51
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Hojo H, Tanaka H, Hagiwara M, Asahina Y, Ueki A, Katayama H, Nakahara Y, Yoneshige A, Matsuda J, Ito Y, Nakahara Y. Chemoenzymatic Synthesis of Hydrophobic Glycoprotein: Synthesis of Saposin C Carrying Complex-Type Carbohydrate. J Org Chem 2012; 77:9437-46. [DOI: 10.1021/jo3010155] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
| | | | | | | | | | | | | | | | | | - Yukishige Ito
- RIKEN Advanced Science Institute, 2-1 Hirosawa, Wako, Saitama 351- 0198, Japan
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52
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Hisaki H, Matsuda J, Tadano-Aritomi K, Uchida S, Okinaga H, Miyagawa M, Tamamori-Adachi M, Iizuka M, Okazaki T. Primary polydipsia, but not accumulated ceramide, causes lethal renal damage in saposin D-deficient mice. Am J Physiol Renal Physiol 2012; 303:F1049-59. [PMID: 22832923 DOI: 10.1152/ajprenal.00047.2012] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Saposin D-deficient (Sap-D(-/-)) mice develop polydipsia/polyuria and die prematurely due to renal failure with robust hydronephrosis. Such symptoms emerged when they were around 3 mo of age. To investigate the pathogenesis of their water mishandling, we attempted to limit water supply and followed sequential changes of physiological and biochemical parameters. We also analyzed renal histological changes at several time points. At 3 mo old just before water restriction challenge was started, their baseline arginine vasopressin level was comparable to the wild-type (WT) level. Twenty-four-hour water deprivation and desamino d-arginine vasopressin administration improved polydipsia and polyuria to certain degrees. However, creatinine concentrations in Sap-D(-/-) mice were significantly higher than those in WT mice, suggesting that some renal impairment already emerged in the affected mice at this age. Renal histological analyses revealed that renal tubules and collecting ducts were expanded after 3 mo old. After 6 mo old, vacuolar formation was observed, many inflammatory cells migrated around the ducts, and epithelial monolayer cells of tubular origin were replaced by plentiful cysts of various sizes. At 10∼12 mo old, severe cystic deformity appeared. On the other hand, 8-mo-long water restriction started at 4 mo old dramatically improved tubular damage and restored once-dampened amount of tubular aquaporin2 protein to the WT level. Furthermore, 10-mo-long water restriction ameliorated their renal function. Remarkably, by continuing water restriction thereafter, overall survival period became comparable with that of the WT. Together, polyuria, devastating renal tubular lesions, and renal failure were ameliorated by the mere 10-mo-long water restriction, which would trigger lethal dehydration if the disease were to be caused by any processes other than primary polydipsia. Our study demonstrates that long-term water restriction surely improved renal histopathological changes leading to prevention of premature death in Sap-D(-/-) mice.
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Affiliation(s)
- Harumi Hisaki
- Dept. of Biochemistry, Teikyo Univ. School of Medicine, Itabashi, Tokyo, Japan
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53
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Tamargo RJ, Velayati A, Goldin E, Sidransky E. The role of saposin C in Gaucher disease. Mol Genet Metab 2012; 106:257-63. [PMID: 22652185 PMCID: PMC3534739 DOI: 10.1016/j.ymgme.2012.04.024] [Citation(s) in RCA: 93] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/12/2012] [Revised: 04/28/2012] [Accepted: 04/29/2012] [Indexed: 12/16/2022]
Abstract
Saposin C is one of four homologous proteins derived from sequential cleavage of the saposin precursor protein, prosaposin. It is an essential activator for glucocerebrosidase, the enzyme deficient in Gaucher disease. Gaucher disease is a rare autosomal recessive lysosomal storage disorder caused by mutations in the GBA gene that exhibits vast phenotypic heterogeneity, despite its designation as a "simple" Mendelian disorder. The observed phenotypic variability has led to a search for disease modifiers that can alter the Gaucher phenotype. The PSAP gene encoding saposin C is a prime candidate modifier for Gaucher disease. In humans, saposin C deficiency due to mutations in PSAP results in a Gaucher-like phenotype, despite normal in vitro glucocerebrosidase activity. Saposin C deficiency has also been shown to modify phenotype in one mouse model of Gaucher disease. The role of saposin C as an activator required for normal glucocerebrosidase function, and the consequences of saposin C deficiency are described, and are being explored as potential modifying factors in patients with Gaucher disease.
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Affiliation(s)
- Rafael J. Tamargo
- Section on Molecular Neurogenetics, Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA
| | - Arash Velayati
- Section on Molecular Neurogenetics, Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA
| | - Ehud Goldin
- Section on Molecular Neurogenetics, Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA
| | - Ellen Sidransky
- Section on Molecular Neurogenetics, Medical Genetics Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, MD, USA
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54
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Abstract
The saposins are small, membrane-active proteins that exist in both soluble and lipid-bound states. Saposin A has roles in sphingolipid catabolism and transport and is required for the breakdown of galactosylceramide by β-galactosylceramidase. In the absence of lipid, saposin A adopts a closed monomeric apo conformation typical of this family. To study a lipid-bound state of this protein, we determined the crystal structure of saposin A in the presence of detergent to 1.9 Å resolution. The structure reveals two chains of saposin A in an open conformation encapsulating 40 internally bound detergent molecules organized in a highly ordered bilayer-like hydrophobic core. The complex provides a high-resolution view of a discoidal lipoprotein particle in which all of the internalized acyl chains are resolved. Saposin A lipoprotein discs exhibit limited selectivity with respect to the incorporated lipid, and can solubilize phospholipids, sphingolipids, and cholesterol into discrete, monodisperse particles with mass of approximately 27 kDa. These discs may be the smallest possible lipoprotein structures that are stabilized by lipid self-assembly.
