scholarly journals Structural basis for the reaction of 3,5,3′-tri-iodothyronine-specific antibodies with thyroxine-containing thyroglobulin

1985 ◽  
Vol 228 (1) ◽  
pp. 155-160 ◽  
Author(s):  
P G H Byfield ◽  
D Clingan ◽  
R L Himsworth
Keyword(s):  
Amino Acids ◽  
Immune Response ◽  
Binding Site ◽  
Antigenic Site ◽  
Structural Basis ◽  
Specific Antibodies ◽  
Dominant Feature ◽  
Tg Structure

A series of human autoantibodies against thyroglobulin (Tg) which exhibit different specificities for iodothyronines were studied. The ability of a thyroxine (T4)-containing peptide (T4P) isolated from human thyroglobulin (Tg) to displace [125I]T3 from human T3-specific autoantisera was 11-50 times greater than that of T4 alone. These antisera therefore strongly recognize amino acids adjacent to T4 in the Tg structure. This was confirmed when a Tg preparation (Tg[0.05]) containing an average of only 0.05 of a T4 residue/molecule and much less T3 had good cross-reactivities with these antisera. Cross-reactivities of other Tg preparations with different T4 contents increased only slowly with increase of T4 content up to a mean of 6.6 residues/molecule and were not proportional to T3 content. In contrast, cross-reactivities with a human T4-specific autoantiserum were strongly dependent on T4 content. Tg[0.05] was 500 times less reactive than T4P and 615 times less than T4. Cross-reactivities rose rapidly as the T4 content of Tg preparations increased from a mean of 0.05 to approx. 1-2 residues/molecule. Thyroxine is therefore a dominant feature of the antigenic site for this antiserum. There was little further increase in cross-reactivities for those Tg preparations containing up to an average of 6.6 residues T4 per molecule, confirming previous conclusions that all T4-containing sites are not immunologically identical and that autoantibodies exhibit a preference for particular sites on Tg. Similar conclusions were reached for a non-specific iodothyronine-binding antiserum. These results indicate that iodothyronine specificity in human autoantisera is not necessarily determined by the iodothyronine present in the immunogenic area, but by the precise site selected by the immune response. T4- or non-specific antibodies have thyroxine as a dominant feature of the antigenic site. T3- specific antibodies have the thyroxine residue as a peripheral feature of the binding site, and it is not necessary to postulate that T3 was part of the immunogen or is required in the epitope. These antisera may have value in mapping the hormonogenic regions in Tg from human and other species.

scholarly journals Antibody Responses to Antigenic Sites 1 and 3 of Serotype 3 Poliovirus after Vaccination with Oral Live Attenuated or Inactivated Poliovirus Vaccine and after Natural Exposure

2000 ◽  
Vol 7 (1) ◽  
pp. 40-44 ◽  
Author(s):  
T. Herremans ◽  
J. H. J. Reimerink ◽  
T. G. Kimman ◽  
H. G. A. M. van der Avoort ◽  
M. P. G. Koopmans
Keyword(s):  
Immune Response ◽  
Antibody Response ◽  
Antigenic Site ◽  
Booster Vaccination ◽  
Antibody Responses ◽  
Virus Neutralization ◽  
Specific Antibodies ◽  
Antigenic Sites ◽  
Natural Exposure ◽  
Immunosorbent Assays

ABSTRACT Three important antigenic sites involved in virus neutralization on polioviruses in mouse experiments have been identified. These sites are located at the surface of the virion and have been designated antigenic sites 1, 2, and 3. In mice, the antibody response to antigenic site 1 of serotype 3 poliovirus is considered to be immunodominant, but little is known about the immunogenicity of these sites in humans. In the present study, we developed inhibition enzyme-linked immunosorbent assays specific for antigenic sites 1 and 3 to measure antibody responses to these sites in fully vaccinated inactivated poliovirus vaccine (IPV) (n = 63) and oral live attenuated poliovirus vaccine (OPV) (n = 63) recipients and in naturally infected persons (n = 25). Similar levels of antibodies to site 1 in IPV and OPV vaccinees were detected. However, significantly more OPV recipients (88.7%) had detectable antibodies to antigenic site 3 (P < 0.01) than did IPV-vaccinated persons (63.1%). After an IPV booster vaccination, both previously IPV- and OPV-vaccinated persons responded with a significant increase in antibodies to sites 1 and 3 (P < 0.01). We conclude that the immune response to serotype 3 poliovirus in humans consists of both site 1- and site 3-specific antibodies and that these responses can be induced by either OPV or recent IPV vaccination.

