Identification of the c3b binding site in a recombinant vWF-A domain of complement factor B by surface-enhanced laser desorption-ionisation affinity mass spectrometry and homology modelling: implications for the activity of factor B

Hinshelwood, Justin; Spencer, Daniel I. R.; Edwards, Yvonne J. K.; Perkins, Stephen J.

doi:10.1006/jmbi.1999.3223

Cited by 45 publications

(32 citation statements)

References 48 publications

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“…We hypothesize that H chains are needed for binding to complement, and that they do so through their vWA domain. Indeed, previous studies have shown that the vWA domain on factor B can bind complement C3 (23) and the vWA domain on complement C2 can bind complement C3 and C4 (24,25). The bikunin L chain acts as the protease-inhibitory moiety.…”

Section: Discussionmentioning

confidence: 99%

Inter-α-Trypsin Inhibitor Attenuates Complement Activation and Complement-Induced Lung Injury

Garantziotis

Hollingsworth

Ghanayem

et al. 2007

The Journal of Immunology

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Complement activation is a central component of inflammation and sepsis and can lead to significant tissue injury. Complement factors are serum proteins that work through a cascade of proteolytic reactions to amplify proinflammatory signals. Inter-α-trypsin inhibitor (IaI) is an abundant serum protease inhibitor that contains potential complement-binding domains, and has been shown to improve survival in animal sepsis models. We hypothesized that IaI can bind complement and inhibit complement activation, thus ameliorating complement-dependent inflammation. We evaluated this hypothesis with in vitro complement activation assays and in vivo in a murine model of complement-dependent lung injury. We found that IaI inhibited complement activation through the classical and alternative pathways, inhibited complement-dependent phagocytosis in vitro, and reduced complement-dependent lung injury in vivo. This novel function of IaI provides a mechanistic explanation for its observed salutary effects in sepsis and opens new possibilities for its use as a treatment agent in inflammatory diseases.

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Section: Discussionmentioning

confidence: 99%

Inter-α-Trypsin Inhibitor Attenuates Complement Activation and Complement-Induced Lung Injury

Garantziotis

Hollingsworth

Ghanayem

et al. 2007

The Journal of Immunology

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“…Therefore, one might speculate that the C4b NH 2 -terminal ␣Ј-chain acidic cluster interacts with the vWFA domain of C2. Through homology modeling, the vWFA domain of factor B has recently been visualized (53,54). Furthermore, a study using the technique of surface-enhanced laser desorption-ionization affinity mass spectrometry, in conjunction with homology modeling, has suggested that peptide segments within the MIDAS cleft were directly involved in C3b binding (54).…”

Section: Figurementioning

confidence: 99%

“…Therefore, by extension, the vWFA domain of C2 should also be involved in contacting C4b. However, electrostatic surface potential renditions of the MIDAS surface for either factor B or modeled factor B-C2 chimeras did not show an obvious electropositive surface that might interact with the highly negatively charged 730 -736 segment of C3 ␣Ј-chain or, by extension, the corresponding 744 -752 segment of C4 ␣Ј-chain (53,54). Indeed, the homology modeling revealed that the floor of the MIDAS cleft is highly negatively charged, and the only significant electropositive patch visualized on the surface of the factor B vWFA is remote from the C3b-binding peptide segments identified by the affinity-based mass spectrometry (54).…”

Section: Figurementioning

confidence: 99%

Two Clusters of Acidic Amino Acids Near the NH2 Terminus of Complement Component C4 α′-Chain Are Important for C2 Binding

Pan

Ebanks

Isenman

2000

The Journal of Immunology

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Previous work has indicated a role for the NH2-terminal segment of the C3 α′-chain in the binding interactions of C3b with a number of its protein ligands. In particular, we have identified two clusters of acidic residues, namely, E736 and E737 and to a lesser extent D730 and E731, as being important in the binding of C3b to factor B and complement receptor 1 and the binding of iC3b to complement receptor 3. Whereas human C3 and C4 have an overall sequence identity of 29%, over a segment near the NH2 termini of their respective α′-chains the sequence identity is 56% (70% chemical similarity). Given the functional similarity between the C4b-C2 and C3b-B interactions in the respective formation of the classical and alternative pathway C3 convertases, as well as the sequence conservation of two acidic clusters, we hypothesized that residues 744EED and 749DEDD within the NH2-terminal segment of the C4 α′-chain would mediate in part the binding of C2 to C4b. We tested this hypothesis using three independent approaches. Site-directed mutagenesis experiments revealed that replacing subsets of the charged residues by their isosteric amides within either acidic cluster resulted in molecules having reduced C2 binding activity. Moreover, a synthetic peptide (C4 residues 740–756) encompassing the two acidic clusters was a specific inhibitor of the binding of C2 to red cell-associated C4b. Finally, Ab raised against the above peptide was able to block the interaction between red cell-associated C4b and fluid phase C2. Taken together, these results strongly suggest that the NH2-terminal acidic residue-rich segment of C4 α′-chain contributes importantly to the interaction of C4b with C2.

