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OUP accepted manuscript. Glycobiology 2022; 32:556-579. [DOI: 10.1093/glycob/cwac014] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Revised: 02/22/2022] [Accepted: 03/09/2022] [Indexed: 11/12/2022] Open
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2
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Kato K, Hansen L, Clausen H. Polypeptide N-acetylgalactosaminyltransferase-Associated Phenotypes in Mammals. Molecules 2021; 26:5504. [PMID: 34576978 PMCID: PMC8472655 DOI: 10.3390/molecules26185504] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Revised: 09/07/2021] [Accepted: 09/08/2021] [Indexed: 01/31/2023] Open
Abstract
Mucin-type O-glycosylation involves the attachment of glycans to an initial O-linked N-acetylgalactosamine (GalNAc) on serine and threonine residues on proteins. This process in mammals is initiated and regulated by a large family of 20 UDP-GalNAc: polypeptide N-acetylgalactosaminyltransferases (GalNAc-Ts) (EC 2.4.1.41). The enzymes are encoded by a large gene family (GALNTs). Two of these genes, GALNT2 and GALNT3, are known as monogenic autosomal recessive inherited disease genes with well characterized phenotypes, whereas a broad spectrum of phenotypes is associated with the remaining 18 genes. Until recently, the overlapping functionality of the 20 members of the enzyme family has hindered characterizing the specific biological roles of individual enzymes. However, recent evidence suggests that these enzymes do not have full functional redundancy and may serve specific purposes that are found in the different phenotypes described. Here, we summarize the current knowledge of GALNT and associated phenotypes.
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Affiliation(s)
- Kentaro Kato
- Department of Eco-Epidemiology, Institute of Tropical Medicine, Nagasaki University, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan
- School of Tropical Medicine and Global Health, Nagasaki University, 1-12-4 Sakamoto, Nagasaki 852-8523, Japan
| | - Lars Hansen
- Copenhagen Center for Glycomics, Department of Cellular and Molecular Medicine, Mærsk Building, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen N, Denmark;
| | - Henrik Clausen
- Copenhagen Center for Glycomics, Department of Cellular and Molecular Medicine, Mærsk Building, University of Copenhagen, Blegdamsvej 3B, 2200 Copenhagen N, Denmark;
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3
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Wandall HH, Nielsen MAI, King-Smith S, de Haan N, Bagdonaite I. Global functions of O-glycosylation: promises and challenges in O-glycobiology. FEBS J 2021; 288:7183-7212. [PMID: 34346177 DOI: 10.1111/febs.16148] [Citation(s) in RCA: 59] [Impact Index Per Article: 19.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2021] [Revised: 07/23/2021] [Accepted: 08/03/2021] [Indexed: 12/13/2022]
Abstract
Mucin type O-glycosylation is one of the most diverse types of glycosylation, playing essential roles in tissue development and homeostasis. In complex organisms, O-GalNAc glycans comprise a substantial proportion of the glycocalyx, with defined functions in hemostatic, gastrointestinal, and respiratory systems. Furthermore, O-GalNAc glycans are important players in host-microbe interactions, and changes in O-glycan composition are associated with certain diseases and metabolic conditions, which in some instances can be used for diagnosis or therapeutic intervention. Breakthroughs in O-glycobiology have gone hand in hand with the development of new technologies, such as advancements in mass spectrometry, as well as facilitation of genetic engineering in mammalian cell lines. High-throughput O-glycoproteomics have enabled us to draw a comprehensive map of O-glycosylation, and mining this information has supported the definition and confirmation of functions related to site-specific O-glycans. This includes protection from proteolytic cleavage, as well as modulation of binding affinity or receptor function. Yet, there is still much to discover, and among the important next challenges will be to define the context-dependent functions of O-glycans in different stages of cellular differentiation, cellular metabolism, host-microbiome interactions, and in disease. In this review, we present the achievements and the promises in O-GalNAc glycobiology driven by technological advances in analytical methods, genetic engineering, and systems biology.
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Affiliation(s)
- Hans H Wandall
- Department of Cellular and Molecular Medicine, Faculty of Health and Medical Sciences, Copenhagen Center for Glycomics, University of Copenhagen, Copenhagen, Denmark
| | - Mathias A I Nielsen
- Department of Cellular and Molecular Medicine, Faculty of Health and Medical Sciences, Copenhagen Center for Glycomics, University of Copenhagen, Copenhagen, Denmark
| | - Sarah King-Smith
- Department of Cellular and Molecular Medicine, Faculty of Health and Medical Sciences, Copenhagen Center for Glycomics, University of Copenhagen, Copenhagen, Denmark
| | - Noortje de Haan
- Department of Cellular and Molecular Medicine, Faculty of Health and Medical Sciences, Copenhagen Center for Glycomics, University of Copenhagen, Copenhagen, Denmark
| | - Ieva Bagdonaite
- Department of Cellular and Molecular Medicine, Faculty of Health and Medical Sciences, Copenhagen Center for Glycomics, University of Copenhagen, Copenhagen, Denmark
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Choi J, Wagner LJS, Timmermans SBPE, Malaker SA, Schumann B, Gray MA, Debets MF, Takashima M, Gehring J, Bertozzi CR. Engineering Orthogonal Polypeptide GalNAc-Transferase and UDP-Sugar Pairs. J Am Chem Soc 2019; 141:13442-13453. [PMID: 31373799 PMCID: PMC6813768 DOI: 10.1021/jacs.9b04695] [Citation(s) in RCA: 46] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
O-Linked α-N-acetylgalactosamine (O-GalNAc) glycans constitute a major part of the human glycome. They are difficult to study because of the complex interplay of 20 distinct glycosyltransferase isoenzymes that initiate this form of glycosylation, the polypeptide N-acetylgalactosaminyltransferases (GalNAc-Ts). Despite proven disease relevance, correlating the activity of individual GalNAc-Ts with biological function remains challenging due to a lack of tools to probe their substrate specificity in a complex biological environment. Here, we develop a "bump-hole" chemical reporter system for studying GalNAc-T activity in vitro. Individual GalNAc-Ts were rationally engineered to contain an enlarged active site (hole) and probed with a newly synthesized collection of 20 (bumped) uridine diphosphate N-acetylgalactosamine (UDP-GalNAc) analogs to identify enzyme-substrate pairs that retain peptide specificities but are otherwise completely orthogonal to native enzyme-substrate pairs. The approach was applicable to multiple GalNAc-T isoenzymes, including GalNAc-T1 and -T2 that prefer nonglycosylated peptide substrates and GalNAcT-10 that prefers a preglycosylated peptide substrate. A detailed investigation of enzyme kinetics and specificities revealed the robustness of the approach to faithfully report on GalNAc-T activity and paves the way for studying substrate specificities in living systems.
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Affiliation(s)
- Junwon Choi
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
- Chemical Kinomics Research Center, Korea Institute of Science and Technology (KIST), 5 Hwarangro 14-gil, Seongbuk-gu, Seoul 02792, Republic of Korea
| | - Lauren J. S. Wagner
- Department of Chemistry, University of California, Berkeley, California 94720, United States
| | - Suzanne B. P. E. Timmermans
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
- Bio-Organic Chemistry Research Group, Department of Chemical Engineering and Chemistry, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, Netherlands
| | - Stacy A. Malaker
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Benjamin Schumann
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Melissa A. Gray
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Marjoke F. Debets
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
| | - Megumi Takashima
- Department of Nutritional Sciences, University of California, Berkeley, California 94720, United States
| | - Jase Gehring
- Department of Molecular and Cell Biology, University of California, Berkeley, California 94720, United States
| | - Carolyn R. Bertozzi
- Department of Chemistry, Stanford University, Stanford, California 94305, United States
- Howard Hughes Medical Institute, Stanford University, Stanford, California 94305, United States
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5
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Toward Spider Glue: Long Read Scaffolding for Extreme Length and Repetitious Silk Family Genes AgSp1 and AgSp2 with Insights into Functional Adaptation. G3-GENES GENOMES GENETICS 2019; 9:1909-1919. [PMID: 30975702 PMCID: PMC6553539 DOI: 10.1534/g3.119.400065] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
An individual orb weaving spider can spin up to seven different types of silk, each with unique functions and material properties. The capture spiral silk of classic two-dimensional aerial orb webs is coated with an amorphous glue that functions to retain prey that get caught in a web. This unique modified silk is partially comprised of spidroins (spider fibroins) encoded by two members of the silk gene family. The glue differs from solid silk fibers as it is a viscoelastic, amorphic, wet material that is responsive to environmental conditions. Most spidroins are encoded by extremely large, highly repetitive genes that cannot be sequenced using short read technology alone, as the repetitive regions are longer than read length. We sequenced for the first time the complete genomic Aggregate Spidroin 1 (AgSp1) and Aggregate Spidroin 2 (AgSp2) glue genes of orb weaving spider Argiope trifasciata using error-prone long reads to scaffold for high accuracy short reads. The massive coding sequences are 42,270 bp (AgSp1) and 20,526 bp (AgSp2) in length, the largest silk genes currently described. The majority of the predicted amino acid sequence of AgSp1 consists of two similar but distinct motifs that are repeated ∼40 times each, while AgSp2 contains ∼48 repetitions of an AgSp1-similar motif, interspersed by regions high in glutamine. Comparisons of AgSp repetitive motifs from orb web and cobweb spiders show regions of strict conservation followed by striking diversification. Glues from these two spider families have evolved contrasting material properties in adhesion (stickiness), extensibility (stretchiness), and elasticity (the ability of the material to resume its native shape), which we link to mechanisms established for related silk genes in the same family. Full-length aggregate spidroin sequences from diverse species with differing material characteristics will provide insights for designing tunable bio-inspired adhesives for a variety of unique purposes.
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DeCicco RePass MA, Bhat N, Heimburg-Molinaro J, Bunnell S, Cummings RD, Ward HD. Molecular cloning, expression, and characterization of UDP N-acetyl-α-d-galactosamine: Polypeptide N-acetylgalactosaminyltransferase 4 from Cryptosporidium parvum. Mol Biochem Parasitol 2018; 221:56-65. [PMID: 29581010 DOI: 10.1016/j.molbiopara.2018.03.002] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2017] [Revised: 03/21/2018] [Accepted: 03/21/2018] [Indexed: 01/06/2023]
Abstract
Cryptosporidium spp. are the causative agents of diarrheal disease worldwide, but effective treatments are lacking. Cryptosporidium employs mucin-like glycoproteins with O-glycans to attach to and infect host intestinal epithelial cells. The Tn antigen (GalNAcα1-Ser/Thr) is an O-glycan essential for these processes, as Tn-specific lectins and a Tn-specific monoclonal antibody block attachment to and infection of host cells in vitro. The enzymes in Cryptosporidium catalyzing their synthesis, however, have not been studied. Previously, we identified four genes encoding putative UDP N-acetyl-α-d-galactosamine:polypeptide N-acetylgalactosaminyltransferases (ppGalNAc-Ts) in the genomes of three Cryptosporidium spp. Here we report the in silico analysis, cloning, expression, purification, and characterization of one of the four enzymes Cryptosporidium parvum (Cp)-ppGalNAc-T4. This enzyme contains the characteristic domains and motifs conserved in ppGalNAc-Ts and is expressed at multiple time points during in vitro infection. Recombinant soluble Cp-ppGalNAc-T4 was enzymatically active against an unmodified EA2 peptide suggesting that it may function as an "initiating" ppGalNAc-T. Cp-ppGalNAc-T4 also exhibited a strong preference for UDP-GalNAc over other nucleotide sugar donors and was active against unmodified and O-glycosylated versions of the C. parvum gp40-derived peptide, with a preference for the former, suggesting it may play a role in modifying this glycoprotein in vivo. Given the importance of mucin-type O-glycosylation in Cryptosporidium spp., the enzymes that catalyze their synthesis may serve as potential therapeutic targets.
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Affiliation(s)
| | | | | | - Stephen Bunnell
- Tufts University Sackler School of Graduate Biomedical Sciences, Boston, MA, USA
| | - Richard D Cummings
- Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA, USA
| | - Honorine D Ward
- Tufts University Sackler School of Graduate Biomedical Sciences, Boston, MA, USA; Tufts Medical Center, Boston, MA, USA.
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7
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CK-2 of rainbow trout (Oncorhynchus mykiss) has two differentially regulated alleles that encode a functional chemokine. Vet Immunol Immunopathol 2018; 198:26-36. [PMID: 29571515 DOI: 10.1016/j.vetimm.2018.02.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Revised: 01/29/2018] [Accepted: 02/06/2018] [Indexed: 01/08/2023]
Abstract
Rainbow trout chemokine 2 (CK-2) is currently the only known CC chemokine to have a mucin stalk. Further analysis of the mucin stalk region revealed a second, related CC chemokine sequence, denoted here as CK-2.1. This second sequence was determined to be an allele of CK-2 following genomic PCR analysis on several outbred individuals. Furthermore, in both in vivo and in vitro trials, CK-2 and CK-2.1 were both present, but appeared to have differential tissue expression in both control and PHA stimulated samples. Upon the development of a polyclonal antibody to rCK-2, CK-2 was only observed in the brain, liver and head kidney of PHA stimulated rainbow trout tissues. In comparison, when using the rainbow trout monocyte/macrophage-like cell line, RTS-11, CK-2 protein was observed in both control and PHA stimulated conditions. When studying the function of CK-2, a chemotaxis assay revealed that both peripheral blood leukocytes and RTS-11 cells migrated towards rCK-2 significantly at all concentrations studied when compared to truncated β2m. Interestingly, this migration was lowest at both the highest concentration and the lowest concentrations of CK-2. Thus, teleostean chemokine receptors may become desensitized when overstimulated as has been observed in mammalian models. The observed chemotactic function was indeed due to rCK-2 as cell migration was inhibited through pre-treatment of both the cells and the polyclonal antibody with rCK-2. As has been observed thus far with all other chemokines, CK-2 does appear to function through binding to a G-coupled protein receptor as chemotaxis could be inhibited through pre-treatment with pertussis toxin. Overall, the results of this study indicate that CK-2 is a functional chemokine that is encoded by two differentially expressed alleles in rainbow trout, CK-2 and CK-2.1.