scholarly journals Generation of Antibodies against Foot-and-Mouth-Disease Virus Capsid Protein VP4 Using Hepatitis B Core VLPs as a Scaffold

Life ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 338
Author(s):  
Jessica Swanson ◽  
Rennos Fragkoudis ◽  
Philippa C. Hawes ◽  
Joseph Newman ◽  
Alison Burman ◽  
...  
Keyword(s):  
Amino Acids ◽  
Hepatitis B ◽  
Capsid Protein ◽  
Disease Virus ◽  
Foot And Mouth Disease ◽  
Mouth Disease ◽  
Specific Antibodies ◽  
Mouth Disease Virus ◽  
N Terminus ◽  
Foot And Mouth

The picornavirus foot-and-mouth disease virus (FMDV) is the causative agent of the economically important disease of livestock, foot-and-mouth disease (FMD). VP4 is a highly conserved capsid protein, which is important during virus entry. Previous published work has shown that antibodies targeting the N-terminus of VP4 of the picornavirus human rhinovirus are broadly neutralising. In addition, previous studies showed that immunisation with the N-terminal 20 amino acids of enterovirus A71 VP4 displayed on the hepatitis B core (HBc) virus-like particles (VLP) can induce cross-genotype neutralisation. To investigate if a similar neutralising response against FMDV VP4 could be generated, HBc VLPs displaying the N-terminus of FMDV VP4 were designed. The N-terminal 15 amino acids of FMDV VP4 was inserted into the major immunodominant region. HBc VLPs were also decorated with peptides of the N-terminus of FMDV VP4 attached using a HBc-spike binding tag. Both types of VLPs were used to immunise mice and the resulting serum was investigated for VP4-specific antibodies. The VLP with VP4 inserted into the spike, induced VP4-specific antibodies, however the VLPs with peptides attached to the spikes did not. The VP4-specific antibodies could recognise native FMDV, but virus neutralisation was not demonstrated. This work shows that the HBc VLP presents a useful tool for the presentation of FMDV capsid epitopes.

scholarly journals Gonococcal pili. Primary structure and receptor binding domain.

1984 ◽  
Vol 159 (5) ◽  
pp. 1351-1370 ◽  
Author(s):  
G K Schoolnik ◽  
R Fernandez ◽  
J Y Tai ◽  
J Rothbard ◽  
E C Gotschlich
Keyword(s):  
Amino Acids ◽  
Receptor Binding ◽  
Binding Domain ◽  
Structural Basis ◽  
Receptor Binding Domain ◽  
Variable Regions ◽  
Disulfide Linkage ◽  
Polymeric Structure ◽  
Antigenic Diversity ◽  
Single Polypeptide Chain

The complete amino acid sequence of pilin from gonococcal strain MS11 and the sequence of constant and variable regions from strain R10 pilin have been determined in order to elucidate the structural basis for adherence function, antigenic diversity, and polymeric structure. The MS11 pilin sequence consists of 159 amino acids in a single polypeptide chain with two cysteines in disulfide linkage and serine-bonded phosphate residues. TC-2 (31-111), a soluble monomeric pilus peptide prepared by arginine-specific digestion, bound human endocervical, but not buccal or HeLa cells and therefore is postulated to encompass the receptor binding domain. Variable regions of CNBr-3 appear to confer antigenic diversity and comprise segments in which changes in the position of charged residues occur in hydrophilic, beta-turns. Residues 2-21 and 202-221 of gonococcal pilins and lower eucaryotic actins, respectively, exhibit 50% homology. When these residues are arranged at intervals of 100 degrees of arc on "helical wheels," the identical amino acids comprise a hydrophobic face on one side of the helix. This observation, the hydrophobic character of this region and the tendency for TC-1 (residues 1-30) to aggregate in water, suggest that this stretch interacts with other subunits to stabilize polymeric structure.