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55
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Pinto MFS, Fensterseifer ICM, Migliolo L, Sousa DA, de Capdville G, Arboleda-Valencia JW, Colgrave ML, Craik DJ, Magalhães BS, Dias SC, Franco OL. Identification and structural characterization of novel cyclotide with activity against an insect pest of sugar cane. J Biol Chem 2012; 287:134-147. [PMID: 22074926 PMCID: PMC3249065 DOI: 10.1074/jbc.m111.294009] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2011] [Revised: 10/31/2011] [Indexed: 02/02/2023] Open
Abstract
Cyclotides are a family of plant-derived cyclic peptides comprising six conserved cysteine residues connected by three intermolecular disulfide bonds that form a knotted structure known as a cyclic cystine knot (CCK). This structural motif is responsible for the pronounced stability of cyclotides against chemical, thermal, or proteolytic degradation and has sparked growing interest in this family of peptides. Here, we isolated and characterized a novel cyclotide from Palicourea rigida (Rubiaceae), which was named parigidin-br1. The sequence indicated that this peptide is a member of the bracelet subfamily of cyclotides. Parigidin-br1 showed potent insecticidal activity against neonate larvae of Lepidoptera (Diatraea saccharalis), causing 60% mortality at a concentration of 1 μm but had no detectable antibacterial effects. A decrease in the in vitro viability of the insect cell line from Spodoptera frugiperda (SF-9) was observed in the presence of parigidin-br1, consistent with in vivo insecticidal activity. Transmission electron microscopy and fluorescence microscopy of SF-9 cells after incubation with parigidin-br1 or parigidin-br1-fluorescein isothiocyanate, respectively, revealed extensive cell lysis and swelling of cells, consistent with an insecticidal mechanism involving membrane disruption. This hypothesis was supported by in silico analyses, which suggested that parigidin-br1 is able to complex with cell lipids. Overall, the results suggest promise for the development of parigidin-br1 as a novel biopesticide.
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Affiliation(s)
- Michelle F S Pinto
- Centro de Análises Proteômicas e Bioquímicas, Programa de Pós-Graduação em Ciências Genômicas e Biotecnologia, Universidade Católica de Brasília, Brasília-DF, Brazil
| | - Isabel C M Fensterseifer
- Centro de Análises Proteômicas e Bioquímicas, Programa de Pós-Graduação em Ciências Genômicas e Biotecnologia, Universidade Católica de Brasília, Brasília-DF, Brazil
| | - Ludovico Migliolo
- Centro de Análises Proteômicas e Bioquímicas, Programa de Pós-Graduação em Ciências Genômicas e Biotecnologia, Universidade Católica de Brasília, Brasília-DF, Brazil
| | - Daniel A Sousa
- Programa de Pós-Graduação em Patologia Molecular, Universidade de Brasília, Brasília-DF, Brazil
| | - Guy de Capdville
- CENARGEN (Centro Nacional de Pesquisa de Recursos Genéticos e Biotecnologia), Embrapa Recursos Genéticos e Biotecnologia, Brasília-DF, Brazil
| | - Jorge W Arboleda-Valencia
- CENARGEN (Centro Nacional de Pesquisa de Recursos Genéticos e Biotecnologia), Embrapa Recursos Genéticos e Biotecnologia, Brasília-DF, Brazil; Departamento de Biologia Celular, Universidade de Brasília, Brasília-DF, Brazil
| | - Michelle L Colgrave
- Commonwealth Scientific and Industrial Research Organization Livestock Industries, 306 Carmody Road, St. Lucia, Queensland 4067, Australia
| | - David J Craik
- Institute for Molecular Bioscience, University of Queensland, Brisbane, Queensland 4072, Australia
| | - Beatriz S Magalhães
- Centro de Análises Proteômicas e Bioquímicas, Programa de Pós-Graduação em Ciências Genômicas e Biotecnologia, Universidade Católica de Brasília, Brasília-DF, Brazil
| | - Simoni C Dias
- Centro de Análises Proteômicas e Bioquímicas, Programa de Pós-Graduação em Ciências Genômicas e Biotecnologia, Universidade Católica de Brasília, Brasília-DF, Brazil
| | - Octávio L Franco
- Centro de Análises Proteômicas e Bioquímicas, Programa de Pós-Graduação em Ciências Genômicas e Biotecnologia, Universidade Católica de Brasília, Brasília-DF, Brazil.
