1
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Oftedal TF, Diep DB, Kjos M. Design of Novel Saposin-like Bacteriocins Using a Hybrid Approach. Probiotics Antimicrob Proteins 2024:10.1007/s12602-024-10264-w. [PMID: 38713419 DOI: 10.1007/s12602-024-10264-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/17/2024] [Indexed: 05/08/2024]
Abstract
A multitude of approaches will be required to respond to the threat posed by the emergence and spread of antibiotic resistant pathogens. Bacteriocins have gained increasing attention as a possible alternative to antibiotics, as such peptide antimicrobials have mechanisms of action different from antibiotics and are therefore equally potent against antibiotic resistant bacteria as their susceptible counterparts. A group of bacteriocins known as saposin-like bacteriocins is believed to act directly on the bacterial membrane. Based on seven saposin-like leaderless bacteriocins, we have constructed a library of hybrid peptides containing all combinations of the N- and C-terminal halves of the native bacteriocins. All hybrid peptides were synthesized using in vitro protein expression and assayed for antimicrobial activity towards several pathogens. Of the 42 hybrid peptides, antimicrobial activity was confirmed for 11 novel hybrid peptides. Furthermore, several of the hybrid peptides exhibited altered antimicrobial spectra and apparent increase in potency compared to the peptides from which they were derived. The most promising hybrid, termed ISP26, was then obtained synthetically and shown to inhibit most of the Gram-positive species tested, including opportunistic pathogens and food spoilage bacteria. Additionally, ISP26 was shown to inhibit Acinetobacter, a species of Gram-negative bacteria frequently isolated from nosocomial infections. The activity of the hybrid library provides valuable insights into the design and screening of new active bacteriocins.
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Affiliation(s)
- Thomas F Oftedal
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Ås, Norway.
| | - Dzung B Diep
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Ås, Norway
| | - Morten Kjos
- Faculty of Chemistry, Biotechnology and Food Science, Norwegian University of Life Sciences, Ås, Norway
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2
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Sawyer TK, Aral E, Staros JV, Bobst CE, Garman SC. Human Saposin B Ligand Binding and Presentation to α-Galactosidase A. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.04.584535. [PMID: 38617236 PMCID: PMC11014568 DOI: 10.1101/2024.04.04.584535] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/16/2024]
Abstract
Sphingolipid activator protein B (saposin B; SapB) is an essential activator of globotriaosylceramide (Gb3) catabolism by α-galactosidase A. However, the manner by which SapB stimulates α-galactosidase A activity remains unknown. To uncover the molecular mechanism of SapB presenting Gb3 to α-galactosidase A, we subjected the fluorescent substrate globotriaosylceramide-nitrobenzoxidazole (Gb3-NBD) to a series of biochemical and structural assays involving SapB. First, we showed that SapB stably binds Gb3-NBD using a fluorescence equilibrium binding assay, isolates Gb3-NBD from micelles, and facilitates α-galactosidase A cleavage of Gb3-NBD in vitro. Second, we crystallized SapB in the presence of Gb3-NBD and validated the ligand-bound assembly. Third, we captured transient interactions between SapB and α-galactosidase A by chemical cross-linking. Finally, we determined the crystal structure of SapB bound to α-galactosidase A. These findings establish general principles for molecular recognition in saposin:hydrolase complexes and highlight the utility of NBD reporter lipids in saposin biochemistry and structural biology.
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Affiliation(s)
- Thomas K Sawyer
- Department of Biochemistry & Molecular Biology, Institute of Applied Life Sciences, University of Massachusetts, Amherst, Massachusetts 01003, USA
- Program in Molecular & Cellular Biology, Institute of Applied Life Sciences, University of Massachusetts, Amherst, Massachusetts 01003, USA
| | - Efecan Aral
- Department of Biochemistry & Molecular Biology, Institute of Applied Life Sciences, University of Massachusetts, Amherst, Massachusetts 01003, USA
- Program in Molecular & Cellular Biology, Institute of Applied Life Sciences, University of Massachusetts, Amherst, Massachusetts 01003, USA
| | - James V Staros
- Department of Biochemistry & Molecular Biology, Institute of Applied Life Sciences, University of Massachusetts, Amherst, Massachusetts 01003, USA
| | - Cedric E Bobst
- Mass Spectrometry Core Facility, Institute of Applied Life Sciences, University of Massachusetts, Amherst, Massachusetts 01003, USA
| | - Scott C Garman
- Department of Biochemistry & Molecular Biology, Institute of Applied Life Sciences, University of Massachusetts, Amherst, Massachusetts 01003, USA
- Program in Molecular & Cellular Biology, Institute of Applied Life Sciences, University of Massachusetts, Amherst, Massachusetts 01003, USA
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3
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Hackney CM, Flórez Salcedo P, Mueller E, Koch TL, Kjelgaard LD, Watkins M, Zachariassen LG, Tuelung PS, McArthur JR, Adams DJ, Kristensen AS, Olivera B, Finol-Urdaneta RK, Safavi-Hemami H, Morth JP, Ellgaard L. A previously unrecognized superfamily of macro-conotoxins includes an inhibitor of the sensory neuron calcium channel Cav2.3. PLoS Biol 2023; 21:e3002217. [PMID: 37535677 PMCID: PMC10437998 DOI: 10.1371/journal.pbio.3002217] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2023] [Revised: 08/18/2023] [Accepted: 06/27/2023] [Indexed: 08/05/2023] Open
Abstract
Animal venom peptides represent valuable compounds for biomedical exploration. The venoms of marine cone snails constitute a particularly rich source of peptide toxins, known as conotoxins. Here, we identify the sequence of an unusually large conotoxin, Mu8.1, which defines a new class of conotoxins evolutionarily related to the well-known con-ikot-ikots and 2 additional conotoxin classes not previously described. The crystal structure of recombinant Mu8.1 displays a saposin-like fold and shows structural similarity with con-ikot-ikot. Functional studies demonstrate that Mu8.1 curtails calcium influx in defined classes of murine somatosensory dorsal root ganglion (DRG) neurons. When tested on a variety of recombinantly expressed voltage-gated ion channels, Mu8.1 displayed the highest potency against the R-type (Cav2.3) calcium channel. Ca2+ signals from Mu8.1-sensitive DRG neurons were also inhibited by SNX-482, a known spider peptide modulator of Cav2.3 and voltage-gated K+ (Kv4) channels. Our findings highlight the potential of Mu8.1 as a molecular tool to identify and study neuronal subclasses expressing Cav2.3. Importantly, this multidisciplinary study showcases the potential of uncovering novel structures and bioactivities within the largely unexplored group of macro-conotoxins.
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Affiliation(s)
- Celeste M. Hackney
- Department of Biology, Linderstrøm-Lang Centre for Protein Science, University of Copenhagen, Copenhagen, Denmark
| | - Paula Flórez Salcedo
- Department of Neurobiology and Anatomy, University of Utah, Salt Lake City, Utah, United States of America
| | - Emilie Mueller
- Enzyme and Protein Chemistry, Section for Protein Chemistry and Enzyme Technology, Department of Biotechnology and Biomedicine, Technical University of Denmark, Kgs. Lyngby, Denmark
| | - Thomas Lund Koch
- Department of Biochemistry, University of Utah, Salt Lake City, Utah, United States of America
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Lau D. Kjelgaard
- Department of Biology, Linderstrøm-Lang Centre for Protein Science, University of Copenhagen, Copenhagen, Denmark
| | - Maren Watkins
- School of Biological Sciences, University of Utah, Salt Lake City, Utah, United States of America
| | - Linda G. Zachariassen
- Department of Drug Design & Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | | | - Jeffrey R. McArthur
- Illawarra Health and Medical Research Institute (IHMRI), Faculty of Science, Medicine and Health, University of Wollongong, Wollongong, Australia
| | - David J. Adams
- Illawarra Health and Medical Research Institute (IHMRI), Faculty of Science, Medicine and Health, University of Wollongong, Wollongong, Australia
| | - Anders S. Kristensen
- Department of Drug Design & Pharmacology, University of Copenhagen, Copenhagen, Denmark
| | - Baldomero Olivera
- School of Biological Sciences, University of Utah, Salt Lake City, Utah, United States of America
| | - Rocio K. Finol-Urdaneta
- Illawarra Health and Medical Research Institute (IHMRI), Faculty of Science, Medicine and Health, University of Wollongong, Wollongong, Australia
- Electrophysiology Facility for Cell Phenotyping and Drug Discovery, Wollongong, Australia
| | - Helena Safavi-Hemami
- Department of Biochemistry, University of Utah, Salt Lake City, Utah, United States of America
- Department of Biomedical Sciences, University of Copenhagen, Copenhagen, Denmark
- School of Biological Sciences, University of Utah, Salt Lake City, Utah, United States of America
| | - Jens Preben Morth
- Enzyme and Protein Chemistry, Section for Protein Chemistry and Enzyme Technology, Department of Biotechnology and Biomedicine, Technical University of Denmark, Kgs. Lyngby, Denmark
| | - Lars Ellgaard
- Department of Biology, Linderstrøm-Lang Centre for Protein Science, University of Copenhagen, Copenhagen, Denmark
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4
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Ladjouzi R, Dussert E, Teiar R, Belguesmia Y, Drider D. A Review on Enterocin DD14, the Leaderless Two-Peptide Bacteriocin with Multiple Biological Functions and Unusual Transport Pathway. Antibiotics (Basel) 2023; 12:1188. [PMID: 37508284 PMCID: PMC10376788 DOI: 10.3390/antibiotics12071188] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Revised: 07/09/2023] [Accepted: 07/11/2023] [Indexed: 07/30/2023] Open
Abstract
Enterocin DD14 (EntDD14) is a two-peptide leaderless bacteriocin (LLB) produced by Enterococcus faecalis 14, a human strain isolated from meconium. Studies performed on EntDD14 enabled it to show its activity against Gram-positive bacteria such as Listeria monocytogenes, Clostridium perfringens, Enterococcus faecalis, and Staphylococcus aureus. EntDD14 was also shown to potentiate the activity of different antibiotics such as erythromycin, kanamycin, and methicillin when assessed against methicillin-resistant Staphylococcus aureus (MRSA) in vitro and in vivo in the NMRI-F holoxenic mouse model. Additionally, EntDD14 has an antiviral activity and decreased the secretion of pro-inflammatory IL-6 and IL-8 in inflamed human intestinal Caco-2 cells. The genome of E. faecalis 14 was sequenced and annotated. Molecular tools such as Bagel4 software enabled us to locate a 6.7kb-EntDD14 cluster. Transport of EntDD14 outside of the cytoplasm was shown to be performed synergistically by a channel composed of two pleckstrin-homology-domain-containing proteins, namely DdE/DdF and the ABC transporter DdGHIJ. This latter could also protect the bacteriocinogenic strain against extracellular EntDD14. Here, we focus on academic data and potential therapeutic issues of EntDD14, as a model of two-peptide LLB.
