scholarly journals Role of C-Terminal Cysteine Residues of Aspergillus fumigatus Allergen Asp f 4 in Immunoglobulin E Binding

2004 ◽  
Vol 11 (2) ◽  
pp. 261-265 ◽  
Author(s):  
Harikrishnan Ramachandran ◽  
Banani Banerjee ◽  
Paul A. Greenberger ◽  
Kevin J. Kelly ◽  
Jordan N. Fink ◽  
...  
Keyword(s):  
Aspergillus Fumigatus ◽  
Conformational Changes ◽  
Immunoglobulin E ◽  
Allergic Bronchopulmonary Aspergillosis ◽  
Allergic Diseases ◽  
Cysteine Residues ◽  
Conformational Structure ◽  
C Terminus ◽  
Function Relationship

ABSTRACT Among the several allergens cloned and expressed from Aspergillus fumigatus, Asp f 4 is a major one associated with allergic bronchopulmonary aspergillosis (ABPA). The structure-function relationship of allergens is important in understanding the immunopathogenesis, diagnosis, and treatment of allergic diseases. These include the epitopes, conformational or linear, deletion of the N or C terminus or both N and C termini, and glycosylation or nonglycosylation, all of which affect immune responses. Similarly, the role of cysteine residues present in allergens may yield useful information regarding the conformational structure of allergens and the immunoglobulin E (IgE) epitope interaction. Such information may help in developing new strategies towards immunotherapy. In order to define the role of cysteine in the interaction of the antibody with Asp f 4, we have constructed mutants by selectively deleting cysteine residues from the C-terminal region of the Asp f 4. Immunological evaluation of these engineered recombinant constructs was conducted by using sera from patients with ABPA, Aspergillus skin test-positive asthmatics, and healthy controls. The results demonstrate strong IgE binding with Asp f 4 and two truncated mutants, Asp f 41-234 (amino acids [aa] 1 to 234) and Asp f 41-241 (aa 1 to 241), while another mutant, Asp f 41-196 (aa 1 to 196), showed reactivity with fewer patients. The result suggests that deletion of cysteines and the alteration of IgE epitopes at the C-terminal end resulted in conformational changes, which may have a potential role in the immunomodulation of the disease.

scholarly journals Role of the cysteine residues in Arabidopsis thaliana cyclophilin CYP20-3 in peptidyl-prolyl cis–trans isomerase and redox-related functions

2006 ◽  
Vol 401 (1) ◽  
pp. 287-297 ◽  
Author(s):  
Miriam Laxa ◽  
Janine König ◽  
Karl-Josef Dietz ◽  
Andrea Kandlbinder
Keyword(s):  
Conformational Changes ◽  
Protein Function ◽  
Redox Regulation ◽  
Catalytic Efficiency ◽  
Structural Rearrangement ◽  
Disulfide Bridge ◽  
Cysteine Residues ◽  
Active Centre ◽  
Independent Functions

Cyps (cyclophilins) are ubiquitous proteins of the immunophilin superfamily with proposed functions in protein folding, protein degradation, stress response and signal transduction. Conserved cysteine residues further suggest a role in redox regulation. In order to get insight into the conformational change mechanism and functional properties of the chloroplast-located CYP20-3, site-directed mutagenized cysteine→serine variants were generated and analysed for enzymatic and conformational properties under reducing and oxidizing conditions. Compared with the wild-type form, elimination of three out of the four cysteine residues decreased the catalytic efficiency of PPI (peptidyl-prolyl cis–trans isomerase) activity of the reduced CYP20-3, indicating a regulatory role of dithiol–disulfide transitions in protein function. Oxidation was accompanied by conformational changes with a predominant role in the structural rearrangement of the disulfide bridge formed between Cys54 and Cys171. The rather negative Em (midpoint redox potential) of −319 mV places CYP20-3 into the redox hierarchy of the chloroplast, suggesting the activation of CYP20-3 in the light under conditions of limited acceptor availability for photosynthesis as realized under environmental stress. Chloroplast Prx (peroxiredoxins) were identified as interacting partners of CYP20-3 in a DNA-protection assay. A catalytic role in the reduction of 2-Cys PrxA and 2-Cys PrxB was assigned to Cys129 and Cys171. In addition, it was shown that the isomerization and disulfide-reduction activities are two independent functions of CYP20-3 that both are regulated by the redox state of its active centre.

scholarly journals Use of a Synthetic Peptide Epitope of Asp f 1, a Major Allergen or Antigen of Aspergillus fumigatus, for Improved Immunodiagnosis of Allergic Bronchopulmonary Aspergillosis

