. The inositol acylation is not essential for the subsequent mannosylation, indicating that glucosaminyl phosphatidylinositol can flip from the cytoplasmic side to the luminal side of the endoplasmic reticulum.
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Affiliation(s)
- Yoshiko Murakami
- Department of Immunoregulation, Research Institute for Microbial Diseases, Osaka University, Osaka 565-0871, Japan
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Schenk B, Fernandez F, Waechter CJ. The ins(ide) and out(side) of dolichyl phosphate biosynthesis and recycling in the endoplasmic reticulum. Glycobiology 2001; 11:61R-70R. [PMID: 11425794 DOI: 10.1093/glycob/11.5.61r] [Citation(s) in RCA: 143] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The precursor oligosaccharide donor for protein N-glycosylation in eukaryotes, Glc3Man9GlcNAc(2)-P-P-dolichol, is synthesized in two stages on both leaflets of the rough endoplasmic reticulum (ER). There is good evidence that the level of dolichyl monophosphate (Dol-P) is one rate-controlling factor in the first stage of the assembly process. In the current topological model it is proposed that ER proteins (flippases) then mediate the transbilayer movement of Man-P-Dol, Glc-P-Dol, and Man5GlcNAc(2)-P-P-Dol from the cytoplasmic leaflet to the lumenal leaflet. The rate of flipping of the three intermediates could plausibly influence the conversion of Man5GlcNAc(2)-P-P-Dol to Glc3Man(9)GlcNAc(2)-P-P-Dol in the second stage on the lumenal side of the rough ER. This article reviews the current understanding of the enzymes involved in the de novo biosynthesis of Dol-P and other polyisoprenoid glycosyl carrier lipids and speculates about the role of membrane proteins and enzymes that could be involved in the transbilayer movement of the lipid intermediates and the recycling of Dol-P and Dol-P-P discharged during glycosylphosphatidylinositol anchor biosynthesis, N-glycosylation, and O- and C-mannosylation reactions on the lumenal surface of the rough ER.
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Affiliation(s)
- B Schenk
- Institute for Microbiology, ETH Zurich, 8092 Zurich, Switzerland
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Marquardt T, Freeze H. Congenital disorders of glycosylation: glycosylation defects in man and biological models for their study. Biol Chem 2001; 382:161-77. [PMID: 11308015 DOI: 10.1515/bc.2001.024] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Several inherited disorders affecting the biosynthetic pathways of N-glycans have been discovered during the past years. This review summarizes the current knowledge in this rapidly expanding field and covers the molecular bases of these disorders as well as their phenotypical consequences.
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Affiliation(s)
- T Marquardt
- Klinik und Poliklinik für Kinderheilkunde, Universität Münster, Germany
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Anand M, Rush JS, Ray S, Doucey MA, Weik J, Ware FE, Hofsteenge J, Waechter CJ, Lehrman MA. Requirement of the Lec35 gene for all known classes of monosaccharide-P-dolichol-dependent glycosyltransferase reactions in mammals. Mol Biol Cell 2001; 12:487-501. [PMID: 11179430 PMCID: PMC30958 DOI: 10.1091/mbc.12.2.487] [Citation(s) in RCA: 66] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022] Open
Abstract
The Lec35 gene product (Lec35p) is required for utilization of the mannose donor mannose-P-dolichol (MPD) in synthesis of both lipid-linked oligosaccharides (LLOs) and glycosylphosphatidylinositols, which are important for functions such as protein folding and membrane anchoring, respectively. The hamster Lec35 gene is shown to encode the previously identified cDNA SL15, which corrects the Lec35 mutant phenotype and predicts a novel endoplasmic reticulum membrane protein. The mutant hamster alleles Lec35.1 and Lec35.2 are characterized, and the human Lec35 gene (mannose-P-dolichol utilization defect 1) was mapped to 17p12-13. To determine whether Lec35p was required only for MPD-dependent mannosylation of LLO and glycosylphosphatidylinositol intermediates, two additional lipid-mediated reactions were investigated: MPD-dependent C-mannosylation of tryptophanyl residues, and glucose-P-dolichol (GPD)-dependent glucosylation of LLO. Both were found to require Lec35p. In addition, the SL15-encoded protein was selective for MPD compared with GPD, suggesting that an additional GPD-selective Lec35 gene product remains to be identified. The predicted amino acid sequence of Lec35p does not suggest an obvious function or mechanism. By testing the water-soluble MPD analog mannose-beta-1-P-citronellol in an in vitro system in which the MPD utilization defect was preserved by permeabilization with streptolysin-O, it was determined that Lec35p is not directly required for the enzymatic transfer of mannose from the donor to the acceptor substrate. These results show that Lec35p has an essential role for all known classes of monosaccharide-P-dolichol-dependent reactions in mammals. The in vitro data suggest that Lec35p controls an aspect of MPD orientation in the endoplasmic reticulum membrane that is crucial for its activity as a donor substrate.