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Lavrsen K, Dabelsteen S, Vakhrushev SY, Levann AMR, Haue AD, Dylander A, Mandel U, Hansen L, Frödin M, Bennett EP, Wandall HH. De novo expression of human polypeptide N-acetylgalactosaminyltransferase 6 (GalNAc-T6) in colon adenocarcinoma inhibits the differentiation of colonic epithelium. J Biol Chem 2017; 293:1298-1314. [PMID: 29187600 DOI: 10.1074/jbc.m117.812826] [Citation(s) in RCA: 47] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2017] [Revised: 11/27/2017] [Indexed: 12/25/2022] Open
Abstract
Aberrant expression of O-glycans is a hallmark of epithelial cancers. Mucin-type O-glycosylation is initiated by a large family of UDP-GalNAc:polypeptide N-acetylgalactosaminyltransferases (GalNAc-Ts) that target different proteins and are differentially expressed in cells and organs. Here, we investigated the expression patterns of all of the GalNAc-Ts in colon cancer by analyzing transcriptomic data. We found that GalNAc-T6 was highly up-regulated in colon adenocarcinomas but absent in normal-appearing adjacent colon tissue. These results were verified by immunohistochemistry, suggesting that GalNAc-T6 plays a role in colon carcinogenesis. To investigate the function of GalNAc-T6 in colon cancer, we used precise gene targeting to produce isogenic colon cancer cell lines with a knockout/rescue system for GALNT6 GalNAc-T6 expression was associated with a cancer-like, dysplastic growth pattern, whereas GALNT6 knockout cells showed a more normal differentiation pattern, reduced proliferation, normalized cell-cell adhesion, and formation of crypts in tissue cultures. O-Glycoproteomic analysis of the engineered cell lines identified a small set of GalNAc-T6-specific targets, suggesting that this isoform has unique cellular functions. In support of this notion, the genetically and functionally closely related GalNAc-T3 homolog did not show compensatory functionality for effects observed for GalNAc-T6. Taken together, these data strongly suggest that aberrant GalNAc-T6 expression and site-specific glycosylation is involved in oncogenic transformation.
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Affiliation(s)
- Kirstine Lavrsen
- From the Copenhagen Center for Glycomics, Departments of Cellular and Molecular Medicine and Odontology, Faculty of Health Sciences, and
| | - Sally Dabelsteen
- From the Copenhagen Center for Glycomics, Departments of Cellular and Molecular Medicine and Odontology, Faculty of Health Sciences, and
| | - Sergey Y Vakhrushev
- From the Copenhagen Center for Glycomics, Departments of Cellular and Molecular Medicine and Odontology, Faculty of Health Sciences, and
| | - Asha M R Levann
- From the Copenhagen Center for Glycomics, Departments of Cellular and Molecular Medicine and Odontology, Faculty of Health Sciences, and
| | - Amalie Dahl Haue
- From the Copenhagen Center for Glycomics, Departments of Cellular and Molecular Medicine and Odontology, Faculty of Health Sciences, and
| | - August Dylander
- From the Copenhagen Center for Glycomics, Departments of Cellular and Molecular Medicine and Odontology, Faculty of Health Sciences, and
| | - Ulla Mandel
- From the Copenhagen Center for Glycomics, Departments of Cellular and Molecular Medicine and Odontology, Faculty of Health Sciences, and
| | - Lars Hansen
- From the Copenhagen Center for Glycomics, Departments of Cellular and Molecular Medicine and Odontology, Faculty of Health Sciences, and
| | - Morten Frödin
- Biotech Research and Innovation Centre (BRIC), University of Copenhagen, DK 2200, Copenhagen N, Denmark
| | - Eric P Bennett
- From the Copenhagen Center for Glycomics, Departments of Cellular and Molecular Medicine and Odontology, Faculty of Health Sciences, and
| | - Hans H Wandall
- From the Copenhagen Center for Glycomics, Departments of Cellular and Molecular Medicine and Odontology, Faculty of Health Sciences, and
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Famiglietti AL, Wei Z, Beres TM, Milac AL, Tran DT, Patel D, Angerer RC, Angerer LM, Tabak LA. Characterization and expression analysis of Galnts in developing Strongylocentrotus purpuratus embryos. PLoS One 2017; 12:e0176479. [PMID: 28448610 PMCID: PMC5407767 DOI: 10.1371/journal.pone.0176479] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Accepted: 04/11/2017] [Indexed: 11/19/2022] Open
Abstract
Mucin-type O-glycosylation is a ubiquitous posttranslational modification in which N-Acetylgalactosamine (GalNAc) is added to the hydroxyl group of select serine or threonine residues of a protein by the family of UDP-GalNAc:Polypeptide N-Acetylgalactosaminyltransferases (GalNAc-Ts; EC 2.4.1.41). Previous studies demonstrate that O-glycosylation plays essential roles in protein function, cell-cell interactions, cell polarity and differentiation in developing mouse and Drosophila embryos. Although this type of protein modification is highly conserved among higher eukaryotes, little is known about this family of enzymes in echinoderms, basal deuterostome relatives of the chordates. To investigate the potential role of GalNAc-Ts in echinoderms, we have begun the characterization of this enzyme family in the purple sea urchin, S. purpuratus. We have fully or partially cloned a total of 13 genes (SpGalnts) encoding putative sea urchin SpGalNAc-Ts, and have confirmed enzymatic activity of five recombinant proteins. Amino acid alignments revealed high sequence similarity among sea urchin and mammalian glycosyltransferases, suggesting the presence of putative orthologues. Structural models underscored these similarities and helped reconcile some of the substrate preferences observed. Temporal and spatial expression of SpGalnt transcripts, was studied by whole-mount in situ hybridization. We found that many of these genes are transcribed early in developing embryos, often with restricted expression to the endomesodermal region. Multicolor fluorescent in situ hybridization (FISH) demonstrated that transcripts encoding SpGalnt7-2 co-localized with both Endo16 (a gene expressed in the endoderm), and Gcm (a gene expressed in secondary mesenchyme cells) at the early blastula stage, 20 hours post fertilization (hpf). At late blastula stage (28 hpf), SpGalnt7-2 message co-expresses with Gcm, suggesting that it may play a role in secondary mesenchyme development. We also discovered that morpholino-mediated knockdown of SpGalnt13 transcripts, results in a deficiency of embryonic skeleton and neurons, suggesting that mucin-type O-glycans play essential roles during embryonic development in S. purpuratus.
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Affiliation(s)
- Amber L. Famiglietti
- Section on Biological Chemistry, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, United States of America
| | - Zheng Wei
- Developmental Mechanisms Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, United States of America
| | - Thomas M. Beres
- Section on Biological Chemistry, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, United States of America
| | - Adina L. Milac
- Department of Bioinformatics and Structural Biochemistry, Institute of Biochemistry of the Romanian Academy, Splaiul Independentei 296, Bucharest, Romania
| | - Duy T. Tran
- Section on Biological Chemistry, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, United States of America
| | - Divya Patel
- Section on Biological Chemistry, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, United States of America
| | - Robert C. Angerer
- Developmental Mechanisms Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, United States of America
| | - Lynne M. Angerer
- Developmental Mechanisms Section, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, United States of America
| | - Lawrence A. Tabak
- Section on Biological Chemistry, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, United States of America
- * E-mail:
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Festari MF, Trajtenberg F, Berois N, Pantano S, Revoredo L, Kong Y, Solari-Saquieres P, Narimatsu Y, Freire T, Bay S, Robello C, Bénard J, Gerken TA, Clausen H, Osinaga E. Revisiting the human polypeptide GalNAc-T1 and T13 paralogs. Glycobiology 2017; 27:140-153. [PMID: 27913570 PMCID: PMC5224595 DOI: 10.1093/glycob/cww111] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Revised: 10/30/2016] [Accepted: 11/02/2016] [Indexed: 11/13/2022] Open
Abstract
Polypeptide GalNAc-transferases (GalNAc-Ts) constitute a family of 20 human glycosyltransferases (comprising 9 subfamilies), which initiate mucin-type O-glycosylation. The O-glycoproteome is thought to be differentially regulated via the different substrate specificities and expression patterns of each GalNAc-T isoforms. Here, we present a comprehensive in vitro analysis of the peptide substrate specificity of GalNAc-T13, showing that it essentially overlaps with the ubiquitous expressed GalNAc-T1 isoform found in the same subfamily as T13. We have also identified and partially characterized nine splice variants of GalNAc-T13, which add further complexity to the GalNAc-T family. Two variants with changes in their lectin domains were characterized by in vitro glycosylation assays, and one (Δ39Ex9) was inactive while the second one (Ex10b) had essentially unaltered activity. We used reverse transcription-polymerase chain reaction analysis of human neuroblastoma cell lines, normal brain and a small panel of neuroblastoma tumors to demonstrate that several splice variants (Ex10b, ΔEx9, ΔEx2-7 and ΔEx6/8-39bpEx9) were highly expressed in tumor cell lines compared with normal brain, although the functional implications remain to be unveiled. In summary, the GalNAc-T13 isoform is predicted to function similarly to GalNAc-T1 against peptide substrates in vivo, in contrast to a prior report, but is unique by being selectively expressed in the brain.
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Affiliation(s)
- María Florencia Festari
- Laboratory of Tumor Immunology and Glycobiology, Institut Pasteur de Montevideo, Mataojo 2020 (C.P. 11400), Montevideo, Uruguay
- Departamento de Inmunobiología, Facultad de Medicina, Universidad de la República, Avenida General Flores 2125 (C.P. 11800), Montevideo, Uruguay
| | | | - Nora Berois
- Laboratory of Tumor Immunology and Glycobiology, Institut Pasteur de Montevideo, Mataojo 2020 (C.P. 11400), Montevideo, Uruguay
| | - Sergio Pantano
- Grupo de Simulaciones Biomoleculares, Institut Pasteur de Montevideo, Mataojo 2020 (C.P. 11400), Montevideo, Uruguay
| | - Leslie Revoredo
- Department of Chemistry, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Yun Kong
- Department of Cellular and Molecular Medicine and Odontology, Copenhagen Center for Glycomics, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark
| | - Patricia Solari-Saquieres
- Laboratory of Tumor Immunology and Glycobiology, Institut Pasteur de Montevideo, Mataojo 2020 (C.P. 11400), Montevideo, Uruguay
| | - Yoshiki Narimatsu
- Department of Cellular and Molecular Medicine and Odontology, Copenhagen Center for Glycomics, University of Copenhagen, Blegdamsvej 3, DK-2200 Copenhagen N, Denmark
| | - Teresa Freire
- Departamento de Inmunobiología, Facultad de Medicina, Universidad de la República, Avenida General Flores 2125 (C.P. 11800), Montevideo, Uruguay
| | - Sylvie Bay
- Unité de Chimie de Biomoleculares, CNRS UMR 3523 Institut Pasteur, Paris, France
| | - Carlos Robello
- Unidad de Biología Molecular, Institut Pasteur de Montevideo, Mataojo 2020 (C.P. 11400), Montevideo, Uruguay
- Departamento de Bioquímica, Facultad de Medicina, Universidad de la República, Avenida General Flores 2125 (C.P. 11800), Montevideo, Uruguay
| | - Jean Bénard
- CNRS UMR 8126, Université Paris-Sud 11, and Département de Biologie et Pathologie Médicales Institut Gustave Roussy, Villejuif Cedex, France
| | - Thomas A Gerken
- Department of Chemistry, Case Western Reserve University, Cleveland, OH 44106, USA
- Departments of Pediatrics and Biochemistry, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Henrik Clausen
- Department of Chemistry, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Eduardo Osinaga
- Laboratory of Tumor Immunology and Glycobiology, Institut Pasteur de Montevideo, Mataojo 2020 (C.P. 11400), Montevideo, Uruguay
- Departamento de Inmunobiología, Facultad de Medicina, Universidad de la República, Avenida General Flores 2125 (C.P. 11800), Montevideo, Uruguay
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11
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Akasaka-Manya K, Kawamura M, Tsumoto H, Saito Y, Tachida Y, Kitazume S, Hatsuta H, Miura Y, Hisanaga SI, Murayama S, Hashimoto Y, Manya H, Endo T. Excess APPO-glycosylation by GalNAc-T6 decreases Aβ production. J Biochem 2016; 161:99-111. [DOI: 10.1093/jb/mvw056] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2016] [Accepted: 08/19/2016] [Indexed: 11/13/2022] Open
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12
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Libisch MG, Casás M, Chiribao M, Moreno P, Cayota A, Osinaga E, Oppezzo P, Robello C. GALNT11 as a new molecular marker in chronic lymphocytic leukemia. Gene 2013; 533:270-9. [PMID: 24076351 DOI: 10.1016/j.gene.2013.09.052] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2013] [Accepted: 09/17/2013] [Indexed: 01/27/2023]
Abstract
Aberrant mucin O-glycosylation often occurs in different cancers and is characterized by immature expression of simple mucin-type carbohydrates. At present, there are some controversial reports about the Tn antigen (GalNAcα-O-Ser/Thr) expression and there is a great lack of information about the [UDP-N-acetyl-α-d-galactosamine:polypeptide N-acetylgalactosaminyltransferase (GalNAc-Ts)] expression in chronic lymphocytic leukemia (CLL). To gain insight in these issues we evaluated the Tn antigen expression in CLL patient samples using two Tn binding proteins with different fine specificity. We also studied the expression from 14 GalNAc-Ts genes in CLL patients by RT-PCR. Our results have provided additional information about the expression level of the Tn antigen, suggesting that a low density of Tn residues is expressed in CLL cells. We also found that GALNT11 was expressed in CLL cells and normal T cell whereas little or no expression was found in normal B cells. Based on these results, GALNT11 expression was assessed by qPCR in a cohort of 50 CLL patients. We found significant over-expression of GALNT11 in 96% of B-CLL cells when compared to normal B cells. Moreover, we confirmed the expression of this enzyme at the protein level. Finally we found that GALNT11 expression was significantly associated with the mutational status of the immunoglobulin heavy chain variable region (IGHV), [א(2)(1)=18.26; P<0.0001], lipoprotein lipase expression [א(2)(1)=13.72; P=0.0002] and disease prognosis [א(2)(1)=15.49; P<0.0001]. Our evidence suggests that CLL patient samples harbor aberrant O-glycosylation highlighted by Tn antigen expression and that the over-expression of GALNT11 constitutes a new molecular marker for CLL.
