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Zhang Y, Zhang L, Xia S, Hou Y, Wu T, Zhou P. Site-specific glycoproteomic analysis of purified lactoferrin from human and animal milk. Int J Biol Macromol 2024; 254:127766. [PMID: 38287599 DOI: 10.1016/j.ijbiomac.2023.127766] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Revised: 10/26/2023] [Accepted: 10/27/2023] [Indexed: 01/31/2024]
Abstract
Lactoferrin is a highly glycosylated protein, which have important biological functions in the growth and development of neonates. However, the glycoforms and glycosylation sites differed between species. The aim of the study was to identify the glycosylation profile (including glycosites, glycan structures, and glycoforms) of purified lactoferrin from human and animal (cow, goat, sheep) milk by using site-specific glycoproteomics technique. In total, a number of 89 N-glycans were identified in human and animal milk lactoferrin. We identified three N-glycosites with 23 different compositions of N-glycans in cow lactoferrin (CLF), four distinctive N-glycosites with 34 dissimilar N-glycan compositions in goat lactoferrin (GLF), five N-glycosites with 57 different N-glycan compositions in sheep lactoferrin (SLF), while five unique N-glycosites with 50 different N-glycan compositions were ascertained in human lactoferrin (HLF). HLF had the most complex glycan, while animal lactoferrin had the most high-mannose glycoforms. The results of this study further our understanding of lactoferrin differences between human and animal milk, which can provide a perspective on the analysis of differences in functional characteristics.
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Affiliation(s)
- Yiqian Zhang
- State Key Laboratory of Food Science & Technology, Jiangnan University, Wuxi, Jiangsu Province 214122, China
| | - Lina Zhang
- State Key Laboratory of Food Science & Technology, Jiangnan University, Wuxi, Jiangsu Province 214122, China; School of Food Science & Technology, Jiangnan University, Wuxi, Jiangsu Province 214122, China.
| | - Siquan Xia
- State Key Laboratory of Food Science & Technology, Jiangnan University, Wuxi, Jiangsu Province 214122, China
| | - Yanmei Hou
- Ausnutria Hyproca Nutrition Co. Ltd., Changsha, Hunan Province 410011, China
| | - Tong Wu
- Ausnutria Hyproca Nutrition Co. Ltd., Changsha, Hunan Province 410011, China
| | - Peng Zhou
- State Key Laboratory of Food Science & Technology, Jiangnan University, Wuxi, Jiangsu Province 214122, China; School of Food Science & Technology, Jiangnan University, Wuxi, Jiangsu Province 214122, China
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Valk-Weeber RL, Eshuis-de Ruiter T, Dijkhuizen L, van Leeuwen SS. Dynamic Temporal Variations in Bovine Lactoferrin Glycan Structures. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2020; 68:549-560. [PMID: 31829588 DOI: 10.1021/acs.jafc.9b06762] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
It has been reported previously that glycosylation of bovine lactoferrin changes over time. A detailed structural overview of these changes over the whole course of lactation, including predry period milk, is lacking. In this study, a high-throughput analysis method was applied to the glycoprofile of lactoferrin isolated from colostrum, mature, and predry period mature milk, which was analyzed over two subsequent lactation cycles for 8 cows from diverse genetic backgrounds. In addition, comparisons are made with commercial bovine lactoferrin samples. During the first 72 h, dynamic changes in lactoferrin glycosylation occurred. Shifts in the oligomannose distribution and the number of sialylated and fucosylated glycans were observed. In some cows, we observed (α2,3)-linked sialic acid in the earliest colostrum samples. The glycoprofiles appeared stable from 1 month after delivery, as well as between cows. In addition, the glycosylation profiles of commercial lactoferrins isolated from pooled mature milk were stable over the year. Lactoferrin glycosylation in the predry period resembles colostrum lactoferrin. The variations in lactoferrin glycosylation profiles, lactoferrin concentrations, and other milk parameters provide detailed information that potentially assists in unraveling the functions and biosynthesis regulation of lactoferrin glycosylation.