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56
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Muñoz F, Palomares-Jerez MF, Daleo G, Villalaín J, Guevara MG. Cholesterol and membrane phospholipid compositions modulate the leakage capacity of the swaposin domain from a potato aspartic protease (StAsp-PSI). Biochim Biophys Acta Mol Cell Biol Lipids 2011; 1811:1038-44. [DOI: 10.1016/j.bbalip.2011.08.013] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2011] [Revised: 07/08/2011] [Accepted: 08/03/2011] [Indexed: 12/26/2022]
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57
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Lieberman RL. A Guided Tour of the Structural Biology of Gaucher Disease: Acid-β-Glucosidase and Saposin C. Enzyme Res 2011; 2011:973231. [PMID: 22145077 PMCID: PMC3226326 DOI: 10.4061/2011/973231] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2011] [Accepted: 09/07/2011] [Indexed: 01/27/2023] Open
Abstract
Mutations in both acid-β-glucosidase (GCase) and saposin C lead to Gaucher disease, the most common lysosomal storage disorder. The past several years have seen an explosion of structural and biochemical information for these proteins, which have provided new insight into the biology and pathogenesis of Gaucher disease, as well as opportunities for new therapeutic directions. Nearly 20 crystal structures of GCase are now available, from different heterologous sources, complexed with different ligands in the active site, in different glycosylation states, as well as one that harbors a prevalent disease-causing mutation, N370S. For saposin C, two NMR and 3 crystal structures have been solved, each with its unique snapshot. This review focuses on the details of these structures to highlight salient common and disparate features that contribute to our current state of knowledge of this complex orphan disease.
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Affiliation(s)
- Raquel L. Lieberman
- School of Chemistry & Biochemistry, Institute for Bioscience and Bioengineering, Georgia Institute of Technology, 901 Atlantic Drive NW Atlanta, GA 30332-0400, USA
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58
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Insights into the membrane interactions of the saposin-like proteins Na-SLP-1 and Ac-SLP-1 from human and dog hookworm. PLoS One 2011; 6:e25369. [PMID: 21991310 PMCID: PMC3184995 DOI: 10.1371/journal.pone.0025369] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2011] [Accepted: 09/01/2011] [Indexed: 12/03/2022] Open
Abstract
Saposin-like proteins (SAPLIPs) from soil-transmitted helminths play pivotal roles in host-pathogen interactions and have a high potential as targets for vaccination against parasitic diseases. We have identified two non-orthologous SAPLIPs from human and dog hookworm, Na-SLP-1 and Ac-SLP-1, and solved their three-dimensional crystal structures. Both proteins share the property of membrane binding as monitored by liposome co-pelleting assays and monolayer adsorption. Neither SAPLIP displayed any significant haemolytic or bactericidal activity. Based on the structural information, as well as the results from monolayer adsorption, we propose models of membrane interactions for both SAPLIPs. Initial membrane contact of the monomeric Na-SLP-1 is most likely by electrostatic interactions between the membrane surface and a prominent basic surface patch. In case of the dimeric Ac-SLP-1, membrane interactions are most likely initiated by a unique tryptophan residue that has previously been implicated in membrane interactions in other SAPLIPs.
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59
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Lung surfactant protein SP-B promotes formation of bilayer reservoirs from monolayer and lipid transfer between the interface and subphase. Biophys J 2011; 100:1678-87. [PMID: 21463581 DOI: 10.1016/j.bpj.2011.02.019] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2011] [Revised: 02/10/2011] [Accepted: 02/14/2011] [Indexed: 12/13/2022] Open
Abstract
We investigated the possible role of SP-B proteins in the function of lung surfactant. To this end, lipid monolayers at the air/water interface, bilayers in water, and transformations between them in the presence of SP-B were simulated. The proteins attached bilayers to monolayers, providing close proximity of the reservoirs with the interface. In the attached aggregates, SP-B mediated establishment of the lipid-lined connection similar to the hemifusion stalk. Via this connection, a lipid flow was initiated between the monolayer at the interface and the bilayer in water in a surface-tension-dependent manner. On interface expansion, the flow of lipids to the monolayer restored the surface tension to the equilibrium spreading value. SP-B induced formation of bilayer folds from the monolayer at positive surface tensions below the equilibrium. In the absence of proteins, lipid monolayers were stable at these conditions. Fold nucleation was initiated by SP-B from the liquid-expanded monolayer phase by local bending, and the proteins lined the curved perimeter of the growing fold. No effect on the liquid-condensed phase was observed. Covalently linked dimers resulted in faster kinetics for monolayer folding. The simulation results are in line with existing hypotheses on SP-B activity in lung surfactant and explain its molecular mechanism.
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60
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Bryksa BC, Bhaumik P, Magracheva E, De Moura DC, Kurylowicz M, Zdanov A, Dutcher JR, Wlodawer A, Yada RY. Structure and mechanism of the saposin-like domain of a plant aspartic protease. J Biol Chem 2011; 286:28265-75. [PMID: 21676875 DOI: 10.1074/jbc.m111.252619] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Many plant aspartic proteases contain an additional sequence of ~100 amino acids termed the plant-specific insert, which is involved in host defense and vacuolar targeting. Similar to all saposin-like proteins, the plant-specific insert functions via protein-membrane interactions; however, the structural basis for such interactions has not been studied, and the nature of plant-specific insert-mediated membrane disruption has not been characterized. In the present study, the crystal structure of the saposin-like domain of potato aspartic protease was resolved at a resolution of 1.9 Å, revealing an open V-shaped configuration similar to the open structure of human saposin C. Notably, vesicle disruption activity followed Michaelis-Menten-like kinetics, a finding not previously reported for saposin-like proteins including plant-specific inserts. Circular dichroism data suggested that secondary structure was pH-dependent in a fashion similar to influenza A hemagglutinin fusion peptide. Membrane effects characterized by atomic force microscopy and light scattering indicated bilayer solubilization as well as fusogenic activity. Taken together, the present study is the first report to elucidate the membrane interaction mechanism of plant saposin-like domains whereby pH-dependent membrane interactions resulted in bilayer fusogenic activity that probably arose from a viral type pH-dependent helix-kink-helix motif at the plant-specific insert N terminus.
