scholarly journals Identification of a Receptor-Binding Domain of Bordetella Dermonecrotic Toxin

2002 ◽  
Vol 70 (7) ◽  
pp. 3427-3432 ◽  
Author(s):  
Takeshi Matsuzawa ◽  
Takashige Kashimoto ◽  
Jun Katahira ◽  
Yasuhiko Horiguchi
Keyword(s):  
Amino Acids ◽  
Receptor Binding ◽  
Focal Adhesions ◽  
Small Gtpase ◽  
Binding Domain ◽  
Cell Surface Receptor ◽  
Target Cells ◽  
Dermonecrotic Toxin ◽  
Surface Receptor ◽  
A Cell

ABSTRACT Bordetella dermonecrotic toxin (DNT) stimulates the assembly of actin stress fibers and focal adhesions by deamidating or polyaminating Gln63 of the small GTPase Rho. DNT is an A-B toxin which is composed of an N-terminal receptor-binding (B) domain and a C-terminal enzymatically active (A) domain. In this study, to analyze the functional and structural organization of DNT, we prepared 10 clones of hybridoma producing anti-DNT monoclonal antibodies. One of these antibodies, 2B3, neutralized the effects of DNT on target cells when mixed with the toxin. When microinjected into cells, however, 2B3 did not inhibit the intoxication by DNT. Western blot analysis revealed that 2B3 recognized the N-terminal region of DNT. To delineate the DNT-binding domain, we examined a series of truncated DNT mutants for the ability to competitively inhibit the intoxication of cells by the full-length DNT and found that a fragment consisting of the N-terminal 54 amino acids (DNT1-54) was the smallest inhibitory fragment. The radioiodinated DNT1-54 actually bound to target cells, which was inhibited by 2B3. These results suggest that the N-terminal 54 amino acids of DNT are responsible for the binding to target cells. DNT1-54 bound to none of the DNT-resistant cells, implying the presence of a cell surface receptor specific to DNT-sensitive cells.

scholarly journals Identification of Functional Domains ofBordetella Dermonecrotizing Toxin

1999 ◽  
Vol 67 (8) ◽  
pp. 3727-3732 ◽  
Author(s):  
Takashige Kashimoto ◽  
Jun Katahira ◽  
Willian R. Cornejo ◽  
Minako Masuda ◽  
Atsushi Fukuoh ◽  
...  
Keyword(s):  
Amino Acids ◽  
Receptor Binding ◽  
Competitive Inhibition ◽  
Focal Adhesions ◽  
Small Gtpase ◽  
Amino Acid Sequences ◽  
Start Codon ◽  
Target Cells ◽  
Catalytic Center ◽  
Catalytically Active

ABSTRACT Bordetella dermonecrotizing toxin (DNT) stimulates the assembly of actin stress fibers and focal adhesions by deamidating Gln63 of the small GTPase Rho. To clarify the functional and structural organization of DNT, we cloned and sequenced the DNT gene and examined the functions of various DNT mutants. Our analyses of the nucleotide and amino acid sequences revealed that the start codon of the DNT gene is a GTG triplet located 39 bp upstream of the reported putative initiation ATG codon; consequently, DNT contains an additional 13 amino acids at its N-terminal end. All of the N-terminally truncated mutants were found to modify Rho. The shortest fragment of DNT possessing the Rho modification activity consists of amino acids from Ile1176 to the C-terminal end. This fragment overlaps the region homologous toEscherichia coli cytotoxic necrotizing factors (CNFs), which show activity similar to that of DNT. The introduction of a mutation at Cys1305 located in the highly conserved region between CNFs and DNT eliminated the activity, indicating that this domain is the catalytic center of DNT. The N-terminal fragment (1 to 531) of DNT failed to modify Rho but reduced the DNT-induced polynucleation in MC3T3-E1 cells when simultaneously added with the holotoxin, suggesting competitive inhibition in the receptor-binding or internalizing step. Our finding that DNT consists of an N-terminal receptor-binding and/or internalizing domain and a C-terminal catalytically active domain may facilitate analysis of the overall action of the toxin on the mammalian target cells.

scholarly journals Monoclonal Antibody 667 Recognizes the Variable Region A Motif of the Ecotropic Retrovirus CasBrE Envelope Glycoprotein and Inhibits Env Binding to the Viral Receptor