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Affiliation(s)
- M G Libisch
- Molecular Biology Unit, Institut Pasteur de Montevideo, Montevideo, Uruguay
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13
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Schjoldager KTBG, Clausen H. Site-specific protein O-glycosylation modulates proprotein processing - deciphering specific functions of the large polypeptide GalNAc-transferase gene family. BIOCHIMICA ET BIOPHYSICA ACTA 2012; 1820:2079-94. [PMID: 23022508 DOI: 10.1016/j.bbagen.2012.09.014] [Citation(s) in RCA: 149] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2012] [Revised: 09/17/2012] [Accepted: 09/19/2012] [Indexed: 01/18/2023]
Abstract
BACKGROUND Posttranslational modifications (PTMs) greatly expand the function and regulation of proteins, and glycosylation is the most abundant and diverse PTM. Of the many different types of protein glycosylation, one is quite unique; GalNAc-type (or mucin-type) O-glycosylation, where biosynthesis is initiated in the Golgi by up to twenty distinct UDP-N-acetyl-α-d-galactosamine:polypeptide N-acetylgalactosaminyltransferases (GalNAc-Ts). These GalNAc-Ts are differentially expressed in cells and have different (although partly overlapping) substrate specificities, which provide for both unique functions and considerable redundancy. Recently we have begun to uncover human diseases associated with deficiencies in GalNAc-T genes (GALNTs). Thus deficiencies in individual GALNTs produce cell and protein specific effects and subtle distinct phenotypes such as hyperphosphatemia with hyperostosis (GALNT3) and dysregulated lipid metabolism (GALNT2). These phenotypes appear to be caused by deficient site-specific O-glycosylation that co-regulates proprotein convertase (PC) processing of FGF23 and ANGPTL3, respectively. SCOPE OF REVIEW Here we summarize recent progress in uncovering the interplay between human O-glycosylation and protease regulated processing and describes other important functions of site-specific O-glycosylation in health and disease. MAJOR CONCLUSIONS Site-specific O-glycosylation modifies pro-protein processing and other proteolytic events such as ADAM processing and thus emerges as an important co-regulator of limited proteolytic processing events. GENERAL SIGNIFICANCE Our appreciation of this function may have been hampered by our sparse knowledge of the O-glycoproteome and in particular sites of O-glycosylation. New strategies for identification of O-glycoproteins have emerged and recently the concept of SimpleCells, i.e. human cell lines made deficient in O-glycan extension by zinc finger nuclease gene targeting, was introduced for broad O-glycoproteome analysis.
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14
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Bennett EP, Mandel U, Clausen H, Gerken TA, Fritz TA, Tabak LA. Control of mucin-type O-glycosylation: a classification of the polypeptide GalNAc-transferase gene family. Glycobiology 2012; 22:736-56. [PMID: 22183981 PMCID: PMC3409716 DOI: 10.1093/glycob/cwr182] [Citation(s) in RCA: 607] [Impact Index Per Article: 50.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2011] [Revised: 12/14/2011] [Accepted: 12/14/2011] [Indexed: 12/15/2022] Open
Abstract
Glycosylation of proteins is an essential process in all eukaryotes and a great diversity in types of protein glycosylation exists in animals, plants and microorganisms. Mucin-type O-glycosylation, consisting of glycans attached via O-linked N-acetylgalactosamine (GalNAc) to serine and threonine residues, is one of the most abundant forms of protein glycosylation in animals. Although most protein glycosylation is controlled by one or two genes encoding the enzymes responsible for the initiation of glycosylation, i.e. the step where the first glycan is attached to the relevant amino acid residue in the protein, mucin-type O-glycosylation is controlled by a large family of up to 20 homologous genes encoding UDP-GalNAc:polypeptide GalNAc-transferases (GalNAc-Ts) (EC 2.4.1.41). Therefore, mucin-type O-glycosylation has the greatest potential for differential regulation in cells and tissues. The GalNAc-T family is the largest glycosyltransferase enzyme family covering a single known glycosidic linkage and it is highly conserved throughout animal evolution, although absent in bacteria, yeast and plants. Emerging studies have shown that the large number of genes (GALNTs) in the GalNAc-T family do not provide full functional redundancy and single GalNAc-T genes have been shown to be important in both animals and human. Here, we present an overview of the GalNAc-T gene family in animals and propose a classification of the genes into subfamilies, which appear to be conserved in evolution structurally as well as functionally.
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Affiliation(s)
- Eric P Bennett
- Department of Odontology, Copenhagen Center for Glycomics, University of Copenhagen, Nørre Alle 20, DK-2200 Copenhagen N, Denmark.
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15
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Tran DT, Lim JM, Liu M, Stalnaker SH, Wells L, Ten Hagen KG, Live D. Glycosylation of α-dystroglycan: O-mannosylation influences the subsequent addition of GalNAc by UDP-GalNAc polypeptide N-acetylgalactosaminyltransferases. J Biol Chem 2012; 287:20967-74. [PMID: 22549772 DOI: 10.1074/jbc.m112.370387] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
O-Linked glycosylation is a functionally and structurally diverse type of protein modification present in many tissues and across many species. α-Dystroglycan (α-DG), a protein linked to the extracellular matrix, whose glycosylation status is associated with human muscular dystrophies, displays two predominant types of O-glycosylation, O-linked mannose (O-Man) and O-linked N-acetylgalactosamine (O-GalNAc), in its highly conserved mucin-like domain. The O-Man is installed by an enzyme complex present in the endoplasmic reticulum. O-GalNAc modifications are initiated subsequently in the Golgi apparatus by the UDP-GalNAc polypeptide N-acetylgalactosaminyltransferase (ppGalNAc-T) enzymes. How the presence and position of O-Man influences the action of the ppGalNAc-Ts on α-DG and the distribution of the two forms of glycosylation in this domain is not known. Here, we investigated the interplay between O-Man and the addition of O-GalNAc by examining the activity of the ppGalNAc-Ts on peptides and O-Man-containing glycopeptides mimicking those found in native α-DG. These synthetic glycopeptides emulate intermediate structures, not otherwise readily available from natural sources. Through enzymatic and mass spectrometric methods, we demonstrate that the presence and specific location of O-Man can impact either the regional exclusion or the site of O-GalNAc addition on α-DG, elucidating the factors contributing to the glycosylation patterns observed in vivo. These results provide evidence that one form of glycosylation can influence another form of glycosylation in α-DG and suggest that in the absence of proper O-mannosylation, as is associated with certain forms of muscular dystrophy, aberrant O-GalNAc modifications may occur and could play a role in disease presentation.
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Affiliation(s)
- Duy T Tran
- Developmental Glycobiology Unit, NIDCR, National Institutes of Health, Bethesda, Maryland 20892, USA
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16
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Bhattacharyya N, Wiench M, Dumitrescu C, Connolly BM, Bugge TH, Patel HV, Gafni RI, Cherman N, Cho M, Hager GL, Collins MT. Mechanism of FGF23 processing in fibrous dysplasia. J Bone Miner Res 2012; 27:1132-41. [PMID: 22247037 PMCID: PMC7448291 DOI: 10.1002/jbmr.1546] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
Abstract
Fibroblast growth factor-23 (FGF23) is a phosphate- and vitamin D-regulating hormone derived from osteoblasts/osteocytes that circulates in both active (intact, iFGF23) and inactive (C-terminal, cFGF23) forms. O-glycosylation by O-glycosyl transferase N-acetylgalactosaminyltransferase 3 (ppGalNAcT3) and differential cleavage by furin have been shown to be involved in regulating the ratio of active to inactive FGF23. Elevated iFGF23 levels are observed in a number of hypophosphatemic disorders, such as X-linked, autosomal recessive, and autosomal dominant hypophosphatemic rickets, whereas low iFGF23 levels are found in the hyperphosphatemic disorder familial tumoral calcinosis/hyperphosphatemic hyperostosis syndrome. Fibrous dysplasia of bone (FD) is associated with increased total FGF23 levels (cFGF23 + iFGF23); however, classic hypophosphatemic rickets is uncommon. Our results suggest that it can be explained by increased FGF23 cleavage leading to an increase in inactive cFGF23 relative to active iFGF23. Given the fact that FD is caused by activating mutations in the small G-protein G(s) α that results in increased cyclic adenosine monophosphate (cAMP) levels, we postulated that there may be altered FGF23 cleavage in FD and that the mechanism may involve alterations in cAMP levels and ppGalNacT3 and furin activities. Analysis of blood specimens from patients with FD confirmed that the elevated total FGF23 levels are the result of proportionally increased cFGF23 levels, consistent with less glycosylation and enhanced cleavage by furin. Analysis of primary cell lines of normal and mutation-harboring bone marrow stromal cells (BMSCs) from patients with FD demonstrated that BMSCs harboring the causative G(s) α mutation had higher cAMP levels, lower ppGalNAcT3, and higher furin activity. These data support the model wherein glycosylation by ppGalNAcT3 inhibits FGF23 cleavage by furin and suggest that FGF23 processing is a regulated process that controls overall FGF23 activity in FD patients.
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Affiliation(s)
- Nisan Bhattacharyya
- Skeletal Clinical Studies Unit, Craniofacial and Skeletal Diseases Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
| | - Malgorzata Wiench
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Claudia Dumitrescu
- Skeletal Clinical Studies Unit, Craniofacial and Skeletal Diseases Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
| | - Brian M Connolly
- Oral and Pharyngeal Cancer Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
| | - Thomas H Bugge
- Oral and Pharyngeal Cancer Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
| | - Himatkumar V Patel
- Section on Biological Chemistry, National Institute of Diabetes and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Rachel I Gafni
- Skeletal Clinical Studies Unit, Craniofacial and Skeletal Diseases Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
| | - Natasha Cherman
- Skeletal Clinical Studies Unit, Craniofacial and Skeletal Diseases Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
| | - Monique Cho
- Kidney Disease Branch, National Institute of Diabetes and Kidney Diseases, National Institutes of Health, Bethesda, MD, USA
| | - Gordon L Hager
- Laboratory of Receptor Biology and Gene Expression, National Cancer Institute, National Institutes of Health, Bethesda, MD, USA
| | - Michael T Collins
- Skeletal Clinical Studies Unit, Craniofacial and Skeletal Diseases Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD, USA
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17
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Raman J, Guan Y, Perrine CL, Gerken TA, Tabak LA. UDP-N-acetyl-α-D-galactosamine:polypeptide N-acetylgalactosaminyltransferases: completion of the family tree. Glycobiology 2011; 22:768-77. [PMID: 22186971 DOI: 10.1093/glycob/cwr183] [Citation(s) in RCA: 67] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The formation of mucin-type O-glycans is initiated by an evolutionarily conserved family of enzymes, the UDP-N-acetyl-α-D-galactosamine:polypeptide N-acetylgalactosaminyltransferases (GalNAc-Ts). The human genome encodes 20 transferases; 17 of which have been characterized functionally. The complexity of the GalNAc-T family reflects the differential patterns of expression among the individual enzyme isoforms and the unique substrate specificities which are required to form the dense arrays of glycans that are essential for mucin function. We report the expression patterns and enzymatic activity of the remaining three members of the family and the further characterization of a recently reported isoform, GalNAc-T17. One isoform, GalNAcT-16 that is most homologous to GalNAc-T14, is widely expressed (abundantly in the heart) and has robust polypeptide transferase activity. The second isoform GalNAc-T18, most similar to GalNAc-T8, -T9 and -T19, completes a discrete subfamily of GalNAc-Ts. It is widely expressed and has low, albeit detectable, activity. The final isoform, GalNAc-T20, is most homologous to GalNAc-T11 but lacks a lectin domain and has no detectable transferase activity with the panel of substrates tested. We have also identified and characterized enzymatically active splice variants of GalNAc-T13 that differ in the sequence of their lectin domain. The variants differ in their affinities for glycopeptide substrates. Our findings provide a comprehensive view of the complexities of mucin-type O-glycan formation and provide insight into the underlying mechanisms employed to heavily decorate mucins and mucin-like domains with carbohydrate.