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Affiliation(s)
- Brian C Bryksa
- Department of Food Science, University of Guelph, Guelph, Ontario N1G 2W1, Canada
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61
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Aerts JM, Boot RG, van Eijk M, Groener J, Bijl N, Lombardo E, Bietrix FM, Dekker N, Groen AK, Ottenhoff R, van Roomen C, Aten J, Serlie M, Langeveld M, Wennekes T, Overkleeft HS. Glycosphingolipids and insulin resistance. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2011; 721:99-119. [PMID: 21910085 DOI: 10.1007/978-1-4614-0650-1_7] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Glycosphingolipids are structural membrane components, residing largely in the plasma membrane with their sugar-moieties exposed at the cell's surface. In recent times a crucial role for glycosphingolipids in insulin resistance has been proposed. A chronic state of insulin resistance is a rapidly increasing disease condition in Western and developing countries. It is considered to be the major underlying cause of the metabolic syndrome, a combination of metabolic abnormalities that increases the risk for an individual to develop Type 2 diabetes, obesity, cardiovascular disease, polycystic ovary syndrome and nonalcoholic fatty liver disease. As discussed in this chapter, the evidence for a direct regulatory interaction of glycosphingolipids with insulin signaling is still largely indirect. However, the recent finding in animal models that pharmacological reduction of glycosphingolipid biosynthesis ameliorates insulin resistance and prevents some manifestations of metabolic syndrome, supports the view that somehow glycosphingolipids act as critical regulators, Importantly, since reductions in glycosphingolipid biosynthesis have been found to be well tolerated, such approaches may have a therapeutic potential.
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Affiliation(s)
- Johannes M Aerts
- Department of Medical Biochemistry, University of Amsterdam, The Netherlands.
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62
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Yoneshige A, Suzuki K, Suzuki K, Matsuda J. A mutation in the saposin C domain of the sphingolipid activator protein (Prosaposin) gene causes neurodegenerative disease in mice. J Neurosci Res 2010; 88:2118-34. [PMID: 20175216 DOI: 10.1002/jnr.22371] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Saposins A, B, C, and D are small amphiphatic glycoproteins that are encoded in tandem within a precursor protein (prosaposin, PSAP), and are required for in vivo degradation of sphingolipids. Humans with saposin C deficiency exhibit the clinical presentation of Gaucher-like disease. We generated two types of saposin C mutant mice, one carrying a homozygous missense mutation (C384S) in the saposin C domain of prosaposin (Sap-C(-/-)) and the other carrying the compound heterozygous mutation with a second null Psap allele (Psap(-/C384S)). During early life stages, both Sap-C(-/-) and Psap(-/C384S) mice grew normally; however, they developed progressive motor and behavioral deficits after 3 months of age and the majority of affected mice could scarcely move by about 15 months. They showed no signs of hepatosplenomegaly throughout their lives. No accumulation of glucosylceramide and glucosylsphingosine was detected in the brain or liver of both Sap-C(-/-) and Psap(-/C384S) mice. Neuropathological analyses revealed patterned loss of cerebellar Purkinje cells, widespread axonal spheroids filled with membrane-derived concentric or lamellar electron-dense bodies, and lipofuscin-like deposition in the neurons. Soap-bubble-like inclusion bodies were detected in the trigeminal ganglion cells and the vascular endothelial cells. Compound heterozygous Psap(-/C384S) mice showed qualitatively identical but faster progression of the neurological phenotypes than Sap-C(-/-) mice. These results suggest the in vivo role of saposin C in axonal membrane homeostasis, the disruption of which leads to neurodegeneration in lysosomal storage disease.
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Affiliation(s)
- Azusa Yoneshige
- Institute of Glycoscience, Tokai University, Hiratsuka, Kanagawa, Japan
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63
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Baoukina S, Tieleman DP. Direct simulation of protein-mediated vesicle fusion: lung surfactant protein B. Biophys J 2010; 99:2134-42. [PMID: 20923647 PMCID: PMC3042587 DOI: 10.1016/j.bpj.2010.07.049] [Citation(s) in RCA: 57] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2010] [Revised: 07/22/2010] [Accepted: 07/23/2010] [Indexed: 10/19/2022] Open
Abstract
We simulated spontaneous fusion of small unilamellar vesicles mediated by lung surfactant protein B (SP-B) using the MARTINI force field. An SP-B monomer triggers fusion events by anchoring two vesicles and facilitating the formation of a lipid bridge between the proximal leaflets. Once a lipid bridge is formed, fusion proceeds via a previously described stalk - hemifusion diaphragm - pore-opening pathway. In the absence of protein, fusion of vesicles was not observed in either unbiased simulations or upon application of a restraining potential to maintain the vesicles in close proximity. The shape of SP-B appears to enable it to bind to two vesicles at once, forcing their proximity, and to facilitate the initial transfer of lipids to form a high-energy hemifusion intermediate. Our results may provide insight into more general mechanisms of protein-mediated membrane fusion, and a possible role of SP-B in the secretory pathway and transfer of lung surfactant to the gas exchange interface.