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Affiliation(s)
- M Anand
- Department of Pharmacology, UT-Southwestern Medical Center, Dallas, Texas 75390-9041, USA
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33
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Kruszewska JS, Saloheimo M, Migdalski A, Orlean P, Penttilä M, Palamarczyk G. Dolichol phosphate mannose synthase from the filamentous fungus Trichoderma reesei belongs to the human and Schizosaccharomyces pombe class of the enzyme. Glycobiology 2000; 10:983-91. [PMID: 11030744 DOI: 10.1093/glycob/10.10.983] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Dolichol phosphate mannose (DPM) synthase activity, which is required in N:-glycosylation, O-mannosylation, and glycosylphosphatidylinositol membrane anchoring of protein, has been postulated to regulate the Trichoderma reesei secretory pathway. We have cloned a T.reesei cDNA that encodes a 243 amino acid protein whose amino acid sequence shows 67% and 65% identity, respectively, to the Schizosaccharomyces pombe and human DPM synthases, and which lacks the COOH-terminal hydrophobic domain characteristic of the Saccharomyces cerevisiae class of synthase. The Trichoderma dpm1 (Trdpm1) gene complements a lethal null mutation in the S.pombe dpm1(+) gene, but neither restores viability of a S.cerevisiae dpm1-disruptant nor complements the temperature-sensitivity of the S. cerevisiae dpm1-6 mutant. The T.reesei DPM synthase is therefore a member of the "human" class of enzyme. Overexpression of Trdpm1 in a dpm1(+)::his7/dpm1(+) S.pombe diploid resulted in a 4-fold increase in specific DPM synthase activity. However, neither the wild type T. reesei DPM synthase, nor a chimera consisting of this protein and the hydrophobic COOH terminus of the S.cerevisiae DPM synthase, complemented an S.cerevisiae dpm1 null mutant or gave active enzyme when expressed in E.coli. The level of the Trdpm1 mRNA in T.reesei QM9414 strain was dependent on the composition of the culture medium. Expression levels of Trdpm1 were directly correlated with the protein secretory capacity of the fungus.
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Affiliation(s)
- J S Kruszewska
- Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawinskiego 5a, 02 106 Warsaw, Poland
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Watanabe R, Murakami Y, Marmor MD, Inoue N, Maeda Y, Hino J, Kangawa K, Julius M, Kinoshita T. Initial enzyme for glycosylphosphatidylinositol biosynthesis requires PIG-P and is regulated by DPM2. EMBO J 2000; 19:4402-11. [PMID: 10944123 PMCID: PMC302040 DOI: 10.1093/emboj/19.16.4402] [Citation(s) in RCA: 115] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Glycosylphosphatidylinositols (GPIs) are attached to the C-termini of many proteins, thereby acting as membrane anchors. Biosynthesis of GPI is initiated by GPI-N-acetylglucosaminyltransferase (GPI-GnT), which transfers N-acetylglucosamine from UDP- N-acetylglucosamine to phosphatidylinositol. GPI-GnT is a uniquely complex glycosyltransferase, consisting of at least four proteins, PIG-A, PIG-H, PIG-C and GPI1. Here, we report that GPI-GnT requires another component, termed PIG-P, and that DPM2, which regulates dolichol-phosphate-mannose synthase, also regulates GPI-GnT. PIG-P, a 134-amino acid protein having two hydrophobic domains, associates with PIG-A and GPI1. PIG-P is essential for GPI-GnT since a cell lacking PIG-P is GPI-anchor negative. DPM2, but not two other components of dolichol-phosphate-mannose synthase, associates with GPI-GnT through interactions with PIG-A, PIG-C and GPI1. Lec15 cell, a null mutant of DPM2, synthesizes early GPI intermediates, indicating that DPM2 is not essential for GPI-GnT; however, the enzyme activity is enhanced 3-fold in the presence of DPM2. These results reveal new essential and regulatory components of GPI-GnT and imply co-regulation of GPI-GnT and the dolichol-phosphate-mannose synthase that generates a mannosyl donor for GPI.
