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Sica MP, Kortsarz MV, Morillas AA, Smulski CR. Protocol to study the oligomeric organization of single-span transmembrane peptides using molecular dynamics simulations. STAR Protoc 2022; 3:101636. [PMID: 36042876 PMCID: PMC9420530 DOI: 10.1016/j.xpro.2022.101636] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Herein, you will find detailed information for the preparation of a coarse-grained array of peptides embedded in a lipid membrane. It contains all the steps to set up and run a molecular dynamic simulation using a coarse-grained approach. We provide analytical tools and scripts for generating a residue-level contact matrix between multiple peptides, as well as geometric analysis of arrangements between multiple peptides. This protocol was designed to study the organization of transmembrane peptides in an unbiased manner using computational approaches. For complete details on the use and execution of this protocol, please refer to Smulski et al. (2022). Protocol to study the oligomeric organization of single-span transmembrane peptides Step-by-step preparation of a coarse-grained array of peptides in a lipid membrane Steps for set up and running molecular dynamic simulation using a coarse-grained approach Tools and scripts for data analysis, contact matrix, and relative orientations
Publisher’s note: Undertaking any experimental protocol requires adherence to local institutional guidelines for laboratory safety and ethics.
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Smulski CR, Zhang L, Burek M, Teixidó Rubio A, Briem JS, Sica MP, Sevdali E, Vigolo M, Willen L, Odermatt P, Istanbullu D, Herr S, Cavallari M, Hess H, Rizzi M, Eibel H, Schneider P. Ligand-independent oligomerization of TACI is controlled by the transmembrane domain and regulates proliferation of activated B cells. Cell Rep 2022; 38:110583. [PMID: 35354034 DOI: 10.1016/j.celrep.2022.110583] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2021] [Revised: 11/03/2021] [Accepted: 03/07/2022] [Indexed: 12/23/2022] Open
Abstract
In mature B cells, TACI controls class-switch recombination and differentiation into plasma cells during T cell-independent antibody responses. TACI binds the ligands BAFF and APRIL. Approximately 10% of patients with common variable immunodeficiency (CVID) carry TACI mutations, of which A181E and C172Y are in the transmembrane domain. Residues A181 and C172 are located on distinct sides of the transmembrane helix, which is predicted by molecular modeling to spontaneously assemble into trimers and dimers. In human B cells, these mutations impair ligand-dependent (C172Y) and -independent (A181E) TACI multimerization and signaling, as well as TACI-enhanced proliferation and/or IgA production. Genetic inactivation of TACI in primary human B cells impaired survival of CpG-activated cells in the absence of ligand. These results identify the transmembrane region of TACI as an active interface for TACI multimerization in signal transduction, in particular for ligand-independent signals. These functions are perturbed by CVID-associated mutations.
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Affiliation(s)
- Cristian R Smulski
- Department of Biochemistry, University of Lausanne, Ch. des Boveresses 155, 1066 Epalinges, Switzerland; Faculty of Medicine and Medical Center, University of Freiburg, Department of Rheumatology and Center for Chronic Immunodeficiency, Breisacherstr. 115, 79106 Freiburg, Germany; Medical Physics Department, Centro Atómico Bariloche, Comisión Nacional de Energía Atómica (CNEA), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Avenida E- Bustillo 9500, R8402AGP Río Negro, San Carlos de Bariloche, Argentina.