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Affiliation(s)
- Rivca L Valk-Weeber
- Microbial Physiology, Groningen Biomolecular Sciences and Biotechnology Institute (GBB) , University of Groningen , Nijenborgh 7 , 9747 AG Groningen , The Netherlands
| | | | - Lubbert Dijkhuizen
- Microbial Physiology, Groningen Biomolecular Sciences and Biotechnology Institute (GBB) , University of Groningen , Nijenborgh 7 , 9747 AG Groningen , The Netherlands
| | - Sander S van Leeuwen
- Microbial Physiology, Groningen Biomolecular Sciences and Biotechnology Institute (GBB) , University of Groningen , Nijenborgh 7 , 9747 AG Groningen , The Netherlands
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Nunes R, Pereira BD, Cerqueira MA, Silva P, Pastrana LM, Vicente AA, Martins JT, Bourbon AI. Lactoferrin-based nanoemulsions to improve the physical and chemical stability of omega-3 fatty acids. Food Funct 2020; 11:1966-1981. [DOI: 10.1039/c9fo02307k] [Citation(s) in RCA: 20] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Omega-3 (ω-3) polyunsaturated fatty acids are highly susceptible to oxidation and have an intense odour and poor water solubility, which make their direct applications in foods extremely difficult.
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Affiliation(s)
- Rafaela Nunes
- Centre of Biological Engineering
- University of Minho
- Braga
- Portugal
| | - Beatriz D'Avó Pereira
- Centre of Biological Engineering
- University of Minho
- Braga
- Portugal
- International Iberian Nanotechnology Laboratory
| | | | - Pedro Silva
- Centre of Biological Engineering
- University of Minho
- Braga
- Portugal
| | | | | | - Joana T. Martins
- Centre of Biological Engineering
- University of Minho
- Braga
- Portugal
| | - Ana I. Bourbon
- International Iberian Nanotechnology Laboratory
- Braga
- Portugal
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Karav S, German JB, Rouquié C, Le Parc A, Barile D. Studying Lactoferrin N-Glycosylation. Int J Mol Sci 2017; 18:E870. [PMID: 28425960 PMCID: PMC5412451 DOI: 10.3390/ijms18040870] [Citation(s) in RCA: 78] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2017] [Revised: 04/10/2017] [Accepted: 04/12/2017] [Indexed: 12/30/2022] Open
Abstract
Lactoferrin is a multifunctional glycoprotein found in the milk of most mammals. In addition to its well-known role of binding iron, lactoferrin carries many important biological functions, including the promotion of cell proliferation and differentiation, and as an anti-bacterial, anti-viral, and anti-parasitic protein. These functions differ among lactoferrin homologs in mammals. Although considerable attention has been given to the many functions of lactoferrin, its primary nutritional contribution is presumed to be related to its iron-binding characteristics, whereas the role of glycosylation has been neglected. Given the critical role of glycan binding in many biological processes, the glycan moieties in lactoferrin are likely to contribute significantly to the biological roles of lactoferrin. Despite the high amino acid sequence homology in different lactoferrins (up to 99%), each exhibits a unique glycosylation pattern that may be responsible for heterogeneity of the biological properties of lactoferrins. An important task for the production of biotherapeutics and medical foods containing bioactive glycoproteins is the assessment of the contributions of individual glycans to the observed bioactivities. This review examines how the study of lactoferrin glycosylation patterns can increase our understanding of lactoferrin functionality.
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Affiliation(s)
- Sercan Karav
- Department of Molecular Biology and Genetics, Canakkale Onsekiz Mart University, 17100 Canakkale, Turkey.
| | - J Bruce German
- Department of Food Science and Technology, University of California, One Shields Avenue, Davis, CA 95616, USA.
- Foods for Health Institute, University of California, One Shields Avenue, Davis, CA 95616, USA.
| | - Camille Rouquié
- Department of Food Science and Technology, University of California, One Shields Avenue, Davis, CA 95616, USA.
| | - Annabelle Le Parc
- Department of Food Science and Technology, University of California, One Shields Avenue, Davis, CA 95616, USA.
| | - Daniela Barile
- Department of Food Science and Technology, University of California, One Shields Avenue, Davis, CA 95616, USA.
