51
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Liu Y, Misulovin Z, Bjorkman PJ. The molecular mechanism of sulfated carbohydrate recognition by the cysteine-rich domain of mannose receptor. J Mol Biol 2001; 305:481-90. [PMID: 11152606 DOI: 10.1006/jmbi.2000.4326] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The mannose receptor (MR) binds foreign and host ligands through interactions with their carbohydrates. Two portions of MR have distinct carbohydrate recognition properties. One is conferred by the amino-terminal cysteine-rich domain (Cys-MR), which plays a critical role in binding sulfated glycoproteins including pituitary hormones. The other is achieved by tandemly arranged C-type lectin domains that facilitate carbohydrate-dependent uptake of infectious microorganisms. This dual carbohydrate binding specificity enables MR to bind ligands by interacting with both sulfated and non-sulfated polysaccharide chains. We previously determined crystal structures of Cys-MR complexed with 4-SO(4)-N-acetylglucosamine and with an unidentified ligand resembling Hepes (N-[2-hydroxyethyl]piperazine-N'-[2-ethanesulfonic acid]). In continued efforts to elucidate the mechanism of sulfated carbohydrate recognition by Cys-MR, we characterized the binding affinities between Cys-MR and potential carbohydrate ligands using a fluorescence-based assay. We find that Cys-MR binds sulfated carbohydrates with relatively high affinities (K(D)=0.1 mM to 1.0 mM) compared to the affinities of other lectins. Cys-MR also binds Hepes with a K(D) value of 3.9 mM, consistent with the suggestion that the ligand in the original Cys-MR crystal structure is Hepes. We also determined crystal structures of Cys-MR complexed with 3-SO(4)-Lewis(x), 3-SO(4)-Lewis(a), and 6-SO(4)-N-acetylglucosamine at 1.9 A, 2.2 A, and 2.5 A resolution, respectively, and the 2.0 A structure of Cys-MR that had been treated to remove Hepes. The conformation of the Cys-MR binding site is virtually identical in all Cys-MR crystal structures, suggesting that Cys-MR does not undergo conformational changes upon ligand binding. The structures are used to rationalize the binding affinities derived from the biochemical studies and to elucidate the molecular mechanism of sulfated carbohydrate recognition by Cys-MR.
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Affiliation(s)
- Y Liu
- Division of Biology 156-29, California Institute of Technology, Pasadena, 91125, USA
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52
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Geijtenbeek TB, Krooshoop DJ, Bleijs DA, van Vliet SJ, van Duijnhoven GC, Grabovsky V, Alon R, Figdor CG, van Kooyk Y. DC-SIGN-ICAM-2 interaction mediates dendritic cell trafficking. Nat Immunol 2000; 1:353-7. [PMID: 11017109 DOI: 10.1038/79815] [Citation(s) in RCA: 366] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Dendritic cells (DCs) are recruited from blood into tissues to patrol for foreign antigens. After antigen uptake and processing, DCs migrate to the secondary lymphoid organs to initiate immune responses. We now show that DC-SIGN, a DC-specific C-type lectin, supports tethering and rolling of DC-SIGN-positive cells on the vascular ligand ICAM-2 under shear flow, a prerequisite for emigration from blood. The DC-SIGN-ICAM-2 interaction regulates chemokine-induced transmigration of DCs across both resting and activated endothelium. Thus, DC-SIGN is central to the unusual trafficking capacity of DCs, further supported by the expression of DC-SIGN on precursors in blood and on immature and mature DCs in both peripheral and lymphoid tissues.