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Affiliation(s)
- R Watanabe
- Department of Immunoregulation, Research Institute for Microbial Diseases, Osaka University, 3-1 Yamada-oka, Suita, Osaka 565-0871, Japan
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Hong Y, Maeda Y, Watanabe R, Inoue N, Ohishi K, Kinoshita T. Requirement of PIG-F and PIG-O for transferring phosphoethanolamine to the third mannose in glycosylphosphatidylinositol. J Biol Chem 2000; 275:20911-9. [PMID: 10781593 DOI: 10.1074/jbc.m001913200] [Citation(s) in RCA: 68] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Many eukaryotic proteins are anchored by glycosylphosphatidylinositol (GPI) to the cell surface membrane. The GPI anchor is linked to proteins by an amide bond formed between the carboxyl terminus and phosphoethanolamine attached to the third mannose. Here, we report the roles of two mammalian genes involved in transfer of phosphoethanolamine to the third mannose in GPI. We cloned a mouse gene termed Pig-o that encodes a 1101-amino acid PIG-O protein bearing regions conserved in various phosphodiesterases. Pig-o knockout F9 embryonal carcinoma cells expressed very little GPI-anchored proteins and accumulated the same major GPI intermediate as the mouse class F mutant cell, which is defective in transferring phosphoethanolamine to the third mannose due to mutant Pig-f gene. PIG-O and PIG-F proteins associate with each other, and the stability of PIG-O was dependent upon PIG-F. However, the class F cell is completely deficient in the surface expression of GPI-anchored proteins. A minor GPI intermediate seen in Pig-o knockout but not class F cells had more than three mannoses with phosphoethanolamines on the first and third mannoses, suggesting that this GPI may account for the low expression of GPI-anchored proteins. Therefore, mammalian cells have redundant activities in transferring phosphoethanolamine to the third mannose, both of which require PIG-F.
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Affiliation(s)
- Y Hong
- Department of Immunoregulation, Research Institute for Microbial Diseases, Osaka University, 3-1 Yamada-oka, Suita, Osaka 565-0871, Japan
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36
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Maeda Y, Tanaka S, Hino J, Kangawa K, Kinoshita T. Human dolichol-phosphate-mannose synthase consists of three subunits, DPM1, DPM2 and DPM3. EMBO J 2000; 19:2475-82. [PMID: 10835346 PMCID: PMC212771 DOI: 10.1093/emboj/19.11.2475] [Citation(s) in RCA: 98] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Dolichol-phosphate-mannose (DPM) synthase generates mannosyl donors for glycosylphosphatidylinositols, N-glycan and protein O- and C-mannosylation. In Saccharomyces cerevisiae, this enzyme is encoded by DPM1. We reported previously that mammalian DPM synthase contains catalytic DPM1 and regulatory DPM2 subunits, and that DPM1 requires DPM2 for its stable expression in the endoplasmic reticulum. Here we report that human DPM synthase consists of three subunits. The third subunit, DPM3, comprises 92 amino acids associated with DPM1 via its C-terminal domain and with DPM2 via its N-terminal portion. The stability of DPM3 was dependent upon DPM2. However, overexpression of DPM3 in Lec15 cells, a null mutant of DPM2, restored the biosynthesis of DPM with an increase in DPM1, indicating that DPM3 directly stabilized DPM1. Therefore, DPM2 stabilizes DPM3 and DPM3 stabilizes DPM1. DPM synthase activity was 10 times higher in the presence of DPM2, indicating that DPM2 also plays a role in the enzymatic reaction. Schizosaccharomyces pombe has proteins that resemble three human subunits; S.pombe DPM3 restored biosynthesis of DPM in Lec15 cells, indicating its orthologous relationship to human DPM3.
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Affiliation(s)
- Y Maeda
- Department of Immunoregulation, Research Institute for Microbial Diseases, Osaka University, 3-1 Yamada-oka, Suita, Osaka 565-0871, Japan
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Imbach T, Schenk B, Schollen E, Burda P, Stutz A, Grunewald S, Bailie NM, King MD, Jaeken J, Matthijs G, Berger EG, Aebi M, Hennet T. Deficiency of dolichol-phosphate-mannose synthase-1 causes congenital disorder of glycosylation type Ie. J Clin Invest 2000; 105:233-9. [PMID: 10642602 PMCID: PMC377434 DOI: 10.1172/jci8691] [Citation(s) in RCA: 134] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
Congenital disorders of glycosylation (CDG), formerly known as carbohydrate-deficient glycoprotein syndromes, lead to diseases with variable clinical pictures. We report the delineation of a novel type of CDG identified in 2 children presenting with severe developmental delay, seizures, and dysmorphic features. We detected hypoglycosylation on serum transferrin and cerebrospinal fluid beta-trace protein. Lipid-linked oligosaccharides in the endoplasmic reticulum of patient fibroblasts showed an accumulation of the dolichyl pyrophosphate Man(5)GlcNAc(2) structure, compatible with the reduced dolichol-phosphate-mannose synthase (DolP-Man synthase) activity detected in these patients. Accordingly, 2 mutant alleles of the DolP-Man synthase DPM1 gene, 1 with a 274C>G transversion, the other with a 628delC deletion, were detected in both siblings. Complementation analysis using DPM1-null murine Thy1-deficient cells confirmed the detrimental effect of both mutations on the enzymatic activity. Furthermore, mannose supplementation failed to improve the glycosylation status of DPM1-deficient fibroblast cells, thus precluding a possible therapeutic application of mannose in the patients. Because DPM1 deficiency, like other subtypes of CDG-I, impairs the assembly of N-glycans, this novel glycosylation defect was named CDG-Ie.