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Affiliation(s)
| | - D. Peter Tieleman
- Department of Biological Sciences, University of Calgary, Calgary, Canada
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64
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Lindholm P, Saarma M. Novel CDNF/MANF family of neurotrophic factors. Dev Neurobiol 2010; 70:360-71. [PMID: 20186704 DOI: 10.1002/dneu.20760] [Citation(s) in RCA: 98] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Current therapeutic interventions for neurodegenerative diseases alleviate only disease symptoms, while treatments that could stop or reverse actual degenerative processes are not available. Parkinson's disease (PD) is a movement disorder with characteristic degeneration of dopaminergic neurons in the midbrain. Few neurotrophic factors (NTFs) that promote survival, maintenance, and differentiation of affected brain neurons are considered as potential therapeutic agents for the treatment of neurodegenerative diseases. Thus, it is important to search and study new NTFs that could also be used in therapy. In this review, we discuss novel evolutionary conserved family of NTFs consisting of two members in the vertebrates, cerebral dopamine neurotrophic factor (CDNF) and mesencephalic astrocyte-derived neurotrophic factor (MANF). Invertebrates, including Drosophila and Caenorhabditis have a single protein homologous to vertebrate CDNF/MANF. Characteristic feature of these proteins is eight structurally conserved cysteine residues, which determine the protein fold. The crystal structure analysis revealed that CDNF and MANF consist of two domains; an amino-terminal saposin-like domain that may interact with lipids or membranes, and a presumably unfolded carboxy-terminal domain that may protect cells against endoplasmic reticulum stress. CDNF and MANF protect midbrain dopaminergic neurons and restore motor function in 6-hydroxydopamine rat model of PD in vivo. In line, Drosophila MANF is needed for the maintenance of dopaminergic neurites and dopamine levels in the fly, suggesting that the function of CDNF/MANF proteins is evolutionary conserved. Future studies will reveal the receptors and mode of action of these novel factors, which are potential therapeutic proteins for the treatment of PD.
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Affiliation(s)
- Päivi Lindholm
- Institute of Biotechnology, Viikinkaari 9, Viikki Biocenter, University of Helsinki, 00014 Helsinki, Finland
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65
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Almlén A, Walther FJ, Waring AJ, Robertson B, Johansson J, Curstedt T. Synthetic surfactant based on analogues of SP-B and SP-C is superior to single-peptide surfactants in ventilated premature rabbits. Neonatology 2010; 98:91-9. [PMID: 20110733 PMCID: PMC2914361 DOI: 10.1159/000276980] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/15/2009] [Accepted: 08/26/2009] [Indexed: 11/19/2022]
Abstract
BACKGROUND Respiratory distress syndrome (RDS) is currently treated with surfactant preparations obtained from natural sources and attempts to develop equally active synthetic surfactants have been unsuccessful. One difference in composition is that naturally derived surfactants contain the two hydrophobic proteins SP-B and SP-C while synthetic preparations contain analogues of either SP-B or SP-C. It was recently shown that both SP-B and SP-C (or SP-C33, an SP-C analogue) are necessary to establish alveolar stability at end-expiration in a rabbit RDS model, as reflected by high lung gas volumes without application of positive end-expiratory pressure. OBJECTIVES To study the efficacy of fully synthetic surfactants containing analogues of both SP-B and SP-C compared to surfactants with only one protein analogue. METHODS Premature newborn rabbits, treated with synthetic surfactants, were ventilated for 30 min without positive end-expiratory pressure. Tidal volumes as well as lung gas volumes at end-expiration were determined. RESULTS Treatment with 2% Mini-B (a short-cut version of SP-B) and 2% SP-C33, or its C-terminally truncated form SP-C30, in 1,2-dipalmitoyl-sn-glycero-3-phosphocholine/1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoglycerol, 68:31 (w/w) resulted in median lung gas volumes of 8-9 ml/kg body weight, while animals treated with 2% Mini-B surfactant or 2% SP-C33/SP-C30 surfactant had lung gas volumes of 3-4 ml/kg, and those treated with Curosurf, a porcine surfactant, 15-17 ml/kg. In contrast, mixing SP-C33 with peptides with different distributions of positively charged and hydrophobic residues did not improve lung gas volumes. CONCLUSIONS The data indicate that synthetic surfactants containing analogues of both SP-B and SP-C might be superior to single-peptide surfactants in the treatment of RDS.