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Affiliation(s)
- T B Geijtenbeek
- Department of Tumor Immunology, University Medical Center St Radboud, Philips van Leydenlaan 25, Nijmegen 6525 EX, The Netherlands
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53
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Kormos J, Johnson PE, Brun E, Tomme P, McIntosh LP, Haynes CA, Kilburn DG. Binding site analysis of cellulose binding domain CBD(N1) from endoglucanse C of Cellulomonas fimi by site-directed mutagenesis. Biochemistry 2000; 39:8844-52. [PMID: 10913296 DOI: 10.1021/bi000607s] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Endoglucanase C (CenC), a beta1,4 glucanase from the soil bacterium Cellulomonas fimi, binds to amorphous cellulose via two homologous cellulose binding domains, termed CBD(N1) and CBD(N2). In this work, the contributions of 10 amino acids within the binding cleft of CBD(N1) were evaluated by single site-directed mutations to alanine residues. Each isolated domain containing a single mutation was analyzed for binding to an insoluble amorphous preparation of cellulose, phosphoric acid swollen Avicel (PASA), and to a soluble glucopyranoside polymer, barley beta-glucan. The effect of any given mutation on CBD binding was similar for both substrates, suggesting that the mechanism of binding to soluble and insoluble substrates is the same. Tyrosines 19 and 85 were essential for tight binding by CBD(N1) as their replacement by alanine results in affinity decrements of approximately 100-fold on PASA, barley beta-glucan, and soluble cellooligosaccharides. The tertiary structures of unbound Y19A and Y85A were assessed by heteronuclear single quantum coherence (HSQC) spectroscopy. These studies indicated that the structures of both mutants were perturbed but that all perturbations are very near to the site of mutation.
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Affiliation(s)
- J Kormos
- Departments of Microbiology and Immunology, University of British Columbia, Vancouver, British Columbia, Canada, V6T 1Z3
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54
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Feinberg H, Park-Snyder S, Kolatkar AR, Heise CT, Taylor ME, Weis WI. Structure of a C-type carbohydrate recognition domain from the macrophage mannose receptor. J Biol Chem 2000; 275:21539-48. [PMID: 10779515 DOI: 10.1074/jbc.m002366200] [Citation(s) in RCA: 88] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The mannose receptor of macrophages and liver endothelium mediates clearance of pathogenic organisms and potentially harmful glycoconjugates. The extracellular portion of the receptor includes eight C-type carbohydrate recognition domains (CRDs), of which one, CRD-4, shows detectable binding to monosaccharide ligands. We have determined the crystal structure of CRD-4. Although the basic C-type lectin fold is preserved, a loop extends away from the core of the domain to form a domain-swapped dimer in the crystal. Of the two Ca(2+) sites, only the principal site known to mediate carbohydrate binding in other C-type lectins is occupied. This site is altered in a way that makes sugar binding impossible in the mode observed in other C-type lectins. The structure is likely to represent an endosomal form of the domain formed when Ca(2+) is lost from the auxiliary calcium site. The structure suggests a mechanism for endosomal ligand release in which the auxiliary calcium site serves as a pH sensor. Acid pH-induced removal of this Ca(2+) results in conformational rearrangements of the receptor, rendering it unable to bind carbohydrate ligands.
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Affiliation(s)
- H Feinberg
- Department of Structural Biology, Stanford University School of Medicine, Stanford, California 94305, USA
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55
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Xu Q, Zeng R, Wu XF, Wang KY. Expression of isolated C-type carbohydrate recognition domains. Biochem Biophys Res Commun 2000; 271:677-81. [PMID: 10814521 DOI: 10.1006/bbrc.2000.2693] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A galactose-binding lectin from the venom of the snake Trimeresurus stejnegeri consists of isolated carbohydrate recognition domains, belonging to group VII of the C-type animal lectins. As a first step toward determining the tertiary structure of the galactose-specific lectin, we produced the lectin in Escherichia coli. By in vitro refolding and affinity chromatography, modest amounts (8 mg/liter) of active recombinant proteins were obtained. The recombinant protein was homogeneous, as determined by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and mass spectrometry. Its amino acid sequence without the initiated methionine at the N-terminus was also characterized by mass spectrometry. The data of hemagglutination and enzyme-linked lectin binding assays demonstrated that the recombinant lectin showed similar sugar-binding activity as the native protein. In addition, fluorescence spectroscopy and circular dichroism also showed obviously their structural similarity.