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Affiliation(s)
- Rabia Ladjouzi
- UMR Transfrontalière BioEcoAgro, INRAe 1158, ICV-Institut Charles Viollette, University Lille, INRAE, University Liège, UPJV, YNCREA, University Artois, University Littoral Côte d'Opale, F-59000 Lille, France
| | - Elodie Dussert
- UMR Transfrontalière BioEcoAgro, INRAe 1158, ICV-Institut Charles Viollette, University Lille, INRAE, University Liège, UPJV, YNCREA, University Artois, University Littoral Côte d'Opale, F-59000 Lille, France
| | - Radja Teiar
- UMR Transfrontalière BioEcoAgro, INRAe 1158, ICV-Institut Charles Viollette, University Lille, INRAE, University Liège, UPJV, YNCREA, University Artois, University Littoral Côte d'Opale, F-59000 Lille, France
| | - Yanath Belguesmia
- UMR Transfrontalière BioEcoAgro, INRAe 1158, ICV-Institut Charles Viollette, University Lille, INRAE, University Liège, UPJV, YNCREA, University Artois, University Littoral Côte d'Opale, F-59000 Lille, France
| | - Djamel Drider
- UMR Transfrontalière BioEcoAgro, INRAe 1158, ICV-Institut Charles Viollette, University Lille, INRAE, University Liège, UPJV, YNCREA, University Artois, University Littoral Côte d'Opale, F-59000 Lille, France
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5
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Kojima R, Zurbruegg M, Li T, Paslawski W, Zhang X, Svenningsson P. Prosaposin Reduces α-Synuclein in Cells and Saposin C Dislodges it from Glucosylceramide-enriched Lipid Membranes. J Mol Neurosci 2022; 72:2313-2325. [PMID: 36152140 PMCID: PMC9726671 DOI: 10.1007/s12031-022-02066-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2022] [Accepted: 09/10/2022] [Indexed: 01/18/2023]
Abstract
Parkinson's disease (PD) is the second most common progressive neurodegenerative disorder affecting over 1% of the 65 + age population. Saposin C, a lysosomal protein required for the normal activity of glucocerebrosidase (GCase), may serve as a disease modifier in PD. Saposin C is cleaved from its precursor, Prosaposin (PSAP), which is secreted as an uncleaved protein and exerts neuroprotective effects. In this study, we aim to elucidate the neuroprotective roles of PSAP and saposin C in PD by evaluating their effects on α-synuclein accumulation in human neuroblastoma cells. Stable overexpression of PSAP reduced monomeric α-synuclein levels in SH-SY5Y cells, while PSAP knockdown by small interfering RNA led to the opposite effect, and those effects were independent of GCase activity. Autophagy flux was decreased by stable PSAP overexpression. Furthermore, a flow-through assay revealed that recombinant saposin C was able to detach α-synuclein from artificial glucosylceramide-enriched lipid membranes at the lysosomal pH. Taken together, our findings provide further evidence that PSAP and saposin C as key proteins involved in α-synuclein clearance by dislodging it from lipid membranes.
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Affiliation(s)
- Rika Kojima
- Department of Clinical Neuroscience, Neuro Svenningsson, Karolinska Institutet, 171 76, Stockholm, Sweden
| | - Mark Zurbruegg
- Department of Clinical Neuroscience, Neuro Svenningsson, Karolinska Institutet, 171 76, Stockholm, Sweden
| | - Tianyi Li
- Department of Clinical Neuroscience, Neuro Svenningsson, Karolinska Institutet, 171 76, Stockholm, Sweden
| | - Wojciech Paslawski
- Department of Clinical Neuroscience, Neuro Svenningsson, Karolinska Institutet, 171 76, Stockholm, Sweden
| | - Xiaoqun Zhang
- Department of Clinical Neuroscience, Neuro Svenningsson, Karolinska Institutet, 171 76, Stockholm, Sweden
| | - Per Svenningsson
- Department of Clinical Neuroscience, Neuro Svenningsson, Karolinska Institutet, 171 76, Stockholm, Sweden.
- Basic and Clinical Neuroscience, King's College London, London, UK.
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6
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Phenotype Expansion for Atypical Gaucher Disease Due to Homozygous Missense PSAP Variant in a Large Consanguineous Pakistani Family. Genes (Basel) 2022; 13:genes13040662. [PMID: 35456468 PMCID: PMC9028228 DOI: 10.3390/genes13040662] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2022] [Revised: 04/04/2022] [Accepted: 04/06/2022] [Indexed: 02/06/2023] Open
Abstract
Atypical Gaucher disease is caused by variants in the PSAP gene. 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, which is deficient in Gaucher disease. Although atypical Gaucher disease due to deficiency of saposin C is rare, it exhibits vast phenotypic heterogeneity. Here, we report on a Pakistani family that exhibits features of Gaucher disease, i.e., prelingual profound sensorineural hearing impairment, vestibular dysfunction, hepatosplenomegaly, kyphosis, and thrombocytopenia. The family was investigated using exome and Sanger sequencing. A homozygous missense variant c.1076A>C: p.(Glu359Ala) in exon 10 of the PSAP gene was observed in all affected family members. In conclusion, we identified a new likely pathogenic missense variant in PSAP in a large consanguineous Pakistani family with atypical Gaucher disease. Gaucher disease due to a deficiency of saposin C has not been previously reported within the Pakistani population. Genetic screening of patients with the aforementioned phenotypes could ensure adequate follow-up and the prevention of further complications. Our finding expands the genetic and phenotypic spectrum of atypical Gaucher disease due to a saposin C deficiency.
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7
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Abstract
Membrane proteins (MPs) play essential roles in numerous cellular processes. Because around 70% of the currently marketed drugs target MPs, a detailed understanding of their structure, binding properties, and functional dynamics in a physiologically relevant environment is crucial for a more detailed understanding of this important protein class. We here summarize the benefits of using lipid nanodiscs for NMR structural investigations and provide a detailed overview of the currently used lipid nanodisc systems as well as their applications in solution-state NMR. Despite the increasing use of other structural methods for the structure determination of MPs in lipid nanodiscs, solution NMR turns out to be a versatile tool to probe a wide range of MP features, ranging from the structure determination of small to medium-sized MPs to probing ligand and partner protein binding as well as functionally relevant dynamical signatures in a lipid nanodisc setting. We will expand on these topics by discussing recent NMR studies with lipid nanodiscs and work out a key workflow for optimizing the nanodisc incorporation of an MP for subsequent NMR investigations. With this, we hope to provide a comprehensive background to enable an informed assessment of the applicability of lipid nanodiscs for NMR studies of a particular MP of interest.
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Affiliation(s)
- Umut Günsel
- Bavarian NMR Center (BNMRZ) at the Department of Chemistry, Technical University of Munich, Ernst-Otto-Fischer-Strasse 2, 85748 Garching, Germany
| | - Franz Hagn
- Bavarian NMR Center (BNMRZ) at the Department of Chemistry, Technical University of Munich, Ernst-Otto-Fischer-Strasse 2, 85748 Garching, Germany.,Institute of Structural Biology, Helmholtz Zentrum München, Ingolstädter Landstraße 1, 85764 Neuherberg, Germany
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8
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Kurgan KW, Chen B, Brown KA, Cobra PF, Ye X, Ge Y, Gellman SH. Stable Picodisc Assemblies from Saposin Proteins and Branched Detergents. Biochemistry 2021; 60:1108-1119. [PMID: 33755420 PMCID: PMC8044043 DOI: 10.1021/acs.biochem.0c00924] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Methods for maintaining membrane proteins in their native state after removal from the lipid bilayer are essential for the study of this important class of biomacromolecules. Common solubilization strategies range from the use of detergents to more complex systems that involve a polypeptide working in concert with lipids or detergents, such as nanodiscs, picodiscs, and peptidiscs, in which an engineered protein or synthetic peptide surrounds the membrane protein along with a lipid sheath. Picodiscs employ the protein saposin A, which naturally functions to facilitate lipid degradation in the lysozome. Saposin A-amphiphile complexes therefore tend to be most stable at acidic pH, which is not optimal for most membrane protein applications. In search of new picodisc assemblies, we have explored pairings of saposin A or other saposin proteins with a range of detergents, and we have identified a number of combinations that spontaneously co-assemble at neutral pH. The resulting picodiscs are stable for weeks and have been characterized by size-exclusion chromatography, native mass spectrometry, and small angle X-ray scattering. The new assemblies are formed by double-tail detergents rather than more traditional single-tail detergents; the double-tail detergents can be seen as structurally intermediate between single-tail detergents and common lipids. In addition to saposin A, an engineered variant of saposin B (designated saposin BW) forms picodisc assemblies. These findings provide a framework for future efforts to solubilize membrane proteins with multiple picodisc systems that were previously unknown.
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Affiliation(s)
- Kathleen W. Kurgan
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Bifan Chen
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
- Human Proteomics Program, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Kyle A. Brown
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
- Human Proteomics Program, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Paulo Falco Cobra
- National Magnetic Resonance Facility at Madison, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Xinyu Ye
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Ying Ge
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
- Department of Cell and Regenerative Biology, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
- Human Proteomics Program, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Samuel H. Gellman
- Department of Chemistry, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
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9
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Sowa ST, Moilanen A, Biterova E, Saaranen MJ, Lehtiö L, Ruddock LW. High-resolution Crystal Structure of Human pERp1, A Saposin-like Protein Involved in IgA, IgM and Integrin Maturation in the Endoplasmic Reticulum. J Mol Biol 2021; 433:166826. [PMID: 33453188 DOI: 10.1016/j.jmb.2021.166826] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Revised: 01/05/2021] [Accepted: 01/05/2021] [Indexed: 01/24/2023]
Abstract
The folding of disulfide bond containing proteins in the endoplasmic reticulum (ER) is a complex process that requires protein folding factors, some of which are protein-specific. The ER resident saposin-like protein pERp1 (MZB1, CNPY5) is crucial for the correct folding of IgA, IgM and integrins. pERp1 also plays a role in ER calcium homeostasis and plasma cell mobility. As an important factor for proper IgM maturation and hence immune function, pERp1 is upregulated in many auto-immune diseases. This makes it a potential therapeutic target. pERp1 belongs to the CNPY family of ER resident saposin-like proteins. To date, five of these proteins have been identified. All are implicated in protein folding and all contain a saposin-like domain. All previously structurally characterized saposins are involved in lipid binding. However, there are no reports of CNPY family members interacting with lipids, suggesting a novel function for the saposin fold. However, the molecular mechanisms of their function remain elusive. To date, no structure of any CNPY protein has been reported. Here, we present the high-resolution (1.4 Å) crystal structure of human pERp1 and confirm that it has a saposin-fold with unique structural elements not present in other saposin-fold structures. The implications for the role of CNPY proteins in protein folding in the ER are discussed.
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Affiliation(s)
- Sven T Sowa
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, Aapistie 7, 90220 Oulu, Finland; Biocenter Oulu, Aapistie 5, 90220 Oulu, Finland.
| | - Antti Moilanen
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, Aapistie 7, 90220 Oulu, Finland.
| | - Ekaterina Biterova
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, Aapistie 7, 90220 Oulu, Finland
| | - Mirva J Saaranen
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, Aapistie 7, 90220 Oulu, Finland.
| | - Lari Lehtiö
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, Aapistie 7, 90220 Oulu, Finland; Biocenter Oulu, Aapistie 5, 90220 Oulu, Finland.
| | - Lloyd W Ruddock
- Faculty of Biochemistry and Molecular Medicine, University of Oulu, Aapistie 7, 90220 Oulu, Finland.
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10
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Boer DE, Mirzaian M, Ferraz MJ, Zwiers KC, Baks MV, Hazeu MD, Ottenhoff R, Marques ARA, Meijer R, Roos JCP, Cox TM, Boot RG, Pannu N, Overkleeft HS, Artola M, Aerts JM. Human glucocerebrosidase mediates formation of xylosyl-cholesterol by β-xylosidase and transxylosidase reactions. J Lipid Res 2021; 62:100018. [PMID: 33361282 PMCID: PMC7903134 DOI: 10.1194/jlr.ra120001043] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2020] [Revised: 12/14/2020] [Accepted: 12/23/2020] [Indexed: 11/20/2022] Open
Abstract
Deficiency of glucocerebrosidase (GBA), a lysosomal β-glucosidase, causes Gaucher disease. The enzyme hydrolyzes β-glucosidic substrates and transglucosylates cholesterol to cholesterol-β-glucoside. Here we show that recombinant human GBA also cleaves β-xylosides and transxylosylates cholesterol. The xylosyl-cholesterol formed acts as an acceptor for the subsequent formation of di-xylosyl-cholesterol. Common mutant forms of GBA from patients with Gaucher disease with reduced β-glucosidase activity were similarly impaired in β-xylosidase, transglucosidase, and transxylosidase activities, except for a slightly reduced xylosidase/glucosidase activity ratio of N370S GBA and a slightly reduced transglucosylation/glucosidase activity ratio of D409H GBA. XylChol was found to be reduced in spleen from patients with Gaucher disease. The origin of newly identified XylChol in mouse and human tissues was investigated. Cultured human cells exposed to exogenous β-xylosides generated XylChol in a manner dependent on active lysosomal GBA but not the cytosol-facing β-glucosidase GBA2. We later sought an endogenous β-xyloside acting as donor in transxylosylation reactions, identifying xylosylated ceramide (XylCer) in cells and tissues that serve as donor in the formation of XylChol. UDP-glucosylceramide synthase (GCS) was unable to synthesize XylChol but could catalyze the formation of XylCer. Thus, food-derived β-D-xyloside and XylCer are potential donors for the GBA-mediated formation of XylChol in cells. The enzyme GCS produces XylCer at a low rate. Our findings point to further catalytic versatility of GBA and prompt a systematic exploration of the distribution and role of xylosylated lipids.
