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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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An Overview of Molecular Mechanisms in Fabry Disease. Biomolecules 2022; 12:biom12101460. [PMID: 36291669 PMCID: PMC9599883 DOI: 10.3390/biom12101460] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2022] [Revised: 10/09/2022] [Accepted: 10/11/2022] [Indexed: 12/24/2022] Open
Abstract
Fabry disease (FD) (OMIM #301500) is a rare genetic lysosomal storage disorder (LSD). LSDs are characterized by inappropriate lipid accumulation in lysosomes due to specific enzyme deficiencies. In FD, the defective enzyme is α-galactosidase A (α-Gal A), which is due to a mutation in the GLA gene on the X chromosome. The enzyme deficiency leads to a continuous deposition of neutral glycosphingolipids (globotriaosylceramide) in the lysosomes of numerous tissues and organs, including endothelial cells, smooth muscle cells, corneal epithelial cells, renal glomeruli and tubules, cardiac muscle and ganglion cells of the nervous system. This condition leads to progressive organ failure and premature death. The increasing understanding of FD, and LSD in general, has led in recent years to the introduction of enzyme replacement therapy (ERT), which aims to slow, if not halt, the progression of the metabolic disorder. In this review, we provide an overview of the main features of FD, focusing on its molecular mechanism and the role of biomarkers.
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Maruyama H, Taguchi A, Mikame M, Izawa A, Morito N, Izaki K, Seto T, Onishi A, Sugiyama H, Sakai N, Yamabe K, Yokoyama Y, Yamashita S, Satoh H, Toyoda S, Hosojima M, Ito Y, Tazawa R, Ishii S. Plasma Globotriaosylsphingosine and α-Galactosidase A Activity as a Combined Screening Biomarker for Fabry Disease in a Large Japanese Cohort. Curr Issues Mol Biol 2021; 43:389-404. [PMID: 34205365 PMCID: PMC8928976 DOI: 10.3390/cimb43010032] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2021] [Revised: 06/15/2021] [Accepted: 06/16/2021] [Indexed: 11/23/2022] Open
Abstract
Fabry disease is an X-linked disorder of α-galactosidase A (GLA) deficiency. Our previous interim analysis (1 July 2014 to 31 December 2015) revealed plasma globotriaosylsphingosine as a promising primary screening biomarker for Fabry disease probands. Herein, we report the final results, including patients enrolled from 1 January to 31 December 2016 for evaluating the potential of plasma globotriaosylsphingosine and GLA activity as a combined screening marker. We screened 5691 patients (3439 males) referred from 237 Japanese specialty clinics based on clinical findings suggestive of Fabry disease using plasma globotriaosylsphingosine and GLA activity as primary screening markers, and GLA variant status as a secondary screening marker. Of the 14 males who tested positive in the globotriaosylsphingosine screen (≥2.0 ng/mL), 11 with low GLA activity (<4.0 nmol/h/mL) displayed GLA variants (four classic, seven late-onset) and one with normal GLA activity and no pathogenic variant displayed lamellar bodies in affected organs, indicating late-onset biopsy-proven Fabry disease. Of the 19 females who tested positive in the globotriaosylsphingosine screen, eight with low GLA activity displayed GLA variants (six classic, two late-onset) and five with normal GLA activity displayed a GLA variant (one classic) and no pathogenic variant (four late-onset biopsy-proven). The combination of plasma globotriaosylsphingosine and GLA activity can be a primary screening biomarker for classic, late-onset, and late-onset biopsy-proven Fabry disease probands.
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Affiliation(s)
- Hiroki Maruyama
- Department of Clinical Nephroscience, Niigata University Graduate School of Medical and Dental Sciences, Niigata 951-8510, Japan; (A.T.); (M.M.)
- Correspondence: ; Tel.: +81-25-227-0436
| | - Atsumi Taguchi
- Department of Clinical Nephroscience, Niigata University Graduate School of Medical and Dental Sciences, Niigata 951-8510, Japan; (A.T.); (M.M.)
| | - Mariko Mikame
- Department of Clinical Nephroscience, Niigata University Graduate School of Medical and Dental Sciences, Niigata 951-8510, Japan; (A.T.); (M.M.)