scholarly journals Structural basis of adhesive binding by desmocollins and desmogleins

2016 ◽  
Vol 113 (26) ◽  
pp. 7160-7165 ◽  
Author(s):  
Oliver J. Harrison ◽  
Julia Brasch ◽  
Gorka Lasso ◽  
Phinikoula S. Katsamba ◽  
Goran Ahlsen ◽  
...  
Keyword(s):  
Amino Acids ◽  
Crystal Structures ◽  
Structural Basis ◽  
Cellular Interactions ◽  
Opposite Charge ◽  
Charged Amino Acids ◽  
Structural Framework ◽  
Classical Cadherins ◽  
Coated Bead

Desmosomes are intercellular adhesive junctions that impart strength to vertebrate tissues. Their dense, ordered intercellular attachments are formed by desmogleins (Dsgs) and desmocollins (Dscs), but the nature of trans-cellular interactions between these specialized cadherins is unclear. Here, using solution biophysics and coated-bead aggregation experiments, we demonstrate family-wise heterophilic specificity: All Dsgs form adhesive dimers with all Dscs, with affinities characteristic of each Dsg:Dsc pair. Crystal structures of ectodomains from Dsg2 and Dsg3 and from Dsc1 and Dsc2 show binding through a strand-swap mechanism similar to that of homophilic classical cadherins. However, conserved charged amino acids inhibit Dsg:Dsg and Dsc:Dsc interactions by same-charge repulsion and promote heterophilic Dsg:Dsc interactions through opposite-charge attraction. These findings show that Dsg:Dsc heterodimers represent the fundamental adhesive unit of desmosomes and provide a structural framework for understanding desmosome assembly.

scholarly journals Peptides presenting the binding site of human CD4 for the HIV-1 envelope glycoprotein gp120

2012 ◽  
Vol 8 ◽  
pp. 1858-1866 ◽  
Author(s):  
Julia Meier ◽  
Kristin Kassler ◽  
Heinrich Sticht ◽  
Jutta Eichler
Keyword(s):  
Amino Acids ◽  
Binding Site ◽  
Envelope Glycoprotein ◽  
Conformational Stability ◽  
Cellular Receptor ◽  
Binding Assays ◽  
Glycoprotein Gp120 ◽  
Dynamics Simulations ◽  
Key Residues ◽  
Hiv 1

Based on the structure of the HIV-1 glycoprotein gp120 in complex with its cellular receptor CD4, we have designed and synthesized peptides that mimic the binding site of CD4 for gp120. The ability of these peptides to bind to gp120 can be strongly enhanced by increasing their conformational stability through cyclization, as evidenced by binding assays, as well as through molecular-dynamics simulations of peptide–gp120 complexes. The specificity of the peptide–gp120 interaction was demonstrated by using peptide variants, in which key residues for the interaction with gp120 were replaced by alanine or D-amino acids.

scholarly journals The Structural Basis of Repertoire Shift in an Immune Response to Phosphocholine

2000 ◽  
Vol 191 (12) ◽  
pp. 2101-2112 ◽  
Author(s):  
McKay Brown ◽  
Maria A. Schumacher ◽  
Gregory D. Wiens ◽  
Richard G. Brennan ◽  
Marvin B. Rittenberg
Keyword(s):  
Immune Response ◽  
Light Chain ◽  
Indirect Effects ◽  
Somatic Mutations ◽  
Variable Region ◽  
Primary Response ◽  
Structural Basis ◽  
Antibody Repertoire ◽  
High Affinity

The immune response to phosphocholine (PC)–protein is characterized by a shift in antibody repertoire as the response progresses. This change in expressed gene combinations is accompanied by a shift in fine specificity toward the carrier, resulting in high affinity to PC–protein. The somatically mutated memory hybridoma, M3C65, possesses high affinity for PC–protein and the phenyl-hapten analogue, p-nitrophenyl phosphocholine (NPPC). Affinity measurements using related PC–phenyl analogues, including peptides of varying lengths, demonstrate that carrier determinants contribute to binding affinity and that somatic mutations alter this recognition. The crystal structure of an M3C65–NPPC complex at 2.35-Å resolution allows evaluation of the three light chain mutations that confer high-affinity binding to NPPC. Only one of the mutations involves a contact residue, whereas the other two have indirect effects on the shape of the combining site. Comparison of the M3C65 structure to that of T15, an antibody dominating the primary response, provides clear structural evidence for the role of carrier determinants in promoting repertoire shift. These two antibodies express unrelated variable region heavy and light chain genes and represent a classic example of the effect of repertoire shift on maturation of the immune response.