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Affiliation(s)
- Daphne E Boer
- Department of Medical Biochemistry, Leiden Institute of Chemistry, Leiden University, The Netherlands
| | - Mina Mirzaian
- Department of Medical Biochemistry, Leiden Institute of Chemistry, Leiden University, The Netherlands
| | - Maria J Ferraz
- Department of Medical Biochemistry, Leiden Institute of Chemistry, Leiden University, The Netherlands
| | - Kimberley C Zwiers
- Department of Medical Biochemistry, Leiden Institute of Chemistry, Leiden University, The Netherlands
| | - Merel V Baks
- Department of Medical Biochemistry, Leiden Institute of Chemistry, Leiden University, The Netherlands
| | - Marc D Hazeu
- Department of Medical Biochemistry, Leiden Institute of Chemistry, Leiden University, The Netherlands
| | - Roelof Ottenhoff
- Department of Medical Biochemistry, Academic Medical Center, Amsterdam, The Netherlands
| | - André R A Marques
- Department of Medical Biochemistry, Leiden Institute of Chemistry, Leiden University, The Netherlands
| | - Rianne Meijer
- Department of Medical Biochemistry, Leiden Institute of Chemistry, Leiden University, The Netherlands
| | - Jonathan C P Roos
- Department of Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Timothy M Cox
- Department of Medicine, University of Cambridge, Cambridge, United Kingdom
| | - Rolf G Boot
- Department of Medical Biochemistry, Leiden Institute of Chemistry, Leiden University, The Netherlands
| | - Navraj Pannu
- Department of Biophysical Structural Chemistry, Leiden Institute of Chemistry, Leiden University, The Netherlands
| | - Herman S Overkleeft
- Department of Bio-organic Synthesis, Leiden Institute of Chemistry, Leiden University, The Netherlands
| | - Marta Artola
- Department of Medical Biochemistry, Leiden Institute of Chemistry, Leiden University, The Netherlands
| | - Johannes M Aerts
- Department of Medical Biochemistry, Leiden Institute of Chemistry, Leiden University, The Netherlands.
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11
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Shamin M, Spratley SJ, Graham SC, Deane JE. A Tetrameric Assembly of Saposin A: Increasing Structural Diversity in Lipid Transfer Proteins. CONTACT (THOUSAND OAKS (VENTURA COUNTY, CALIF.)) 2021; 4:251525642110523. [PMID: 37143956 PMCID: PMC7614494 DOI: 10.1177/25152564211052382] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Saposins are lipid transfer proteins required for the degradation of sphingolipids in the lysosome. These small proteins bind lipids by transitioning from a closed, monomeric state to an open conformation exposing a hydrophobic surface that binds and shields hydrophobic lipid tails from the aqueous environment. Saposins form a range of multimeric assemblies to encompass these bound lipids and present them to hydrolases in the lysosome. This lipid-binding property of human saposin A has been exploited to form lipoprotein nanodiscs suitable for structural studies of membrane proteins. Here we present the crystal structure of a unique tetrameric assembly of murine saposin A produced serendipitously, following modifications of published protocols for making lipoprotein nanodiscs. The structure of this new saposin oligomer highlights the diversity of tertiary arrangement that can be adopted by these important lipid transfer proteins.
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Affiliation(s)
- Maria Shamin
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, UK
| | - Samantha J. Spratley
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, UK
| | - Stephen C. Graham
- Department of Pathology, University of Cambridge, Cambridge CB2 1QP, UK
| | - Janet E. Deane
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge CB2 0XY, UK
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12
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The Droserasin 1 PSI: A Membrane-Interacting Antimicrobial Peptide from the Carnivorous Plant Drosera capensis. Biomolecules 2020; 10:biom10071069. [PMID: 32709016 PMCID: PMC7407137 DOI: 10.3390/biom10071069] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2020] [Revised: 07/08/2020] [Accepted: 07/13/2020] [Indexed: 12/11/2022] Open
Abstract
The Droserasins, aspartic proteases from the carnivorous plant Drosera capensis, contain a 100-residue plant-specific insert (PSI) that is post-translationally cleaved and independently acts as an antimicrobial peptide. PSIs are of interest not only for their inhibition of microbial growth, but also because they modify the size of lipid vesicles and strongly interact with biological membranes. PSIs may therefore be useful for modulating lipid systems in NMR studies of membrane proteins. Here we present the expression and biophysical characterization of the Droserasin 1 PSI (D1 PSI.) This peptide is monomeric in solution and maintains its primarily α-helical secondary structure over a wide range of temperatures and pH values, even under conditions where its three disulfide bonds are reduced. Vesicle fusion assays indicate that the D1 PSI strongly interacts with bacterial and fungal lipids at pH 5 and lower, consistent with the physiological pH of D. capensis mucilage. It binds lipids with a variety of head groups, highlighting its versatility as a potential stabilizer for lipid nanodiscs. Solid-state NMR spectra collected at a field strength of 36 T, using a unique series-connected hybrid magnet, indicate that the peptide is folded and strongly bound to the membrane. Molecular dynamics simulations indicate that the peptide is stable as either a monomer or a dimer in a lipid bilayer. Both the monomer and the dimer allow the passage of water through the membrane, albeit at different rates.
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13
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Molecular models should not be published without the corresponding atomic coordinates. Proc Natl Acad Sci U S A 2020; 116:11099-11100. [PMID: 31164476 DOI: 10.1073/pnas.1904409116] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
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14
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Shamin M, Benedyk TH, Graham SC, Deane JE. The lipid transfer protein Saposin B does not directly bind CD1d for lipid antigen loading. Wellcome Open Res 2019; 4:117. [PMID: 31667358 PMCID: PMC6807164 DOI: 10.12688/wellcomeopenres.15368.2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/14/2019] [Indexed: 12/13/2022] Open
Abstract
Background: Lipid antigens are presented on the surface of cells by the CD1 family of glycoproteins, which have structural and functional similarity to MHC class I molecules. The hydrophobic lipid antigens are embedded in membranes and inaccessible to the lumenal lipid-binding domain of CD1 molecules. Therefore, CD1 molecules require lipid transfer proteins for lipid loading and editing. CD1d is loaded with lipids in late endocytic compartments, and lipid transfer proteins of the saposin family have been shown to play a crucial role in this process. However, the mechanism by which saposins facilitate lipid binding to CD1 molecules is not known and is thought to involve transient interactions between protein components to ensure CD1-lipid complexes can be efficiently trafficked to the plasma membrane for antigen presentation. Of the four saposin proteins, the importance of Saposin B (SapB) for loading of CD1d is the most well-characterised. However, a direct interaction between CD1d and SapB has yet to be described. Methods: In order to determine how SapB might load lipids onto CD1d, we used purified, recombinant CD1d and SapB and carried out a series of highly sensitive binding assays to monitor direct interactions. We performed equilibrium binding analysis, chemical cross-linking and co-crystallisation experiments, under a range of different conditions. Results: We could not demonstrate a direct interaction between SapB and CD1d using any of these binding assays. Conclusions: This work strongly indicates that the role of SapB in lipid loading does not involve direct binding to CD1d. We discuss the implication of this for our understanding of lipid loading of CD1d and propose several factors that may influence this process.
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Affiliation(s)
- Maria Shamin
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, CB2 0XY, UK
- Department of Pathology, University of Cambridge, Cambridge, CB2 1QP, UK
| | - Tomasz H. Benedyk
- Department of Pathology, University of Cambridge, Cambridge, CB2 1QP, UK
| | - Stephen C. Graham
- Department of Pathology, University of Cambridge, Cambridge, CB2 1QP, UK
| | - Janet E. Deane
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, CB2 0XY, UK
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, CB2 0QQ, UK
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15
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Klöpfer K, Hagn F. Beyond detergent micelles: The advantages and applications of non-micellar and lipid-based membrane mimetics for solution-state NMR. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2019; 114-115:271-283. [PMID: 31779883 DOI: 10.1016/j.pnmrs.2019.08.001] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2019] [Revised: 08/20/2019] [Accepted: 08/22/2019] [Indexed: 06/10/2023]
Abstract
Membrane proteins are important players in signal transduction and the exchange of metabolites within or between cells. Thus, this protein class is the target of around 60 % of currently marketed drugs, emphasizing their essential biological role. Besides functional assays, structural and dynamical investigations on this protein class are crucial to fully understanding their functionality. Even though X-ray crystallography and electron microscopy are the main methods to determine structures of membrane proteins and their complexes, NMR spectroscopy can contribute essential information on systems that (a) do not crystallize and (b) are too small for EM. Furthermore, NMR is a versatile tool for monitoring functional dynamics of biomolecules at various time scales. A crucial aspect of such studies is the use of a membrane mimetic that resembles a native environment and thus enables the extraction of functional insights. In recent decades, the membrane protein NMR community has moved from rather harsh detergents to membrane systems having more native-like properties. In particular, most recently phospholipid nanodiscs have been developed and optimized mainly for solution-state NMR but are now also being used for solid-state NMR spectroscopy. Nanodiscs consist of a patch of a planar lipid bilayer that is encircled by different (bio-)polymers to form particles of defined and tunable size. In this review, we provide an overview of available membrane mimetics, including nanodiscs, amphipols and bicelles, that are suitable for high-resolution NMR spectroscopy and describe how these advanced membrane mimetics can facilitate NMR studies on the structure and dynamics of membrane proteins. Since the stability of membrane proteins depends critically on the chosen membrane mimetic, we emphasize the importance of a suitable system that is not necessarily developed for solution-state NMR applications and hence requires optimization for each membrane protein. However, lipid-based membrane mimetics offer the possibility of performing NMR experiments at elevated temperatures and studying ligand and partner protein complexes as well as their functional dynamics in a realistic membrane environment. In order to be able to make an informed decision during the selection of a suitable membrane system, we provide a detailed overview of the available options for various membrane protein classes and thereby facilitate this often-difficult selection process for a broad range of desired NMR applications.
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Affiliation(s)
- Kai Klöpfer
- Bavarian NMR Center at the Department of Chemistry, Technical University of Munich, Ernst-Otto-Fischer-Str. 2, 85747 Garching, Germany; Institute of Structural Biology, Helmholtz Zentrum München, Ingolstädter Landstrasse 1, 85764 Neuherberg, Germany
| | - Franz Hagn
- Bavarian NMR Center at the Department of Chemistry, Technical University of Munich, Ernst-Otto-Fischer-Str. 2, 85747 Garching, Germany; Institute of Structural Biology, Helmholtz Zentrum München, Ingolstädter Landstrasse 1, 85764 Neuherberg, Germany.