| | - Luyao Zhang
- Faculty of Medicine and Medical Center, University of Freiburg, Department of Rheumatology and Center for Chronic Immunodeficiency, Breisacherstr. 115, 79106 Freiburg, Germany
| | - Malte Burek
- Faculty of Medicine and Medical Center, University of Freiburg, Department of Rheumatology and Center for Chronic Immunodeficiency, Breisacherstr. 115, 79106 Freiburg, Germany
| | - Ariadna Teixidó Rubio
- Faculty of Medicine and Medical Center, University of Freiburg, Department of Rheumatology and Center for Chronic Immunodeficiency, Breisacherstr. 115, 79106 Freiburg, Germany
| | - Jana-Susann Briem
- Faculty of Medicine and Medical Center, University of Freiburg, Department of Rheumatology and Center for Chronic Immunodeficiency, Breisacherstr. 115, 79106 Freiburg, Germany
| | - Mauricio P Sica
- Medical Physics Department, Centro Atómico Bariloche, Comisión Nacional de Energía Atómica (CNEA), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Avenida E- Bustillo 9500, R8402AGP Río Negro, San Carlos de Bariloche, Argentina; Instituto de Energía y Desarrollo Sustentable, Centro Atómico Bariloche, Comisión Nacional de Energía Atómica (CNEA), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Avenida E- Bustillo 9500, R8402AGP Río Negro, San Carlos de Bariloche, Argentina
| | - Eirini Sevdali
- Faculty of Medicine and Medical Center, University of Freiburg, Department of Rheumatology and Center for Chronic Immunodeficiency, Breisacherstr. 115, 79106 Freiburg, Germany
| | - Michele Vigolo
- Department of Biochemistry, University of Lausanne, Ch. des Boveresses 155, 1066 Epalinges, Switzerland
| | - Laure Willen
- Department of Biochemistry, University of Lausanne, Ch. des Boveresses 155, 1066 Epalinges, Switzerland
| | - Patricia Odermatt
- Faculty of Medicine and Medical Center, University of Freiburg, Department of Rheumatology and Center for Chronic Immunodeficiency, Breisacherstr. 115, 79106 Freiburg, Germany
| | - Duygu Istanbullu
- Faculty of Medicine and Medical Center, University of Freiburg, Department of Rheumatology and Center for Chronic Immunodeficiency, Breisacherstr. 115, 79106 Freiburg, Germany
| | - Stephanie Herr
- Faculty of Medicine and Medical Center, University of Freiburg, Department of Rheumatology and Center for Chronic Immunodeficiency, Breisacherstr. 115, 79106 Freiburg, Germany
| | - Marco Cavallari
- BIOSS Centre for Biological Signalling Studies, University of Freiburg, Schänzlestr. 18, 79104 Freiburg, Germany
| | | | - Marta Rizzi
- Faculty of Medicine and Medical Center, University of Freiburg, Department of Rheumatology and Center for Chronic Immunodeficiency, Breisacherstr. 115, 79106 Freiburg, Germany
| | - Hermann Eibel
- Faculty of Medicine and Medical Center, University of Freiburg, Department of Rheumatology and Center for Chronic Immunodeficiency, Breisacherstr. 115, 79106 Freiburg, Germany
| | - Pascal Schneider
- Department of Biochemistry, University of Lausanne, Ch. des Boveresses 155, 1066 Epalinges, Switzerland.
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Sica MP, Smulski CR. Coarse Grained Molecular Dynamic Simulations for the Study of TNF Receptor Family Members' Transmembrane Organization. Front Cell Dev Biol 2021; 8:577278. [PMID: 33553138 PMCID: PMC7859260 DOI: 10.3389/fcell.2020.577278] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/29/2020] [Accepted: 12/21/2020] [Indexed: 11/21/2022] Open
Abstract
The Tumor Necrosis Factor (TNF) and the TNF receptor (TNFR) superfamilies are composed of 19 ligands and 30 receptors, respectively. The oligomeric properties of ligands, both membrane bound and soluble, has been studied most. However, less is known about the oligomeric properties of TNFRs. Earlier reports identified the extracellular, membrane-distal, cysteine-rich domain as a pre-ligand assembly domain which stabilizes receptor dimers and/or trimers in the absence of ligand. Nevertheless, recent reports based on structural nuclear magnetic resonance (NMR) highlight the intrinsic role of the transmembrane domains to form dimers (p75NTR), trimers (Fas), or dimers of trimers (DR5). Thus, understanding the structural basis of transmembrane oligomerization may shed light on the mechanism for signal transduction and the impact of disease-associated mutations in this region. To this end, here we used an in silico coarse grained molecular dynamics approach with Martini force field to study TNFR transmembrane homotypic interactions. We have first validated this approach studying the three TNFR described by NMR (p75NTR, Fas, and DR5). We have simulated membrane patches composed of 36 helices of the same receptor equidistantly distributed in order to get unbiassed information on spontaneous proteins assemblies. Good agreement was found in the specific residues involved in homotypic interactions and we were able to observe dimers, trimers, and higher-order oligomers corresponding to those reported in NMR experiments. We have, applied this approach to study the assembly of disease-related mutations being able to assess their impact on oligomerization stability. In conclusion, our results showed the usefulness of coarse grained simulations with Martini force field to study in an unbiased manner higher order transmembrane oligomerization.