scholarly journals Human Group C Rotavirus VP8*s Recognize Type A Histo-Blood Group Antigens as Ligands

2018 ◽  
Vol 92 (11) ◽  
Author(s):  
Xiaoman Sun ◽  
Lihong Wang ◽  
Jianxun Qi ◽  
Dandi Li ◽  
Mengxuan Wang ◽  
...  
Keyword(s):  
Ligand Binding ◽  
Binding Site ◽  
Blood Group ◽  
Specific Interaction ◽  
Type A ◽  
Host Susceptibility ◽  
Structural Basis ◽  
Receptor Interaction ◽  
Blood Group Antigens ◽  
Group Species

ABSTRACTGroup/species C rotaviruses (RVCs) have been identified as important pathogens of acute gastroenteritis (AGE) in children, family-based outbreaks, as well as animal infections. However, little is known regarding their host-specific interaction, infection, and pathogenesis. In this study, we performed serial studies to characterize the function and structural features of a human G4P[2] RVC VP8* that is responsible for the host receptor interaction. Glycan microarrays demonstrated that the human RVC VP8* recognizes type A histo-blood group antigens (HBGAs), which was confirmed by synthetic glycan-/saliva-based binding assays and hemagglutination of red blood cells, establishing a paradigm of RVC VP8*-glycan interactions. Furthermore, the high-resolution crystal structure of the human RVC VP8* was solved, showing a typical galectin-like structure consisting of two β-sheets but with significant differences from cogent proteins of group A rotaviruses (RVAs). The VP8* in complex with a type A trisaccharide displays a novel ligand binding site that consists of a particular set of amino acid residues of the C-D, G-H, and K-L loops. RVC VP8* interacts with type A HBGAs through a unique mechanism compared with that used by RVAs. Our findings shed light on the host-virus interaction and the coevolution of RVCs and will facilitate the development of specific antivirals and vaccines.IMPORTANCEGroup/species C rotaviruses (RVCs), members ofReoviridaefamily, infect both humans and animals, but our knowledge about the host factors that control host susceptibility and specificity is rudimentary. In this work, we characterized the glycan binding specificity and structural basis of a human RVC that recognizes type A HBGAs. We found that human RVC VP8*, the rotavirus host ligand binding domain that shares only ∼15% homology with the VP8* domains of RVAs, recognizes type A HBGA at an as-yet-unknown glycan binding site through a mechanism distinct from that used by RVAs. Our new advancements provide insights into RVC-cell attachment, the critical step of virus infection, which will in turn help the development of control and prevention strategies against RVs.

scholarly journals Comprehensive understanding of acetohydroxyacid synthase inhibition by different herbicide families

2017 ◽  
Vol 114 (7) ◽  
pp. E1091-E1100 ◽  
Author(s):  
Mario D. Garcia ◽  
Amanda Nouwens ◽  
Thierry G. Lonhienne ◽  
Luke W. Guddat
Keyword(s):  
Binding Site ◽  
Crystal Structures ◽  
Kinetic Studies ◽  
Herbicidal Activity ◽  
Structural Basis ◽  
Acetohydroxyacid Synthase ◽  
Branched Chain Amino Acid ◽  
Application Rates ◽  
Herbicide Binding ◽  
Branched Chain