- Foods for Health Institute, University of California, One Shields Avenue, Davis, CA 95616, USA.
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Aly E, López-Nicolás R, Darwish AA, Frontela-Saseta C, Ros-Berruezo G. Supplementation of infant formulas with recombinant human lactoferrin and/or galactooligosaccharides increases iron bioaccessibility as measured by ferritin formed in Caco-2 cell model. Food Res Int 2016. [DOI: 10.1016/j.foodres.2016.08.030] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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Lactoferrin: A Modulator for Immunity against Tuberculosis Related Granulomatous Pathology. Mediators Inflamm 2015; 2015:409596. [PMID: 26788020 PMCID: PMC4691619 DOI: 10.1155/2015/409596] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Accepted: 11/30/2015] [Indexed: 01/21/2023] Open
Abstract
There is great need for a therapeutic that would limit tuberculosis related pathology and thus curtail spread of disease between individuals by establishing a "firebreak" to slow transmission. A promising avenue to increase current therapeutic efficacy may be through incorporation of adjunct components that slow or stop development of aggressive destructive pulmonary pathology. Lactoferrin, an iron-binding glycoprotein found in mucosal secretions and granules of neutrophils, is just such a potential adjunct therapeutic agent. The focus of this review is to explore the utility of lactoferrin to serve as a therapeutic tool to investigate "disruption" of the mycobacterial granuloma. Proposed concepts for mechanisms underlying lactoferrin efficacy to control immunopathology are supported by data generated based on in vivo models using nonpathogenic trehalose 6,6'-dimycolate (TDM, cord factor).
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Hwang SA, Kruzel ML, Actor JK. Effects of CHO-expressed recombinant lactoferrins on mouse dendritic cell presentation and function. Innate Immun 2014; 21:553-61. [PMID: 25537452 DOI: 10.1177/1753425914564609] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Accepted: 11/15/2014] [Indexed: 12/11/2022] Open
Abstract
Lactoferrin (LF), a natural iron-binding protein, has previously demonstrated effectiveness in enhancing the Bacillus Calmette-Guérin (BCG) tuberculosis vaccine. This report investigates immune modulatory effects of Chinese hamster ovary (CHO) cell-expressed recombinant mouse and human LFs on mouse bone marrow-derived dendritic cells (BMDCs), comparing homologous and heterologous functions. BCG-infected BMDCs were cultured with LF, and examined for class II presentation molecule expression. Culturing of BCG-infected BMDCs with either LF decreased the class II molecule-expressing population. Mouse LF significantly increased the production of IL-12p40, IL-1β and IL-10, while human LF-treated BMDCs increased only IL-1β and IL-10. Overlaying naïve CD4 T-cells onto BCG-infected BMDCs cultured with mouse LF increased IFN-γ, whereas the human LF-exposed group increased IFN-γ and IL-17 from CD4 T cells. Overlay of naïve CD8 T cells onto BCG-infected BMDCs treated with mouse LF increased the production of IFN-γ and IL-17, while similar experiments using human LF only increased IL-17. This report is the first to examine mouse and human recombinant LFs in parallel experiments to assess murine DC function. These results detail the efficacy of the human LF counterpart used in a heterologous system to understand LF-mediated events that confer BCG efficacy against Mycobacterium tuberculosis challenge.
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Affiliation(s)
- Shen-An Hwang
- Department of Pathology, University of Texas-Houston Medical School, Houston, TX, USA
| | - Marian L Kruzel
- Department of Integrative Biology and Pharmacology, University of Texas-Houston Medical School, Houston, TX, USA
| | - Jeffrey K Actor
- Department of Pathology, University of Texas-Houston Medical School, Houston, TX, USA Program in Immunology, University of Texas Health Science Center, Houston, TX, USA
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O'Riordan N, Kane M, Joshi L, Hickey RM. Structural and functional characteristics of bovine milk protein glycosylation. Glycobiology 2014; 24:220-36. [PMID: 24398766 DOI: 10.1093/glycob/cwt162] [Citation(s) in RCA: 116] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Most secreted and cell membrane proteins in mammals are glycosylated. Many of these glycoproteins are also prevalent in milk and play key roles in the biomodulatory properties of milk and ultimately in determining milk's nutritional quality. Although a significant amount of information exists on the types and roles of free oligosaccharides in milk, very little is known about the glycans associated with milk glycoproteins, in particular, the biological properties that are linked to their presence. The main glycoproteins found in bovine milk are lactoferrin, the immunoglobulins, glycomacropeptide, a glycopeptide derived from κ-casein, and the glycoproteins of the milk fat globule membrane. Here, we review the glycoproteins present in bovine milk, the information currently available on their glycosylation and the biological significance of their oligosaccharide chains.