2003 ◽  
Vol 77 (20) ◽  
pp. 10984-10993 ◽  
Author(s):  
Hanna Dreja ◽  
Laurent Gros ◽  
Sylvie Villard ◽  
Estanislao Bachrach ◽  
Anna Oates ◽  
...  
Keyword(s):  
Amino Acids ◽  
Monoclonal Antibody ◽  
Receptor Binding ◽  
Envelope Glycoprotein ◽  
Critical Role ◽  
Variable Region ◽  
Binding Domain ◽  
Target Cells ◽  
Kinetic Properties ◽  
Receptor Binding Domain

ABSTRACT Monoclonal antibody (MAb) 667 is a neutralizing mouse monoclonal antibody recognizing the envelope glycoprotein (Env) of the ecotropic neurotropic murine retrovirus CasBrE but not that of other murine retroviruses. Since 667 can be used for preclinical studies of antiviral gene therapy as well as for studying the early events of retroviral infection, we have cloned its cDNAs and molecularly characterized it in detail. Spot technique-based experiments showed that 667 recognizes a linear epitope of 12 amino acids located in the variable region A of the receptor binding domain. Alanine scanning experiments showed that six amino acids within the epitope are critical for MAb binding. One of them, D57, is not present in any other murine retroviral Env, which suggests a critical role for this residue in the selectivity of 667. MAb 667 heavy- and light-chain cDNAs were functionally characterized by transient transfection into Cos-7 cells. Enzyme-linked immunosorbent assays and Biacore studies showed that the specificities as well as the antigen-binding thermodynamic and kinetic properties of the recombinant 667 MAb (r667) produced by Cos-7 cells and those of the parental hybridoma-produced MAb (h667) were similar. However, h667 was shown to contain contaminating retroviral and/or retrovirus-like particles which interfere with both viral binding and neutralization experiments. These contaminants could successfully be removed by a stringent purification protocol. Importantly, this purified 667 could completely prevent retrovirus binding to target cells and was as efficient as the r667 MAb produced by transfected Cos-7 cells in neutralization assays. In conclusion, this study shows that the primary mechanism of virus neutralization by MAb 667 is the blocking of the retroviral receptor binding domain of CasBrE Env. In addition, the findings of this study constitute a warning against the direct use of hybridoma cell culture supernatants for studying the initial events of retroviral cell infection as well as for carrying out in vivo neutralization experiments and suggest that either recombinant antibodies or highly purified antibodies are preferable for these purposes.

scholarly journals Identification of a Putative Coreceptor on Vero Cells That Participates in Dengue 4 Virus Infection

2001 ◽  
Vol 75 (17) ◽  
pp. 7818-7827 ◽  
Author(s):  
José de Jesús Martı́nez-Barragán ◽  
Rosa M. del Angel
Keyword(s):  
Virus Infection ◽  
Dengue Virus ◽  
Vero Cells ◽  
Host Cells ◽  
Cell Surface Receptor ◽  
Target Cells ◽  
Virus Binding ◽  
Dengue Virus Infection ◽  
Surface Receptor ◽  
A Cell

ABSTRACT Dengue virus infects target cells by attaching to a cell surface receptor through the envelope (E) glycoprotein, located on the surface of the viral membrane. On Vero and BHK cells, heparan sulfate (HS) moieties of proteoglycans are the receptors for dengue virus; however, additional proteins have also been described as putative dengue virus receptors on C6/36, HL60, and BM cells. HS can also act as a receptor for other types of viruses or as an attachment molecule for viruses that require additional host cell molecules to allow viral penetration. In this study we searched for molecules other than HS that could participate in dengue virus infection of Vero cells. Labeled dengue 4 virus bound with high affinity to two molecules of 74 and 44 kDa. Binding of dengue virus to the 74-kDa molecule was susceptible to protease and sodium periodate treatment and resistant to heparinase treatments. Lectins such as concanavalin A and wheat germ agglutinin prevented dengue virus binding to both the 74- and the 44-kDa protein in overlay assays, while phytohemagglutinin P did not affect binding, suggesting that carbohydrate residues (α-mannose orN-acetylglucosamine) are important in virus binding to host cells. Protease susceptibility, biotin labeling, and immunofluorescence with a polyclonal antibody raised against the 74-kDa protein consistently identified the protein on the surfaces of Vero cells. Moreover, the antibody against the 74-kDa protein was able to inhibit dengue virus infection. These data suggest that HS might serve as a primary receptor, probably concentrating virus particles on the surfaces of Vero cells, and then other molecules, such as the 74-kDa protein, might participate as coreceptors in viral penetration. The 74-kDa protein possibly constitutes part of a putative receptor complex for dengue virus infection of Vero cells.