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Affiliation(s)
- T Imbach
- Institute of Physiology, University of Zurich, 8057 Zurich, Switzerland
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Kim S, Westphal V, Srikrishna G, Mehta DP, Peterson S, Filiano J, Karnes PS, Patterson MC, Freeze HH. Dolichol phosphate mannose synthase (DPM1) mutations define congenital disorder of glycosylation Ie (CDG-Ie). J Clin Invest 2000; 105:191-8. [PMID: 10642597 PMCID: PMC377427 DOI: 10.1172/jci7302] [Citation(s) in RCA: 119] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/1999] [Accepted: 12/08/1999] [Indexed: 11/17/2022] Open
Abstract
Congenital disorders of glycosylation (CDGs) are metabolic deficiencies in glycoprotein biosynthesis that usually cause severe mental and psychomotor retardation. Different forms of CDGs can be recognized by altered isoelectric focusing (IEF) patterns of serum transferrin (Tf). Two patients with these symptoms and similar abnormal Tf IEF patterns were analyzed by metabolic labeling of fibroblasts with ¿2-(3)Hmannose. The patients produced a truncated dolichol-linked precursor oligosaccharide with 5 mannose residues, instead of the normal precursor with 9 mannose residues. Addition of 250 microM mannose to the culture medium corrected the size of the truncated oligosaccharide. Microsomes from fibroblasts of these patients were approximately 95% deficient in dolichol-phosphate-mannose (Dol-P-Man) synthase activity, with an apparent K(m) for GDP-Man approximately 6-fold higher than normal. DPM1, the gene coding for the catalytic subunit of Dol-P-Man synthase, was altered in both patients. One patient had a point mutation, C(274)G, causing an R(92)G change in the coding sequence. The other patient also had the C(274)G mutation and a 13-bp deletion that presumably resulted in an unstable transcript. Defects in DPM1 define a new glycosylation disorder, CDG-Ie.
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Affiliation(s)
- S Kim
- The Burnham Institute, La Jolla, California 92037, USA
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39
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Abstract
Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired clonal hematopoietic stem cell disorder characterized by an intravascular hemolytic anemia. Abnormal blood cells lack a series of glycosylphosphatidylinositol (GPI)-anchored proteins. The lack of GPI-anchored complement regulatory proteins, such as decay-accelerating factor (DAF) and CD59, results in complement-mediated hemolysis and hemoglobinuria. In the affected hematopoietic cells from patients with PNH, the first step in biosynthesis of the GPI anchor is defective. At least four genes are involved in this reaction step, and one of them, an X-linked gene termed PIG-A, is mutated in affected cells. The PIG-A gene is mutated in all patients with PNH reported to date. Here, we review recent advances in the understanding of the molecular pathogenesis of PNH.
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Affiliation(s)
- J Nishimura
- Department of Immunoregulation, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
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40
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Tomita M. Biochemical background of paroxysmal nocturnal hemoglobinuria. BIOCHIMICA ET BIOPHYSICA ACTA 1999; 1455:269-86. [PMID: 10571018 DOI: 10.1016/s0925-4439(99)00068-x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Paroxysmal nocturnal hemoglobinuria (PNH) is an acquired disorder characterized by paroxysms of intravascular hemolysis. A considerable part of erythrocytes in patient blood is susceptible to autologous complement activation because of the deficiency of CD59, which is a glycosylphosphatidylinositol (GPI)-anchored protein and inhibits the formation of the membrane attack complex (MAC) of complement. The deficiency of CD59 is derived from the inability of GPI-anchor synthesis. Although more than 10 proteins are involved in the GPI-anchor synthesis, the mutation of only one protein, PIG-A, causes the defect in about 200 patients with PNH who have been analyzed. The reason why only PIG-A causes the deficiency of GPI anchor is due to the location of its gene on X chromosome. The clonal stem cell mutated with PIG-A gene in the bone marrow loses the capability of the synthesis of GPI-anchor. The mutation of PIG-A gene alone, however, seems to be insufficient to account for the survival of the PIG-A-deficient cells in the bone marrow. Thus, a fraction of the mutant stem cells probably gain a survival advantage by some additional changes, either additional mutations or changes in immunological circumstances. The release of the surviving cells into blood stream results in a clinical syndrome with PNH.