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Affiliation(s)
- Andreas Almlén
- Department of Molecular Medicine and Surgery, Section of Clinical Chemistry, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden
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66
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Pearse BR, Tamura T, Sunryd JC, Grabowski GA, Kaufman RJ, Hebert DN. The role of UDP-Glc:glycoprotein glucosyltransferase 1 in the maturation of an obligate substrate prosaposin. J Cell Biol 2010; 189:829-41. [PMID: 20498017 PMCID: PMC2878942 DOI: 10.1083/jcb.200912105] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2009] [Accepted: 04/28/2010] [Indexed: 01/02/2023] Open
Abstract
An endoplasmic reticulum (ER) quality control system assists in efficient folding and disposal of misfolded proteins. N-linked glycans are critical in these events because their composition dictates interactions with molecular chaperones. UDP-glucose:glycoprotein glucosyltransferase 1 (UGT1) is a key quality control factor of the ER. It adds glucoses to N-linked glycans of nonglucosylated substrates that fail a quality control test, supporting additional rounds of chaperone binding and ER retention. How UGT1 functions in its native environment is poorly understood. The role of UGT1 in the maturation of glycoproteins at basal expression levels was analyzed. Prosaposin was identified as a prominent endogenous UGT1 substrate. A dramatic decrease in the secretion of prosaposin was observed in ugt1(-/-) cells with prosaposin localized to large juxtanuclear aggresome-like inclusions, which is indicative of its misfolding and the essential role that UGT1 plays in its proper maturation. A model is proposed that explains how UGT1 may aid in the folding of sequential domain-containing proteins such as prosaposin.
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Affiliation(s)
- Bradley R. Pearse
- Department of Biochemistry and Molecular Biology and Program in Molecular and Cellular Biology, University of Massachusetts, Amherst, MA 01003
| | - Taku Tamura
- Department of Biochemistry and Molecular Biology and Program in Molecular and Cellular Biology, University of Massachusetts, Amherst, MA 01003
| | - Johan C. Sunryd
- Department of Biochemistry and Molecular Biology and Program in Molecular and Cellular Biology, University of Massachusetts, Amherst, MA 01003
| | - Gregory A. Grabowski
- Division of Human Genetics, Department of Pediatrics, Cincinnati Children’s Hospital Medical Center, Cincinnati, OH 45229
| | - Randal J. Kaufman
- Howard Hughes Medical Institute, Department of Biological Chemistry, and Department of Internal Medicine, University of Michigan Medical Center, Ann Arbor, MI 48109
| | - Daniel N. Hebert
- Department of Biochemistry and Molecular Biology and Program in Molecular and Cellular Biology, University of Massachusetts, Amherst, MA 01003
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67
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Abdul-Hammed M, Breiden B, Adebayo MA, Babalola JO, Schwarzmann G, Sandhoff K. Role of endosomal membrane lipids and NPC2 in cholesterol transfer and membrane fusion. J Lipid Res 2010; 51:1747-60. [PMID: 20179319 PMCID: PMC2882726 DOI: 10.1194/jlr.m003822] [Citation(s) in RCA: 63] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
We examined the effect of Niemann-Pick disease type 2 (NPC2) protein and some late endosomal lipids [sphingomyelin, ceramide and bis(monoacylglycero)phosphate (BMP)] on cholesterol transfer and membrane fusion. Of all lipid-binding proteins tested, only NPC2 transferred cholesterol at a substantial rate, with no transfer of ceramide, GM3, galactosylceramide, sulfatide, phosphatidylethanolamine, or phosphatidylserine. Cholesterol transfer was greatly stimulated by BMP, little by ceramide, and strongly inhibited by sphingomyelin. Cholesterol and ceramide were also significantly transferred in the absence of protein. This spontaneous transfer of cholesterol was greatly enhanced by ceramide, slightly by BMP, and strongly inhibited by sphingomyelin. In our transfer assay, biotinylated donor liposomes were separated from fluorescent acceptor liposomes by streptavidin-coated magnetic beads. Thus, the loss of fluorescence indicated membrane fusion. Ceramide induced spontaneous fusion of lipid vesicles even at very low concentrations, while BMP and sphingomyelin did so at about 20 mol% and 10 mol% concentrations, respectively. In addition to transfer of cholesterol, NPC2 induced membrane fusion, although less than saposin-C. In this process, BMP and ceramide had a strong and mild stimulating effect, and sphingomyelin an inhibiting effect, respectively. Note that the effects of the lipids on cholesterol transfer mediated by NPC2 were similar to their effect on membrane fusion induced by NPC2 and saposin-C.