2004 ◽  
Vol 11 (3) ◽  
pp. 552-558 ◽  
Author(s):  
Taruna Madan ◽  
Priyanka Priyadarsiny ◽  
Mudit Vaid ◽  
Neel Kamal ◽  
Ashok Shah ◽  
...  
Keyword(s):  
Aspergillus Fumigatus ◽  
Synthetic Peptide ◽  
Immunoglobulin E ◽  
Allergic Bronchopulmonary Aspergillosis ◽  
Major Allergen ◽  
Specific Ige ◽  
Diagnostic Efficiency ◽  
Intradermal Testing ◽  
Peptide Epitope ◽  
Asp F 1

ABSTRACT Allergic bronchopulmonary aspergillosis (ABPA) is an immunologically complex allergic disorder caused by the fungal pathogen Aspergillus fumigatus. Elevated levels of total immunoglobulin E (IgE), specific IgE, and IgG antibodies in sera are important immunodiagnostic criteria for ABPA. International reference standards or standardized immunodiagnostic assays are not available due to a lack of well-defined diagnostic antigens. The present study was carried out to identify and evaluate the immunodiagnostic relevance of synthetic epitopic peptides of Asp f 1, a major allergen, antigen, or cytotoxin of A. fumigatus. Five overlapping peptides were synthesized from the N terminus of Asp f 1, one of the potential immunodominant regions predicted by algorithmic programs. The 11-amino-acid synthetic peptide (P1) significantly inhibited both IgG binding (89.10% ± 4.45%) and IgE binding (77.32% ± 3.38%) of the standardized diagnostic antigen (SDA) (a well-defined pool of diagnostically relevant allergens and antigens of A. fumigatus). With a panel of sera of ABPA patients, allergic patients with skin test negativity to A. fumigatus, and healthy individuals, P1 showed a higher diagnostic efficiency than SDA (specific IgG, 100%; specific IgE, 98.3%). The diagnostic efficiency of P1 could be attributed to the presence of homologous epitopes in various immunodominant allergens or antigens of A. fumigatus. The ability of P1 to induce histamine release from sensitized mast cells and a Th2 type of cytokine profile in peripheral blood mononuclear cells of ABPA patients suggests its potential for use in intradermal testing. P1 could be further explored for development of a standardized, specific, and sensitive immunodiagnostic test for aspergillosis.

scholarly journals Conformational Landscape Reduction of a Dynamic 29-Residue Peptide by a Perfluoroaromatic Small Molecule

2020 ◽  
Author(s):  
ethan evans
Keyword(s):  
Small Molecule ◽  
Conformational Changes ◽  
Dynamic Systems ◽  
Biochemical Properties ◽  
State Dependent ◽  
C Terminus ◽  
Explicit Solvent ◽  
Conformational Landscape

Conformationally dynamic peptides and proteins display both important biochemical properties and present a challenge for computational modeling. Characterizing the accessible structural landscape represents one route to understand their function with molecular level detail. We characterize a self-labeling 29-residue peptide, MP01-Gen4, that undergoes structural alterations in the presence of a perfluoroaromatic reaction partner. Replica exchange molecular dynamics (REMD) shows MP01 to access a broad set of states, that microsecond-long explicit solvent simulations only minimally sample. REMD and structural network analysis find an altered and reduced conformational landscape when MP01 interacts non-covalently or is covalently attached to the perfluoroaromatic small molecule. Residues throughout the peptide, notably at the C-terminus, interact with the small molecule in conformational state-dependent manners. The results help explain and generate hypotheses for experimental observations including the importance of flexibility and the role of the N- and C-terminal regions, both of which are distant from the active cysteine. The simulations highlight the importance of substantial sampling in minimally stabilized, conformationally dynamic systems and supplies a case study for small molecule-mediated, peptide conformational changes.<br>

scholarly journals Conformational and Linear B-Cell Epitopes of Asp f 2, a Major Allergen of Aspergillus fumigatus, Bind Differently to Immunoglobulin E Antibody in the Sera of Allergic Bronchopulmonary Aspergillosis Patients

1999 ◽  
Vol 67 (5) ◽  
pp. 2284-2291 ◽  
Author(s):  
Banani Banerjee ◽  
Paul A. Greenberger ◽  
Jordan N. Fink ◽  
Viswanath P. Kurup
Keyword(s):  
Amino Acid ◽  
Aspergillus Fumigatus ◽  
B Cell ◽  
Immunoglobulin E ◽  
Allergic Bronchopulmonary Aspergillosis ◽  
Amino Acid Sequences ◽  
Epitope Region ◽  
B Cell Epitopes ◽  
Ige Binding ◽  
Binding Regions