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Affiliation(s)
- Jayalakshmi Raman
- Department of Health and Human Services, Section on Biological Chemistry, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20892, USA
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18
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Holleboom AG, Karlsson H, Lin RS, Beres TM, Sierts JA, Herman DS, Stroes ES, Aerts JM, Kastelein JJ, Motazacker MM, Dallinga-Thie GM, Levels JH, Zwinderman AH, Seidman JG, Seidman CE, Ljunggren S, Lefeber DJ, Morava E, Wevers RA, Fritz TA, Tabak LA, Lindahl M, Hovingh GK, Kuivenhoven JA. Heterozygosity for a loss-of-function mutation in GALNT2 improves plasma triglyceride clearance in man. Cell Metab 2011; 14:811-8. [PMID: 22152306 PMCID: PMC3523677 DOI: 10.1016/j.cmet.2011.11.005] [Citation(s) in RCA: 85] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/12/2011] [Revised: 08/15/2011] [Accepted: 11/13/2011] [Indexed: 01/31/2023]
Abstract
Genome-wide association studies have identified GALNT2 as a candidate gene in lipid metabolism, but it is not known how the encoded enzyme ppGalNAc-T2, which contributes to the initiation of mucin-type O-linked glycosylation, mediates this effect. In two probands with elevated plasma high-density lipoprotein cholesterol and reduced triglycerides, we identified a mutation in GALNT2. It is shown that carriers have improved postprandial triglyceride clearance, which is likely attributable to attenuated glycosylation of apolipoprotein (apo) C-III, as observed in their plasma. This protein inhibits lipoprotein lipase (LPL), which hydrolyses plasma triglycerides. We show that an apoC-III-based peptide is a substrate for ppGalNAc-T2 while its glycosylation by the mutant enzyme is impaired. In addition, neuraminidase treatment of apoC-III which removes the sialic acids from its glycan chain decreases its potential to inhibit LPL. Combined, these data suggest that ppGalNAc-T2 can affect lipid metabolism through apoC-III glycosylation, thereby establishing GALNT2 as a lipid-modifying gene.
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Affiliation(s)
- Adriaan G. Holleboom
- Department of Vascular Medicine, Academic Medical Center, Amsterdam 1105AZ, The Netherlands
| | - Helen Karlsson
- Center of Occupational and Environmental Medicine, County Council of Östergötland, Linköping S-581 85, Sweden
- Occupational and Environmental Medicine, Department of Clinical and Experimental Medicine, Linköping University, Linköping S-581 85, Sweden
| | - Ruei-Shiuan Lin
- Section on Biological Chemistry, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892, USA
| | - Thomas M. Beres
- Section on Biological Chemistry, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892, USA
| | - Jeroen A. Sierts
- Department of Experimental Vascular Medicine, Academic Medical Center, Amsterdam 1105AZ, The Netherlands
| | - Daniel S. Herman
- Department of Genetics, Harvard Medical School, Boston, MA 02115, USA
| | - Erik S.G. Stroes
- Department of Vascular Medicine, Academic Medical Center, Amsterdam 1105AZ, The Netherlands
| | - Johannes M. Aerts
- Department of Medical Biochemistry, Academic Medical Center, Amsterdam 1105AZ, The Netherlands
| | - John J.P. Kastelein
- Department of Vascular Medicine, Academic Medical Center, Amsterdam 1105AZ, The Netherlands
| | - Mohammad M. Motazacker
- Department of Experimental Vascular Medicine, Academic Medical Center, Amsterdam 1105AZ, The Netherlands
| | - Geesje M. Dallinga-Thie
- Department of Vascular Medicine, Academic Medical Center, Amsterdam 1105AZ, The Netherlands
- Department of Experimental Vascular Medicine, Academic Medical Center, Amsterdam 1105AZ, The Netherlands
| | - Johannes H.M. Levels
- Department of Experimental Vascular Medicine, Academic Medical Center, Amsterdam 1105AZ, The Netherlands
| | - Aeilko H. Zwinderman
- Department of Clinical Epidemiology, Biostatistics, and Bioinformatics, Academic Medical Center, Amsterdam 1105AZ, The Netherlands
| | | | | | - Stefan Ljunggren
- Occupational and Environmental Medicine, Department of Clinical and Experimental Medicine, Linköping University, Linköping S-581 85, Sweden
| | - Dirk J. Lefeber
- Department of Neurology, Radboud University Nijmegen Medical Center, Nijmegen 6525GA, The Netherlands
- Department of Laboratory Medicine, Radboud University Nijmegen Medical Center, Nijmegen 6525GA, The Netherlands
- Institute for Genetic and Metabolic Disease, Radboud University Nijmegen Medical Center, Nijmegen 6525GA, The Netherlands
| | - Eva Morava
- Institute for Genetic and Metabolic Disease, Radboud University Nijmegen Medical Center, Nijmegen 6525GA, The Netherlands
- Department of Pediatrics, Radboud University Nijmegen Medical Center, Nijmegen 6525GA, The Netherlands
| | - Ron A. Wevers
- Department of Laboratory Medicine, Radboud University Nijmegen Medical Center, Nijmegen 6525GA, The Netherlands
- Institute for Genetic and Metabolic Disease, Radboud University Nijmegen Medical Center, Nijmegen 6525GA, The Netherlands
| | | | - Lawrence A. Tabak
- Section on Biological Chemistry, National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892, USA
| | - Mats Lindahl
- Occupational and Environmental Medicine, Department of Clinical and Experimental Medicine, Linköping University, Linköping S-581 85, Sweden
| | - G. Kees Hovingh
- Department of Vascular Medicine, Academic Medical Center, Amsterdam 1105AZ, The Netherlands
| | - Jan Albert Kuivenhoven
- Department of Experimental Vascular Medicine, Academic Medical Center, Amsterdam 1105AZ, The Netherlands
- Department of Pathology and Medical Biology, University Medical Center Groningen, University of Groningen, Groningen 9713AV, The Netherlands
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Schilling CI, Jung N, Biskup M, Schepers U, Bräse S. Bioconjugation via azide–Staudinger ligation: an overview. Chem Soc Rev 2011; 40:4840-71. [DOI: 10.1039/c0cs00123f] [Citation(s) in RCA: 234] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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20
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Peng C, Togayachi A, Kwon YD, Xie C, Wu G, Zou X, Sato T, Ito H, Tachibana K, Kubota T, Noce T, Narimatsu H, Zhang Y. Identification of a novel human UDP-GalNAc transferase with unique catalytic activity and expression profile. Biochem Biophys Res Commun 2010; 402:680-6. [PMID: 20977886 DOI: 10.1016/j.bbrc.2010.10.084] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2010] [Accepted: 10/19/2010] [Indexed: 12/18/2022]
Abstract
A novel member of the human ppGalNAc-T family, ppGalNAc-T20, was identified and characterized. Amino acid alignment revealed a high sequence identity between ppGalNAc-T20 and -T10. In the GalNAc transfer assay towards mucin-derived peptide substrates, the recombinant ppGalNAc-T20 demonstrated to be a typical glycopeptide GalNAc-transferase that exhibits activity towards mono-GalNAc-glycosylated peptide EA2 derived from rat submandibular gland mucin but no activity towards non-modified EA2. The in vitro catalytic property of ppGalNAc-T20 was compared with that of ppGalNAc-T10 to show different acceptor substrate specificities and kinetic constants. The ppGalNAc-T20 transcript was found exclusively in testis and brain. In situ hybridization further reveals that ppGalNAc-T20 was specifically localized in primary and secondary spermatocytes of the two meiotic periods, suggesting that it may involve in O-glycosylation during mouse spermatogenesis.
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Affiliation(s)
- Can Peng
- Ministry of Education Key Laboratory of Systems Biomedicine, Shanghai Center for Systems Biomedicine (SCSB), Shanghai Jiao Tong University, Shanghai, China
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21
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Reis CA, Osorio H, Silva L, Gomes C, David L. Alterations in glycosylation as biomarkers for cancer detection. J Clin Pathol 2010; 63:322-9. [PMID: 20354203 DOI: 10.1136/jcp.2009.071035] [Citation(s) in RCA: 320] [Impact Index Per Article: 22.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Glycoconjugates constitute a major class of biomolecules which include glycoproteins, glycosphingolipids and proteoglycans. Glycans are involved in several physiological and pathological conditions, such as host-pathogen interactions, cell differentiation, migration, tumour invasion and metastisation, cell trafficking and signalling. Cancer is associated with glycosylation alterations in glycoproteins and glycolipids. This review describes various aspects of protein glycosylation with the focus on alterations associated with human cancer. The application of these glycosylation modifications as biomarkers for cancer detection in tumour tissues and serological assays is summarised.
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Affiliation(s)
- Celso A Reis
- Institute of Molecular Pathology and Immunology of the University of Porto - IPATIMUP, Porto 4200-465, Portugal.
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22
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23
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Kato K, Takeuchi H, Kanoh A, Miyahara N, Nemoto-Sasaki Y, Morimoto-Tomita M, Matsubara A, Ohashi Y, Waki M, Usami K, Mandel U, Clausen H, Higashi N, Irimura T. Loss of UDP-GalNAc:polypeptide N-acetylgalactosaminyltransferase 3 and reduced O-glycosylation in colon carcinoma cells selected for hepatic metastasis. Glycoconj J 2010; 27:267-76. [PMID: 20077002 DOI: 10.1007/s10719-009-9275-4] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2009] [Revised: 12/04/2009] [Accepted: 12/09/2009] [Indexed: 11/30/2022]
Abstract
O-glycosylation of mucin is initiated by the attachment of N-acetyl-D-galactosamine (GalNAc) to serine or threonine residues in mucin core polypeptides by UDPGalNAc:polypeptide N-acetylgalactosaminyltransferases (ppGalNAc-Ts). It is not well understood how GalNAc attachment is regulated by multiple ppGalNAc-Ts in each cell. In the present study, the expression levels of murine ppGalNAc-Ts (mGalNAc-Ts), T1, T2, T3, T4, T6, and T7 were compared between mouse colon carcinoma colon 38 cells and variant SL4 cells, selected for their metastatic potentials, by using the competitive RT-PCR method. The expression levels of mGalNAc-T1, T2, and T7 were slightly higher in the SL4 cells than in the colon 38 cells, whereas the expression level of mGalNAc-T3 in the SL4 cells was 1.5% of that in the colon 38 cells. Products of enzymatic incorporations of GalNAc residues into FITCPTTTPITTTTK peptide by the use of microsome fractions of these cells as the enzyme source were separated and characterized for the number of attached GalNAc residues and their positions. The maximum number of attached GalNAc residues was 6 and 4 when the microsome fractions of the colon 38 cells and SL4 cells were used, respectively. When the microsome fractions of the colon 38 cells were treated with a polyclonal antibody raised against mGalNAc-T3, the maximum number of incorporated GalNAc residues was 4. These results strongly suggest that mGalNAc-T3 in colon 38 cells is involved in additional transfer of GalNAc residues to this peptide.
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Affiliation(s)
- Kentaro Kato
- Laboratory of Cancer Biology and Molecular Immunology, Graduate School of Pharmaceutical Sciences, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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24
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Miwa HE, Gerken TA, Jamison O, Tabak LA. Isoform-specific O-glycosylation of osteopontin and bone sialoprotein by polypeptide N-acetylgalactosaminyltransferase-1. J Biol Chem 2010; 285:1208-19. [PMID: 19880513 PMCID: PMC2801249 DOI: 10.1074/jbc.m109.035436] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2009] [Revised: 10/08/2009] [Indexed: 11/06/2022] Open
Abstract
Mucin-type O-glycan biosynthesis is regulated by the family of UDP-GalNAc polypeptide:N-acetylgalactosaminlytransfersases (ppGalNAcTs) that catalyzes the first step in the pathway by transferring GalNAc to Ser or Thr residues in a protein from the sugar donor UDP-GalNAc. Because not all Ser/Thr residues are glycosylated, rules must exist that signal which hydroyxamino acids acquire sugar. To date, no universal consensus signal has emerged. Therefore, strategies to deduce the subset of proteins that will be glycosylated by distinct ppGalNAcTs must be developed. Mucin-type O-glycoproteins are present abundantly in bone, where we found multiple ppGalNAcT isoforms, including ppGalNAcT-1, to be highly expressed. Thus, we compared glycoproteins expressed in wild-type and Galnt1-null mice to identify bone-associated proteins that were glycosylated in a ppGalNAcT-1-dependent manner. A reduction in the apparent molecular masses of two SIBLINGs (small integrin binding ligand N-linked glycoproteins), osteopontin (OPN) and bone sialoprotein (BSP) in the Galnt1-null mice relative to those of the wild-type was observed. Several synthetic peptides derived from OPN and BSP sequences were designed to include either known or predicted (in silico) glycosylation sites. In vitro glycosylation assays of these peptides with recombinant ppGalNAcT-1, ppGalNAcT-2, or ppGalNAcT-3 demonstrated that both SIBLINGs contained Thr/Ser residues that were preferentially glycosylated by ppGalNAcT-1. In addition, lysates prepared from wild-type, but not those from Galnt1-null derived osteoblasts, could glycosylate these peptides efficiently, suggesting that OPN and BSP contain sites that are specific for ppGalNAcT-1. Our study presents a novel and systematic approach for identification of isoform-specific substrates of the ppGalNAcT family and suggests ppGalNAcT-1 to be indispensable for O-glycosylation at specific sites of the bone glycoproteins OPN and BSP.