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16
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Robichaud NAS, Khatami MH, Saika-Voivod I, Booth V. All-Atom Molecular Dynamics Simulations of Dimeric Lung Surfactant Protein B in Lipid Multilayers. Int J Mol Sci 2019; 20:ijms20163863. [PMID: 31398818 PMCID: PMC6719169 DOI: 10.3390/ijms20163863] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2019] [Revised: 07/29/2019] [Accepted: 08/06/2019] [Indexed: 02/07/2023] Open
Abstract
Although lung surfactant protein B (SP-B) is an essential protein that plays a crucial role in breathing, the details of its structure and mechanism are not well understood. SP-B forms covalent homodimers, and in this work we use all-atom molecular dynamics simulations to study dimeric SP-B’s structure and its behavior in promoting lipid structural transitions. Four initial system configurations were constructed based on current knowledge of SP-B’s structure and mechanism, and the protein maintained a helicity consistent with experiment in all systems. Several SP-B-induced lipid reorganization behaviors were observed, and regions of the protein particularly important for these activities included SP-B’s “central loop” and “hinge” regions. SP-B dimers with one subunit initially positioned in each of two adjacent bilayers appeared to promote close contact between two bilayers. When both subunits were initially positioned in the same bilayer, SP-B induced the formation of a defect in the bilayer, with water penetrating into the centre of the bilayer. Similarly, dimeric SP-B showed a propensity to interact with preformed interpores in the bilayer. SP-B dimers also promoted bilayer thinning and creasing. This work fleshes out the atomistic details of the dimeric SP-B structures and SP-B/lipid interactions that underlie SP-B’s essential functions.
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Affiliation(s)
- Nicholas A S Robichaud
- Department of Physics and Physical Oceanography, Memorial University of Newfoundland, St. John's, NL A1B 3X7, Canada
| | - Mohammad Hassan Khatami
- Department of Physics and Physical Oceanography, Memorial University of Newfoundland, St. John's, NL A1B 3X7, Canada
| | - Ivan Saika-Voivod
- Department of Physics and Physical Oceanography, Memorial University of Newfoundland, St. John's, NL A1B 3X7, Canada.
| | - Valerie Booth
- Department of Physics and Physical Oceanography, Memorial University of Newfoundland, St. John's, NL A1B 3X7, Canada.
- Department of Biochemistry, Memorial University of Newfoundland, St. John's, NL A1B 3X9, Canada.
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17
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Shamin M, Benedyk TH, Graham SC, Deane JE. The lipid transfer protein Saposin B does not directly bind CD1d for lipid antigen loading. Wellcome Open Res 2019; 4:117. [PMID: 31667358 PMCID: PMC6807164 DOI: 10.12688/wellcomeopenres.15368.1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/19/2019] [Indexed: 10/15/2023] Open
Abstract
Background: Lipid antigens are presented on the surface of cells by the CD1 family of glycoproteins, which have structural and functional similarity to MHC class I molecules. The hydrophobic lipid antigens are embedded in membranes and inaccessible to the lumenal lipid-binding domain of CD1 molecules. Therefore, CD1 molecules require lipid transfer proteins for lipid loading and editing. CD1d is loaded with lipids in late endocytic compartments, and lipid transfer proteins of the saposin family have been shown to play a crucial role in this process. However, the mechanism by which saposins facilitate lipid binding to CD1 molecules is not known and is thought to involve transient interactions between protein components to ensure CD1-lipid complexes can be efficiently trafficked to the plasma membrane for antigen presentation. Of the four saposin proteins, the importance of Saposin B (SapB) for loading of CD1d is the most well-characterised. However, a direct interaction between CD1d and SapB has yet to be described. Methods: In order to determine how SapB might load lipids onto CD1d, we used purified, recombinant CD1d and SapB and carried out a series of highly sensitive binding assays to monitor direct interactions. We performed equilibrium binding analysis, chemical cross-linking and co-crystallisation experiments, under a range of different conditions. Results: We could not demonstrate a direct interaction between SapB and CD1d using any of these binding assays. Conclusions: This work establishes comprehensively that the role of SapB in lipid loading does not involve direct binding to CD1d. We discuss the implication of this for our understanding of lipid loading of CD1d and propose several factors that may influence this process.
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Affiliation(s)
- Maria Shamin
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, CB2 0XY, UK
- Department of Pathology, University of Cambridge, Cambridge, CB2 1QP, UK
| | - Tomasz H. Benedyk
- Department of Pathology, University of Cambridge, Cambridge, CB2 1QP, UK
| | - Stephen C. Graham
- Department of Pathology, University of Cambridge, Cambridge, CB2 1QP, UK
| | - Janet E. Deane
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, CB2 0XY, UK
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, CB2 0QQ, UK
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18
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Autzen HE, Julius D, Cheng Y. Membrane mimetic systems in CryoEM: keeping membrane proteins in their native environment. Curr Opin Struct Biol 2019; 58:259-268. [PMID: 31279500 DOI: 10.1016/j.sbi.2019.05.022] [Citation(s) in RCA: 50] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Revised: 05/24/2019] [Accepted: 05/27/2019] [Indexed: 01/02/2023]
Abstract
Advances in electron microscopes, detectors and data processing algorithms have greatly facilitated the structural determination of many challenging integral membrane proteins that have been evasive to crystallization. These breakthroughs facilitate the application and development of various membrane protein solubilization approaches for structural studies, including reconstitution into lipid nanoparticles. In this review, we discuss various approaches for preparing transmembrane proteins for structural determination with single-particle electron cryo microscopy (cryoEM).
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Affiliation(s)
- Henriette E Autzen
- Department of Biochemistry and Biophysics, University of California, San Francisco, CA 94143, USA; Department of Molecular Biology and Genetics, Aarhus University, 8000 Aarhus, Denmark
| | - David Julius
- Department of Physiology, University of California, San Francisco, CA 94143, USA.
| | - Yifan Cheng
- Department of Biochemistry and Biophysics, University of California, San Francisco, CA 94143, USA; Howard Hughes Medical Institute, University of California, San Francisco, CA 94143, USA.
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19
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Romero R, Yuen T, New MI, Zaidi M, Haider S. Reply to Graham et al.: In silico atomistic coordinates and molecular dynamics simulation trajectories of the glucocerebrosidase-saposin C complex. Proc Natl Acad Sci U S A 2019; 116:11101-11102. [PMID: 31164477 PMCID: PMC6561302 DOI: 10.1073/pnas.1905744116] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Affiliation(s)
- Raquel Romero
- Department of Pharmaceutical and Biological Chemistry, University College London School of Pharmacy, London WC1N 1AX, United Kingdom
| | - Tony Yuen
- Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY 10029
| | - Maria I New
- Department of Pediatrics, Icahn School of Medicine at Mount Sinai, New York, NY 10029
| | - Mone Zaidi
- Department of Medicine, Icahn School of Medicine at Mount Sinai, New York, NY 10029;
| | - Shozeb Haider
- Department of Pharmaceutical and Biological Chemistry, University College London School of Pharmacy, London WC1N 1AX, United Kingdom;
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20
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Mechanism of glucocerebrosidase activation and dysfunction in Gaucher disease unraveled by molecular dynamics and deep learning. Proc Natl Acad Sci U S A 2019; 116:5086-5095. [PMID: 30808805 DOI: 10.1073/pnas.1818411116] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
The lysosomal enzyme glucocerebrosidase-1 (GCase) catalyzes the cleavage of a major glycolipid glucosylceramide into glucose and ceramide. The absence of fully functional GCase leads to the accumulation of its lipid substrates in lysosomes, causing Gaucher disease, an autosomal recessive disorder that displays profound genotype-phenotype nonconcordance. More than 250 disease-causing mutations in GBA1, the gene encoding GCase, have been discovered, although only one of these, N370S, causes 70% of disease. Here, we have used a knowledge-based docking protocol that considers experimental data of protein-protein binding to generate a complex between GCase and its known facilitator protein saposin C (SAPC). Multiscale molecular-dynamics simulations were used to study lipid self-assembly, membrane insertion, and the dynamics of the interactions between different components of the complex. Deep learning was applied to propose a model that explains the mechanism of GCase activation, which requires SAPC. Notably, we find that conformational changes in the loops at the entrance of the substrate-binding site are stabilized by direct interactions with SAPC and that the loss of such interactions induced by N370S and another common mutation, L444P, result in destabilization of the complex and reduced GCase activation. Our findings provide an atomistic-level explanation for GCase activation and the precise mechanism through which N370S and L444P cause Gaucher disease.
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21
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Johansson J, Curstedt T. Synthetic surfactants with SP-B and SP-C analogues to enable worldwide treatment of neonatal respiratory distress syndrome and other lung diseases. J Intern Med 2019; 285:165-186. [PMID: 30357986 DOI: 10.1111/joim.12845] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Treatment of neonatal respiratory distress syndrome (RDS) using animal-derived lung surfactant preparations has reduced the mortality of handling premature infants with RDS to a 50th of that in the 1960s. The supply of animal-derived lung surfactants is limited and only a part of the preterm babies is treated. Thus, there is a need to develop well-defined synthetic replicas based on key components of natural surfactant. A synthetic product that equals natural-derived surfactants would enable cost-efficient production and could also facilitate the development of the treatments of other lung diseases than neonatal RDS. Recently the first synthetic surfactant that contains analogues of the two hydrophobic surfactant proteins B (SP-B) and SP-C entered clinical trials for the treatment of neonatal RDS. The development of functional synthetic analogues of SP-B and SP-C, however, is considerably more challenging than anticipated 30 years ago when the first structural information of the native proteins became available. For SP-B, a complex three-dimensional dimeric structure stabilized by several disulphides has necessitated the design of miniaturized analogues. The main challenge for SP-C has been the pronounced amyloid aggregation propensity of its transmembrane region. The development of a functional non-aggregating SP-C analogue that can be produced synthetically was achieved by designing the amyloidogenic native sequence so that it spontaneously forms a stable transmembrane α-helix.
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Affiliation(s)
- J Johansson
- Department of Neurobiology, Care Sciences and Society, Section for Neurogeriatrics, Karolinska Institutet, Huddinge, Sweden
| | - T Curstedt
- Laboratory for Surfactant Research, Department of Molecular Medicine and Surgery, Karolinska Institutet at Karolinska University Hospital, Stockholm, Sweden
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22
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pH dependent membrane binding of the Solanum tuberosum plant specific insert: An in silico study. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1860:2608-2618. [PMID: 30291921 DOI: 10.1016/j.bbamem.2018.10.001] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2018] [Revised: 09/27/2018] [Accepted: 10/01/2018] [Indexed: 01/07/2023]
Abstract
The Solanum tuberosum plant-specific insert (StPSI) has been shown to possess potent antimicrobial activity against both human and plant pathogens. Furthermore, in vitro, the StPSI is capable of fusing phospholipid vesicles, provided the conditions of net anionic vesicle charge and acidic pH are met. Constant pH replica-exchange simulations indicate several acidic residues on the dimer have highly perturbed pKas (<3.0; E15, D28, E85 & E100) due to involvement in salt bridges. After setting the pH of the system to either 3.0 or 7.4, all-atom simulations provided details of the effect of pH on secondary structural elements, particularly in the previously unresolved crystallographic structure of the loop section. Coarse-grained dimer-bilayer simulations demonstrated that at pH 7.4, the dimer had no affinity for neutral or anionic membranes over the course of 1 μs simulations. Conversely, at pH 3.0 two binding modes were observed. Mode 1 is mediated primarily via strong N-terminal interactions on one monomer only, whereas in mode 2, N- and C-terminal residues of one monomer and numerous polar and basic residues on the second monomer, particularly in the third helix, participate in membrane interactions. Mode 2 was accompanied by re-orientation of the dimer to a more vertical position with respect to helices 1 and 4, positioning the dimer for membrane interactions. These results offer the first examination at near-atomic resolution of residues mediating the StPSI-membrane interactions, and allow for the postulation of a possible fusion mechanism.