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“…More recently, Hinshelwood et al 20 have described the use of SELDI affinity mass spectrometry to study the interaction between a recombinant von Willebrand factor type A domain (vWF-A) in complement factor B with C3. Briefly, C3 is covalently attached to the surface of a ProteinChip array and used to specifically capture the vWF-A domain.…”

Section: Discussionmentioning

confidence: 99%

Identification of prostate specific membrane antigen (PSMA) as the target of monoclonal antibody 107-1A4 by proteinchip�; array, surface-enhanced laser desorption/ionization (seldi) technology

Wang

Diamond²,

Hass

et al. 2001

Int. J. Cancer

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Recently we described the generation of the prostate tissue-specific monoclonal antibody (MAb) 107-1A4, its expression pattern and preliminary targeting of human prostate cancer xenografts. In this report we demonstrate that the target antigen for MAb 107-1A4 is prostate-specific membrane antigen (PSMA) using immunoaffinity absorption followed by SDS-PAGE and mass spectrometric analysis of peptides produced by in-gel tryptic digestion. Prostate cancer is the most frequently diagnosed cancer and the second leading cause of cancer death in men in the United States. In spite of increasing attention and accumulating knowledge, advances in treatment that improve survival remain elusive. Prostate specific antigen (PSA) is the most widely used marker of prostate cancer. Immunoassays for PSA using monoclonal (MAb) or polyclonal antibodies have clinical applications, such as monitoring and early detection of prostate cancer. However, PSA is not a perfect tumor marker because serum levels often are elevated in men with benign prostatic hyperplasia, prostatitis and other nonmalignant disorders and also because levels are not always elevated in individuals with early prostate cancer. 1 In an effort to identify additional proteins that could be of value for the diagnosis and treatment of prostate cancer, we have recently described the generation of a new prostate cancer-reactive MAb, designated 107-1A4, using a two-phase immunization protocol involving the prostate cancer cell line, LNCaP. 2 This MAb recognizes an antigen, which appeared to be distinct from those previously described and shows specific tumor targeting in preliminary in vivo studies. In part because MAb 107-1A4 recognized a conformational epitope and, thus, could not be used in Western blots, we were unable to characterize its antigen using conventional approaches. 2 In this report we describe the identification of the target antigen of MAb 107-1A4 using ProteinChip array, surface-enhanced laser desorption/ionization (SELDI) technology from Ciphergen Biosystems (Fremont, CA). SELDI, a concept introduced by Hutchens and Yip 3 combines ProteinChip technology with timeof-flight mass spectrometry and offers the advantages of speed, simplicity, sensitivity and accuracy. Briefly, each ProteinChip array has a number of spots that contain functional groups, chemical or biological "docking sites," for the selective binding and washing of proteins/peptides from complex mixtures. After the sample is applied to the surface, unbound proteins and interfering substances are washed away. A solution containing laser energyabsorbing molecules, often referred to as a matrix, is then added and allowed to dry. In this fashion, the laser energy absorbing matrix molecules co-crystallize with the adsorbed proteins. The captured proteins are then detected using laser desorption ionization time-of-flight mass spectrometry (LDI-TOF MS). A more comprehensive description of the overall history and recent advances in SELDI technology and comparisons with other laserbased mass spectrometry...

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Identification of the c3b binding site in a recombinant vWF-A domain of complement factor B by surface-enhanced laser desorption-ionisation affinity mass spectrometry and homology modelling: implications for the activity of factor B

Cited by 45 publications

References 48 publications

Inter-α-Trypsin Inhibitor Attenuates Complement Activation and Complement-Induced Lung Injury

Inter-α-Trypsin Inhibitor Attenuates Complement Activation and Complement-Induced Lung Injury

Two Clusters of Acidic Amino Acids Near the NH2 Terminus of Complement Component C4 α′-Chain Are Important for C2 Binding

Identification of prostate specific membrane antigen (PSMA) as the target of monoclonal antibody 107-1A4 by proteinchip�; array, surface-enhanced laser desorption/ionization (seldi) technology

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