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Affiliation(s)
- Q Xu
- Shanghai Institute of Biochemistry, Chinese Academy of Sciences, 320 Yue-Yang Road, Shanghai, 200031, People's Republic of China
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56
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Liu Y, Chirino AJ, Misulovin Z, Leteux C, Feizi T, Nussenzweig MC, Bjorkman PJ. Crystal structure of the cysteine-rich domain of mannose receptor complexed with a sulfated carbohydrate ligand. J Exp Med 2000; 191:1105-16. [PMID: 10748229 PMCID: PMC2193177 DOI: 10.1084/jem.191.7.1105] [Citation(s) in RCA: 99] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The macrophage and epithelial cell mannose receptor (MR) binds carbohydrates on foreign and host molecules. Two portions of MR recognize carbohydrates: tandemly arranged C-type lectin domains facilitate carbohydrate-dependent macrophage uptake of infectious organisms, and the NH(2)-terminal cysteine-rich domain (Cys-MR) binds to sulfated glycoproteins including pituitary hormones. To elucidate the mechanism of sulfated carbohydrate recognition, we determined crystal structures of Cys-MR alone and complexed with 4-sulfated-N-acetylgalactosamine at 1.7 and 2.2 A resolution, respectively. Cys-MR folds into an approximately three-fold symmetric beta-trefoil shape resembling fibroblast growth factor. The sulfate portions of 4-sulfated-N-acetylgalactosamine and an unidentified ligand found in the native crystals bind in a neutral pocket in the third lobe. We use the structures to rationalize the carbohydrate binding specificities of Cys-MR and compare the recognition properties of Cys-MR with other beta-trefoil proteins.
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Affiliation(s)
- Yang Liu
- Division of Biology 156-29, California Institute of Technology, Pasadena, California 91125
| | - Arthur J. Chirino
- Division of Biology 156-29, California Institute of Technology, Pasadena, California 91125
- Howard Hughes Medical Institute, California Institute of Technology, Pasadena, California 91125
| | - Ziva Misulovin
- Department of Molecular Immunology and the Howard Hughes Medical Institute, The Rockefeller University, New York, New York 10021-6399
| | - Christine Leteux
- Glycosciences Laboratory, Imperial College School of Medicine, Northwick Park Hospital, Harrow HA1 3UJ, United Kingdom
| | - Ten Feizi
- Glycosciences Laboratory, Imperial College School of Medicine, Northwick Park Hospital, Harrow HA1 3UJ, United Kingdom
| | - Michel C. Nussenzweig
- Department of Molecular Immunology and the Howard Hughes Medical Institute, The Rockefeller University, New York, New York 10021-6399
| | - Pamela J. Bjorkman
- Division of Biology 156-29, California Institute of Technology, Pasadena, California 91125
- Howard Hughes Medical Institute, California Institute of Technology, Pasadena, California 91125
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57
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Sheikh H, Yarwood H, Ashworth A, Isacke CM. Endo180, an endocytic recycling glycoprotein related to the macrophage mannose receptor is expressed on fibroblasts, endothelial cells and macrophages and functions as a lectin receptor. J Cell Sci 2000; 113 ( Pt 6):1021-32. [PMID: 10683150 DOI: 10.1242/jcs.113.6.1021] [Citation(s) in RCA: 113] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Endo180 was previously characterized as a novel, cell type specific, recycling transmembrane glycoprotein. This manuscript describes the isolation of a full length human Endo180 cDNA clone which was shown to encode a fourth member of a family of proteins comprising the macrophage mannose receptor, the phospholipase A(2) receptor and the DEC-205/MR6 receptor. This receptor family is unusual in that they contain 8–10 C-type lectin carbohydrate recognition domains in a single polypeptide backbone, however, only the macrophage mannose receptor had been shown to function as a lectin. Sequence analysis of Endo180 reveals that the second carbohydrate recognition domain has retained key conserved amino acids found in other functional C-type lectins. Furthermore, it is demonstrated that this protein displays Ca(2+)-dependent binding to N-acetylglucosamine but not mannose affinity columns. In order to characterize the physiological function of Endo180, a series of biochemical and morphological studies were undertaken. Endo180 is found to be predominantly expressed in vivo and in vitro on fibroblasts, endothelial cells and macrophages, and the distribution and post-translational processing in these cells is consistent with Endo180 functioning to internalize glycosylated ligands from the extracellular milieu for release in an endosomal compartment.