| | - Atsushi Izawa
- School of Health Sciences, Shinshu University, Matsumoto 390-8621, Japan;
| | - Naoki Morito
- Department of Nephrology, Faculty of Medicine, University of Tsukuba, Tsukuba 305-8575, Japan;
| | - Kazufumi Izaki
- Department of Pediatrics, Yao Municipal Hospital, Yao 581-0069, Japan;
| | - Toshiyuki Seto
- Department of Medical Genetics, Osaka City University Graduate School of Medicine, Osaka 545-8585, Japan;
| | - Akifumi Onishi
- Department of Internal Medicine, Fukuyama City Hospital, Fukuyama 721-8511, Japan;
| | - Hitoshi Sugiyama
- Department of Human Resource Development of Dialysis Therapy for Kidney Disease, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Science, Okayama 700-8558, Japan;
| | - Norio Sakai
- Child Healthcare and Genetic Science Laboratory, Division of Health Sciences, Osaka University Graduate School of Medicine, Suita 565-0871, Japan;
| | - Kenji Yamabe
- Department of Cardiology, Toyooka Hospital, Toyooka 668-8501, Japan;
| | - Yukio Yokoyama
- Division of Nephrology, Hiroshima Red Cross Hospital & Atomic-bomb Survivors Hospital, Hiroshima 730-8619, Japan;
| | - Satoshi Yamashita
- Department of Cardiology, Hamamatsu University School of Medicine, Hamamatsu 431-3192, Japan;
| | - Hiroshi Satoh
- Department of Cardiology, Fujinomiya City Hospital, Fujinomiya 418-0076, Japan;
| | - Shigeru Toyoda
- Department of Cardiovascular Medicine, Dokkyo Medical University, Mibu 321-0293, Japan;
| | - Michihiro Hosojima
- Department of Clinical Nutrition Science, Kidney Research Center, Niigata University Graduate School of Medical and Dental Sciences, Niigata 951-8510, Japan;
| | - Yumi Ito
- Department of Health Promotion Medicine, Niigata University Graduate School of Medical and Dental Sciences, Niigata 951-8510, Japan;
| | - Ryushi Tazawa
- Health Administration Center, Student Support and Health Administration Organization, Tokyo Medical and Dental University, Bunkyo-ku 113-8510, Japan;
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Kang TS, Stevens RC. Structural aspects of therapeutic enzymes to treat metabolic disorders. Hum Mutat 2010; 30:1591-610. [PMID: 19790257 DOI: 10.1002/humu.21111] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Protein therapeutics represents a niche subset of pharmacological agents that is rapidly gaining importance in medicine. In addition to the exceptional specificity that is characteristic of protein therapeutics, several classes of proteins have also been effectively utilized for treatment of conditions that would otherwise lack effective pharmacotherapeutic options. A particularly striking class of protein therapeutics is exogenous enzymes administered for replacement therapy in patients afflicted with metabolic disorders. To date, at least 11 enzymes have either been approved for use, or are in clinical trials for the treatment of selected inherited metabolic disorders. With the recent advancement in structural biology, a significantly larger amount of structural information for several of these enzymes is now available. This article is an overview of the correlation between structural perturbations of these enzymes with the clinical presentation of the respective metabolic conditions, as well as a discussion of the relevant structural modification strategies engaged in improving these enzymes for replacement therapies.
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Affiliation(s)
- Tse Siang Kang
- Department of Molecular Biology, The Scripps Research Institute, La Jolla, California 92037, USA
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Zhou D, Cantu C, Sagiv Y, Schrantz N, Kulkarni AB, Qi X, Mahuran DJ, Morales CR, Grabowski GA, Benlagha K, Savage P, Bendelac A, Teyton L. Editing of CD1d-bound lipid antigens by endosomal lipid transfer proteins. Science 2004; 303:523-7. [PMID: 14684827 PMCID: PMC2918537 DOI: 10.1126/science.1092009] [Citation(s) in RCA: 257] [Impact Index Per Article: 12.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
It is now established that CD1 molecules present lipid antigens to T cells, although it is not clear how the exchange of lipids between membrane compartments and the CD1 binding groove is assisted. We report that mice deficient in prosaposin, the precursor to a family of endosomal lipid transfer proteins (LTP), exhibit specific defects in CD1d-mediated antigen presentation and lack Valpha14 NKT cells. In vitro, saposins extracted monomeric lipids from membranes and from CD1, thereby promoting the loading as well as the editing of lipids on CD1. Transient complexes between CD1, lipid, and LTP suggested a "tug-of-war" model in which lipid exchange between CD1 and LTP is on the basis of their respective affinities for lipids. LTPs constitute a previously unknown link between lipid metabolism and immunity and are likely to exert a profound influence on the repertoire of self, tumor, and microbial lipid antigens.