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Affiliation(s)
- Misbaudeen Abdul-Hammed
- Membrane Biology and Biochemistry Unit, Life and Medical Sciences Institute (LIMES), Bonn, Germany
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68
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Kenoth R, Simanshu DK, Kamlekar RK, Pike HM, Molotkovsky JG, Benson LM, Bergen HR, Prendergast FG, Malinina L, Venyaminov SY, Patel DJ, Brown RE. Structural determination and tryptophan fluorescence of heterokaryon incompatibility C2 protein (HET-C2), a fungal glycolipid transfer protein (GLTP), provide novel insights into glycolipid specificity and membrane interaction by the GLTP fold. J Biol Chem 2010; 285:13066-78. [PMID: 20164530 DOI: 10.1074/jbc.m109.093203] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023] Open
Abstract
HET-C2 is a fungal protein that transfers glycosphingolipids between membranes and has limited sequence homology with human glycolipid transfer protein (GLTP). The human GLTP fold is unique among lipid binding/transfer proteins, defining the GLTP superfamily. Herein, GLTP fold formation by HET-C2, its glycolipid transfer specificity, and the functional role(s) of its two Trp residues have been investigated. X-ray diffraction (1.9 A) revealed a GLTP fold with all key sugar headgroup recognition residues (Asp(66), Asn(70), Lys(73), Trp(109), and His(147)) conserved and properly oriented for glycolipid binding. Far-UV CD showed secondary structure dominated by alpha-helices and a cooperative thermal unfolding transition of 49 degrees C, features consistent with a GLTP fold. Environmentally induced optical activity of Trp/Tyr/Phe (2:4:12) detected by near-UV CD was unaffected by membranes containing glycolipid but was slightly altered by membranes lacking glycolipid. Trp fluorescence was maximal at approximately 355 nm and accessible to aqueous quenchers, indicating free exposure to the aqueous milieu and consistent with surface localization of the two Trps. Interaction with membranes lacking glycolipid triggered significant decreases in Trp emission intensity but lesser than decreases induced by membranes containing glycolipid. Binding of glycolipid (confirmed by electrospray injection mass spectrometry) resulted in a blue-shifted emission wavelength maximum (approximately 6 nm) permitting determination of binding affinities. The unique positioning of Trp(208) at the HET-C2 C terminus revealed membrane-induced conformational changes that precede glycolipid uptake, whereas key differences in residues of the sugar headgroup recognition center accounted for altered glycolipid specificity and suggested evolutionary adaptation for the simpler glycosphingolipid compositions of filamentous fungi.
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Affiliation(s)
- Roopa Kenoth
- Hormel Institute, University of Minnesota, Austin, Minnesota 55912, USA
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69
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Wennekes T, van den Berg RJBHN, Boot RG, van der Marel GA, Overkleeft HS, Aerts JMFG. Glycosphingolipids--nature, function, and pharmacological modulation. Angew Chem Int Ed Engl 2010; 48:8848-69. [PMID: 19862781 DOI: 10.1002/anie.200902620] [Citation(s) in RCA: 218] [Impact Index Per Article: 15.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
The discovery of the glycosphingolipids is generally attributed to Johan L. W. Thudichum, who in 1884 published on the chemical composition of the brain. In his studies he isolated several compounds from ethanolic brain extracts which he coined cerebrosides. He subjected one of these, phrenosin (now known as galactosylceramide), to acid hydrolysis, and this produced three distinct components. One he identified as a fatty acid and another proved to be an isomer of D-glucose, which is now known as D-galactose. The third component, with an "alkaloidal nature", presented "many enigmas" to Thudichum, and therefore he named it sphingosine, after the mythological riddle of the Sphinx. Today, sphingolipids and their glycosidated derivatives are the subjects of intense study aimed at elucidating their role in the structural integrity of the cell membrane, their participation in recognition and signaling events, and in particular their involvement in pathological processes that are at the basis of human disease (for example, sphingolipidoses and diabetes type 2). This Review details some of the recent findings on the biosynthesis, function, and degradation of glycosphingolipids in man, with a focus on the glycosphingolipid glucosylceramide. Special attention is paid to the clinical relevance of compounds directed at interfering with the factors responsible for glycosphingolipid metabolism.
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Affiliation(s)
- Tom Wennekes
- Leiden Institute of Chemistry, Gorlaeus Laboratories, Leiden University, P.O. Box 9502, Leiden, The Netherlands
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70
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Abstract
Saposins or sphingolipid activator proteins (SAPs) are small, nonenzymatic glycoproteins that are ubiquitously present in lysosomes. SAPs comprise the five molecules saposins A-D and the GM2 activator protein. Saposins are essential for sphingolipid degradation and membrane digestion. On the one hand, they bind the respective hydrolases required to catabolize sphingolipid molecules; on the other hand, saposins can interact with intralysosomal membrane structures to render lipids accessible to their degrading enzymes. Thus, saposins bridge the physicochemical gap between lipid substrate and hydrophilic hydrolases. Accordingly, defects in saposin function can lead to lysosomal lipid accumulation. In addition to their specific functions in sphingolipid metabolism, saposins have membrane-perturbing properties. At the low pH of lysosomes, saposins get protonated and exhibit a high binding affinity for anionic phospholipids. Based on their universal principle to interact with membrane bilayers, we present the immunological functions of saposins with regard to lipid antigen presentation to CD1-restricted T cells, processing of apoptotic bodies for antigen delivery and cross-priming, as well as their potential antimicrobial impact.