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Affiliation(s)
- H Sheikh
- Department of Biology, Sir Alexander Fleming Building, Imperial College of Science, Technology and Medicine, Imperial College Road, London SW7 2AZ, UK
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58
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Geijtenbeek TB, Torensma R, van Vliet SJ, van Duijnhoven GC, Adema GJ, van Kooyk Y, Figdor CG. Identification of DC-SIGN, a novel dendritic cell-specific ICAM-3 receptor that supports primary immune responses. Cell 2000; 100:575-85. [PMID: 10721994 DOI: 10.1016/s0092-8674(00)80693-5] [Citation(s) in RCA: 1279] [Impact Index Per Article: 53.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Contact between dendritic cells (DC) and resting T cells is essential to initiate a primary immune response. Here, we demonstrate that ICAM-3 expressed by resting T cells is important in this first contact with DC. We discovered that instead of the common ICAM-3 receptors LFA-1 and alphaDbeta2, a novel DC-specific C-type lectin, DC-SIGN, binds ICAM-3 with high affinity. DC-SIGN, which is abundantly expressed by DC both in vitro and in vivo, mediates transient adhesion with T cells. Since antibodies against DC-SIGN inhibit DC-induced proliferation of resting T cells, our findings predict that DC-SIGN enables T cell receptor engagement by stabilization of the DC-T cell contact zone.
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MESH Headings
- Animals
- Antibodies, Monoclonal/pharmacology
- Antigen Presentation
- Antigens/metabolism
- Antigens, CD
- Antigens, Differentiation
- Calcium/physiology
- Cell Adhesion
- Cell Adhesion Molecules/immunology
- Cell Adhesion Molecules/isolation & purification
- Cell Adhesion Molecules/metabolism
- Cell Communication
- Cells, Cultured
- Dendritic Cells/immunology
- Flow Cytometry
- Gene Expression
- Humans
- Intercellular Adhesion Molecule-1/physiology
- K562 Cells
- Lectins/immunology
- Lectins/physiology
- Lectins, C-Type
- Lymphocyte Activation/physiology
- Lymphocyte Function-Associated Antigen-1/physiology
- Mannans/pharmacology
- Mannose/metabolism
- Mice
- Mice, Inbred BALB C
- Models, Immunological
- Molecular Weight
- Receptors, Cell Surface/immunology
- Receptors, Cell Surface/physiology
- Receptors, HIV/isolation & purification
- Recombinant Fusion Proteins/physiology
- T-Lymphocytes/cytology
- T-Lymphocytes/immunology
- Transfection
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Affiliation(s)
- T B Geijtenbeek
- Department of Tumor Immunology, University Medical Center St. Radboud, Nijmegen, The Netherlands
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59
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Drickamer K, Dodd RB. C-Type lectin-like domains in Caenorhabditis elegans: predictions from the complete genome sequence. Glycobiology 1999; 9:1357-69. [PMID: 10561461 DOI: 10.1093/glycob/9.12.1357] [Citation(s) in RCA: 98] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Protein modules related to the C-type carbohydrate-recognition domains of animal lectins are found in at least 125 proteins encoded in the Caenorhabditis elegans genome. Within these proteins, 183 C-type lectin-like domains (CTLDs) have been identified. The proteins have been classified based on the overall arrangement of modules within the polypeptides and based on sequence similarity between the CTLDs. The C.elegans proteins generally have different domain organization from known mammalian proteins containing CTLDs. Most of the CTLDs are divergent in sequence from those in mammalian proteins. However, 19 show conservation of most of the amino acid residues that ligate Ca(2+)to form a carbohydrate-binding site in vertebrate C-type carbohydrate-recognition domains. Seven of these domains are particularly similar in sequence to mannose- and N-acetylglucosamine-binding domains in the vicinity of this Ca(2+)site.