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Affiliation(s)
- Mauricio P Sica
- Instituto de Energía y Desarrollo Sustentable, Centro Atómico Bariloche, Comisión Nacional de Energía Atómica (CNEA), San Carlos de Bariloche, Argentina.,Medical Physics Department, Centro Atómico Bariloche, Comisión Nacional de Energía Atómica (CNEA), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), San Carlos de Bariloche, Argentina
| | - Cristian R Smulski
- Medical Physics Department, Centro Atómico Bariloche, Comisión Nacional de Energía Atómica (CNEA), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), San Carlos de Bariloche, Argentina
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Lescano MI, Gasnier A, Pedano ML, Sica MP, Pasquevich DM, Prados MB. Development and characterisation of self-assembled graphene hydrogel-based anodes for bioelectrochemical systems. RSC Adv 2018; 8:26755-26763. [PMID: 35541082 PMCID: PMC9083133 DOI: 10.1039/c8ra03846e] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Accepted: 07/12/2018] [Indexed: 11/23/2022] Open
Abstract
In this work, we report a simple and scalable method to produce high efficiency 3D graphene-based electrodes (GH) for bioelectrochemical systems. GH were obtained by self-assembly of graphene oxide, through slow reduction with ascorbic acid over conductive mesh-works (carbon cloth and stainless-steel). The GH structure and composition were characterised by electron microscopy (SEM) and spectroscopy (FTIR and Raman), whereas the electrodes' performance was tested by chronoamperometry and cyclic voltammetry in a microbial electrolysis cell (MEC) inoculated with a pure culture of G. sulfurreducens. The hydrogel had a broad pore size distribution (>1 μm), which allowed bacterial colonisation within the framework. The macro-porous structure and chemical properties of the hydrogel rendered a higher bacterial loading capacity and substrate oxidation rate than other carbonaceous materials, including different reported graphene electrodes, which significantly increased MEC performance. A cheap, robust and versatile hydrogel-electrode is easily obtained by reduction of graphene-oxide; its colonisation by Geobacter resulted in high current densities.![]()
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Affiliation(s)
- Mariela I. Lescano
- Instituto de Energia y Desarrollo Sustentable
- Centro Atomico Bariloche
- Comision Nacional de Energia Atomica
- Argentina
| | - Aurelien Gasnier
- Gerencia de Investigacion Aplicada
- Centro Atomico Bariloche
- Comision Nacional de Energia Atomica
- CONICET
- Argentina
| | - Maria L. Pedano
- Lab. de Fotonica y Optoelectronica
- Centro Atomico Bariloche
- Comision Nacional de Energia Atomica
- CONICET
- Argentina
| | - Mauricio P. Sica
- Instituto de Energia y Desarrollo Sustentable
- Centro Atomico Bariloche
- Comision Nacional de Energia Atomica
- Argentina
- Instituto Balseiro
| | - Daniel M. Pasquevich
- Instituto de Energia y Desarrollo Sustentable
- Centro Atomico Bariloche
- Comision Nacional de Energia Atomica
- Argentina
| | - Maria B. Prados
- Instituto de Energia y Desarrollo Sustentable
- Centro Atomico Bariloche
- Comision Nacional de Energia Atomica
- Argentina
- Instituto Balseiro
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Vazquez DS, Sánchez IE, Garrote A, Sica MP, Santos J. The E. coli thioredoxin folding mechanism: The key role of the C-terminal helix. Biochimica et Biophysica Acta (BBA) - Proteins and Proteomics 2015; 1854:127-37. [DOI: 10.1016/j.bbapap.2014.11.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/16/2014] [Revised: 10/23/2014] [Accepted: 11/10/2014] [Indexed: 10/24/2022]
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Binolfi A, Fernández CO, Sica MP, Delfino JM, Santos J. Recognition between a short unstructured peptide and a partially folded fragment leads to the thioredoxin fold sharing native-like dynamics. Proteins 2012; 80:1448-64. [DOI: 10.1002/prot.24043] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2011] [Revised: 12/27/2011] [Accepted: 01/11/2012] [Indexed: 11/09/2022]
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Primo ME, Jakoncic J, Noguera ME, Risso VA, Sosa L, Sica MP, Solimena M, Poskus E, Ermácora MR. Protein-protein interactions in crystals of the human receptor-type protein tyrosine phosphatase ICA512 ectodomain. PLoS One 2011; 6:e24191. [PMID: 21935384 PMCID: PMC3174154 DOI: 10.1371/journal.pone.0024191] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2011] [Accepted: 08/02/2011] [Indexed: 11/19/2022] Open