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23
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Perez RH, Zendo T, Sonomoto K. Circular and Leaderless Bacteriocins: Biosynthesis, Mode of Action, Applications, and Prospects. Front Microbiol 2018; 9:2085. [PMID: 30233551 PMCID: PMC6131525 DOI: 10.3389/fmicb.2018.02085] [Citation(s) in RCA: 103] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2018] [Accepted: 08/15/2018] [Indexed: 01/02/2023] Open
Abstract
Bacteriocins are a huge family of ribosomally synthesized peptides known to exhibit a range of bioactivities, most predominantly antibacterial activities. Bacteriocins from lactic acid bacteria are of particular interest due to the latter's association to food fermentation and the general notion of them to be safe. Among the family of bacteriocins, the groups known as circular bacteriocins and leaderless bacteriocins are gaining more attention due to their enormous potential for industrial application. Circular bacteriocins and leaderless bacteriocins, arguably the least understood groups of bacteriocins, possess distinctively peculiar characteristics in their structures and biosynthetic mechanisms. Circular bacteriocins have N-to-C- terminal covalent linkage forming a structurally distinct circular peptide backbone. The circular nature of their structures provides them superior stability against various stresses compared to most linear bacteriocins. The molecular mechanism of their biosynthesis, albeit has remained poorly understood, is believed to possesses huge application prospect as it can serve as scaffold in bioengineering other biologically important peptides. On the other hand, while most bacteriocins are synthesized as inactive precursor peptides, which possess an N-terminal leader peptide attached to a C-terminal propeptide, leaderless bacteriocins are atypical as they do not have an N-terminal leader peptide, hence the name. Leaderless bacteriocins are active right after translation as they do not undergo any post-translational processing common to other groups of bacteriocins. This "simplicity" in the biosynthesis of leaderless bacteriocins offers a huge commercial potential as scale-up production systems are considerably easier to assemble. In this review, we summarize the current studies of both circular and leaderless bacteriocins, highlighting the progress in understanding their biosynthesis, mode of action, application and their prospects.
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Affiliation(s)
- Rodney H Perez
- Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School, Kyushu University, Fukuoka, Japan.,National Institute of Molecular Biology and Biotechnology, University of the Philippines Los Baños, Los Baños, Philippines
| | - Takeshi Zendo
- Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School, Kyushu University, Fukuoka, Japan
| | - Kenji Sonomoto
- Department of Bioscience and Biotechnology, Faculty of Agriculture, Graduate School, Kyushu University, Fukuoka, Japan
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24
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Gebai A, Gorelik A, Nagar B. Crystal structure of saposin D in an open conformation. J Struct Biol 2018; 204:145-150. [PMID: 30026085 DOI: 10.1016/j.jsb.2018.07.011] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2018] [Revised: 07/10/2018] [Accepted: 07/16/2018] [Indexed: 11/30/2022]
Abstract
Saposins are accessory proteins that aid in the degradation of sphingolipids by hydrolytic enzymes. Their structure usually comprises four α-helices arranged in various conformations including an open, V-shaped form that is generally associated with the ability to interact with membranes and/or enzymes to accentuate activity. Saposin D is required by the lysosomal hydrolase, acid ceramidase, which breaks down ceramide into sphingosine and free fatty acid, to display optimal activity. The structure of saposin D was previously determined in an inactive conformation, revealing a monomeric, closed and compact form. Here, we present the crystal structure of the open, V-shaped form of saposin D. The overall shape is similar to the open conformation found in other saposins with slight differences in the angles between the α-helices. The structure forms a dimer that serves to stabilize the hydrophobic surface exposed in the open form, which results in an internal, hydrophobic cavity that could be used to carry extracted membrane lipids.
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Affiliation(s)
- Ahmad Gebai
- Department of Biochemistry and Groupe de Recherche Axé sur la Structure des Protéines, McGill University, Montreal, QC H3G 0B1, Canada
| | - Alexei Gorelik
- Department of Biochemistry and Groupe de Recherche Axé sur la Structure des Protéines, McGill University, Montreal, QC H3G 0B1, Canada
| | - Bhushan Nagar
- Department of Biochemistry and Groupe de Recherche Axé sur la Structure des Protéines, McGill University, Montreal, QC H3G 0B1, Canada.
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25
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Teyton L. Role of lipid transfer proteins in loading CD1 antigen-presenting molecules. J Lipid Res 2018; 59:1367-1373. [PMID: 29559523 PMCID: PMC6071766 DOI: 10.1194/jlr.r083212] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2018] [Revised: 03/18/2018] [Indexed: 11/20/2022] Open
Abstract
Research to connect lipids with immunology is growing, but details about the specific roles of lipid transfer proteins (LTPs) in antigen presentation remain unclear. A single class of major histocompatibility class-like molecules, called CD1 molecules, can present lipids and glycolipids to the immune system. These molecules all have a common hydrophobic antigen-binding groove. The loading of this groove with various lipids throughout the life of a CD1 molecule defines the immune recognition of lipids by T cells. At each location of residence, CD1 molecules are exposed to particular physicochemical conditions, particular collections of lipids, and unique combinations of LTPs that will define which lipids bind to CD1 and which do not. The lipid transfer machinery that is used by CD1 molecules is entirely hijacked from the normal synthetic and catalytic pathways of lipids. The precise determinants that regulate the presentation of certain lipids over others with respect to chemistry, solubility, and abundance are still poorly defined and require investigation to allow the use of lipids as regular antigenic targets of immunotherapy and vaccine.
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Affiliation(s)
- Luc Teyton
- Department of Immunology and Microbiology, Scripps Research Institute, La Jolla, CA 92037
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26
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Garrido-Arandia M, Cuevas-Zuviría B, Díaz-Perales A, Pacios LF. A Comparative Study of Human Saposins. Molecules 2018; 23:molecules23020422. [PMID: 29443946 PMCID: PMC6017893 DOI: 10.3390/molecules23020422] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2018] [Revised: 02/12/2018] [Accepted: 02/13/2018] [Indexed: 12/02/2022] Open
Abstract
Saposins are small proteins implicated in trafficking and loading of lipids onto Cluster of Differentiation 1 (CD1) receptor proteins that in turn present lipid antigens to T cells and a variety of T-cell receptors, thus playing a crucial role in innate and adaptive immune responses in humans. Despite their low sequence identity, the four types of human saposins share a similar folding pattern consisting of four helices linked by three conserved disulfide bridges. However, their lipid-binding abilities as well as their activities in extracting, transporting and loading onto CD1 molecules a variety of sphingo- and phospholipids in biological membranes display two striking characteristics: a strong pH-dependence and a structural change between a compact, closed conformation and an open conformation. In this work, we present a comparative computational study of structural, electrostatic, and dynamic features of human saposins based upon their available experimental structures. By means of structural alignments, surface analyses, calculation of pH-dependent protonation states, Poisson-Boltzmann electrostatic potentials, and molecular dynamics simulations at three pH values representative of biological media where saposins fulfill their function, our results shed light into their intrinsic features. The similarities and differences in this class of proteins depend on tiny variations of local structural details that allow saposins to be key players in triggering responses in the human immune system.
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MESH Headings
- Amino Acid Sequence
- Antigens, CD/chemistry
- Antigens, CD/immunology
- Antigens, CD1/chemistry
- Antigens, CD1/immunology
- Cell Membrane/chemistry
- Cell Membrane/immunology
- Humans
- Immunity, Innate
- Lipids/chemistry
- Lipids/immunology
- Molecular Dynamics Simulation
- Phospholipids/chemistry
- Phospholipids/immunology
- Protein Binding/immunology
- Protein Structure, Secondary
- Receptors, Antigen, T-Cell/chemistry
- Receptors, Antigen, T-Cell/immunology
- Saposins/chemistry
- Saposins/immunology
- T-Lymphocytes/immunology
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Affiliation(s)
- María Garrido-Arandia
- Centro de Biotecnología y Genómica de Plantas (CBGP, UPM-INIA), Campus de Montegancedo-UPM, 28223 Madrid, Spain.
| | - Bruno Cuevas-Zuviría
- Centro de Biotecnología y Genómica de Plantas (CBGP, UPM-INIA), Campus de Montegancedo-UPM, 28223 Madrid, Spain.
| | - Araceli Díaz-Perales
- Centro de Biotecnología y Genómica de Plantas (CBGP, UPM-INIA), Campus de Montegancedo-UPM, 28223 Madrid, Spain.
- Departamento de Biotecnología-Biología Vegetal, ETSIAAB, Universidad Politécnica de Madrid (UPM), Ciudad Universitaria, 28040 Madrid, Spain.
| | - Luis F Pacios
- Centro de Biotecnología y Genómica de Plantas (CBGP, UPM-INIA), Campus de Montegancedo-UPM, 28223 Madrid, Spain.
- Departamento de Biotecnología-Biología Vegetal, ETSIAAB, Universidad Politécnica de Madrid (UPM), Ciudad Universitaria, 28040 Madrid, Spain.
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Hill CH, Cook GM, Spratley SJ, Fawke S, Graham SC, Deane JE. The mechanism of glycosphingolipid degradation revealed by a GALC-SapA complex structure. Nat Commun 2018; 9:151. [PMID: 29323104 PMCID: PMC5764952 DOI: 10.1038/s41467-017-02361-y] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2017] [Accepted: 11/23/2017] [Indexed: 11/10/2022] Open
Abstract
Sphingolipids are essential components of cellular membranes and defects in their synthesis or degradation cause severe human diseases. The efficient degradation of sphingolipids in the lysosome requires lipid-binding saposin proteins and hydrolytic enzymes. The glycosphingolipid galactocerebroside is the primary lipid component of the myelin sheath and is degraded by the hydrolase β-galactocerebrosidase (GALC). This enzyme requires the saposin SapA for lipid processing and defects in either of these proteins causes a severe neurodegenerative disorder, Krabbe disease. Here we present the structure of a glycosphingolipid-processing complex, revealing how SapA and GALC form a heterotetramer with an open channel connecting the enzyme active site to the SapA hydrophobic cavity. This structure defines how a soluble hydrolase can cleave the polar glycosyl headgroups of these essential lipids from their hydrophobic ceramide tails. Furthermore, the molecular details of this interaction provide an illustration for how specificity of saposin binding to hydrolases is encoded.
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Affiliation(s)
- Chris H Hill
- Cambridge Institute for Medical Research, Department of Pathology, University of Cambridge, Cambridge Biomedical Campus, Hills Road, Cambridge, CB2 0XY, UK.,MRC Laboratory of Molecular Biology, Francis Crick Avenue, Cambridge Biomedical Campus, Cambridge, CB2 0QH, UK
| | - Georgia M Cook
- Cambridge Institute for Medical Research, Department of Pathology, University of Cambridge, Cambridge Biomedical Campus, Hills Road, Cambridge, CB2 0XY, UK
| | - Samantha J Spratley
- Cambridge Institute for Medical Research, Department of Pathology, University of Cambridge, Cambridge Biomedical Campus, Hills Road, Cambridge, CB2 0XY, UK.,Antibody Discovery and Protein Engineering, MedImmune, Cambridge, CB21 6GH, UK
| | - Stuart Fawke
- Cambridge Institute for Medical Research, Department of Pathology, University of Cambridge, Cambridge Biomedical Campus, Hills Road, Cambridge, CB2 0XY, UK
| | - Stephen C Graham
- Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge, CB2 1QP, UK
| | - Janet E Deane
- Cambridge Institute for Medical Research, Department of Pathology, University of Cambridge, Cambridge Biomedical Campus, Hills Road, Cambridge, CB2 0XY, UK.
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28
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Bryksa BC, Yada RY. Protein Structure Insights into the Bilayer Interactions of the Saposin-Like Domain of Solanum tuberosum Aspartic Protease. Sci Rep 2017; 7:16911. [PMID: 29208977 PMCID: PMC5717070 DOI: 10.1038/s41598-017-16734-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2017] [Accepted: 11/16/2017] [Indexed: 12/26/2022] Open
Abstract
Many plant aspartic proteases contain a saposin-like domain whose principal functions are intracellular sorting and host defence. Its structure is characterised by helical segments cross-linked by three highly conserved cystines. The present study on the saposin-like domain of Solanum tuberosum aspartic protease revealed that acidification from inactive to active conditions causes dimerisation and a strand-to-helix secondary structure transition independent of bilayer interaction. Bilayer fusion was shown to occur under reducing conditions yielding a faster shift to larger vesicle sizes relative to native conditions, implying that a lower level structural motif might be bilayer-active. Characterisation of peptide sequences based on the domain’s secondary structural regions showed helix-3 to be active (~4% of the full domain’s activity), and mutation of its sole positively charged residue resulted in loss of activity and disordering of structure. Also, the peptides’ respective circular dichroism spectra suggested that native folding within the full domain is dependent on surrounding structure. Overall, the present study reveals that the aspartic protease saposin-like domain active structure is an open saposin fold dimer whose formation is pH-dependent, and that a bilayer-active motif shared among non-saposin membrane-active proteins including certain plant defence proteins is nested within an overall structure essential for native functionality.