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Affiliation(s)
- Noelle O'Riordan
- Teagasc Food Research Centre, Moorepark, Fermoy, County Cork, Ireland
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Lactoferrin inhibits Porphyromonas gingivalis proteinases and has sustained biofilm inhibitory activity. Antimicrob Agents Chemother 2012; 56:1548-56. [PMID: 22214780 DOI: 10.1128/aac.05100-11] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Porphyromonas gingivalis is a bacterial pathogen associated with chronic periodontitis that results in destruction of the tooth's supporting tissues. The major virulence determinants of P. gingivalis are its cell surface Arg- and Lys-specific cysteine proteinases, RgpA/B and Kgp. Lactoferrin (LF), an 80-kDa iron-binding glycoprotein found in saliva and gingival crevicular fluid, is believed to play an important role in innate immunity. In this study, bovine milk LF displayed proteinase inhibitory activity against P. gingivalis whole cells, significantly inhibiting both Arg- and Lys-specific proteolytic activities. LF inhibited the Arg-specific activity of purified RgpB, which lacks adhesin domains, and also inhibited the same activity of the RgpA/Kgp proteinase-adhesin complexes in a time-dependent manner, with a first-order inactivation rate constant (k(inact)) of 0.023 min(-1) and an inhibitor affinity constant (K(I)) of 5.02 μM. LF inhibited P. gingivalis biofilm formation by >80% at concentrations above 0.625 μM. LF was relatively resistant to hydrolysis by P. gingivalis cells but was cleaved into two major polypeptides (53 and 33 kDa) at R(284) to S(285), as determined by in-source decay mass spectrometry; however, these polypeptides remained associated with each other and retained inhibitory activity. The biofilm inhibitory activity of LF against P. gingivalis was not attributed to direct antibacterial activity, as LF displayed little growth inhibitory activity against planktonic cells. As the known RgpA/B and Kgp inhibitor N-α-p-tosyl-l-lysine chloromethylketone also inhibited P. gingivalis biofilm formation, the antibiofilm effect of LF may at least in part be attributable to its antiproteinase activity.
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van Leeuwen SS, Schoemaker RJW, Timmer CJAM, Kamerling JP, Dijkhuizen L. Use of Wisteria floribunda agglutinin affinity chromatography in the structural analysis of the bovine lactoferrin N-linked glycosylation. Biochim Biophys Acta Gen Subj 2012; 1820:1444-55. [PMID: 22245701 DOI: 10.1016/j.bbagen.2011.12.014] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2011] [Revised: 12/21/2011] [Accepted: 12/22/2011] [Indexed: 12/29/2022]
Abstract
BACKGROUND Over the years, the N-glycosylation of both human and bovine lactoferrin (LF) has been studied extensively, however not all aspects have been studied in as much detail. Typically, the bovine LF complex-type N-glycans include certain epitopes, not found in human LF N-glycans, i.e. Gal(α1-3)Gal(β1-4)GlcNAc (αGal), GalNAc(β1-4)GlcNAc (LacdiNAc), and N-glycolylneuraminic acid (Neu5Gc). The combined presence of complex-type N-glycans, with αGal, LacdiNAc, LacNAc [Gal(β1-4)GlcNAc], Neu5Ac (N-acetylneuraminic acid), and Neu5Gc epitopes, and oligomannose-type N-glycans complicates the high-throughput analysis of such N-glycoprofiles highly. METHODS For the structural analysis of enzymatically released N-glycan pools, containing both LacNAc and LacdiNAc epitopes, a prefractionation protocol based on Wisteria floribunda agglutinin affinity chromatography was developed. The sub pools were analysed by MALDI-TOF-MS and HPLC-FD profiling, including sequential exoglycosidase treatments. RESULTS This protocol separates the N-glycan pool into three sub pools, with (1) free of LacdiNAc epitopes, (2) containing LacdiNAc epitopes, partially shielded by sialic acid, and (3) containing LacdiNAc epitopes, without shielding by sialic acid. Structural analysis by MALDI-TOF-MS and HPLC-FD showed a complex pattern of oligomannose-, hybrid-, and complex-type di-antennary structures, both with, and without LacdiNAc, αGal and sialic acid. CONCLUSIONS Applying the approach to bovine LF has led to a more detailed N-glycome pattern, including LacdiNAc, αGal, and Neu5Gc epitopes, than was shown in previous studies. GENERAL SIGNIFICANCE Bovine milk proteins contain glycosylation patterns that are absent in human milk proteins; particularly, the LacdiNAc epitope is abundant. Analysis of bovine milk serum proteins is therefore excessively complicated. The presented sub fractionation protocol allows a thorough analysis of the full scope of bovine milk protein glycosylation. This article is part of a Special Issue entitled Glycoproteomics.