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Affiliation(s)
- M Tomita
- Department of Physiological Chemistry, Faculty of Pharmaceutical Science, Showa University, Tokyo, Japan.
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Tiede A, Bastisch I, Schubert J, Orlean P, Schmidt RE. Biosynthesis of glycosylphosphatidylinositols in mammals and unicellular microbes. Biol Chem 1999; 380:503-23. [PMID: 10384957 DOI: 10.1515/bc.1999.066] [Citation(s) in RCA: 97] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Membrane anchoring of cell surface proteins via glycosylphosphatidylinositol (GPI) occurs in all eukaryotic organisms. In addition, GPI-related glycophospholipids are important constituents of the glycan coat of certain protozoa. Defects in GPI biosynthesis can retard, if not abolish growth of these organisms. In humans, a defect in GPI biosynthesis can cause paroxysmal nocturnal hemoglobinuria (PNH), a severe acquired bone marrow disorder. Here, we review advances in the characterization of GPI biosynthesis in parasitic protozoa, yeast and mammalian cells. The GPI core structure as well as the major steps in its biosynthesis are conserved throughout evolution. However, there are significant biosynthetic differences between mammals and microbes. First indications are that these differences could be exploited as targets in the design of novel pharmacotherapeutics that selectively inhibit GPI biosynthesis in unicellular microbes.
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Affiliation(s)
- A Tiede
- Department of Clinical Immunology, Hannover Medical School, Germany
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42
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Abstract
The oligosaccharide substrate for the N-linked protein glycosylation is assembled at the membrane of the endoplasmic reticulum. Dolichyl pyrophosphate serves as a carrier in this biosynthetic pathway. In this review, we discuss the function of the lipid carrier dolichol in oligosaccharide assembly and give an overview of the biosynthesis of the different sugar donors required for the building of the oligosaccharide. Yeast genetic techniques have made it possible to identify many different loci encoding specific glycosyltransferases required for the precise and ordered assembly of the dolichyl pyrophosphate-linked oligosaccharide. Based on the knowledge obtained from studying this pathway in yeast, we compare it to the process of N-linked protein glycosylation in archaea. We suggest that N-linked glycosylation in eukaryotes and in archaea share a common evolutionary origin.
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Affiliation(s)
- P Burda
- Mikrobiologisches Institut, ETH Zürich, Schmelzbergstr. 7, CH-092 Zürich, Switzerland
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43
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Maeda Y, Tomita S, Watanabe R, Ohishi K, Kinoshita T. DPM2 regulates biosynthesis of dolichol phosphate-mannose in mammalian cells: correct subcellular localization and stabilization of DPM1, and binding of dolichol phosphate. EMBO J 1998; 17:4920-9. [PMID: 9724629 PMCID: PMC1170821 DOI: 10.1093/emboj/17.17.4920] [Citation(s) in RCA: 95] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Biosynthesis of glycosylphosphatidylinositol and N-glycan precursor is dependent upon a mannosyl donor, dolichol phosphate-mannose (DPM). The Thy-1negative class E mutant of mouse lymphoma and Lec15 mutant Chinese hamster ovary (CHO) cells are incapable of DPM synthesis. The class E mutant is defective in the DPM1 gene which encodes a mammalian homologue of Saccharomyces cerevisiae Dpm1p that is a DPM synthase, whereas Lec15 is a different mutant, indicating that mammalian DPM1 is not sufficient for DPM synthesis. Here we report expression cloning of a new gene, DPM2, which is defective in Lec15 cells. DPM2, an 84 amino acid membrane protein expressed in the endoplasmic reticulum (ER), makes a complex with DPM1 that is essential for the ER localization and stable expression of DPM1. Moreover, DPM2 enhances binding of dolichol phosphate, a substrate of DPM synthase. Mammalian DPM1 is catalytic because a fusion protein of DPM1 that was stably expressed in the ER synthesized DPM without DPM2. Therefore, biosynthesis of DPM in mammalian cells is regulated by DPM2.
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Affiliation(s)
- Y Maeda
- Department of Immunoregulation, Research Institute for Microbial Diseases, Osaka University, Suita, Osaka 565-0871, Japan
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