Abstract
ICA512 (or IA-2) is a transmembrane protein-tyrosine phosphatase located in secretory granules of neuroendocrine cells. Initially, it was identified as one of the main antigens of autoimmune diabetes. Later, it was found that during insulin secretion, the cytoplasmic domain of ICA512 is cleaved and relocated to the nucleus, where it stimulates the transcription of the insulin gene. The role of the other parts of the receptor in insulin secretion is yet to be unveiled. The structures of the intracellular pseudocatalytic and mature extracellular domains are known, but the transmembrane domain and several intracellular and extracellular parts of the receptor are poorly characterized. Moreover the overall structure of the receptor remains to be established. We started to address this issue studying by X-ray crystallography the structure of the mature ectodomain of ICA512 (ME ICA512) and variants thereof. The variants and crystallization conditions were chosen with the purpose of exploring putative association interfaces, metal binding sites and all other structural details that might help, in subsequent works, to build a model of the entire receptor. Several structural features were clarified and three main different association modes of ME ICA512 were identified. The results provide essential pieces of information for the design of new experiments aimed to assess the structure in vivo.
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Affiliation(s)
- María E. Primo
- Consejo Nacional de Investigaciones Científicas y Técnicas (Conicet), Ciudad Autónoma de Buenos Aires, Argentina
- Cátedra de Inmunología de la Facultad de Farmacia y Bioquímica, Idehu, and División Endocrinología del Hospital de Clínicas J. de San Martín, Universidad de Buenos Aires—Conicet, Ciudad Autónoma de Buenos Aires, Argentina
| | - Jean Jakoncic
- Photon Science Directorate, Brookhaven National Laboratory, Upton, New York, United States of America
| | - Martín E. Noguera
- Consejo Nacional de Investigaciones Científicas y Técnicas (Conicet), Ciudad Autónoma de Buenos Aires, Argentina
- Departamento de Ciencia y Tecnología, Universidad Nacional de Quilmes, Bernal, Buenos Aires, Argentina
| | - Valeria A. Risso
- Consejo Nacional de Investigaciones Científicas y Técnicas (Conicet), Ciudad Autónoma de Buenos Aires, Argentina
- Departamento de Ciencia y Tecnología, Universidad Nacional de Quilmes, Bernal, Buenos Aires, Argentina
| | - Laura Sosa
- Consejo Nacional de Investigaciones Científicas y Técnicas (Conicet), Ciudad Autónoma de Buenos Aires, Argentina
- Cátedra de Inmunología de la Facultad de Farmacia y Bioquímica, Idehu, and División Endocrinología del Hospital de Clínicas J. de San Martín, Universidad de Buenos Aires—Conicet, Ciudad Autónoma de Buenos Aires, Argentina
| | - Mauricio P. Sica
- Consejo Nacional de Investigaciones Científicas y Técnicas (Conicet), Ciudad Autónoma de Buenos Aires, Argentina
- Departamento de Ciencia y Tecnología, Universidad Nacional de Quilmes, Bernal, Buenos Aires, Argentina
| | - Michele Solimena
- Paul Langerhans Institute Dresden, Molecular Diabetology, Universitätsklinikum “Carl Gustav Carus”, University of Technology Dresden, Dresden, Germany
- Max Planck Institute of Molecular Cell Biology and Genetics Dresden, Dresden, Germany
| | - Edgardo Poskus
- Consejo Nacional de Investigaciones Científicas y Técnicas (Conicet), Ciudad Autónoma de Buenos Aires, Argentina
- Cátedra de Inmunología de la Facultad de Farmacia y Bioquímica, Idehu, and División Endocrinología del Hospital de Clínicas J. de San Martín, Universidad de Buenos Aires—Conicet, Ciudad Autónoma de Buenos Aires, Argentina
| | - Mario R. Ermácora
- Consejo Nacional de Investigaciones Científicas y Técnicas (Conicet), Ciudad Autónoma de Buenos Aires, Argentina
- Departamento de Ciencia y Tecnología, Universidad Nacional de Quilmes, Bernal, Buenos Aires, Argentina