scholarly journals Role of Aromatic Amino Acids in Receptor Binding Activity and Subunit Assembly of the Cytolethal Distending Toxin of Aggregatibacter actinomycetemcomitans

2008 ◽  
Vol 76 (7) ◽  
pp. 2812-2821 ◽  
Author(s):  
Linsen Cao ◽  
Georges Bandelac ◽  
Alla Volgina ◽  
Jonathan Korostoff ◽  
Joseph M. DiRienzo
Keyword(s):  
Amino Acids ◽  
Receptor Binding ◽  
Aromatic Amino Acids ◽  
Aggregatibacter Actinomycetemcomitans ◽  
Binding Activity ◽  
Cell Surface Receptor ◽  
Periodontal Pathogen ◽  
Cytolethal Distending Toxin ◽  
Receptor Binding Activity ◽  
Surface Receptor

ABSTRACT The periodontal pathogen Aggregatibacter actinomycetemcomitans produces a cytolethal distending toxin (Cdt) that inhibits the proliferation of oral epithelial cells. Structural models suggest that the CdtA and CdtC subunits of the Cdt heterotrimer form two putative lectin domains with a central groove. A region of CdtA rich in heterocyclic amino acids (aromatic patch) appears to play an important role in receptor recognition. In this study site-specific mutagenesis was used to assess the contributions of aromatic amino acids (tyrosine and phenylalanine) to receptor binding and CdtA-CdtC assembly. Predominant surface-exposed aromatic residues that are adjacent to the aromatic patch region in CdtA or are near the groove located at the junction of CdtA and CdtC were studied. Separately replacing residues Y105, Y140, Y188, and Y189 with alanine in CdtA resulted in differential effects on binding related to residue position within the aromatic region. The data indicate that an extensive receptor binding domain extends from the groove across the entire face of CdtA that is oriented 180° from the CdtB subunit. Replacement of residue Y105 in CdtA and residues Y61 and F141 in CdtC, which are located in or at the periphery of the groove, inhibited toxin assembly. Taken together, these results, along with the lack of an aromatic amino acid-rich region in CdtC similar to that in CdtA, suggest that binding of the heterotoxin to its cell surface receptor is mediated predominantly by the CdtA subunit. These findings are important for developing strategies designed to block the activity of this prominent virulence factor.

scholarly journals Characterization of the Interaction of Lassa Fever Virus with Its Cellular Receptor α-Dystroglycan

2005 ◽  
Vol 79 (10) ◽  
pp. 5979-5987 ◽  
Author(s):  
Stefan Kunz ◽  
Jillian M. Rojek ◽  
Mar Perez ◽  
Christina F. Spiropoulou ◽  
Michael B. A. Oldstone
Keyword(s):  
Receptor Binding ◽  
Lassa Fever ◽  
Lymphocytic Choriomeningitis ◽  
Fever Virus ◽  
Cell Surface Receptor ◽  
Cellular Receptor ◽  
Binding Characteristics ◽  
Lassa Fever Virus ◽  
Surface Receptor ◽  
A Cell

ABSTRACT The cellular receptor for the Old World arenaviruses Lassa fever virus (LFV) and lymphocytic choriomeningitis virus (LCMV) has recently been identified as α-dystroglycan (α-DG), a cell surface receptor that provides a molecular link between the extracellular matrix and the actin-based cytoskeleton. In the present study, we show that LFV binds to α-DG with high affinity in the low-nanomolar range. Recombinant vesicular stomatitis virus pseudotyped with LFV glycoprotein (GP) adopted the receptor binding characteristics of LFV and depended on α-DG for infection of cells. Mapping of the binding site of LFV on α-DG revealed that LFV binding required the same domains of α-DG that are involved in the binding of LCMV. Further, LFV was found to efficiently compete with laminin α1 and α2 chains for α-DG binding. Together with our previous studies on receptor binding of the prototypic immunosuppressive LCMV isolate LCMV clone 13, these findings indicate a high degree of conservation in the receptor binding characteristics between the highly human-pathogenic LFV and murine-immunosuppressive LCMV isolates.

scholarly journals Mitogenesis, cell migration, and loss of focal adhesions induced by tenascin-C interacting with its cell surface receptor, annexin II.