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Affiliation(s)
- K Drickamer
- Glycobiology Institute, Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
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60
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Harris JM, McIntosh EM, Muscat GE. Structure/function analysis of a dUTPase: catalytic mechanism of a potential chemotherapeutic target. J Mol Biol 1999; 288:275-87. [PMID: 10329142 DOI: 10.1006/jmbi.1999.2680] [Citation(s) in RCA: 33] [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
dUTP pyrophosphatase catalyses hydrolysis of deoxyuridine triphosphate (dUTP) to deoxyuridine monophosphate (dUMP) and inorganic pyrophosphate (PPi). Elimination of dUTP is vital since its misincorporation into DNA by DNA polymerases can initiate a damaging iterative repair and misincorporation cycle, resulting in DNA fragmentation and cell death. The anti-tumour activity of folate agonists and thymidylate synthase inhibitors is thought to rely on dUTP misincorporation. Furthermore, retroviral cDNA production may be particularly susceptible to the effects of dUTP misincorporation by virtue of the error-prone nature of reverse trans criptase. Consequently, dUTPase activity is an ideal point of intervention in both chemotherapy and anti-retroviral therapy. In particular, the dUTPase encoded by a human endogenous retrovirus (HERV-K) has been suggested to complement HIV infection and so is an attractive target for specific inhibition. Hence, we used site photoaffinity labelling, site-directed mutagenesis and molecular modelling to assign catalytic roles to the conserved amino acid residues in the active site of the HERV-K dUTPase and to identify structural differences with other dUTPase enzymes. We found that dUTP photoaffinity labelling was specific for a beta-hairpin motif in HERV-K dUTPase. Mutagenesis of aspartate residues Asp84 and 86 to asparagine within this beta-hairpin showed the carboxylate moiety of both residues was required for catalysis but not for dUTP binding. An increase in the pKa of both aspartate residues brought about by substitution of a serine residue with a glutamate residue adjacent to the aspartate residues increased activity by a factor of 1.67 at pH 8.0, implicating general base catalysis as the enzyme's catalytic mechanism. Conservative mutagenesis of Tyr87 to Phe resulted in a sevenfold reduction of dUTPase activity and a 3.3-fold reduction in binding activity, whilst substitution with an isoleucine residue totally abolished both catalytic activity and dUTP binding, suggesting that binding/activity is dependent on an aromatic side-chain at the base of the hairpin. Comparison of a homology-based three-dimensional model structure of HERV-K dUTPase with a crystallographic structure of the human dUTPase revealed displacement of a conserved alpha-helix in the HERV-K enzyme causing expansion of the HERV-K active site. This expansion may be responsible for the ability of the HERV-K enzyme to hydrolyse dTTP and bind the bulkier dNTPs in contrast to the majority of dUTPases which are highly specific for dUTP. Knowledge of the dUTPase catalytic mechanism and the distinctive topography of the HERV-K active site provides a molecular basis for the design of HERV-K dUTPase-specific inhibitors.
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Affiliation(s)
- J M Harris
- Centre for Molecular and Cellular Biology, University of Queensland, St Lucia, Australia.
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61
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Ng KK, Park-Snyder S, Weis WI. Ca2+-dependent structural changes in C-type mannose-binding proteins. Biochemistry 1998; 37:17965-76. [PMID: 9922165 DOI: 10.1021/bi981972a] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
C-type animal lectins are a diverse family of proteins which mediate cell-surface carbohydrate-recognition events through a conserved carbohydrate-recognition domain (CRD). Most members of this family possess a carbohydrate-binding activity that depends strictly on the binding of Ca2+ at two sites, designated 1 and 2, in the CRD. The structural transitions associated with Ca2+ binding in C-type lectins have been investigated by determining high-resolution crystal structures of rat serum mannose-binding protein (MBP) bound to one Ho3+ in place of Ca2+, and the apo form of rat liver MBP. The removal of Ca2+ does not affect the core structure of the CRD, but dramatic conformational changes occur in the loops. The most significant structural change in the absence of Ca2+ is the isomerization of a cis-peptide bond preceding a conserved proline residue in Ca2+ site 2. This bond adopts the cis conformation in all Ca2+-bound structures, whereas both cis and trans conformations are observed in the absence of Ca2+. The pattern of structural changes in the three loops that interact with Ca2+ is dictated in large part by the conformation of the prolyl peptide bond. The highly conserved nature of Ca2+ site 2 suggests that the transitions observed in MBPs are general features of Ca2+ binding in C-type lectins.