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Affiliation(s)
- Brian C Bryksa
- Ontario Agricultural College, University of Guelph, N1G 2W1, Guelph, Ontario, Canada
| | - Rickey Y Yada
- Faculty of Land and Food Systems, University of British Columbia, Vancouver, V6T 1Z4, British Columbia, Canada.
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29
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Abstract
Membrane proteins depend on their natural lipid environment for function, which makes them more difficult to study in isolation. A number of approaches that mimic the lipid bilayer of biological membranes have been described (nanodiscs, SMALPs), enabling novel ways to assay activity and elucidate structures of this important class of proteins. More recently, the use of saposin A, a protein that is involved in lipid transport, to form Salipro (saposin-lipid-protein) complexes was demonstrated for a range of membrane protein targets (Frauenfeld et al., 2016). The method is fast and requires few resources. The saposin-lipid-scaffold adapts to various sizes of transmembrane regions during self-assembly, forming a minimal lipid nanoparticle. This results in the formation of a well-defined membrane protein-lipid complex, which is desirable for structural characterization. Here, we describe a protocol to reconstitute the sarco-endoplasmic reticulum calcium ATPase (SERCA) into Salipro nanoparticles. The complex formation is analyzed using negative stain electron microscopy (EM), allowing to quickly determine an initial structure of the membrane protein and to evaluate sample conditions for structural studies using single-particle cryo-EM in a detergent-free environment.
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30
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Tordesillas L, Cubells-Baeza N, Gómez-Casado C, Berin C, Esteban V, Barcik W, O'Mahony L, Ramirez C, Pacios LF, Garrido-Arandia M, Díaz-Perales A. Mechanisms underlying induction of allergic sensitization by Pru p 3. Clin Exp Allergy 2017; 47:1398-1408. [PMID: 28618148 DOI: 10.1111/cea.12962] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2017] [Revised: 05/17/2017] [Accepted: 06/01/2017] [Indexed: 02/03/2023]
Abstract
BACKGROUND Recently, the nature of the lipid-ligand of Pru p 3, one of the most common plant food allergens in southern Europe, has been identified as a derivative of the alkaloid camptothecin bound to phytosphingosine. However, the origin of its immunological activity is still unknown. OBJECTIVE We sought to evaluate the role of the Pru p 3 lipid-ligand in the immunogenic activity of Pru p 3. METHODS In vitro cultures of different cell types (monocyte-derived dendritic cells [moDCs], PBMCs [peripheral blood mononuclear cells] and epithelial and iNKT-hybridoma cell lines) have been used to determine the immunological capacity of the ligand, by measuring cell proliferation, maturation markers and cytokine production. To study the capacity of the lipid-ligand to promote sensitization to Pru p 3 in vivo, a mouse model of anaphylaxis to peach has been produced and changes in the humoral and basophil responses have been analysed. RESULTS The lipid-ligand of Pru p 3 induced maturation of moDCsc and proliferation of PBMCs. Its immunological activity resided in the phytosphingosine tail of the ligand. The adjuvant activity of the ligand was also confirmed in vivo, where the complex of Pru p 3-ligand induced higher levels of IgE than Pru p 3 alone. The immunological capacity of the Pru p 3 ligand was mediated by CD1d, as maturation of moDCs was inhibited by anti-CD1d antibodies and Pru p 3-ligand co-localized with CD1d on epithelial cells. Finally, Pru p 3-ligand presented by CD1d was able to interact with iNKTs. CONCLUSIONS AND CLINICAL RELEVANCE The Pru p 3 lipid-ligand could act as an adjuvant to promote sensitization to Pru p 3, through its recognition by CD1d receptors. This intrinsic adjuvant activity of the accompanying lipid cargo could be a general essential feature of the mechanism underlying the phenomenon of allergenicity.
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Affiliation(s)
- L Tordesillas
- Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - N Cubells-Baeza
- Centre for Plant Genomics and Biotechnology (UPM-INIA), Pozuelo de Alarcon, Madrid, Spain
| | - C Gómez-Casado
- Institute of Applied Molecular Medicine (IMMA), CEU San Pablo University, Boadilla del Monte, Spain
| | - C Berin
- Icahn School of Medicine at Mount Sinai, New York, NY, USA
| | - V Esteban
- Fundacion Jimenez Díaz, Madrid, Spain
| | - W Barcik
- Swiss Institute of Allergy and Asthma Research (SIAF), University of Zurich, Davos, Switzerland
| | - L O'Mahony
- Swiss Institute of Allergy and Asthma Research (SIAF), University of Zurich, Davos, Switzerland
| | - C Ramirez
- Centre for Plant Genomics and Biotechnology (UPM-INIA), Pozuelo de Alarcon, Madrid, Spain.,Department of Biotechnology and Plant Biology, ETSI Agronómica, Alimentaria y de Biosistemas, Technical University of Madrid, Madrid, Spain
| | - L F Pacios
- Centre for Plant Genomics and Biotechnology (UPM-INIA), Pozuelo de Alarcon, Madrid, Spain.,Department of Natural Systems and Resources, ETSI Montes, Technical University of Madrid, Madrid, Spain
| | - M Garrido-Arandia
- Centre for Plant Genomics and Biotechnology (UPM-INIA), Pozuelo de Alarcon, Madrid, Spain
| | - A Díaz-Perales
- Centre for Plant Genomics and Biotechnology (UPM-INIA), Pozuelo de Alarcon, Madrid, Spain.,Department of Biotechnology and Plant Biology, ETSI Agronómica, Alimentaria y de Biosistemas, Technical University of Madrid, Madrid, Spain
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31
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Sellin J, Schulze H, Paradis M, Gosejacob D, Papan C, Shevchenko A, Psathaki OE, Paululat A, Thielisch M, Sandhoff K, Hoch M. Characterization of Drosophila Saposin-related mutants as a model for lysosomal sphingolipid storage diseases. Dis Model Mech 2017; 10:737-750. [PMID: 28389479 PMCID: PMC5483003 DOI: 10.1242/dmm.027953] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2016] [Accepted: 04/04/2017] [Indexed: 11/20/2022] Open
Abstract
Sphingolipidoses are inherited diseases belonging to the class of lysosomal storage diseases (LSDs), which are characterized by the accumulation of indigestible material in the lysosome caused by specific defects in the lysosomal degradation machinery. While some LSDs can be efficiently treated by enzyme replacement therapy (ERT), this is not possible if the nervous system is affected due to the presence of the blood-brain barrier. Sphingolipidoses in particular often present as severe, untreatable forms of LSDs with massive sphingolipid and membrane accumulation in lysosomes, neurodegeneration and very short life expectancy. The digestion of intralumenal membranes within lysosomes is facilitated by lysosomal sphingolipid activator proteins (saposins), which are cleaved from a prosaposin precursor. Prosaposin mutations cause some of the severest forms of sphingolipidoses, and are associated with perinatal lethality in mice, hampering studies on disease progression. We identify the Drosophila prosaposin orthologue Saposin-related (Sap-r) as a key regulator of lysosomal lipid homeostasis in the fly. Its mutation leads to a typical spingolipidosis phenotype with an enlarged endolysosomal compartment and sphingolipid accumulation as shown by mass spectrometry and thin layer chromatography. Sap-r mutants show reduced viability with ∼50% survival to adulthood, allowing us to study progressive neurodegeneration and analyze their lipid profile in young and aged flies. Additionally, we observe a defect in sterol homeostasis with local sterol depletion at the plasma membrane. Furthermore, we find that autophagy is increased, resulting in the accumulation of mitochondria in lysosomes, concomitant with increased oxidative stress. Together, we establish Drosophila Sap-r mutants as a lysosomal storage disease model suitable for studying the age-dependent progression of lysosomal dysfunction associated with lipid accumulation and the resulting pathological signaling events.
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Affiliation(s)
- Julia Sellin
- LIMES-Institute, Program Unit Development & Genetics, Laboratory for Molecular Developmental Biology, University of Bonn, Carl-Troll-Strasse 31, 53115 Bonn, Germany
| | - Heike Schulze
- LIMES-Institute, Program Unit Membrane Biology & Lipid Biochemistry, c/o Kekulé Institute of Organic Chemistry and Biochemistry, University of Bonn, Gerhard-Domagk-Strasse 1, 53121 Bonn, Germany
| | - Marie Paradis
- LIMES-Institute, Program Unit Development & Genetics, Laboratory for Molecular Developmental Biology, University of Bonn, Carl-Troll-Strasse 31, 53115 Bonn, Germany
| | - Dominic Gosejacob
- LIMES-Institute, Program Unit Development & Genetics, Laboratory for Molecular Developmental Biology, University of Bonn, Carl-Troll-Strasse 31, 53115 Bonn, Germany
| | - Cyrus Papan
- Max-Planck-Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany
| | - Andrej Shevchenko
- Max-Planck-Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, 01307 Dresden, Germany
| | - Olympia Ekaterina Psathaki
- University of Osnabrück, Department of Zoology and Developmental Biology, Barbarastraße 11, 49076 Osnabrueck, Germany
| | - Achim Paululat
- University of Osnabrück, Biology, EM unit, Barbarastraße 11, 49076 Osnabrueck, Germany
| | - Melanie Thielisch
- LIMES-Institute, Program Unit Development & Genetics, Laboratory for Molecular Developmental Biology, University of Bonn, Carl-Troll-Strasse 31, 53115 Bonn, Germany
| | - Konrad Sandhoff
- LIMES-Institute, Program Unit Membrane Biology & Lipid Biochemistry, c/o Kekulé Institute of Organic Chemistry and Biochemistry, University of Bonn, Gerhard-Domagk-Strasse 1, 53121 Bonn, Germany
| | - Michael Hoch
- LIMES-Institute, Program Unit Development & Genetics, Laboratory for Molecular Developmental Biology, University of Bonn, Carl-Troll-Strasse 31, 53115 Bonn, Germany
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32
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Malinina L, Patel DJ, Brown RE. How α-Helical Motifs Form Functionally Diverse Lipid-Binding Compartments. Annu Rev Biochem 2017; 86:609-636. [PMID: 28375742 DOI: 10.1146/annurev-biochem-061516-044445] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Lipids are produced site-specifically in cells and then distributed nonrandomly among membranes via vesicular and nonvesicular trafficking mechanisms. The latter involves soluble amphitropic proteins extracting specific lipids from source membranes to function as molecular solubilizers that envelope their insoluble cargo before transporting it to destination sites. Lipid-binding and lipid transfer structural motifs range from multi-β-strand barrels, to β-sheet cups and baskets covered by α-helical lids, to multi-α-helical bundles and layers. Here, we focus on how α-helical proteins use amphipathic helical layering and bundling to form modular lipid-binding compartments and discuss the functional consequences. Preformed compartments generally rely on intramolecular disulfide bridging to maintain conformation (e.g., albumins, nonspecific lipid transfer proteins, saposins, nematode polyprotein allergens/antigens). Insights into nonpreformed hydrophobic compartments that expand and adapt to accommodate a lipid occupant are few and provided mostly by the three-layer, α-helical ligand-binding domain of nuclear receptors. The simple but elegant and nearly ubiquitous two-layer, α-helical glycolipid transfer protein (GLTP)-fold now further advances understanding.