Five commercial herbicide families inhibit acetohydroxyacid synthase (AHAS, E.C. 2.2.1.6), which is the first enzyme in the branched-chain amino acid biosynthesis pathway. The popularity of these herbicides is due to their low application rates, high crop vs. weed selectivity, and low toxicity in animals. Here, we have determined the crystal structures of Arabidopsis thaliana AHAS in complex with two members of the pyrimidinyl-benzoate (PYB) and two members of the sulfonylamino-carbonyl-triazolinone (SCT) herbicide families, revealing the structural basis for their inhibitory activity. Bispyribac, a member of the PYBs, possesses three aromatic rings and these adopt a twisted “S”-shaped conformation when bound to A. thaliana AHAS (AtAHAS) with the pyrimidinyl group inserted deepest into the herbicide binding site. The SCTs bind such that the triazolinone ring is inserted deepest into the herbicide binding site. Both compound classes fill the channel that leads to the active site, thus preventing substrate binding. The crystal structures and mass spectrometry also show that when these herbicides bind, thiamine diphosphate (ThDP) is modified. When the PYBs bind, the thiazolium ring is cleaved, but when the SCTs bind, ThDP is modified to thiamine 2-thiazolone diphosphate. Kinetic studies show that these compounds not only trigger reversible accumulative inhibition of AHAS, but also can induce inhibition linked with ThDP degradation. Here, we describe the features that contribute to the extraordinarily powerful herbicidal activity exhibited by four classes of AHAS inhibitors.

scholarly journals Finding the Binding Site of Peloruside A and its Secondary Effects in Saccharomyces Cerevisiae using a  Chemical Genetics Approach

2021 ◽  
Author(s):  
◽  
Reem Hanna
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Cell Cycle ◽  
Amino Acids ◽  
Flow Cytometry ◽  
Binding Site ◽  
Mammalian Cells ◽  
Site Directed Mutagenesis ◽  
Directed Mutagenesis ◽  
Peloruside A ◽  
Microtubule Function

<p>Peloruside A, a natural product isolated from the marine sponge Mycale hentscheli, is a microtubule-stabilising agent that has a similar mechanism of action to the anticancer drug paclitaxel and is cytotoxic to cultured mammalian cells. Peloruside appears to bind to a distinct site on mammalian tubulin that is different from that of the taxoid-site drugs. Because of the high sequence homology between yeast and mammalian tubulin, Saccharomyces cerevisiae (S. cerevisiae) was used as a model organism to characterise the peloruside-binding site with the aim of advancing our understanding about this site on mammalian tubulin. Wild type S. cerevisiae (BY4741) was sensitive to peloruside at uM concentrations; however, a strain that lacks the mad2 (Mitotic Arrest Deficient 2) gene showed increased sensitivity to the drug at much lower uM concentrations. This gene is a component of the spindle-assembly checkpoint complex that delays the onset of anaphase in cells with defects in mitotic spindle assembly. The main aims of this project were to define the binding site of peloruside A using yeast tubulin to see if microtubule function and/or morphology is altered in yeast by peloruside, and to identify any secondary drug targets "friends of the target" through chemical genetic interactions profiling (Homozygous deletion profiling microarray). Site-directed mutagenesis was used to mutate two conserved amino acids (A296T; R306H) known to confer resistance to peloruside in mammalian cells. Based on a published computer model of the peloruside binding site on mammalian tubulin, we also mutated three other amino acids, two that were predicted to affect peloruside binding (Q291M and N337L), and one that was predicted to affect laulimalide binding but have little affect on peloruside binding (V333W). We also included a negative control that was predicted to have no effect on peloruside binding (R282Q) and would affect epothilone binding. We found that of the six point mutations, only Q291M failed to confer resistance in yeast and instead it increased the inhibition to the drug. Using a bud index assay, confocal microscopy, and flow cytometry, 40-50 uM peloruside was shown to block cells in G2/M of the cell cycle, confirming a direct action of the drug on microtubule function. Homozygous profiling (HOP) microarray analysis of a deletion mutant set of yeast genes was also carried out to identify gene products that interact with peloruside in order to link the drug to specific networks or biochemical pathways in the cells. From site-directed mutagenesis, we concluded that peloruside binds to yeast B-tubulin in the region predicted by the published model of the binding site, and therefore mapping the site on yeast tubulin could provide useful information about the mammalian binding site for peloruside. The bud index, flow cytometry, and confocal microscopy experiments provided further evidence that peloruside interacts with yeast tubulin. From HOP we found that peloruside has roles in the cell cycle, as expected, and has effects on protein transport, secretion, cell wall synthesis, and steroid biosynthesis pathways.</p>

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