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Affiliation(s)
- K K Ng
- Department of Structural Biology, Stanford University School of Medicine, California 94305, USA
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62
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Wang S, Vidon S, Leblanc RM. Chemical and Photochemical Dual Polymerization in a Mixed Langmuir Monolayer of Diacetylene Derivatives and Octadecyltrimethoxysilane. J Colloid Interface Sci 1998; 207:303-308. [PMID: 9792773 DOI: 10.1006/jcis.1998.5803] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A chemical-and-photochemical-induced dual polymerization at the air-water interface was performed for the first time, by using a ternary mixture of a octadecyltrimethoxysilane (C18TMS), 10,12-pentacosadiynoic acid (PDA), and N-(11-O-alpha-d-mannopyranosyl-3,6,9-trioxa) undecyl 10,12-pentacosa-diynamide (PDTM). Different dual polymerization behaviors of the mixed monolayers of PDA/PDTM/C18TMS (7:1:8 molar ratio) at different subphase pH were monitored by surface pressure-area isotherms and UV-vis spectra. At pH 1, the C18TMS formed a long linear polymer network by strong intermolecular condensation. The PDA/PDTM was isolated to small domains by this network and can only be polymerized weakly upon UV irradiation. At pH 2.6, the weak condensation of C18TMS formed short linear polymers, which caused phase separation between C18TMS and PDA/PDTM. The strong photochemical polymerization of the PDA/PDTM rich domain was similar to the PDA/PDTM binary mixed monolayer. At pH 4.0, the partially hydrolyzed C18TMS was miscible with PDA/PDTM and slowed the polymerization process of PDA/PDTM upon UV irradiation. These results show geometry and kinetic controls of the PDA/PDTM polymer in 2D by using the C18TMS polymer network. Copyright 1998 Academic Press.
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Affiliation(s)
- S Wang
- Department of Chemistry, University of Miami, Coral Gables, Florida, 33124
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63
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Hitchen PG, Mullin NP, Taylor ME. Orientation of sugars bound to the principal C-type carbohydrate-recognition domain of the macrophage mannose receptor. Biochem J 1998; 333 ( Pt 3):601-8. [PMID: 9677318 PMCID: PMC1219622 DOI: 10.1042/bj3330601] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
The extracellular region of the macrophage mannose receptor, a protein involved in the innate immune response, contains eight C-type carbohydrate-recognition domains (CRDs). The fourth of these domains, CRD-4, is central to ligand binding by the receptor, and binds mannose, fucose and N-acetylglucosamine by direct ligation to Ca2+. Site-directed mutagenesis combined with NMR and molecular modelling have been used to determine the orientation of monosaccharides bound to CRD-4. Two resonances in the 1H NMR spectrum of CRD-4 that are perturbed on sugar binding are identified as a methyl proton from a leucine side chain in the core of the domain and the H-2 proton of a histidine close to the predicted sugar-binding site. The effects of mutagenesis of this histidine residue, a nearby isoleucine residue and a tyrosine residue previously shown to stack against sugars bound to CRD-4 show the absolute orientation of sugars in the binding site. N-Acetylglucosamine binds to CRD-4 of the mannose receptor in the orientation seen in crystal structures of the CRD of rat liver mannose-binding protein. Mannose binds to CRD-4 in the orientation seen in the CRD of rat serum mannose-binding protein and is rotated by 180 degrees relative to GlcNAc bound to CRD-4. Interaction of the O-methyl group and C-1 of alpha-methyl Fuc with the tyrosine residue accounts for the strong preference of CRD-4 for this anomer of fucose. Both anomers of fucose bind to CRD-4 in the orientation seen in rat liver mannose-binding protein.
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Affiliation(s)
- P G Hitchen
- Glycobiology Institute, Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
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64
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Abstract
Gaucher disease was first described by Philippe Gaucher in his 1882 medical thesis. Gaucher's original concept was of an unusual epithelioma of the spleen. By the early 1900s, Mandelbaum recognized the systemic nature of the disease. Several children with Gaucher disease were described at the turn of the century, but Rusca described a rapidly progressive fatal neurodegenerative type of disease, i.e. type 2, in the 1920s. The 'juvenile' form (type 3) of the disease was described in Sweden in the 1950s. In 1965, the deficient enzyme, acid beta-glucosidase, was discovered and the lysosomal nature of the disease was elucidated. Currently, three variants of Gaucher disease have been defined clinically and are distinguished by the presence and severity of neuronopathic involvement (Table 1). Each of these clinical types has substantial phenotypic variation, but types 1 and 3 have significantly heterogeneous rates of disease progression and degrees of visceral organs involvement. The neuronopathic involvement in type 3 also has substantial variation in the age of onset and disease progression even within relatively isolated communities. An extensive review of the clinical and pathologic involvement by Gaucher disease is available.
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Affiliation(s)
- G A Grabowski
- Division in Human Genetics, Children's Hospital Research Foundation, Cincinnati, OH 45229-3039, USA.