ABSTRACT Asp f 2 is a major Aspergillus fumigatus allergen involved in allergic bronchopulmonary aspergillosis. Knowledge of the B-cell epitopes may contribute to the understanding of immunoregulation and immunodiagnosis. To elucidate the immunoglobulin E (IgE) binding epitopes in the linear sequence of Asp f 2, we synthesized decamer peptides spanning the whole molecule of Asp f 2 on derivatized cellulose membranes and evaluated IgE binding in ABPA patient and control sera. Peptides three to five amino acids long were synthesized based on amino acid sequences within the IgE binding regions and evaluated for the specificity of epitope antibody interactions. Nine IgE binding regions were recognized in this protein of 268 amino acid residues. Of the nine epitopes, seven (ATQRRQI, RKYFG, HWR, YTTRR, DHFAD, ALEAYA, and THEGGQ) are present in the hydrophilic regions of Asp f 2. Immunologic evaluation of the three recombinant fragments, Asp f 2A encompassing the N-terminal epitope region, Asp f 2B without N- and C-terminal regions of the protein, and Asp f 2C representing C-terminal epitopes, revealed that either the N- or C-terminal region of the protein is essential for the correct folding and conformation for IgE antibody binding.

Role of Aspergillus fumigatus-Specific IgE in the Diagnosis of Allergic Bronchopulmonary Aspergillosis

2019 ◽  
Vol 178 (4) ◽  
pp. 338-344 ◽  
Author(s):  
Bin Lou ◽  
Zhen Xu ◽  
Guangdie Yang ◽  
Chuangen Guo ◽  
Shufa Zheng ◽  
...  
Keyword(s):  
Aspergillus Fumigatus ◽  
Allergic Bronchopulmonary Aspergillosis ◽  
Specific Ige

scholarly journals Epigenetic modification in the expression of p73 p73 - epigenetic target for anticancer therapy

2019 ◽  
Vol 13 (2) ◽  
Author(s):  
Faiza Naseer ◽  
Mohammad Saleem
Keyword(s):  
Conformational Changes ◽  
Posttranslational Modifications ◽  
Epigenetic Modification ◽  
Amino Acid Residues ◽  
P53 Family ◽  
After Effects ◽  
Cycle Arrest ◽  
C Terminus ◽  
Upstream Promoter

A p73 is a new member of p53 family of transcription factor, having two types. First is TAp73, transcriptionally active and expressed via upstream promoter as a tumor suppressor and vital apoptotic inductor, it also has a key role in cell cycle arrest/differentiation and Second is ΔNp73 that is transcriptionally inactive and expressed via downstream regulator as oncogenes. Both types are expressed in various isoforms, which originate from alternative splicing events at the C-terminus. Upon DNA damage, posttranslational modifications cause conformational changes in various amino acid residues via induction or inhibition of various proteins, which are present in the structural domains of p73. These modifications may cause up- or down-regulation of p73 expression levels, as well as alters the transcriptional activity and/or stability of the protein. In this review, we have made an effort to assemble all existing data regarding the role of p73, its modification and after effects in cancer.

Chloride-dependent conformational changes in the GlyT1 glycine transporter

2020 ◽  
Author(s):  
Yuan-Wei Zhang ◽  
Stacy Uchendu ◽  
Vanessa Leone ◽  
Richard T. Bradshaw ◽  
Ntumba Sangwa ◽  
...  
Keyword(s):  
Conformational Changes ◽  
Ion Pair ◽  
Cysteine Residues ◽  
Glycine Transporter ◽  
Open Conformation ◽  
Transporter Family ◽  
Transport Cycle ◽  
Dynamics Simulations ◽  
Insight Into

AbstractThe human GlyT1 glycine transporter requires chloride for its function. However, the mechanism by which Cl- exerts its influence is unknown. To examine the role that Cl- plays in the transport cycle, we measured the effect of Cl- on both glycine binding and conformational changes. The ability of glycine to displace the high-affinity radioligand [3H]CHIBA-3007 required Na+ and was potentiated over 1000-fold by Cl-. We generated GlyT1b mutants containing reactive cysteine residues in either the extracellular or cytoplasmic permeation pathways and measured changes in the reactivity of those cysteine residues as indicators of conformational changes in response to ions and substrate. Na+ increased accessibility in the extracellular pathway and decreased it in the cytoplasmic pathway, consistent with stabilizing an outward-open conformation as observed in other members of this transporter family. In the presence of Na+, both glycine and Cl- independently shifted the conformation of GlyT1b toward an outward-closed conformation. Together, Na+, glycine and Cl- stabilized an inward-open conformation of GlyT1b. We then examined whether Cl- acts by interacting with a conserved glutamine to allow formation of an ion pair that stabilizes the closed state of the extracellular pathway. Molecular dynamics simulations of a GlyT1 homologue indicated that this ion pair is formed more frequently as that pathway closes. Mutation of the glutamine blocked the effect of Cl-, and substituting it with glutamate or lysine resulted in outward- or inward-facing transporter conformations, respectively. These results provide novel and unexpected insight into the role of Cl- in this family of transporters.