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Santos J, Sica MP, Buslje CM, Garrote AM, Ermácora MR, Delfino JM. Structural selection of a native fold by peptide recognition. Insights into the thioredoxin folding mechanism. Biochemistry 2009; 48:595-607. [PMID: 19119857 DOI: 10.1021/bi801969w] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Thioredoxins (TRXs) are monomeric alpha/beta proteins with a fold characterized by a central twisted beta-sheet surrounded by alpha-helical elements. The interaction of the C-terminal alpha-helix 5 of TRX against the remainder of the protein involves a close packing of hydrophobic surfaces, offering the opportunity of studying a fine-tuned molecular recognition phenomenon with long-range consequences on the acquisition of tertiary structure. In this work, we focus on the significance of interactions involving residues L94, L99, E101, F102, L103 and L107 on the formation of the noncovalent complex between reduced TRX1-93 and TRX94-108. The conformational status of the system was assessed experimentally by circular dichroism, intrinsic fluorescence emission and enzymic activity; and theoretically by molecular dynamics simulations (MDS). Alterations in tertiary structure of the complexes, resulting as a consequence of site specific mutation, were also examined. To distinguish the effect of alanine scanning mutagenesis on secondary structure stability, the intrinsic helix-forming ability of the mutant peptides was monitored experimentally by far-UV CD spectroscopy upon the addition of 2,2,2-trifluoroethanol, and also theoretically by Monte Carlo conformational search and MDS. This evidence suggests a key role of residues L99, F102 and L103 on the stabilization of the secondary structure of alpha-helix 5, and on the acquisition of tertiary structure upon complex formation. We hypothesize that the transition between a partially folded and a native-like conformation of reduced TRX1-93 would fundamentally depend on the consolidation of a cooperative tertiary unit based on the interaction between alpha-helix 3 and alpha-helix 5.
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Affiliation(s)
- Javier Santos
- Department of Biological Chemistry and Institute of Biochemistry and Biophysics (IQUIFIB), School of Pharmacy and Biochemistry, University of Buenos Aires, Junín 956, C1113AAD, Buenos Aires, Argentina
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Primo ME, Klinke S, Sica MP, Goldbaum FA, Jakoncic J, Poskus E, Ermácora MR. Structure of the Mature Ectodomain of the Human Receptor-type Protein-tyrosine Phosphatase IA-2. J Biol Chem 2008; 283:4674-81. [DOI: 10.1074/jbc.m708144200] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
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Primo ME, Niepomniszcze H, Poskus E, Sala MS, Guaita SS, Sica MP, Villalba A, Cardoso A, Bruno OD. Frequency of pancreatic beta-cell autoimmunity markers in patients with autoimmune thyroid disease. Medicina (B Aires) 2008; 68:37-42. [PMID: 18416318] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/26/2023] Open
Abstract
A total of 305 ambulatory patients recruited at the Division of Endocrinology, Hospital de Clínicas, University of Buenos Aires, with autoimmune thyroid disease (AITD) were studied to search for associations between autoimmune thyroid disease and presence of serum markers of autoimmune diabetes mellitus. Screening for markers of pancreatic beta-cell autoimmunity was performed by radioligand binding assays (RBA) as follows: autoantibodies to glutamic acid decarboxylase (GADA) and proinsulin (PAA) were determined in all sera, whereas autoantibodies to protein tyrosine phosphatase (IA-2A) and insulin (IAA) were additionally measured in 200 sera randomly selected from the total collection. In addition, every GADA positive serum among the remaining 105 sera was systematically tested for the presence of IA-2A and IAA. In the cohort of 305 AITD patients 22 (7.2%) were previously diagnosed as type 1, type 2 or insulin-requiring type 2 diabetics. Ten of these patients presented serum marker positivity specific for beta-cell autoantigens and 12 were marker negative. On the other hand, considering the majority of non-diabetic AITD patients (n = 283), beta3-cell marker positivity was detected in 17 individuals (6.0%). The prevalence of autoimmune diabetes markers was much higher in the studied population than in the general population utilized as a control group, and GADA was the most frequent marker.
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Affiliation(s)
- María E Primo
- División de Endocrinología, Hospital de Clínicas, Facultad de Medicina, Buenos Aires, Argentina.