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Affiliation(s)
- Lucy Malinina
- The Hormel Institute, University of Minnesota, Austin, Minnesota 55912; ,
| | - Dinshaw J Patel
- Structural Biology Program, Memorial Sloan Kettering Cancer Center, New York, NY 10065;
| | - Rhoderick E Brown
- The Hormel Institute, University of Minnesota, Austin, Minnesota 55912; ,
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33
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Towle KM, Vederas JC. Structural features of many circular and leaderless bacteriocins are similar to those in saposins and saposin-like peptides. MEDCHEMCOMM 2017; 8:276-285. [PMID: 30108744 PMCID: PMC6072434 DOI: 10.1039/c6md00607h] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Accepted: 12/09/2016] [Indexed: 12/14/2022]
Abstract
Bacteriocins are potent antimicrobial peptides that are ribosomally produced and exported by bacteria, presumably to aid elimination of competing microorganisms. Many circular and linear leaderless bacteriocins have a recuring three dimensional structural motif known as a saposin-like fold. Although these bacteriocin sizes and sequences are often quite different, and their mechanisms of action vary, this conserved motif of multiple helices appears critical for activity and may enable peptide-lipid and peptide-receptor interactions in target bacterial cell membranes. Comparisons between electrostatic surfaces and hydrophobic surface maps of different bacteriocins are discussed emphasizing similarities and differences in the context of proposed modes of action.
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Affiliation(s)
- K M Towle
- Department of Chemistry , University of Alberta , Edmonton , Alberta , T6G 2G2 Canada .
| | - J C Vederas
- Department of Chemistry , University of Alberta , Edmonton , Alberta , T6G 2G2 Canada .
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34
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All-atom molecular dynamics simulations of lung surfactant protein B: Structural features of SP-B promote lipid reorganization. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1858:3082-3092. [DOI: 10.1016/j.bbamem.2016.09.018] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2016] [Revised: 08/30/2016] [Accepted: 09/20/2016] [Indexed: 01/07/2023]
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35
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Walther FJ, Gordon LM, Waring AJ. Design of Surfactant Protein B Peptide Mimics Based on the Saposin Fold for Synthetic Lung Surfactants. Biomed Hub 2016; 1. [PMID: 28503550 PMCID: PMC5424708 DOI: 10.1159/000451076] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Surfactant protein (SP)-B is a 79-residue polypeptide crucial for the biophysical and physiological function of endogenous lung surfactant. SP-B is a member of the saposin or saposin-like proteins (SAPLIP) family of proteins that share an overall three-dimensional folding pattern based on secondary structures and disulfide connectivity and exhibit a wide diversity of biological functions. Here, we review the synthesis, molecular biophysics and activity of synthetic analogs of saposin proteins designed to mimic those interactions of the parent proteins with lipids that enhance interfacial activity. Saposin proteins generally interact with target lipids as either monomers or multimers via well-defined amphipathic helices, flexible hinge domains, and insertion sequences. Based on the known 3D-structural motif for the saposin family, we show how bioengineering techniques may be used to develop minimal peptide constructs that maintain desirable structural properties and activities in biomedical applications. One important application is the molecular design, synthesis and activity of Saposin mimics based on the SP-B structure. Synthetic lung surfactants containing active SP-B analogs may be potentially useful in treating diseases of surfactant deficiency or dysfunction including the neonatal respiratory distress syndrome and acute lung injury/acute respiratory distress syndrome.
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Affiliation(s)
- Frans J Walther
- Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA, USA.,Department of Pediatrics, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA
| | - Larry M Gordon
- Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA, USA
| | - Alan J Waring
- Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Torrance, CA, USA.,Department of Medicine, David Geffen School of Medicine, University of California Los Angeles, Los Angeles, CA, USA
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36
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Human acid sphingomyelinase structures provide insight to molecular basis of Niemann-Pick disease. Nat Commun 2016; 7:13082. [PMID: 27725636 PMCID: PMC5062611 DOI: 10.1038/ncomms13082] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Accepted: 09/01/2016] [Indexed: 12/18/2022] Open
Abstract
Acid sphingomyelinase (ASM) hydrolyzes sphingomyelin to ceramide and phosphocholine, essential components of myelin in neurons. Genetic alterations in ASM lead to ASM deficiency (ASMD) and have been linked to Niemann–Pick disease types A and B. Olipudase alfa, a recombinant form of human ASM, is being developed as enzyme replacement therapy to treat the non-neurological manifestations of ASMD. Here we present the human ASM holoenzyme and product bound structures encompassing all of the functional domains. The catalytic domain has a metallophosphatase fold, and two zinc ions and one reaction product phosphocholine are identified in a histidine-rich active site. The structures reveal the underlying catalytic mechanism, in which two zinc ions activate a water molecule for nucleophilic attack of the phosphodiester bond. Docking of sphingomyelin provides a model that allows insight into the selectivity of the enzyme and how the ASM domains collaborate to complete hydrolysis. Mapping of known mutations provides a basic understanding on correlations between enzyme dysfunction and phenotypes observed in ASMD patients. Genetic alterations in the protein acid sphingomyelinase (ASM) lead to ASM deficiency and have been associated with Niemann–Pick disease. Here, the authors report the crystal structures of ASM alone and bound to its product, and discuss the catalytic mechanism and its possible significance for patients with ASM deficiency.
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37
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Xiong ZJ, Huang J, Poda G, Pomès R, Privé GG. Structure of Human Acid Sphingomyelinase Reveals the Role of the Saposin Domain in Activating Substrate Hydrolysis. J Mol Biol 2016; 428:3026-42. [PMID: 27349982 DOI: 10.1016/j.jmb.2016.06.012] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2016] [Revised: 06/14/2016] [Accepted: 06/16/2016] [Indexed: 11/29/2022]
Abstract
Acid sphingomyelinase (ASM) is a lysosomal phosphodiesterase that catalyzes the hydrolysis of sphingomyelin to produce ceramide and phosphocholine. While other lysosomal sphingolipid hydrolases require a saposin activator protein for full activity, the ASM polypeptide incorporates a built-in N-terminal saposin domain and does not require an external activator protein. Here, we report the crystal structure of human ASM and describe the organization of the three main regions of the enzyme: the N-terminal saposin domain, the proline-rich connector, and the catalytic domain. The saposin domain is tightly associated along an edge of the large, bowl-shaped catalytic domain and adopts an open form that exposes a hydrophobic concave surface approximately 30Å from the catalytic center. The calculated electrostatic potential of the enzyme is electropositive at the acidic pH of the lysosome, consistent with the strict requirement for the presence of acidic lipids in target membranes. Docking studies indicate that sphingomyelin binds with the ceramide-phosphate group positioned at the binuclear zinc center and molecular dynamic simulations indicate that the intrinsic flexibility of the saposin domain is important for monomer-dimer exchange and for membrane interactions. Overall, ASM uses a combination of electrostatic and hydrophobic interactions to cause local disruptions of target bilayers in order to bring the lipid headgroup to the catalytic center in a membrane-bound reaction.
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Affiliation(s)
- Zi-Jian Xiong
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Jingjing Huang
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada
| | - Gennady Poda
- Drug Discovery, Ontario Institute for Cancer Research, Toronto, Ontario, Canada; Leslie Dan Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada
| | - Régis Pomès
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada; Molecular Structure and Function, Hospital for Sick Children, Toronto, Ontario, Canada
| | - Gilbert G Privé
- Department of Biochemistry, University of Toronto, Toronto, Ontario, Canada; Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada; Princess Margaret Cancer Centre, Toronto, Ontario, Canada.
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38
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Vadlamudi Y, Muthu K, M. SK. Structural exploration of acid sphingomyelinase at different physiological pH through molecular dynamics and docking studies. RSC Adv 2016. [DOI: 10.1039/c6ra16584b] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Acid sphingomyelinase (ASM) hydrolysis the sphingomyelin at physiological pH 5.0 and subsequently leads to ceramide production.
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Affiliation(s)
| | - Kannan Muthu
- Centre for Bioinformatics
- Pondicherry University
- Pondicherry 605014
- India
| | - Suresh Kumar M.
- Centre for Bioinformatics
- Pondicherry University
- Pondicherry 605014
- India
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39
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Huta BP, Mehlenbacher MR, Nie Y, Lai X, Zubieta C, Bou-Abdallah F, Doyle RP. The Lysosomal Protein Saposin B Binds Chloroquine. ChemMedChem 2015; 11:277-82. [PMID: 26616259 DOI: 10.1002/cmdc.201500494] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2015] [Indexed: 11/09/2022]
Abstract
Chloroquine (CQ) has been widely used in the treatment of malaria since the 1950s, though toxicity and resistance is increasingly limiting its use in the clinic. More recently, CQ is also becoming recognized as an important therapeutic compound for the treatment of autoimmune disorders and has shown activity as an anticancer agent. However, the full extent of CQ pharmacology in humans is still unclear. Herein, we demonstrate that the lysosomal protein saposin B (sapB), critical for select lipid degradation, binds CQ with implications for both CQ function and toxicity. Using isothermal titration calorimetry (ITC) and fluorescence quenching experiments, CQ was shown to bind to the dimeric form of sapB at both pH 5.5 and pH 7.4 with an average binding affinity of 2.3×10(4) m(-1). X-ray crystallography confirmed this, and the first complete crystal structure of sapB with a bound small molecule (CQ) is reported. The results suggest that sapB might play a role in mitigating CQ-based toxicity and that sapB might itself be overwhelmed by CQ causing impaired lipid degradation.
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Affiliation(s)
- Brian P Huta
- Department of Chemistry, Syracuse University, 111 College Place, Syracuse, NY, 13244, USA
| | - Matthew R Mehlenbacher
- Department of Chemistry, State University of New York at Potsdam, Potsdam, NY, 13676, USA
| | - Yan Nie
- Department of Chemistry, Syracuse University, 111 College Place, Syracuse, NY, 13244, USA
| | - Xuelei Lai
- European Synchrotron Radiation Facility, Grenoble, 38054, France
| | - Chloe Zubieta
- Laboratoire de Physiologie Cellulaire & Végétale, iRTSV, UMR 5168, CNRS/CEA/INRA/Univ. Grenoble Alpes, Grenoble, 38054, France.
| | - Fadi Bou-Abdallah
- Department of Chemistry, State University of New York at Potsdam, Potsdam, NY, 13676, USA.
| | - Robert P Doyle
- Department of Chemistry, Syracuse University, 111 College Place, Syracuse, NY, 13244, USA.
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Hill CH, Read RJ, Deane JE. Structure of human saposin A at lysosomal pH. ACTA CRYSTALLOGRAPHICA SECTION F-STRUCTURAL BIOLOGY COMMUNICATIONS 2015; 71:895-900. [PMID: 26144235 PMCID: PMC4498711 DOI: 10.1107/s2053230x15008584] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/06/2015] [Accepted: 05/01/2015] [Indexed: 11/10/2022]
Abstract
The saposins are essential cofactors for the normal lysosomal degradation of complex glycosphingolipids by acid hydrolase enzymes; defects in either saposin or hydrolase function lead to severe metabolic diseases. Saposin A (SapA) activates the enzyme β-galactocerebrosidase (GALC), which catalyzes the breakdown of β-D-galactocerebroside, the principal lipid component of myelin. SapA is known to bind lipids and detergents in a pH-dependent manner; this is accompanied by a striking transition from a `closed' to an `open' conformation. However, previous structures were determined at non-lysosomal pH. This work describes a 1.8 Å resolution X-ray crystal structure determined at the physiologically relevant lysosomal pH 4.8. In the absence of lipid or detergent at pH 4.8, SapA is observeed to adopt a conformation closely resembling the previously determined `closed' conformation, showing that pH alone is not sufficient for the transition to the `open' conformation. Structural alignments reveal small conformational changes, highlighting regions of flexibility.