1996 ◽  
Vol 7 (6) ◽  
pp. 883-892 ◽  
Author(s):  
C Y Chung ◽  
J E Murphy-Ullrich ◽  
H P Erickson
Keyword(s):  
Endothelial Cells ◽  
Cell Migration ◽  
Cell Surface ◽  
Focal Adhesions ◽  
Cell Surface Receptor ◽  
Annexin Ii ◽  
Tenascin C ◽  
Subsequent Response ◽  
Surface Receptor ◽  
A Cell

In a previous study we demonstrated that the alternatively spliced region of tenascin-C, TNfnA-D, bound with high affinity to a cell surface receptor, annexin II. In the present study we demonstrate three changes in cellular activity that are produced by adding intact tenascin-C or TNfnA-D to cells, and we show that all three activities are blocked by antibodies against annexin II. 1) TNfnA-D added to confluent endothelial cells induced loss of focal adhesions. 2) TNfnA-D produced a mitogenic response of confluent, growth-arrested endothelial cells in 1% serum. TNfnA-D stimulated mitogenesis only when it was added to cells before or during exposure to other mitogens, such as basic fibroblast growth factor or serum. Thus the effect of TNfnA-D seems to be to facilitate the subsequent response to growth factors. 3) TNfnA-D enhanced cell migration in a cell culture wound assay. Antibodies to annexin II blocked all three cellular responses to TNfnA-D. These data show that annexin II receptors on endothelial cells mediate several cell regulatory functions attributed to tenascin-C, potentially through modulation of intracellular signalling pathways.

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.

The transfer of transthyretin and receptor-binding properties from the plasma retinol-binding protein to the epididymal retinoic acid-binding protein

2002 ◽  
Vol 362 (2) ◽  
pp. 265-271 ◽  
Author(s):  
Manickavasagam SUNDARAM ◽  
Daan M. F. van AALTEN ◽  
John B. C. FINDLAY ◽  
Asipu SIVAPRASADARAO
Keyword(s):  
Retinoic Acid ◽  
Binding Protein ◽  
Binding Pocket ◽  
Retinol Binding Protein ◽  
Cell Surface Receptor ◽  
Acid Binding Protein ◽  
The Family ◽  
Surface Receptor ◽  
A Cell ◽  
Plasma Retinol

Members of the lipocalin superfamily share a common structural fold, but differ from each other with respect to the molecules with which they interact. They all contain eight β-strands (A—H) that fold to form a well-defined β-barrel, which harbours a binding pocket for hydrophobic ligands. These strands are connected by loops that vary in size and structure and make up the closed and open ends of the pocket. In addition to binding ligands, some members of the family interact with other macromolecules, the specificity of which is thought to be associated with the variable loop regions. Here, we have investigated whether the macromolecular-recognition properties can be transferred from one member of the family to another. For this, we chose the prototypical lipocalin, the plasma retinol-binding protein (RBP) and its close structural homologue the epididymal retinoic acid-binding protein (ERABP). RBP exhibits three molecular-recognition properties: it binds to retinol, to transthyretin (TTR) and to a cell-surface receptor. ERABP binds retinoic acid, but whether it interacts with other macromolecules is not known. Here, we show that ERABP does not bind to TTR and the RBP receptor, but when the loops of RBP near the open end of the pocket (L-1, L-2 and L-3, connecting β-strands A—B, C—D and E—F, respectively) were substituted into the corresponding regions of ERABP, the resulting chimaera acquired the ability to bind TTR and the receptor. L-2 and L-3 were found to be the major determinants of the receptor- and TTR-binding specificities respectively. Thus we demonstrate that lipocalins serve as excellent scaffolds for engineering novel biological functions.

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