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Affiliation(s)
- Hazuki E. Miwa
- From the Section on Biological Chemistry, NIDDK, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland 20892 and
| | - Thomas A. Gerken
- the Departments of Pediatrics and Biochemistry, W. A. Bernbaum Center for Cystic Fibrosis Research, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106
| | - Oliver Jamison
- the Departments of Pediatrics and Biochemistry, W. A. Bernbaum Center for Cystic Fibrosis Research, Case Western Reserve University School of Medicine, Cleveland, Ohio 44106
| | - Lawrence A. Tabak
- From the Section on Biological Chemistry, NIDDK, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland 20892 and
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25
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Inactivating germ-line and somatic mutations in polypeptide N-acetylgalactosaminyltransferase 12 in human colon cancers. Proc Natl Acad Sci U S A 2009; 106:12921-5. [PMID: 19617566 DOI: 10.1073/pnas.0901454106] [Citation(s) in RCA: 116] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Aberrant glycosylation is a pathological alteration that is widespread in colon cancer, and usually accompanies the onset and progression of the disease. To date, the molecular mechanisms underlying aberrant glycosylation remain largely unknown. In this study, we identify somatic and germ-line mutations in the gene encoding for polypeptide N-acetylgalactosaminyltransferase 12 (GALNT12) in individuals with colon cancer. Biochemical analyses demonstrate that each of the 8 GALNT12 mutations identified inactivates the normal function of the GALNT enzyme in initiating mucin type O-linked protein glycosylation. Two of these inactivating GALNT12 mutations were identified as acquired somatic mutations in a set of 30 microsatellite stable colon tumors. Relative to background gene mutation rates, finding these somatic GALNT12 mutations was statistically significant at P < 0.001. Six additional inactivating GALNT12 mutations were detected as germ-line changes carried by patients with colon cancer; however, no inactivating variants were detected among cancer-free controls (P = 0.005). Notably, in 3 of the 6 individuals harboring inactivating germ-line GALNT12 mutations, both a colon cancer and a second independent epithelial cancer had developed. These findings suggest that genetic defects in the O-glycosylation pathway in part underlie aberrant glycosylation in colon cancers, and they contribute to the development of a subset of these malignancies.
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26
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Ichikawa S, Sorenson AH, Austin AM, Mackenzie DS, Fritz TA, Moh A, Hui SL, Econs MJ. Ablation of the Galnt3 gene leads to low-circulating intact fibroblast growth factor 23 (Fgf23) concentrations and hyperphosphatemia despite increased Fgf23 expression. Endocrinology 2009; 150:2543-50. [PMID: 19213845 PMCID: PMC2689800 DOI: 10.1210/en.2008-0877] [Citation(s) in RCA: 122] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/10/2008] [Accepted: 02/02/2009] [Indexed: 12/24/2022]
Abstract
Familial tumoral calcinosis is characterized by ectopic calcifications and hyperphosphatemia. The disease is caused by inactivating mutations in fibroblast growth factor 23 (FGF23), Klotho (KL), and uridine diphosphate-N-acetyl-alpha-D-galactosamine:polypeptide N-acetylgalactosaminyltransferase 3 (GALNT3). In vitro studies indicate that GALNT3 O-glycosylates a phosphaturic hormone, FGF23, and prevents its proteolytic processing, thereby allowing secretion of intact FGF23. In this study we generated mice lacking the Galnt3 gene, which developed hyperphosphatemia without apparent calcifications. In response to hyperphosphatemia, Galnt3-deficient mice had markedly increased Fgf23 expression in bone. However, compared with wild-type and heterozygous littermates, homozygous mice had only about half of circulating intact Fgf23 levels and higher levels of C-terminal Fgf23 fragments in bone. Galnt3-deficient mice also exhibited an inappropriately normal 1,25-dihydroxyvitamin D level and decreased alkaline phosphatase activity. Furthermore, renal expression of sodium-phosphate cotransporters and Kl were elevated in Galnt3-deficient mice. Interestingly, there were sex-specific phenotypes; only Galnt3-deficient males showed growth retardation, infertility, and significantly increased bone mineral density. In summary, ablation of Galnt3 impaired secretion of intact Fgf23, leading to decreased circulating Fgf23 and hyperphosphatemia, despite increased Fgf23 expression. Our findings indicate that Galnt3-deficient mice have a biochemical phenotype of tumoral calcinosis and provide in vivo evidence that Galnt3 plays an essential role in proper secretion of Fgf23 in mice.
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Affiliation(s)
- Shoji Ichikawa
- Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana 46202-5121, USA
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27
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Gerken TA, Ten Hagen KG, Jamison O. Conservation of peptide acceptor preferences between Drosophila and mammalian polypeptide-GalNAc transferase ortholog pairs. Glycobiology 2008; 18:861-70. [PMID: 18669915 PMCID: PMC2574660 DOI: 10.1093/glycob/cwn073] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2008] [Revised: 07/18/2008] [Accepted: 07/29/2008] [Indexed: 12/22/2022] Open
Abstract
UDP-GalNAc:polypeptide alpha-N-acetylgalactosaminyltrans- ferases (ppGalNAc Ts) comprise a large family of glycosyltransferases that initiate mucin-type protein O-glycosylation, transferring alpha-GalNAc to Thr and Ser residues of polypeptide acceptors. Families of ppGalNAc Ts are found across diverse eukaryotes with orthologs identifiable from mammals to single-cell organisms. The peptide substrate specificity and specific protein targets of the individual ppGalNAc T family members remain poorly understood. Previously, we reported a series of oriented random peptide substrate libraries for quantitatively determining the peptide substrate specificities of the mammalian ppGalNAc T1 and T2 (Gerken TA, Raman J, Fritz TA, Jamison O. 2006. Identification of common and unique peptide substrate preferences for the UDP-GalNAc:polypeptide alpha-N-acetylgalactosaminyltransferases T1 & T2 (ppGalNAc T1 & T2) derived from oriented random peptide substrates. J Biol Chem. 281:32403-32416). With these substrates, previously unknown features of the transferases were revealed. Utilizing these and a new lengthened set of random peptides, studies have now been performed on PGANT5 and PGANT2, the Drosophila orthologs of T1 and T2. The results from these studies suggest that the major peptide substrate determinants for these transferases are contained within 2 to 3 residues flanking the site of glycosylation. It is further found that the mammalian and fly T1 orthologs display very similar peptide substrate preferences, while the T2 orthologs are nearly indistinguishable, suggesting similar peptide preferences amongst orthologous pairs have been maintained across evolution. This conclusion is further supported by sequence homology comparisons of each of the transferase orthologs, showing that the peptide substrate and UDP binding site residues are more highly conserved between species relative to their remaining catalytic and lectin domain residues.
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Affiliation(s)
- Thomas A Gerken
- Department of Biochemistry, Case Western Reserve University, Cleveland, OH 44106, USA.
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28
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Gomes J, Marcos NT, Berois N, Osinaga E, Magalhães A, Pinto-de-Sousa J, Almeida R, Gärtner F, Reis CA. Expression of UDP-N-acetyl-D-galactosamine: polypeptide N-acetylgalactosaminyltransferase-6 in gastric mucosa, intestinal metaplasia, and gastric carcinoma. J Histochem Cytochem 2008; 57:79-86. [PMID: 18854599 DOI: 10.1369/jhc.2008.952283] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Aberrant mucin O-glycosylation is often observed in cancer and is characterized by the expression of immature simple mucin-type carbohydrate antigens. UDP-N-acetyl-d-galactosamine:polypeptide N-acetylgalactosaminyltransferase-6 (ppGalNAc-T6) is one of the enzymes responsible for the initial step in O-glycosylation. This study evaluated the expression of ppGalNAc-T6 in human gastric mucosa, intestinal metaplasia, and gastric carcinomas. Our results showed that ppGalNAc-T6 is expressed in normal gastric mucosa and in intestinal metaplasia. A heterogeneous expression and staining pattern for this enzyme was observed in gastric carcinomas. ppGalNAc-T6 was expressed in 79% of the cases, and its expression level was associated with the presence of venous invasion. Our results provide evidence that ppGalNAc-T6 is an IHC marker associated with venous invasion in gastric carcinoma and may contribute to the understanding of the molecular mechanisms that underlie aberrant glycosylation in gastric carcinogenesis and in gastric carcinoma.
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Affiliation(s)
- Joana Gomes
- Institute of Molecular Pathology and Immunology, University of Porto (IPATIMUP), Rua Dr. Roberto Frias s/n, 4200-465 Porto, Portugal
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29
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Raman J, Fritz TA, Gerken TA, Jamison O, Live D, Liu M, Tabak LA. The catalytic and lectin domains of UDP-GalNAc:polypeptide alpha-N-Acetylgalactosaminyltransferase function in concert to direct glycosylation site selection. J Biol Chem 2008; 283:22942-51. [PMID: 18562306 PMCID: PMC2517002 DOI: 10.1074/jbc.m803387200] [Citation(s) in RCA: 67] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2008] [Revised: 06/17/2008] [Indexed: 11/06/2022] Open
Abstract
UDP-GalNAc:polypeptide alpha-N-Acetylgalactosaminyltransferases (ppGalNAcTs), a family (EC 2.4.1.41) of enzymes that initiate mucin-type O-glycosylation, are structurally composed of a catalytic domain and a lectin domain. Previous studies have suggested that the lectin domain modulates the glycosylation of glycopeptide substrates and may underlie the strict glycopeptide specificity of some isoforms (ppGalNAcT-7 and -10). Using a set of synthetic peptides and glycopeptides based upon the sequence of the mucin, MUC5AC, we have examined the activity and glycosylation site preference of lectin domain deletion and exchange constructs of the peptide/glycopeptide transferase ppGalNAcT-2 (hT2) and the glycopeptide transferase ppGalNAcT-10 (hT10). We demonstrate that the lectin domain of hT2 directs glycosylation site selection for glycopeptide substrates. Pre-steady-state kinetic measurements show that this effect is attributable to two mechanisms, either lectin domain-aided substrate binding or lectin domain-aided product release following glycosylation. We find that glycosylation of peptide substrates by hT10 requires binding of existing GalNAcs on the substrate to either its catalytic or lectin domain, thereby resulting in its apparent strict glycopeptide specificity. These results highlight the existence of two modes of site selection used by these ppGalNAcTs: local sequence recognition by the catalytic domain and the concerted recognition of distal sites of prior glycosylation together with local sequence binding mediated, respectively, by the lectin and catalytic domains. The latter mode may facilitate the glycosylation of serine or threonine residues, which occur in sequence contexts that would not be efficiently glycosylated by the catalytic domain alone. Local sequence recognition by the catalytic domain differs between hT2 and hT10 in that hT10 requires a pre-existing GalNAc residue while hT2 does not.
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Affiliation(s)
- Jayalakshmi Raman
- Section on Biological Chemistry, NIDDK, National Institutes of Health, Department of Health and Human Services, Bethesda, Maryland 20892, USA
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30
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Recent insights into the biological roles of mucin-type O-glycosylation. Glycoconj J 2008; 26:325-34. [PMID: 18695988 DOI: 10.1007/s10719-008-9162-4] [Citation(s) in RCA: 135] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2008] [Accepted: 06/12/2008] [Indexed: 12/19/2022]
Abstract
In this special issue of the Glycoconjugate Journal focusing on glycosciences and development, we summarize recent advances in our understanding of the role of mucin-type O-glycans in development and disease. The presence of this widespread protein modification has been known for decades, yet identification of its biological functions has been hampered by the redundancy and complexity of the enzyme family controlling the initiation of O-glycosylation, as well as the diversity of extensions of the core sugar. Recent studies in organisms as diverse as mammals and Drosophila have yielded insights into the function of this highly abundant and evolutionarily-conserved protein modification. Gaining an understanding of mucin-type O-glycans in these diverse systems will elucidate crucial conserved processes underlying many aspects of development and homeostasis.