scholarly journals The role of the C terminus of the SNARE protein SNAP-25 in fusion pore opening and a model for fusion pore mechanics

2008 ◽  
Vol 105 (40) ◽  
pp. 15388-15392 ◽  
Author(s):  
Qinghua Fang ◽  
Khajak Berberian ◽  
Liang-Wei Gong ◽  
Ismail Hafez ◽  
Jakob B. Sørensen ◽  
...  
Keyword(s):  
Conformational Changes ◽  
Mechanistic Model ◽  
Snare Complex ◽  
Fusion Pore ◽  
Snare Protein ◽  
C Terminus ◽  
Target Membrane ◽  
Pore Opening ◽  
Fusion Pores

Formation of a fusion pore between a vesicle and its target membrane is thought to involve the so-called SNARE protein complex. However, there is no mechanistic model explaining how the fusion pore is opened by conformational changes in the SNARE complex. It has been suggested that C-terminal zipping triggers fusion pore opening. A SNAP-25 mutant named SNAP-25Δ9 (lacking the last nine C-terminal residues) should lead to a less-tight C-terminal zipping. Single exocytotic events in chromaffin cells expressing this mutant were characterized by carbon fiber amperometry and cell-attached patch capacitance measurements. Cells expressing SNAP-25Δ9 displayed smaller amperometric “foot-current” currents, reduced fusion pore conductances, and lower fusion pore expansion rates. We propose that SNARE/lipid complexes form proteolipid fusion pores. Fusion pores involving the SNAP-25Δ9 mutant will be less tightly zipped and may lead to a longer fusion pore structure, consistent with the observed decrease of fusion pore conductance.

scholarly journals IN SILICO MODELING OF MONOMERIC DEXAMETHASONE-INDUCED RAS-RELATED PROTEIN 1 AND RAS HOMOLOG ENRICHED IN STRIATUM: ROLE OF N TERMINUS AND STRUCTURE‑FUNCTION RELATIONSHIP

2019 ◽  
Vol 12 (1) ◽  
pp. 84
Author(s):  
Rashmi Verma ◽  
Navin Kumar ◽  
Ashish Thapliyal
Keyword(s):  
3D Structure ◽  
Three Dimensional ◽  
Therapeutic Drug ◽  
Related Protein ◽  
Binding Domains ◽  
Gtp Binding ◽  
C Terminus ◽  
N Terminus ◽  
Function Relationship

Objective: Dexamethasone-induced Ras-related protein 1 (Dexras1) and Ras homolog enriched in striatum (RHES) are the two monomeric small G proteins that belong to Ras superfamily. These two proteins show 62% similarity. Both of these proteins are involved in signaling and modulation of several pathophysiological processes. They have unique GTP binding domain and a unique C and N terminus. C terminus is known to interact with several proteins; however, the role of its unique N terminus is still not known. The three-dimensional (3D) structure of these proteins is also not available in any of the databases yet. This present study approaches bioinformatics tools and servers to predict the 3D structure of these two proteins in silico.Methods: In this study, two bioinformatics servers were used, namely Swiss modeling server and Iterative Threading ASSEmbly Refinement (I-TASSER) server.Results: Both servers developed many alignment templates of Dexras1 and RHES. These alignments were used to develop 3D structure using Pymol. These models have different regions of proteins such as N terminus, GTP-binding domains, effector loop, C terminus, and the unique CAAX site. The models deduce that the N-terminals of both Dexras1 and RHES are unique regions that might possible be dangling out of the protein while it gets inserted into the membrane. We hypothesize that this unique N-terminal might have a distinct role in the modulation of N-type calcium channels.Conclusion: All the models generated show predicted 3D structure of Dexras1 and RHES protein. This study of structural prediction will be helpful in knowing the interaction of Dexras1 and RHES and a step forward to target these two proteins as a novel therapeutic drug.

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