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65
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Abstract
Protein-carbohydrate interactions serve multiple functions in the immune system. Many animal lectins (sugar-binding proteins) mediate both pathogen recognition and cell-cell interactions using structurally related Ca(2+)-dependent carbohydrate-recognition domains (C-type CRDs). Pathogen recognition by soluble collections such as serum mannose-binding protein and pulmonary surfactant proteins, and also the macrophage cell-surface mannose receptor, is effected by binding of terminal monosaccharide residues characteristic of bacterial and fungal cell surfaces. The broad selectivity of the monosaccharide-binding site and the geometrical arrangement of multiple CRDs in the intact lectins explains the ability of the proteins to mediate discrimination between self and non-self. In contrast, the much narrower binding specificity of selectin cell adhesion molecules results from an extended binding site within a single CRD. Other proteins, particularly receptors on the surface of natural killer cells, contain C-type lectin-like domains (CTLDs) that are evolutionarily divergent from the C-type lectins and which would be predicted to function through different mechanisms.
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Affiliation(s)
- W I Weis
- Department of Structural Biology, Stanford University School of Medicine, California, USA.
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66
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Stahl PD, Ezekowitz RA. The mannose receptor is a pattern recognition receptor involved in host defense. Curr Opin Immunol 1998; 10:50-5. [PMID: 9523111 DOI: 10.1016/s0952-7915(98)80031-9] [Citation(s) in RCA: 451] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The mannose receptor recognizes the patterns of carbohydrates that decorate the surfaces and cell walls of infectious agents. This macrophage and dendritic cell pattern-recognition receptor mediates endocytosis and phagocytosis. The mannose receptor is the prototype of a new family of multilectin receptor proteins (membrane-spanning receptors containing eight-ten lectin-like domains, which appear to play a key role in host defense) and provides a link between innate and adaptive immunity. Recent advances include the identification of three new members of the mannose receptor family, additional work on defining the molecular requirements for sugar binding, a role for the mannose receptor in antigen presentation of lipoglycan antigens and evidence that the mannose receptor is associated with a signal transduction pathway leading to cytokine production.
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Affiliation(s)
- P D Stahl
- Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, MO 63110, USA.
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67
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Poveda A, Jiménez-Barbero J. NMR studies of carbohydrate–protein interactions in solution. Chem Soc Rev 1998. [DOI: 10.1039/a827133z] [Citation(s) in RCA: 81] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Fiete D, Beranek MC, Baenziger JU. The macrophage/endothelial cell mannose receptor cDNA encodes a protein that binds oligosaccharides terminating with SO4-4-GalNAcbeta1,4GlcNAcbeta or Man at independent sites. Proc Natl Acad Sci U S A 1997; 94:11256-61. [PMID: 9326596 PMCID: PMC23433 DOI: 10.1073/pnas.94.21.11256] [Citation(s) in RCA: 62] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Lutropin (LH) and other glycoproteins bearing oligosaccharides with the terminal sequence SO4-4-GalNAcbeta1,4GlcNAcbeta1,4Man- (S4GGnM) are rapidly removed from the circulation by an S4GGnM-specific receptor (S4GGnM-R) expressed at the surface of hepatic endothelial cells. The S4GGnM-R isolated from rat liver is closely related to the macrophage mannose-specific receptor (Man-R) isolated from rat lung both antigenically and structurally. The S4GGnM-R and Man-R isolated from these tissues nonetheless differ in their ability to bind ligands bearing terminal GalNAc-4-SO4 or Man. In this paper, we have explored the structural relationship between the Man-R and the S4GGnM-R by examining the properties of the recombinant Man-R in the form of a transmembrane protein and a soluble chimeric fusion protein in which the transmembrane and cytosolic domains have been replaced by the Fc region of human IgG1. Like the S4GGnM-R isolated from liver, the chimeric fusion protein is able to bind ligands terminating with GalNAc-4-SO4 and Man at independent sites. When expressed in CHO cells the recombinant Man-R is able to mediate the uptake of ligands bearing either terminal GalNAc-4-SO4 or terminal Man. We propose that the Man-R be renamed the Man/S4GGnM receptor on the basis of its multiple and independent specificities.
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Affiliation(s)
- D Fiete
- Department of Pathology, Washington University Medical School, St. Louis, MO 63110, USA
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