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Affiliation(s)
- Sander S van Leeuwen
- Department of Microbial Physiology, Groningen Biomolecular Sciences and Biotechnology Institute (GBB), University of Groningen, Nijenborgh 7, NL-9747 AG Groningen, The Netherlands
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Puddu P, Latorre D, Valenti P, Gessani S. Immunoregulatory role of lactoferrin-lipopolysaccharide interactions. Biometals 2010; 23:387-97. [PMID: 20191308 DOI: 10.1007/s10534-010-9307-3] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2010] [Accepted: 02/12/2010] [Indexed: 12/27/2022]
Abstract
Lactoferrin (Lf) is a mammalian exclusive protein widely distributed in milk and exocrine secretions exhibiting multifunctional properties. Many of the proven or proposed functions of Lf, apart from its iron binding activity, depend on its capacity to bind to other macromolecules. Lf can bind and sequester lipopolysaccharide (LPS), thus preventing pro-inflammatory pathway activation, sepsis and tissue damage. However, the interplay between Lf and LPS is complex, and may result in different outcomes, including both suppression of the inflammatory response and immune activation. These findings are critically relevant in the development of Lf-based therapeutic interventions in humans. Understanding the molecular basis and functional consequences of Lf-LPS interaction will provide insights for determining its role in health and disease.
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Affiliation(s)
- Patrizia Puddu
- Department of Cell Biology and Neurosciences, Istituto Superiore di Sanità, Viale Regina Elena 299, Rome, Italy
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Recombinant human lactoferrin expressed in glycoengineered Pichia pastoris: effect of terminal N-acetylneuraminic acid on in vitro secondary humoral immune response. Glycoconj J 2008; 25:581-93. [PMID: 18365311 DOI: 10.1007/s10719-008-9123-y] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2007] [Revised: 02/22/2008] [Accepted: 02/26/2008] [Indexed: 12/24/2022]
Abstract
Traditional production of therapeutic glycoproteins relies on mammalian cell culture technology. Glycoproteins produced by mammalian cells invariably display N-glycan heterogeneity resulting in a mixture of glycoforms the composition of which varies from production batch to production batch. However, extent and type of N-glycosylation has a profound impact on the therapeutic properties of many commercially relevant therapeutic proteins making control of N-glycosylation an emerging field of high importance. We have employed a combinatorial library approach to generate glycoengineered Pichia pastoris strains capable of displaying defined human-like N-linked glycans at high uniformity. The availability of these strains allows us to elucidate the relationship between specific N-linked glycans and the function of glycoproteins. The aim of this study was to utilize this novel technology platform and produce two human-like N-linked glycoforms of recombinant human lactoferrin (rhLF), sialylated and non-sialylated, and to evaluate the effects of terminal N-glycan structures on in vitro secondary humoral immune responses. Lactoferrin is considered an important first line defense protein involved in protection against various microbial infections. Here, it is established that glycoengineered P. pastoris strains are bioprocess compatible. Analytical protein and glycan data are presented to demonstrate the capability of glycoengineered P. pastoris to produce fully humanized, active and immunologically compatible rhLF. In addition, the biological activity of the rhLF glycoforms produced was tested in vitro revealing the importance of N-acetylneuraminic (sialic) acid as a terminal sugar in propagation of proper immune responses.