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31
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Tenno M, Ohtsubo K, Hagen FK, Ditto D, Zarbock A, Schaerli P, von Andrian UH, Ley K, Le D, Tabak LA, Marth JD. Initiation of protein O glycosylation by the polypeptide GalNAcT-1 in vascular biology and humoral immunity. Mol Cell Biol 2007; 27:8783-96. [PMID: 17923703 PMCID: PMC2169402 DOI: 10.1128/mcb.01204-07] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2007] [Revised: 09/18/2007] [Accepted: 09/25/2007] [Indexed: 12/24/2022] Open
Abstract
Core-type protein O glycosylation is initiated by polypeptide N-acetylgalactosamine (GalNAc) transferase (ppGalNAcT) activity and produces the covalent linkage of serine and threonine residues of proteins. More than a dozen ppGalNAcTs operate within multicellular organisms, and they differ with respect to expression patterns and substrate selectivity. These distinctive features imply that each ppGalNAcT may differentially modulate regulatory processes in animal development, physiology, and perhaps disease. We found that ppGalNAcT-1 plays key roles in cell and glycoprotein selective functions that modulate the hematopoietic system. Loss of ppGalNAcT-1 activity in the mouse results in a bleeding disorder which tracks with reduced plasma levels of blood coagulation factors V, VII, VIII, IX, X, and XII. ppGalNAcT-1 further supports leukocyte trafficking and residency in normal homeostatic physiology as well as during inflammatory responses, in part by providing a scaffold for the synthesis of selectin ligands expressed by neutrophils and endothelial cells of peripheral lymph nodes. Animals lacking ppGalNAcT-1 are also markedly impaired in immunoglobulin G production, coincident with increased germinal center B-cell apoptosis and reduced levels of plasma B cells. These findings reveal that the initiation of protein O glycosylation by ppGalNAcT-1 provides a distinctive repertoire of advantageous functions that support vascular responses and humoral immunity.
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Affiliation(s)
- Mari Tenno
- Howard Hughes Medical Institute, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA
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32
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Tenno M, Saeki A, Elhammer AP, Kurosaka A. Function of conserved aromatic residues in the Gal/GalNAc-glycosyltransferase motif of UDP-GalNAc:polypeptide N-acetylgalactosaminyltransferase 1. FEBS J 2007; 274:6037-45. [PMID: 17970754 DOI: 10.1111/j.1742-4658.2007.06124.x] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
UDP-GalNAc:polypeptide N-acetylgalactosaminyltransferases (GalNAc transferases), which initiate mucin-type O-glycan biosynthesis, have broad acceptor substrate specificities, and it is still unclear how they recognize peptides with different sequences. To increase our understanding of the catalytic mechanism of GalNAc-T1, one of the most ubiquitous isozymes, we studied the effect of substituting six conserved aromatic residues in the highly conserved Gal/GalNAc-glycosyltransferase motif with leucine on the catalytic properties of the enzyme. Our results indicate that substitutions of Trp302 and Phe325 have little impact on enzyme function and that substitutions of Phe303 and Tyr309 could be made with only limited impact on the interaction(s) with donor and/or acceptor substrates. By contrast, Trp328 and Trp316 are essential residues for enzyme functions, as substitution with leucine, at either site, led to complete inactivation of the enzymes. The roles of these tryptophan residues were further analyzed by evaluating the impact of substitutions with additional amino acids. All evaluated substitutions at Trp328 resulted in enzymes that were completely inactive, suggesting that the invariant Trp328 is essential for enzymatic activity. Trp316 mutant enzymes with nonaromatic replacements were again completely inactive, whereas two mutant enzymes containing a different aromatic amino acid, at position 316, showed low catalytic activity. Somewhat surprisingly, a kinetic analysis revealed that these two amino acid substitutions had a moderate impact on the enzyme's affinity for the donor substrate. By contrast, the drastically reduced affinity of the Trp316 mutant enzymes for the acceptor substrates suggests that Trp316 is important for this interaction.
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Affiliation(s)
- Mari Tenno
- Department of Biotechnology, Faculty of Engineering, Kyoto Sangyo University, Japan
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Brooks SA, Carter TM, Bennett EP, Clausen H, Mandel U. Immunolocalisation of members of the polypeptide N-acetylgalactosaminyl transferase (ppGalNAc-T) family is consistent with biologically relevant altered cell surface glycosylation in breast cancer. Acta Histochem 2007; 109:273-84. [PMID: 17448526 DOI: 10.1016/j.acthis.2007.02.009] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2007] [Accepted: 02/28/2007] [Indexed: 11/18/2022]
Abstract
An extensive family of UDP-N-alpha-d-galactosamine: polypeptide N-acetylgalactosaminyltransferases (polypeptide N-acetylgalactosaminyltransferases, ppGalNAc-T's) catalyse the attachment of the first N-acetylgalactosamine (GalNAc) monosaccharide to the polypeptide at the initiation of O-linked glycosylation of proteins. Some members of the family are broadly expressed while others are more restricted in their distribution, their expression and activity being confined to certain cells or tissues, being associated with physiological states or differentiation. Their careful regulation, which is not well understood, may mediate the synthesis of varied glycoforms of cellular proteins with different biological activities. Disruptions in glycosylation are a common feature of cancer and may have functional significance. Immunocytochemistry with confocal scanning laser microscopy was employed to detect members of the ppGalNAc-T family, ppGalNAc-T1, -T2, -T3, -T4 and -T6 in a range of breast cell lines. The cells were chosen to represent a range of phenotypes from 'normal'/benign (HMT 3,522), primary, non-metastatic breast cancer (BT 474), to aggressive, metastatic breast cancer (ZR75-1, T47D, MCF-7, DU 4,475). They stably synthesise varying levels, consistent with origin and phenotype, of aberrantly glycosylated glycoproteins featuring exposed, terminal GalNAc residues, including the cancer-associated Tn antigen, which, in numerous studies, have been associated with metastatic competence and poor cancer prognosis. GalNAc-T1 and -T2 were detectable at low levels in all cell lines studied. ppGalNAc-T4, which has never been described in breast, was very weakly detectable in BT 474, MCF7 and T47D. ppGalNAc-T3 and -T6 were weakly detectable or undetectable, respectively, in the cell line HMT 3,522 derived from 'normal'/benign breast epithelium, but were readily detectable in all malignant cell lines. Thus, a broader range of ppGalNAc-T's were detectable in the malignant cell lines in comparison to the 'normal'/benign cells, where only the 'housekeeping' ppGalNAc-T1 and -T2 were present. Expression of normally tightly restricted ppGalNAc-T's may result in initiation of O-linked glycosylation at normally unoccupied potential glycosylation sites leading to altered glycoforms of proteins with changed biological activity which may contribute to the pathogenesis of cancer.
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Affiliation(s)
- Susan A Brooks
- School of Life Sciences, Oxford Brookes University, Gipsy Lane, Headington, Oxford OX3 0BP, UK.
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Gerken TA, Raman J, Fritz TA, Jamison O. Identification of common and unique peptide substrate preferences for the UDP-GalNAc:polypeptide alpha-N-acetylgalactosaminyltransferases T1 and T2 derived from oriented random peptide substrates. J Biol Chem 2006; 281:32403-16. [PMID: 16912039 DOI: 10.1074/jbc.m605149200] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A large family of UDP-GalNAc:polypeptide alpha-N-acetylgalactosaminyltransferases (ppGalNAc Ts) catalyzes the first step of mucin-type protein O-glycosylation by transferring GalNAc to serine and threonine residues of acceptor polypeptides. The acceptor peptide substrate specificity and specific protein targets of the individual ppGalNAc T family members remain poorly characterized and poorly understood, despite the fact that mutations in two individual isoforms are deleterious to man and the fly. In this work a series of oriented random peptide substrate libraries, based on the GAGAXXXTXXXAGAGK sequence motif (where X = randomized positions), have been used to obtain the first comprehensive determination of the peptide substrate specificities of the mammalian ppGalNAc T1 and T2 isoforms. ppGalNAc T-glycosylated random peptides were isolated by lectin affinity chromatography, and transferase amino acid preferences were determined by Edman amino acid sequencing. The results reveal common and unique position-sensitive features for both transferases, consistent with previous reports of the preferences of ppGalNAc T1 and T2. The random peptide substrates also reveal additional specific features that have never been described before that are consistent with the x-ray crystal structures of the two transferases and furthermore are reflected in a data base analysis of in vivo O-glycosylation sites. By using the transferase-specific preferences, optimum and selective acceptor peptide substrates have been generated for each transferase. This approach represents a relatively complete, facile, and reproducible method for obtaining ppGalNAc T peptide substrate specificity. Such information will be invaluable for identifying isoform-specific peptide acceptors, creating isoform-specific substrates, and predicting O-glycosylation sites.
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Affiliation(s)
- Thomas A Gerken
- W. A. Bernbaum Center for Cystic Fibrosis Research, Departments of Pediatrics and Biochemistry, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
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Kubota T, Shiba T, Sugioka S, Furukawa S, Sawaki H, Kato R, Wakatsuki S, Narimatsu H. Structural basis of carbohydrate transfer activity by human UDP-GalNAc: polypeptide alpha-N-acetylgalactosaminyltransferase (pp-GalNAc-T10). J Mol Biol 2006; 359:708-27. [PMID: 16650853 DOI: 10.1016/j.jmb.2006.03.061] [Citation(s) in RCA: 91] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2006] [Revised: 03/22/2006] [Accepted: 03/29/2006] [Indexed: 10/24/2022]
Abstract
Mucin-type O-glycans are important carbohydrate chains involved in differentiation and malignant transformation. Biosynthesis of the O-glycan is initiated by the transfer of N-acetylgalactosamine (GalNAc) which is catalyzed by UDP-GalNAc:polypeptide alpha-N-acetylgalactosaminyltransferases (pp-GalNAc-Ts). Here we present crystal structures of the pp-GalNAc-T10 isozyme, which has specificity for glycosylated peptides, in complex with the hydrolyzed donor substrate UDP-GalNAc and in complex with GalNAc-serine. A structural comparison with uncomplexed pp-GalNAc-T1 suggests that substantial conformational changes occur in two loops near the catalytic center upon donor substrate binding, and that a distinct interdomain arrangement between the catalytic and lectin domains forms a narrow cleft for acceptor substrates. The distance between the catalytic center and the carbohydrate-binding site on the lectin beta sub-domain influences the position of GalNAc glycosylation on GalNAc-glycosylated peptide substrates. A chimeric enzyme in which the two domains of pp-GalNAc-T10 are connected by a linker from pp-GalNAc-T1 acquires activity toward non-glycosylated acceptors, identifying a potential mechanism for generating the various acceptor specificities in different isozymes to produce a wide range of O-glycans.
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Affiliation(s)
- Tomomi Kubota
- Glycogene Function Team of Research Center for Glycoscience (RCG), National Institute of Advanced Industrial Science and Technology (AIST), Central 2, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568, Japan
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36
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Fritz TA, Raman J, Tabak LA. Dynamic association between the catalytic and lectin domains of human UDP-GalNAc:polypeptide alpha-N-acetylgalactosaminyltransferase-2. J Biol Chem 2006; 281:8613-9. [PMID: 16434399 DOI: 10.1074/jbc.m513590200] [Citation(s) in RCA: 125] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The family of UDP-GalNAc:polypeptide alpha-N-acetylgalactosaminyltransferases (ppGalNAcTs) is unique among glycosyltransferases, containing both catalytic and lectin domains that we have previously shown to be closely associated. Here we describe the x-ray crystal structures of human ppGalNAcT-2 (hT2) bound to the product UDP at 2.75 A resolution and to UDP and an acceptor peptide substrate EA2 (PTTDSTTPAPTTK) at 1.64 A resolution. The conformations of both UDP and residues Arg362-Ser372 vary greatly between the two structures. In the hT2-UDP-EA2 complex, residues Arg362-Ser373 comprise a loop that forms a lid over UDP, sealing it in the active site, whereas in the hT2-UDP complex this loop is folded back, exposing UDP to bulk solvent. EA2 binds in a shallow groove with threonine 7 positioned consistent with in vitro data showing it to be the preferred site of glycosylation. The relative orientations of the hT2 catalytic and lectin domains differ dramatically from that of murine ppGalNAcT-1 and also vary considerably between the two hT2 complexes. Indeed, in the hT2-UDP-EA2 complex essentially no contact is made between the catalytic and lectin domains except for the peptide bridge between them. Thus, the hT2 structures reveal an unexpected flexibility between the catalytic and lectin domains and suggest a new mechanism used by hT2 to capture glycosylated substrates. Kinetic analysis of hT2 lacking the lectin domain confirmed the importance of this domain in acting on glycopeptide but not peptide substrates. The structure of the hT2-UDP-EA2 complex also resolves long standing questions regarding ppGalNAcT acceptor substrate specificity.
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Affiliation(s)
- Timothy A Fritz
- Section on Biological Chemistry, NIDDK, National Institutes of Health, Bethesda, Maryland 20892, USA
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Dube DH, Prescher JA, Quang CN, Bertozzi CR. Probing mucin-type O-linked glycosylation in living animals. Proc Natl Acad Sci U S A 2006; 103:4819-24. [PMID: 16549800 PMCID: PMC1405625 DOI: 10.1073/pnas.0506855103] [Citation(s) in RCA: 158] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2005] [Indexed: 11/18/2022] Open
Abstract
Changes in O-linked protein glycosylation are known to correlate with disease states but are difficult to monitor in a physiological setting because of a lack of experimental tools. Here, we report a technique for rapid profiling of O-linked glycoproteins in living animals by metabolic labeling with N-azidoacetylgalactosamine (GalNAz) followed by Staudinger ligation with phosphine probes. After injection of mice with a peracetylated form of GalNAz, azide-labeled glycoproteins were observed in a variety of tissues, including liver, kidney, and heart, in serum, and on isolated splenocytes. B cell glycoproteins were robustly labeled with GalNAz but T cell glycoproteins were not, suggesting fundamental differences in glycosylation machinery or metabolism. Furthermore, GalNAz-labeled B cells could be selectively targeted with a phosphine probe by Staudinger ligation within the living animal. Metabolic labeling with GalNAz followed by Staudinger ligation provides a means for proteomic analysis of this posttranslational modification and for identifying O-linked glycoprotein fingerprints associated with disease.