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Abstract
B. licheniformis exo-small beta-lactamase (ESBL) has two nonsequential domains and a complex architecture. We replaced ESBL serine residues 126 and 265 with cysteine to probe the conformation of buried regions in each domain. Spectroscopic, hydrodynamic, and chemical methods revealed that the mutations do not alter the native fold but distinctly change stability (S-126C > wild-type > S-126/265C > S-265C ESBL) and the features of partially folded states. The observed wild-type ESBL equilibrium intermediate has decreased fluorescence but full secondary structure. S-126C ESBL intermediate has the fluorescence of the unfolded state, no thiol reactivity, and partial secondary structure. S-265C and S-126/265C ESBL populate intermediate states unfolded by fluorescence and thiol reactivity but with full secondary structure. Mass analysis of S-126/265C ESBL in the partially folded state proved that both thiol groups become exposed simultaneously. None of the intermediates is compatible with sequential domain unfolding. Molecular dynamics simulation suggests that the stabilizing effect of the S-126C substitution is due to optimization of van der Waals interactions and packing. On the other hand, destabilization induced by the S-265C mutation results from alteration of the hydrogen-bond network. The results illustrate the large impact that seemingly conservative serine-to-cysteine changes can have on the energy landscape of proteins.
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Affiliation(s)
- Javier Santos
- Departamento de Ciencia y Tecnología, Universidad Nacional de Quilmes, Roque Sáenz Peña 352, B1876XD Bernal, Buenos Aires, Argentina
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Primo ME, Sica MP, Risso VA, Poskus E, Ermácora MR. Expression and physicochemical characterization of an extracellular segment of the receptor protein tyrosine phosphatase IA-2. Biochim Biophys Acta 2005; 1764:174-81. [PMID: 16413232 DOI: 10.1016/j.bbapap.2005.11.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/14/2005] [Revised: 11/14/2005] [Accepted: 11/23/2005] [Indexed: 10/25/2022]
Abstract
The receptor protein tyrosine phosphatase superfamily (RPTP) includes proteins with a single transmembrane, one or more intracellular phosphatase, and a variety of extracellular domains. The 106-kDa insulinoma-associated protein (IA-2, ICA512) receptor is unique among RPTP members because: (a) it has a single, phosphatase-like intracellular domain identified as one of the most prominent self antigens in autoimmune diabetes; (b) its extracellular region bears no sequence similarity to known domains; (c) it is present in the membrane of secretory granules in neurons and pancreatic beta-cells where it suffers a complex processing; and (d) it has very poorly understood biological properties. In this work, we describe the expression, purification, and physicochemical characterization of residues 449-576 of IA-2 (IA-2ec(449-576)). Judging from CD, fluorescence, hydrodynamic, and thermal unfolding analyses, this fragment forms an autonomously folding unit with tight packing and well-defined secondary and tertiary structure. CD analysis suggests that about 25% of IA-2ec(449-576) residues are alpha-helical, whereas about the same amount are in beta-sheet structure. The availability of soluble and folded IA-2ec(449-576) is a step forward toward the characterization of a part of IA-2 at atomic detail, which may provide new insight in the biology of diabetes, the neurotransmission process, and the dynamic of secretory granules.
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Affiliation(s)
- María E Primo
- Cátedra de Inmunología, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires (UBA) and IDEHU (CONICET-UBA), Argentina
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Sica MP, Primo ME, Ermácora MR, Poskus E. High-yield expression of properly folded insulinoma-associated protein intracellular domain (IA-2ic) in Escherichia coli. Biotechnol Appl Biochem 2003; 37:301-9. [PMID: 12515576 DOI: 10.1042/ba20020090] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2002] [Revised: 11/19/2002] [Accepted: 01/06/2003] [Indexed: 11/17/2022]
Abstract
The intracellular domain of insulinoma-associated protein (IA-2), IA-2ic, is a prominent antigen in autoimmune diabetes, and autoantibodies to it are early markers of the disease. The high-yield expression of properly folded IA-2ic is needed for basic research and crucial for low-cost immunoassays aimed at the detection of these autoantibodies in diagnostic and preventive medicine. In previous work, the expression of IA-2ic fused to glutathione S-transferase or to a biotinylatable peptide was reported; however, these methods had very poor yield. Here we show that, utilizing a codon-optimized gene, up to 80 mg of pure and properly folded autoantigen per litre of Escherichia coli culture may be obtained. Furthermore, the addition of a C-terminal His-tag greatly facilitates IA-2ic purification without compromising either its immunoreactivity or its expression yield. To take advantage of the recombinant antigen, an enzyme immunoassay format was developed which proved to be highly specific and sensitive.