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Affiliation(s)
- Dapeng Zhou
- Department of Pathology, University of Chicago, Chicago, IL 60637, USA
| | - Carlos Cantu
- Department of Immunology, Scripps Research Institute, La Jolla, CA 92037, USA
| | - Yuval Sagiv
- Department of Pathology, University of Chicago, Chicago, IL 60637, USA
| | - Nicolas Schrantz
- Department of Immunology, Scripps Research Institute, La Jolla, CA 92037, USA
| | - Ashok B. Kulkarni
- National Institute of Dental and Craniofacial Research, National Institutes of Health, Bethesda, MD 20892, USA
| | - Xiaoyang Qi
- Children Hospital Medical Center, Cincinnati, OH 45229–3039, USA
| | - Don J. Mahuran
- Department of Medicine and Pathobiology, University of Toronto, Toronto, ON M5G 1X8, Canada
| | - Carlos R. Morales
- Department of Anatomy and Cell Biology, McGill University, Montreal, QC H3A 2B2, Canada
| | | | - Kamel Benlagha
- Department of Pathology, University of Chicago, Chicago, IL 60637, USA
| | - Paul Savage
- Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT 84602–5700, USA
| | - Albert Bendelac
- Department of Pathology, University of Chicago, Chicago, IL 60637, USA
| | - Luc Teyton
- Department of Immunology, Scripps Research Institute, La Jolla, CA 92037, USA
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Kase R, Bierfreund U, Klein A, Kolter T, Utsumi K, Itoha K, Sandhoff K, Sakuraba H. Characterization of two alpha-galactosidase mutants (Q279E and R301Q) found in an atypical variant of Fabry disease. BIOCHIMICA ET BIOPHYSICA ACTA 2000; 1501:227-35. [PMID: 10838196 DOI: 10.1016/s0925-4439(00)00024-7] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
The mutant products Q279E ((279)Gln to Glu) and R301Q ((301)Arg to Gln) of the X-chromosomal inherited alpha-galactosidase (EC 3.2.1. 22) gene, found in unrelated male patients with variant Fabry disease (late-onset cardiac form) were characterized. In contrast to patients with classic Fabry disease, who have no detectable alpha-galactosidase activity, atypical variants have residual enzyme activity. First, the properties of insect cell-derived recombinant enzymes were studied. The K(m) and V(max) values of Q279E, R301Q, and wild-type alpha-galactosidase toward an artificial substrate, 4-methylumbelliferyl-alpha-D-galactopyranoside, were almost the same. In order to mimic intralysosomal conditions, the degradation of the natural substrate, globotriaosylceramide, by the alpha-galactosidases was analyzed in a detergent-free-liposomal system, in the presence of sphingolipid activator protein B (SAP-B, saposin B). Kinetic analysis revealed that there was no difference in the degradative activity between the mutants and wild-type alpha-galactosidase activity toward the natural substrate. Then, immunotitration studies were carried out to determine the amounts of the mutant gene products naturally occurring in cells. Cultured lymphoblasts, L-57 (Q279E) and L-148 (R301Q), from patients with variant Fabry disease, and L-20 (wild-type) from a normal subject were used. The 50% precipitation doses were 7% (L-57) and 10% (L-148) of that for normal lymphoblast L-20, respectively. The residual alpha-galactosidase activity was 3 and 5% of the normal level in L-57 and L-148, respectively. The quantities of immuno cross-reacting materials roughly correlated with the residual alpha-galactosidase activities in lymphoblast cells from the patients. Compared to normal control cells, fibroblast cells from a patient with variant Fabry disease, Q279E mutation, secreted only small amounts of alpha-galactosidase activity even in the presence of 10 mM NH(4)Cl. It is concluded that Q279E and R301Q substitutions do not significantly affect the enzymatic activity, but the mutant protein levels are decreased presumably in the ER of the cells.
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Affiliation(s)
- R Kase
- Department of Clinical Genetics, the Tokyo Metropolitan Institute of Medical Science, Tokyo Metropolitan Organization for Medical Research, Japan.
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Affiliation(s)
- U Bierfreund
- Kekulé-Institut für Organische Chemie und Biochemie, Universität Bonn, Germany
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Harzer K, Paton BC, Christomanou H, Chatelut M, Levade T, Hiraiwa M, O'Brien JS. Saposins (sap) A and C activate the degradation of galactosylceramide in living cells. FEBS Lett 1997; 417:270-4. [PMID: 9409731 DOI: 10.1016/s0014-5793(97)01302-1] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
In loading tests using galactosylceramide which had been labelled with tritium in the ceramide moiety, living skin fibroblast lines derived from the original prosaposin-deficient patients had a markedly reduced capacity to degrade galactosylceramide. The hydrolysis of galactosylceramide could be partially restored in these cells, up to about half the normal rate, by adding pure saposin A, pure saposin C, or a mixture of these saposins to the culture medium. By contrast, saposins B and D had little effect on galactosylceramide hydrolysis in the prosaposin-deficient cells. Cells from beta-galactocerebrosidase-deficient (Krabbe) patients had a relatively high residual galactosylceramide degradation, which was similar to the rate observed for prosaposin-deficient cells in the presence of saposin A or C. An SV40-transformed fibroblast line from the original saposin C-deficient patient, where saposin A is not affected, showed normal degradation of galactosylceramide. The findings support the hypothesis, which was deduced originally from in vitro experiments, that saposins A and C are the in vivo activators of galactosylceramide degradation. Although the results with saposin C-deficient fibroblasts suggest that the presence of only saposin A allows galactosylceramide breakdown to proceed at a normal rate in fibroblasts, it remains to be determined whether saposins A and C can substitute for each other with respect to their effects on galactosylceramide metabolism in the whole organism.
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Affiliation(s)
- K Harzer
- Institut für Hirnforschung, Universität Tübingen, Germany
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