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Affiliation(s)
| | | | | | - Carolyn R. Bertozzi
- Departments of *Chemistry and
- Molecular and Cell Biology and
- Howard Hughes Medical Institute, University of California, Berkeley, CA 94720; and
- Molecular Foundry, Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA 94720
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38
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Hang HC, Bertozzi CR. The chemistry and biology of mucin-type O-linked glycosylation. Bioorg Med Chem 2005; 13:5021-34. [PMID: 16005634 DOI: 10.1016/j.bmc.2005.04.085] [Citation(s) in RCA: 203] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2005] [Accepted: 04/26/2005] [Indexed: 02/04/2023]
Abstract
Mucin-type O-linked glycosylation is a fundamental post-translational modification that is involved in a variety of important biological processes. However, the lack of chemical tools to study mucin-type O-linked glycosylation has hindered our molecular understanding of O-linked glycans in many biological contexts. The review discusses the significance of mucin-type O-linked glycosylation initiated by the polypeptide N-acetylgalactosaminyltransferases in biology and development of chemical tools to study these enzymes and their substrates.
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Affiliation(s)
- Howard C Hang
- Department of Chemistry, University of California, Berkeley 94720-1460, USA.
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39
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Aluoch AO, Sadik OA, Bedi G. Development of an oral biosensor for salivary amylase using a monodispersed silver for signal amplification. Anal Biochem 2005; 340:136-44. [PMID: 15802139 DOI: 10.1016/j.ab.2005.02.003] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2004] [Indexed: 11/21/2022]
Abstract
An amperometric biosensor for monitoring the level of protein amylase in human saliva is described. A novel design and the preparation of amylase antibodies and antigens, essential for the development of the biosensor, are reported. The biosensor sensing elements comprise a layer of salivary antibody (or antigen) self-assembled onto Au-electrode via covalent attachment. Molecular recognition between the immobilized antibody and the salivary amylase proteins was monitored via an electroactive indicator (e.g., K(3)Fe(CN)(6)) or a monodispersed silver layer present in solution or electrochemically deposited onto the solid electrode. This electroactive indicator was oxidized or reduced and the resulting current change provided the analytical information about the concentration of the salivary proteins. The limit of detection of 1.57 pg/ml was obtained, in comparison to detection limits of 4.95 pg/ml obtained using potassium ferrocyanide as the redox probe and 10 ng/ml obtained using enzyme-linked immunosorbent assay. Cross-reactivity was tested against cystatin antibodies and was found to be less than 2.26%.
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Affiliation(s)
- Austin O Aluoch
- Chemistry Department, State University of New York at Binghamton, P.O. Box 6000, Binghamton, NY 13902-6000, USA
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40
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Pratt MR, Hang HC, Ten Hagen KG, Rarick J, Gerken TA, Tabak LA, Bertozzi CR. Deconvoluting the functions of polypeptide N-alpha-acetylgalactosaminyltransferase family members by glycopeptide substrate profiling. ACTA ACUST UNITED AC 2005; 11:1009-16. [PMID: 15271359 DOI: 10.1016/j.chembiol.2004.05.009] [Citation(s) in RCA: 77] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2004] [Revised: 05/05/2004] [Accepted: 05/06/2004] [Indexed: 10/26/2022]
Abstract
The polypeptide N-alpha-acetylgalactosaminyltransferases (ppGalNAcTs) play a key role in mucin-type O-linked glycan biosynthesis by installing the initial GalNAc residue on the protein scaffold. The preferred substrates and functions of the >20 isoforms in mammals are not well understood. However, current data suggest that glycosylated mucin domains are created by the successive, often hierarchical, action of several specific ppGalNAcTs. Herein we analyzed the glycopeptide substrate preferences of several ppGalNAcT family members using a library screening approach. A 56-member glycopeptide library designed to reflect a diversity of glycan clustering was assayed for substrate activity with ppGalNAcT isoforms using an azido-ELISA. The data suggest that the ppGalNAcTs can be classified into at least four types, which working together, are able to produce densely glycosylated mucin glycoproteins.
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Affiliation(s)
- Matthew R Pratt
- Department of Chemistry, University of California, Berkeley, Berkeley, California 94720, USA
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41
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Nakamura N, Toba S, Hirai M, Morishita S, Mikami T, Konishi M, Itoh N, Kurosaka A. Cloning and expression of a brain-specific putative UDP-GalNAc: polypeptide N-acetylgalactosaminyltransferase gene. Biol Pharm Bull 2005; 28:429-33. [PMID: 15744064 DOI: 10.1248/bpb.28.429] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We isolated a rat cDNA clone and its human orthologue, which are most homologous to UDP-GalNAc: polypeptide N-acetylgalactosaminyltransferase 9, by homology-based PCR from brain. Nucleotide sequence analysis of these putative GalNAc-transferases (designated pt-GalNAc-T) showed that they contained structural features characteristic of the GalNAc-transferase family. It was also found that human pt-GalNAc-T was identical to the gene WBSCR17, which is reported to be in the critical region of patients with Williams-Beuren Syndrome, a neurodevelopmental disorder, and to be predominantly expressed in brain and heart. In order to investigate the expression of pt-GalNAc-T in brain in more detail, we first examined that of human pt-GalNAc-T by Northern blot analysis and found the expression of the 5.0-kb mRNA to be most abundant in cerebral cortex with somewhat less abundant in cellebellum. The expression of rat pt-GalNAc-T was investigated more extensively. The brain-specific expression of 2.0-kb and 5.0-kb transcripts was demonstrated by Northern blot analysis. In situ hybridization in the adult brain revealed high levels of expression in cerebellum, hippocampus, thalamus, and cerebral cortex. Moreover, observation at high magnification revealed the expression to be associated with neurons, but not with glial cells. Analysis of the rat embryos also demonstrated that rat pt-GalNAc-T was expressed in the nervous system, including in the diencephalons, cerebellar primordium, and dorsal root ganglion. However, recombinant human pt-GalNAc-T, which was expressed in insect cells, did not glycosylate several peptides derived from mammalian mucins, suggesting that it may have a strict substrate specificity. The brain-specific expression of pt-GalNAc-T suggested its involvement in brain development, through O-glycosylation of proteins in the neurons.
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Affiliation(s)
- Naosuke Nakamura
- Department of Biotechnology, Faculty of Engineering, Kyoto Sangyo University, Kamigamo-motoyama, Kyoto, Japan
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42
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Sangadala S, Swain JB, McNear A, Mendicino J. Cloning, expression and properties of porcine trachea UDP-galnac: polypeptide N-acetylgalactosaminyl transferase. Mol Cell Biochem 2004; 266:117-26. [PMID: 15646032 DOI: 10.1023/b:mcbi.0000049148.73497.01] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
A UDP-GalNAc:polypeptide N-acetyl-galactosaminyl transferase which catalyses the transfer of GalNAc from UDP-GalNAc to serine and threonine residues in mucin polypeptide chains was purified to homogeneity from swine trachea epithelium (Mendicino J, Sangadala S: Mol Cell Biochem 185: 135-145, 1998). Peptides obtained by proteolysis of the purified enzyme were isolated, sequenced and used to prepare degenerate oligonucleotide primers. Amplified segments of a gene encoding GalNAc transferase were synthesised using the primers and a swine trachea epithelial cDNA library. Selected cDNA fragments were then used to screen the cDNA library, and a clone containing an open reading frame encoding 559 amino acids was isolated. The predicted amino acid sequence contains type II transmembrane region, three potential N-glycosylation sites as well as all of the isolated peptide sequences. The nucleotide sequence and predicted primary protein structure of the transferase were very similar to those of type T-1 GalNAc transferases. The isolated clone was transiently expressed in COS 7 cells and the recombinant enzyme, which contained an N-terminal hexa-histidine tag, was purified to homogeneity and its enzymatic properties were examined. The Vmax of the recombinant enzyme, 2.08 micromol/(min mg), was nearly the same as the native enzyme, 2.12 micromol/(min mg), when assayed with partially deglycosylated mucins as glycosyl acceptors. Both enzymes showed much higher activities when assayed with peptides prepared by limited acid hydrolysis of incompletely deglycosylated Cowper's gland, swine, and human respiratory mucins and tryptic peptides isolated from deglycosylated mucin polypeptide chains. However, as noted earlier (Mendicino J, Sangadala S: Mol Cell Biochem 185: 135-145, 1998), these enzymes showed very little activity with completely deglycosylated mucin polypeptide chains. When completely deglycosylated polypeptide chains were partially glycosylated by incubation with microsome preparations they were again good glycosyl acceptors for the T1-GalNAc transferases isolated from swine trachea. These results show for the first time that multiple isoforms of GalNAc transferases acting in sequence may be required for the complete O-glycosylation of mucin polypeptide chains, and those acting on the nacent polypeptide chain synthesize intermediates which can serve as glycosyl acceptors for other isoforms of the enzyme.
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Affiliation(s)
- Sreedhara Sangadala
- Department of Biochemistry and Molecular Biology, University of Georgia, Athens, GA 30602, USA
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43
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Freire T, FERNáNDEZ C, Chalar C, Maizels R, Alzari P, Osinaga E, Robello C. Characterization of a UDP-N-acetyl-D-galactosamine:polypeptide N-acetylgalactosaminyltransferase with an unusual lectin domain from the platyhelminth parasite Echinococcus granulosus. Biochem J 2004; 382:501-10. [PMID: 15142032 PMCID: PMC1133806 DOI: 10.1042/bj20031877] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2003] [Revised: 05/06/2004] [Accepted: 05/14/2004] [Indexed: 11/17/2022]
Abstract
As part of a general project aimed at elucidating the initiation of mucin-type O-glycosylation in helminth parasites, we have characterized a novel ppGalNAc-T (UDP-N-acetyl-D-galactosamine:polypeptide N-acetylgalactosaminyltransferase) from the cestode Echinococcus granulosus (Eg-ppGalNAc-T1). A full-length cDNA was isolated from a library of the tissue-dwelling larval stage of the parasite, and found to code for a 654-amino-acid protein containing all the structural features of ppGalNAc-Ts. Functional characterization of a recombinant protein lacking the transmembrane domain showed maximal activity at 28 degrees C, in the range 6.5-7.5 pH units and in the presence of Cu2+. In addition, it transferred GalNAc to a broad range of substrate peptides, derived from human mucins and O-glycosylated parasite proteins, including acceptors containing only serine or only threonine residues. Interestingly, the C-terminal region of Eg-ppGalNAc-T1 bears a highly unusual lectin domain, considerably longer than the one from other members of the family, and including only one of the three ricin B repeats generally present in ppGalNAc-Ts. Furthermore, a search for conserved domains within the protein C-terminus identified a fragment showing similarity to a recently defined domain, specialized in the binding of organic phosphates (CYTH). The role of the lectin domain in the determination of the substrate specificity of these enzymes suggests that Eg-ppGalNAc-T1 would be involved in the glycosylation of a special type of substrate. Analysis of the tissue distribution by in situ hybridization and immunohistochemistry revealed that this transferase is expressed in the hydatid cyst wall and the subtegumental region of larval worms. Therefore it could participate in the biosynthesis of O-glycosylated parasite proteins exposed at the interface between E. granulosus and its hosts.