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Affiliation(s)
- Mauricio P Sica
- School of Pharmacy and Biochemistry, University of Buenos Aires and IDEHU-CONICET, Buenos Aires, Argentina
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Valdez SN, Sica MP, Labovsky V, Iacono RF, Cardoso AL, Krochik AG, Mazza CS, Ermácora MR, Cédola N, Poskus E. Combined measurement of diabetes mellitus immunological markers: an assessment of its benefits in adult-onset patients. Autoimmunity 2002; 33:227-36. [PMID: 11683397 DOI: 10.1080/08916934.2002.11873699] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
The convenience of combining the measurement of antibodies to glutamic acid decarboxylase (GADA), protein tyrosine phosphatase (IA-2A), and autoantibodies to insulin (IAA) in diabetic patients was assessed. We analysed 71 type 1 and 115 adult-onset diabetic patients. The latter were grouped into three categories according to the time of evolution to insulin dependence. The main findings were as follows: (i) in type 1 diabetes, the combined analysis of GADA and IA-2A showed a sensitivity of 87.4% and was not appreciably improved by adding IAA; (ii) out of 31 adults who required insulin immediately or within the first two years of diagnosis, 41.9, 29.0, and 6.5% were positive for at least one, two or all three, and all three markers, respectively; GADA was the most prevalent (35.5%) and IA-2A the least represented (16.1%); (iii) 34 adult patients with slow evolution to insulin dependence showed a completely different profile: 5.9% were GADA positive and 23.5% were IAA positive and no double or triple positivity was observed as all patients were IA-2A negative; and (iv) 50 type 2 patients who had not required insulin treatment showed a low incidence of GADA (4%) as the only marker present. We conclude that a combined double-antigen test for GADA and IA-2A is a useful strategy for prospective screening of type 1 diabetes. However, in adults, the profile of individual markers discloses the course to insulin dependence. Therefore, it seems advisable to measure the markers separately, to allow a better classification of these patients, and help define their treatment.
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Affiliation(s)
- S N Valdez
- Chair of Immunology, School of Pharmacy and Biochemistry, University of Buenos Aires, Argentina
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Krochik AG, Mazza CS, Valdez SN, Stumpo RR, Papouchado ML, Iacono RF, Cardoso Landaburu AC, Sica MP, Ozuna B, Poskus E. Immunologic and genetic markers in insulin-dependent diabetes mellitus (type 1) in an Argentine population. Medicina (B Aires) 2001; 61:279-83. [PMID: 11474874] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/20/2023] Open
Abstract
The objective was to evaluate the prevalence and association of several markers (islet cell antibodies: ICA, insulin autoantibodies: IAA, glutamic acid decarboxylase antibodies: GADA and ICA512 antibodies: ICA512A) along with HLA DQB1 genotype in type 1 diabetes mellitus of recent onset, including siblings and individuals without any history of this disease, in an Argentine population. A total of 79 children with type 1 diabetes mellitus of recent onset were studied, as well as 79 control children, and 68 healthy siblings of type 1 diabetic cases. IAA, ICA, GADA, ICA512A and HLA DQB1 alleles were determined. Sensitivity was 67.1% for ICA, 36.7% for IAA, 74.6% for GADA and 63.4% for ICA512A. None of the control subjects was positive for the immunological markers. Combined sensitivity of ICA-IAA-GADA was 89.8%, similar to the ICA512A-GADA (87.3%) or ICA512A-GADA-IAA combination (91.1%). GADA correlated positively with ICA, but no such correlation was found between IAA, ICA512A and ICA. IAA correlated negatively and GADA positively with age. IAA was associated to DQB1*0201, whereas ICA and ICA512A associated to DQB1*0302. Among siblings, 3/68 (4.4%) were positive for IAA and a single case (1.5%) was positive for GADA and one for ICA512A. Our findings show that the combination of multiple tests increases the sensitivity for prediction, with the ICA512A-GADA combination proving highly sensitive and equivalent to other proposed combinations, such as ICA-IAA-GADA.
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Affiliation(s)
- A G Krochik
- Servicio de Nutrición, Hospital Nacional de Pediatría Juan P. Garrahan, Buenos Aires
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