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Affiliation(s)
- Chris H Hill
- Department of Haematology, Cambridge Institute for Medical Research, University of Cambridge, Wellcome Trust/MRC Building, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, England
| | - Randy J Read
- Department of Haematology, Cambridge Institute for Medical Research, University of Cambridge, Wellcome Trust/MRC Building, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, England
| | - Janet E Deane
- Department of Haematology, Cambridge Institute for Medical Research, University of Cambridge, Wellcome Trust/MRC Building, Cambridge Biomedical Campus, Hills Road, Cambridge CB2 0XY, England
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41
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Olmeda B, García‐Álvarez B, Gómez MJ, Martínez‐Calle M, Cruz A, Pérez‐Gil J. A model for the structure and mechanism of action of pulmonary surfactant protein B. FASEB J 2015; 29:4236-47. [DOI: 10.1096/fj.15-273458] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2015] [Accepted: 06/15/2015] [Indexed: 11/11/2022]
Affiliation(s)
- Bárbara Olmeda
- Departmento de Bioquímica, Facultad de BiologíaUniversidad ComplutenseMadridSpain
| | | | - Manuel J. Gómez
- Centro de Astrobiología (INTA‐CSIC), Torrejón de ArdozMadridSpain
| | - Marta Martínez‐Calle
- Departmento de Bioquímica, Facultad de BiologíaUniversidad ComplutenseMadridSpain
| | - Antonio Cruz
- Departmento de Bioquímica, Facultad de BiologíaUniversidad ComplutenseMadridSpain
| | - Jesús Pérez‐Gil
- Departmento de Bioquímica, Facultad de BiologíaUniversidad ComplutenseMadridSpain
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42
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Michalek M, Leippe M. Mechanistic insights into the lipid interaction of an ancient saposin-like protein. Biochemistry 2015; 54:1778-86. [PMID: 25715682 DOI: 10.1021/acs.biochem.5b00094] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The members of the expanding family of saposin-like proteins (SAPLIPs) have various biological functions in plants, animals, and humans. In addition to a similar protein backbone, these proteins have in common the fact that they interact with lipid membranes. According to their phylogenetic position, it has long been thought that amoeboid protozoans produce archetypes of SAPLIPs and that these are lytic proteins that can perforate membranes of prokaryotic and eukaryotic target cells. Here, we show that an amoebic SAPLIP from Entamoeba invadens does not form lytic pores in membranes but displays several characteristics that are known from human saposins. The protein named invaposin changes the conformation from a closed to an open form in the presence of lipid membranes, acts in a pH-dependent manner, selectively binds anionic lipids, aggregates lipid vesicles of the preferred composition, and dimerizes upon acidification. Our data indicate that the principal features of the lipid-binding saposins evolved long before the appearance of the vertebrate lineage and push the origin of saposins even deeper down the phylogenetic tree to unicellular organisms.
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Affiliation(s)
- Matthias Michalek
- Zoological Institute, Comparative Immunobiology, University of Kiel , Olshausenstrasse 40, 24098 Kiel, Germany
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43
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De Moura DC, Bryksa BC, Yada RY. In silico insights into protein-protein interactions and folding dynamics of the saposin-like domain of Solanum tuberosum aspartic protease. PLoS One 2014; 9:e104315. [PMID: 25188221 PMCID: PMC4154668 DOI: 10.1371/journal.pone.0104315] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2014] [Accepted: 06/09/2014] [Indexed: 12/29/2022] Open
Abstract
The plant-specific insert is an approximately 100-residue domain found exclusively within the C-terminal lobe of some plant aspartic proteases. Structurally, this domain is a member of the saposin-like protein family, and is involved in plant pathogen defense as well as vacuolar targeting of the parent protease molecule. Similar to other members of the saposin-like protein family, most notably saposins A and C, the recently resolved crystal structure of potato (Solanum tuberosum) plant-specific insert has been shown to exist in a substrate-bound open conformation in which the plant-specific insert oligomerizes to form homodimers. In addition to the open structure, a closed conformation also exists having the classic saposin fold of the saposin-like protein family as observed in the crystal structure of barley (Hordeum vulgare L.) plant-specific insert. In the present study, the mechanisms of tertiary and quaternary conformation changes of potato plant-specific insert were investigated in silico as a function of pH. Umbrella sampling and determination of the free energy change of dissociation of the plant-specific insert homodimer revealed that increasing the pH of the system to near physiological levels reduced the free energy barrier to dissociation. Furthermore, principal component analysis was used to characterize conformational changes at both acidic and neutral pH. The results indicated that the plant-specific insert may adopt a tertiary structure similar to the characteristic saposin fold and suggest a potential new structural motif among saposin-like proteins. To our knowledge, this acidified PSI structure presents the first example of an alternative saposin-fold motif for any member of the large and diverse SAPLIP family.
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Affiliation(s)
- Dref C. De Moura
- Biophysics Interdepartmental Group, University of Guelph, Guelph, Ontario, Canada
- Department of Food Science, University of Guelph, Guelph, Ontario, Canada
| | - Brian C. Bryksa
- Department of Food Science, University of Guelph, Guelph, Ontario, Canada
| | - Rickey Y. Yada
- Biophysics Interdepartmental Group, University of Guelph, Guelph, Ontario, Canada
- Department of Food Science, University of Guelph, Guelph, Ontario, Canada
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Kashiba M, Oizumi M, Suzuki M, Sawamura Y, Nagashima K, Yoshimura S, Yamamoto Y. Prosaposin regulates coenzyme Q10 levels in HepG2 cells, especially those in mitochondria. J Clin Biochem Nutr 2014; 55:85-9. [PMID: 25320454 PMCID: PMC4186375 DOI: 10.3164/jcbn.13-106] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Accepted: 04/24/2014] [Indexed: 12/13/2022] Open
Abstract
Coenzyme Q10 (CoQ10) is a key component of the mitochondrial electron transfer chain and is one of the most important cellular antioxidants. We previously reported that glycoprotein saposin B (SapB) binds CoQ10 in human cells. To elucidate the physiological role of SapB and its precursor, prosaposin (Psap), we prepared stable transfectants of HepG2 that overexpress wild-type human Psap (Wt-Tf). We also established a SapB domain mutated Psap (Mt-Tf) in which cysteine(198) was replaced with serine to disrupt three dimensional protein structure by the loss of S-S bridging. Psap knockdown (KD) strains were also examined. Western blotting analysis confirmed overexpression or knockdown of Psap in these HepG2 cells. The cellular ratios of CoQ10 to free cholesterol (FC) significantly decreased in the order of Wt-Tf>parental>Mt-Tf>KD. Additionally, the ratios of CoQ10/FC in mitochondrial fractions decreased in the order of Wt-Tf>parental>KD. These data indicate that Psap and/or SapB regulate CoQ10 levels in HepG2 cells, especially in their mitochondria.
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Affiliation(s)
- Misato Kashiba
- School of Health Sciences, Tokyo University of Technology, 1404-1 Katakura-cho, Hachioji, Tokyo 192-0982, Japan
| | - Mikiko Oizumi
- School of Bioscience and Biotechnology, Tokyo University of Technology, 1404-1 Katakura-cho, Hachioji, Tokyo 192-0982, Japan
| | - Masaru Suzuki
- School of Bioscience and Biotechnology, Tokyo University of Technology, 1404-1 Katakura-cho, Hachioji, Tokyo 192-0982, Japan
| | - Yoshimi Sawamura
- School of Bioscience and Biotechnology, Tokyo University of Technology, 1404-1 Katakura-cho, Hachioji, Tokyo 192-0982, Japan
| | - Kohei Nagashima
- School of Bioscience and Biotechnology, Tokyo University of Technology, 1404-1 Katakura-cho, Hachioji, Tokyo 192-0982, Japan
| | - Shinichi Yoshimura
- School of Bioscience and Biotechnology, Tokyo University of Technology, 1404-1 Katakura-cho, Hachioji, Tokyo 192-0982, Japan
| | - Yorihiro Yamamoto
- School of Bioscience and Biotechnology, Tokyo University of Technology, 1404-1 Katakura-cho, Hachioji, Tokyo 192-0982, Japan
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Catena R, Bhattacharya N, El Rayes T, Wang S, Choi H, Gao D, Ryu S, Joshi N, Bielenberg D, Lee SB, Haukaas SA, Gravdal K, Halvorsen OJ, Akslen LA, Watnick RS, Mittal V. Bone marrow-derived Gr1+ cells can generate a metastasis-resistant microenvironment via induced secretion of thrombospondin-1. Cancer Discov 2013; 3:578-89. [PMID: 23633432 DOI: 10.1158/2159-8290.cd-12-0476] [Citation(s) in RCA: 98] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
UNLABELLED Metastatic tumors have been shown to establish permissive microenvironments for metastases via recruitment of bone marrow-derived cells. Here, we show that metastasis-incompetent tumors are also capable of generating such microenvironments. However, in these situations, the otherwise prometastatic Gr1(+) myeloid cells create a metastasis-refractory microenvironment via the induction of thrombospondin-1 (Tsp-1) by tumor-secreted prosaposin. Bone marrow-specific genetic deletion of Tsp-1 abolished the inhibition of metastasis, which was restored by bone marrow transplant from Tsp-1(+) donors. We also developed a 5-amino acid peptide from prosaposin as a pharmacologic inducer of Tsp-1 in Gr1(+) bone marrow cells, which dramatically suppressed metastasis. These results provide mechanistic insights into why certain tumors are deficient in metastatic potential and implicate recruited Gr1(+) myeloid cells as the main source of Tsp-1. The results underscore the plasticity of Gr1(+) cells, which, depending on the context, promote or inhibit metastasis, and suggest that the peptide could be a potential therapeutic agent against metastatic cancer. SIGNIFICANCE The mechanisms of metastasis suppression are poorly understood. Here, we have identified a novel mechanism whereby metastasis-incompetent tumors generate metastasis-suppressive microenvironments in distant organs by inducing Tsp-1 expression in the bone marrow–derived Gr1+myeloid cells. A 5-amino acid peptide with Tsp-1–inducing activity was identified as a therapeutic agent against metastatic cancer.
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Affiliation(s)
- Raúl Catena
- Department of Cardiothoracic Surgery, College of Cornell University, New York, NY, USA
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Olmeda B, García-Álvarez B, Pérez-Gil J. Structure–function correlations of pulmonary surfactant protein SP-B and the saposin-like family of proteins. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2012; 42:209-22. [DOI: 10.1007/s00249-012-0858-9] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2012] [Revised: 08/18/2012] [Accepted: 09/03/2012] [Indexed: 02/06/2023]
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47
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Topology and lipid selectivity of pulmonary surfactant protein SP-B in membranes: Answers from fluorescence. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2012; 1818:1717-25. [DOI: 10.1016/j.bbamem.2012.03.008] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2012] [Revised: 03/12/2012] [Accepted: 03/13/2012] [Indexed: 01/13/2023]
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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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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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50
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Insights into Krabbe disease from structures of galactocerebrosidase. Proc Natl Acad Sci U S A 2011; 108:15169-73. [PMID: 21876145 DOI: 10.1073/pnas.1105639108] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Krabbe disease is a devastating neurodegenerative disease characterized by widespread demyelination that is caused by defects in the enzyme galactocerebrosidase (GALC). Disease-causing mutations have been identified throughout the GALC gene. However, a molecular understanding of the effect of these mutations has been hampered by the lack of structural data for this enzyme. Here we present the crystal structures of GALC and the GALC-product complex, revealing a novel domain architecture with a previously uncharacterized lectin domain not observed in other hydrolases. All three domains of GALC contribute residues to the substrate-binding pocket, and disease-causing mutations are widely distributed throughout the protein. Our structures provide an essential insight into the diverse effects of pathogenic mutations on GALC function in human Krabbe variants and a compelling explanation for the severity of many mutations associated with fatal infantile disease. The localization of disease-associated mutations in the structure of GALC will facilitate identification of those patients that would be responsive to pharmacological chaperone therapies. Furthermore, our structure provides the atomic framework for the design of such drugs.
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