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Glenn KA, Nelson RF, Wen HM, Mallinger AJ, Paulson HL. Diversity in tissue expression, substrate binding, and SCF complex formation for a lectin family of ubiquitin ligases. J Biol Chem 2008; 283:12717-29. [PMID: 18203720 DOI: 10.1074/jbc.m709508200] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Post-translational modification of proteins regulates many cellular processes. Some modifications, including N-linked glycosylation, serve multiple functions. For example, the attachment of N-linked glycans to nascent proteins in the endoplasmic reticulum facilitates proper folding, whereas retention of high mannose glycans on misfolded glycoproteins serves as a signal for retrotranslocation and ubiquitin-mediated proteasomal degradation. Here we examine the substrate specificity of the only family of ubiquitin ligase subunits thought to target glycoproteins through their attached glycans. The five proteins comprising this FBA family (FBXO2, FBXO6, FBXO17, FBXO27, and FBXO44) contain a conserved G domain that mediates substrate binding. Using a variety of complementary approaches, including glycan arrays, we show that each family member has differing specificity for glycosylated substrates. Collectively, the F-box proteins in the FBA family bind high mannose and sulfated glycoproteins, with one FBA protein, FBX044, failing to bind any glycans on the tested arrays. Site-directed mutagenesis of two aromatic amino acids in the G domain demonstrated that the hydrophobic pocket created by these amino acids is necessary for high affinity glycan binding. All FBA proteins co-precipitated components of the canonical SCF complex (Skp1, Cullin1, and Rbx1), yet FBXO2 bound very little Cullin1, suggesting that FBXO2 may exist primarily as a heterodimer with Skp1. Using subunit-specific antibodies, we further demonstrate marked divergence in tissue distribution and developmental expression. These differences in substrate recognition, SCF complex formation, and tissue distribution suggest that FBA proteins play diverse roles in glycoprotein quality control.
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Affiliation(s)
- Kevin A Glenn
- Veterans Affairs Medical Center, Iowa City, Iowa 52242, USA.
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15
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van Veen HA, Geerts MEJ, van Berkel PHC, Nuijens JH. The role of N-linked glycosylation in the protection of human and bovine lactoferrin against tryptic proteolysis. ACTA ACUST UNITED AC 2004; 271:678-84. [PMID: 14764083 DOI: 10.1111/j.1432-1033.2003.03965.x] [Citation(s) in RCA: 88] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Lactoferrin (LF) is an iron-binding glycoprotein of the innate host defence system. To elucidate the role of N-linked glycosylation in protection of LF against proteolysis, we compared the tryptic susceptibility of human LF (hLF) variants from human milk, expressed in human 293(S) cells or in the milk of transgenic mice and cows. The analysis revealed that recombinant hLF (rhLF) with mutations Ile130-->Thr and Gly404-->Cys was about twofold more susceptible than glycosylated and unglycosylated variants with the naturally occurring Ile130 and Gly404. Hence, N-linked glycosylation is not involved in protection of hLF against tryptic proteolysis. Apparently, the previously reported protection by N-linked glycosylation of hLF [van Berkel, P.H.C., Geerts, M.E.J., van Veen, H.A., Kooiman, P.M., Pieper, F., de Boer, H.A. & Nuijens, J.H. (1995) Biochem. J. 312, 107-114] is restricted to rhLF containing the Thr130 and Cys404. Comparison of the tryptic proteolysis of hLF and bovine LF (bLF) revealed that hLF is about 100-fold more resistant than bLF. Glycosylation variants A and B of bLF differed by about 10-fold in susceptibility to trypsin. This difference is due to glycosylation at Asn281 in bLF-A. Hence, glycosylation at Asn281 protects bLF against cleavage by trypsin at Lys282.
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