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Affiliation(s)
- Teresa Freire
- *Departamento de Bioquímica, Facultad de Medicina, Universidad de la República, Av. Gral. Flores 2125, Montevideo CP 11800, Uruguay
| | - Cecilia FERNáNDEZ
- †Institute of Cell, Animal and Population Biology, University of Edinburgh, Edinburgh, U.K
| | - Cora Chalar
- ‡Sección Bioquímica, Instituto de Biología, Facultad de Ciencias, Universidad de la República, Montevideo, Uruguay
| | - Rick M. Maizels
- †Institute of Cell, Animal and Population Biology, University of Edinburgh, Edinburgh, U.K
| | - Pedro Alzari
- §Unité de Biochimie Structurale, URA 2185 CNRS, Institut Pasteur, Paris, France
| | - Eduardo Osinaga
- *Departamento de Bioquímica, Facultad de Medicina, Universidad de la República, Av. Gral. Flores 2125, Montevideo CP 11800, Uruguay
| | - Carlos Robello
- *Departamento de Bioquímica, Facultad de Medicina, Universidad de la República, Av. Gral. Flores 2125, Montevideo CP 11800, Uruguay
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44
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Stwora-Wojczyk MM, Dzierszinski F, Roos DS, Spitalnik SL, Wojczyk BS. Functional characterization of a novel Toxoplasma gondii glycosyltransferase: UDP-N-acetyl-D-galactosamine:polypeptide N-acetylgalactosaminyltransferase-T3. Arch Biochem Biophys 2004; 426:231-40. [PMID: 15158673 DOI: 10.1016/j.abb.2004.02.013] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2003] [Revised: 02/12/2004] [Indexed: 11/26/2022]
Abstract
We report the functional characterization of a new UDP-GalNAc:polypeptide N-acetylgalactosaminyltransferase (ppGalNAc-T) (EC 2.4.1.41) from the human disease-causing parasite, Toxoplasma gondii. This glycosyltransferase is denoted as T. gondii ppGalNAc-T3. These enzymes are responsible for the initial step of mucin-type O-glycosylation: the transfer of GalNAc from the UDP-GalNAc nucleotide sugar donor onto a peptide acceptor. Following an in silico analysis of the publicly available T. gondii DNA database, we used molecular biology approaches to identify and isolate the cDNA encoding this enzyme. The resulting type II membrane protein contains N-terminal cytoplasmic, transmembrane, and C-terminal lumenal domains. Conceptual translation of the cDNA sequence also reveals a stem region and the presence of several important sequence motifs. When the recombinant construct was expressed in stably transfected Drosophila melanogaster S2 cells, the purified protein exhibited glycosyltransferase activity in vitro against glycopeptide, but not "naked" peptide, acceptors. In addition, using reverse transcriptase-PCR, T. gondii ppGalNAc-T3 mRNA was equivalently expressed during the tachyzoite and bradyzoite developmental stages. The identification of T. gondii ppGalNAc-T3 as a functional "follow-up" glycopeptide glycosyltransferase further confirms that this human parasite has its own enzymatic O-glycosylation machinery.
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Affiliation(s)
- Magdalena M Stwora-Wojczyk
- Department of Biology, University of Pennsylvania, Goddard Laboratories, 415 South University Avenue, Philadelphia, PA 19104, USA
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45
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Cheng L, Tachibana K, Iwasaki H, Kameyama A, Zhang Y, Kubota T, Hiruma T, Tachibana K, Kudo T, Guo JM, Narimatsu H. Characterization of a novel human UDP-GalNAc transferase, pp-GalNAc-T15. FEBS Lett 2004; 566:17-24. [PMID: 15147861 DOI: 10.1016/j.febslet.2004.03.108] [Citation(s) in RCA: 56] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2004] [Revised: 03/23/2004] [Accepted: 03/29/2004] [Indexed: 11/23/2022]
Abstract
We have cloned, expressed and characterized a novel member of the human UDP-GalNAc:polypeptide N-acetylgalactosaminyltransferase (pp-GalNAc-T) family, pp-GalNAc-T15. The pp-GalNAc-T15 transcript was ubiquitously expressed in human tissues. Recombinant pp-GalNAc-T15 transferred N-acetylgalactosamine (GalNAc) toward a panel of mucin-derived peptide substrates in vitro. Although pp-GalNAc-T15 showed significantly less catalytic activity than pp-GalNAc-T2, T15 transferred up to seven GalNAcs to the Muc5AC peptide, while T2 transferred up to five GalNAcs. These results clearly indicated that pp-GalNAc-T15 is a novel member of the human pp-GalNAc-T family with unique catalytic activity.
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Affiliation(s)
- Lamei Cheng
- Glycogene Function Team, Research Center for Glycoscience, National Institute of Advanced Industrial Science and Technology (AIST), Central-2, 1-1-1 Umezono, Tsukuba, Ibaraki 305-8568, Japan
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46
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Hang HC, Yu C, Ten Hagen KG, Tian E, Winans KA, Tabak LA, Bertozzi CR. Small Molecule Inhibitors of Mucin-Type O-Linked Glycosylation from a Uridine-Based Library. ACTA ACUST UNITED AC 2004; 11:337-45. [PMID: 15123263 DOI: 10.1016/j.chembiol.2004.02.023] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2003] [Revised: 11/10/2003] [Accepted: 12/12/2003] [Indexed: 10/26/2022]
Abstract
The polypeptide N-acetyl-alpha-galactosaminyltransferases (ppGalNAcTs, also abbreviated ppGaNTases) initiate mucin-type O-linked glycosylation and therefore play pivotal roles in cell-cell communication and protection of tissues. In order to develop new tools for studying mucin-type O-linked glycosylation, we screened a 1338 member uridine-based library to identify small molecule inhibitors of ppGalNAcTs. Using a high-throughput enzyme-linked lectin assay (ELLA), two inhibitors of murine ppGalNAcT-1 (K(I) approximately 8 microM) were identified that also inhibit several other members of the family. The compounds did not inhibit other mammalian glycosyltransferases or nucleotide sugar utilizing enzymes, suggesting selectivity for the ppGalNAcTs. Treatment of cells with the compounds abrogated mucin-type O-linked glycosylation but not N-linked glycosylation and also induced apoptosis. These uridine analogs represent the first generation of chemical tools to study the functions of mucin-type O-linked glycosylation.
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Affiliation(s)
- Howard C Hang
- Department of Chemistry, University of California, Berkeley, Berkeley, CA 94720, USA
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47
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Nakamura N, Katano K, Toba S, Kurosaka A. Characterization of a Novel Polypeptide N-Acetylgalactosaminyltransferase (dGalNAc-T3) from Drosophila. Biol Pharm Bull 2004; 27:1509-14. [PMID: 15467186 DOI: 10.1248/bpb.27.1509] [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: 11/22/2022]
Abstract
Polypeptide N-acetylgalactosaminyltransferases (GalNAc-transferases) catalyze the initial reaction of mucin-type O-glycosylation. Here, we report the first biochemical characterization of one of the Drosophila GalNAc-transferases, dGalNAc-T3. This enzyme retains conserved motifs essential for the catalytic activity, but is a novel isozyme in that it has several inserted sequences in its lectin-like domain. Northern hybridization analysis of this isozyme identified a 2.5-kb mRNA in Drosophila larva. Biochemical characterization was carried out using the recombinant soluble dGalNAc-T3 expressed in COS7 cells. dGalNAc-T3, which required Mn2+ for the activity, had a pH optimum ranging from pH 7.5 to 8.5, and glycosylated most effectively at 29-33 degrees C. Its Km for UDP-GalNAc was 10.7 microM, which is as low as that of mammalian isozymes. dGalNAc-T3 glycosylated the peptides containing a sequence of XTPXP or TTAAP most efficiently. The enzyme was irreversibly inhibited by p-chloromercuriphenylsulphonic acid, indicating the presence of essential Cys residues for the activity.
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Affiliation(s)
- Naosuke Nakamura
- Department of Biotechnology, Faculty of Engineering, Kyoto Sangyo University, Kamigamo-motoyama, Kita-ku, Japan
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48
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Wojczyk BS, Stwora-Wojczyk MM, Hagen FK, Striepen B, Hang HC, Bertozzi CR, Roos DS, Spitalnik SL. cDNA cloning and expression of UDP-N-acetyl-D-galactosamine:polypeptide N-acetylgalactosaminyltransferase T1 from Toxoplasma gondii. Mol Biochem Parasitol 2003; 131:93-107. [PMID: 14511808 DOI: 10.1016/s0166-6851(03)00196-8] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We report the cloning, expression, and characterization of the first UDP-GalNAc:polypetide N-acetylgalactosaminyltransferase (ppGalNAc-T) from the human disease-causing parasite, Toxoplasma gondii. This enzyme is also the first characterized ppGalNAc-T of protozoan origin. This type of enzyme catalyzes the initial step of mucin-type O-glycosylation, that is, the transfer of GalNAc in O-glycosidic linkage to serine and threonine residues in polypeptides. We used polymerase chain reaction amplification with degenerate primers and hybridization screening of a T. gondii cDNA library to identify this enzyme. The resulting 84-kDa type II membrane protein contains a 49-amino acid N-terminal cytoplasmic domain, a 22-amino acid hydrophobic transmembrane domain, and a 680-amino acid C-terminal lumenal domain. Conceptual translation of the cDNA sequence reveals a relatively long (i.e. 135 amino acids) stem region and the presence of several important sequence motifs. The latter include a glycosyltransferase 1 (GT1) motif containing a DXH sequence, a Gal/GalNAc-T motif, and a region homologous to ricin lectin. Northern blot analysis identified a single 5.5-kb ppGalNAc-T transcript. Comparison of the cDNA and genomic DNA sequences reveals that this transferase is encoded by 10 exons in a 10 kb region. When the recombinant construct was expressed in stably transfected Drosophila melanogaster S2 cells, the purified protein exhibited transferase activity in vitro. The identification of this enzyme in T. gondii demonstrates that this human parasite has its own enzymatic machinery for the O-glycosylation of toxoplasmal proteins.
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Affiliation(s)
- Boguslaw S Wojczyk
- Department of Pathology and Laboratory Medicine, University of Rochester Medical Center, Box 626, 601 Elmwood Avenue, Rochester, NY 14642, USA.
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49
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Ten Hagen KG, Tran DT, Gerken TA, Stein DS, Zhang Z. Functional characterization and expression analysis of members of the UDP-GalNAc:polypeptide N-acetylgalactosaminyltransferase family from Drosophila melanogaster. J Biol Chem 2003; 278:35039-48. [PMID: 12829714 DOI: 10.1074/jbc.m303836200] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Here we report the cloning and functional characterization of eight members of the UDP-GalNAc:polypeptide N-acetylgalactosaminyltransferase gene family from Drosophila melanogaster (polypeptide GalNAc transferase = pgant1-8). Full-length cDNAs were isolated from a Drosophila embryonic library based on homology to known ppGaNTases. Alignments with characterized mammalian isoforms revealed strong sequence similarities between certain fly and mammalian isoforms, highlighting putative orthologues between the species. In vitro activity assays demonstrated biochemical transferase activity for each gene, with three isoforms requiring glycosylated substrates. Comparison of the activities of Drosophila and mammalian orthologues revealed conservation of substrate preferences against a panel of peptide and glycopeptide substrates. Furthermore, Edman degradation analysis demonstrated that preferred sites of GalNac addition were also conserved between certain fly and mammalian orthologues. Semi-quantitative PCR amplification of Drosophila cDNA revealed expression of most isoforms at each developmental stage, with some isoforms being less abundant at certain stages relative to others. In situ hybridization to Drosophila embryos revealed specific staining of pgant5 and pgant6 in the salivary glands and pgant5 in the developing hindgut. Additionally, pgant5 and pgant6 expression within the egg chamber was restricted to the follicle cells, cells known to be involved in egg formation and subsequent embryonic patterning. The characterization reported here provides additional insight into the use of this model system to dissect the biological role of this enzyme family in vivo during both fly and mammalian development.
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Affiliation(s)
- Kelly G Ten Hagen
- Section of Biological Chemistry, National Institutes of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA.
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50
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Izumi H, Ohta R, Nagatani G, Ise T, Nakayama Y, Nomoto M, Kohno K. p300/CBP-associated factor (P/CAF) interacts with nuclear respiratory factor-1 to regulate the UDP-N-acetyl-alpha-d-galactosamine: polypeptide N-acetylgalactosaminyltransferase-3 gene. Biochem J 2003; 373:713-22. [PMID: 12720548 PMCID: PMC1223531 DOI: 10.1042/bj20021902] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2002] [Revised: 04/23/2003] [Accepted: 04/30/2003] [Indexed: 11/17/2022]
Abstract
We demonstrated recently that expression of the UDP- N -acetyl-alpha-D-galactosamine: polypeptide N -acetylgalactosaminyltrans-ferase-3 (GalNAc-T3) gene is restricted to epithelial glands [Nomoto, Izumi, Ise, Kato, Takano, Nagatani, Shibao, Ohta, Imamura, Kuwano, Matsuo, Yamada, Itoh and Kohno (1999) Cancer Res. 59, 6214-6222]. In the present study, we show that sodium butyrate treatment of human breast cancer MCF-7 cells transcriptionally activates the GalNAc-T3 gene. Transient transfection of plasmids containing a reporter gene under the control of GalNAc-T3 indicated that several transcriptional elements are involved in response to sodium butyrate, with the nuclear respiratory factor-1 (NRF-1)-binding motif located between -88 and -77nt being the most important. Incubation of a labelled probe encompassing the NRF-1-binding motif with a nuclear extract of sodium butyrate-treated MCF-7 cells yielded a higher level of specific DNA-protein complex versus controls. Flag-tagged NRF-1 expressed in MCF-7 cells can bind to the NRF-1-binding motif of the GalNAc-T3 promoter. Nuclear content of NRF-1 remained constant in MCF-7 cells treated with or without sodium butyrate. Moreover, NRF-1 interacts with and is acetylated by p300/CBP-associated factor (P/CAF). Acetylation of NRF-1 enhances DNA binding. Co-transfection of the GalNAc-T3 reporter plasmid with either NRF-1 or P/CAF expression plasmid resulted in the activation of the GalNAc-T3 promoter. These results indicate a correlation between acetylation of NRF-1 by P/CAF and the butyrate-induced expression of the GalNAc-T3 gene. Additionally, induced expression of P/CAF may be a component of the adenocarcinoma differentiation process.
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Affiliation(s)
- Hiroto Izumi
- Department of Molecular Biology, School of Medicine, University of Occupational and Environmental Health Japan, Kitakyushu, Fukuoka 807-8555, Japan
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