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Affiliation(s)
- Alexandre Darmoise
- Program in Cellular and Molecular Medicine at Children's Hospital, Immune Disease Institute, Department of Pathology, Harvard Medical School, Boston, MA, USA
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71
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Wennekes T, van den Berg R, Boot R, van der Marel G, Overkleeft H, Aerts J. Glycosphingolipide - Natur, Funktion und pharmakologische Modulierung. Angew Chem Int Ed Engl 2009. [DOI: 10.1002/ange.200902620] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
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72
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Kolter T, Sandhoff K. Lysosomal degradation of membrane lipids. FEBS Lett 2009; 584:1700-12. [PMID: 19836391 DOI: 10.1016/j.febslet.2009.10.021] [Citation(s) in RCA: 201] [Impact Index Per Article: 13.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2009] [Accepted: 10/09/2009] [Indexed: 01/05/2023]
Abstract
The constitutive degradation of membrane components takes place in the acidic compartments of a cell, the endosomes and lysosomes. Sites of lipid degradation are intralysosomal membranes that are formed in endosomes, where the lipid composition is adjusted for degradation. Cholesterol is sorted out of the inner membranes, their content in bis(monoacylglycero)phosphate increases, and, most likely, sphingomyelin is degraded to ceramide. Together with endosomal and lysosomal lipid-binding proteins, the Niemann-Pick disease, type C2-protein, the GM2-activator, and the saposins sap-A, -B, -C, and -D, a suitable membrane lipid composition is required for degradation of complex lipids by hydrolytic enzymes.
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Affiliation(s)
- Thomas Kolter
- LiMES - Life and Medical Sciences Institute, Membrane Biology and Lipid Biochemistry Unit, c/o Kekulé-Institut für Organische Chemie und Biochemie, University of Bonn, Bonn, Germany
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73
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Parkash V, Lindholm P, Peränen J, Kalkkinen N, Oksanen E, Saarma M, Leppänen VM, Goldman A. The structure of the conserved neurotrophic factors MANF and CDNF explains why they are bifunctional. Protein Eng Des Sel 2009; 22:233-41. [PMID: 19258449 DOI: 10.1093/protein/gzn080] [Citation(s) in RCA: 95] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
We have solved the structures of mammalian mesencephalic astrocyte-derived neurotrophic factor (MANF) and conserved dopamine neurotrophic factor (CDNF). CDNF protects and repairs midbrain dopaminergic neurons in vivo; MANF supports their survival in culture and is also cytoprotective against endoplasmic reticulum (ER) stress. Neither protein structure resembles any known growth factor but the N-terminal domain is a saposin-like lipid-binding domain. MANF and CDNF may thus bind lipids or membranes. Consistent with this, there are two patches of conserved lysines and arginines. The natively unfolded MANF C-terminus contains a CKGC disulphide bridge, such as reductases and disulphide isomerases, consistent with a role in ER stress response. The structure thus explains why MANF and CDNF are bifunctional; neurotrophic activity may reside in the N-terminal domain and ER stress response in the C-terminal domain. Finally, we identified three changes, (MANF)I10-->K(CDNF), (MANF)E79-->M(CDNF) and (MANF)K88-->L(CDNF), that may account for the biological differences between the proteins.
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Affiliation(s)
- Vimal Parkash
- Institute of Biotechnology, University of Helsinki, Helsinki, Finland
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74
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Beck MR, Dekoster GT, Cistola DP, Goldman WE. NMR structure of a fungal virulence factor reveals structural homology with mammalian saposin B. Mol Microbiol 2009; 72:344-53. [PMID: 19298372 DOI: 10.1111/j.1365-2958.2009.06647.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
The fungal protein CBP (calcium binding protein) is a known virulence factor with an unknown virulence mechanism. The protein was identified based on its ability to bind calcium and its prevalence as Histoplasma capsulatum's most abundant secreted protein. However, CBP has no sequence homology with other CBPs and contains no known calcium binding motifs. Here, the NMR structure of CBP reveals a highly intertwined homodimer and represents the first atomic level NMR model of any fungal virulence factor. Each CBP monomer is comprised of four alpha-helices that adopt the saposin fold, characteristic of a protein family that binds to membranes and lipids. This structural homology suggests that CBP functions as a lipid binding protein, potentially interacting with host glycolipids in the phagolysosome of host cells.
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Affiliation(s)
- Moriah R Beck
- Department of Molecular Microbiology, Washington University in St Louis, St Louis, MO, USA
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75
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Kacher Y, Brumshtein B, Boldin-Adamsky S, Toker L, Shainskaya A, Silman I, Sussman JL, Futerman AH. Acid beta-glucosidase: insights from structural analysis and relevance to Gaucher disease therapy. Biol Chem 2008; 389:1361-9. [PMID: 18783340 DOI: 10.1515/bc.2008.163] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
In mammalian cells, glucosylceramide (GlcCer), the simplest glycosphingolipid, is hydrolyzed by the lysosomal enzyme acid beta-glucosidase (GlcCerase). In the human metabolic disorder Gaucher disease, GlcCerase activity is significantly decreased owing to one of approximately 200 mutations in the GlcCerase gene. The most common therapy for Gaucher disease is enzyme replacement therapy (ERT), in which patients are given intravenous injections of recombinant human GlcCerase; the Genzyme product Cerezyme has been used clinically for more than 15 years and is administered to approximately 4000 patients worldwide. Here we review the crystal structure of Cerezyme and other recombinant forms of GlcCerase, as well as of their complexes with covalent and non-covalent inhibitors. We also discuss the stability of Cerezyme, which can be altered by modification of its N-glycan chains with possible implications for improved ERT in Gaucher disease.
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Affiliation(s)
- Yaacov Kacher
- Department of Biological Chemistry, Weizmann Institute of Science, Rehovot 76100, Israel
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