1
|
Shuck SC, Wauchope OR, Rose KL, Kingsley PJ, Rouzer CA, Shell SM, Sugitani N, Chazin WJ, Zagol-Ikapitte I, Boutaud O, Oates JA, Galligan JJ, Beavers WN, Marnett LJ. Protein modification by adenine propenal. Chem Res Toxicol 2014; 27:1732-42. [PMID: 25211669 PMCID: PMC4203390 DOI: 10.1021/tx500218g] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
![]()
Base propenals are products of the
reaction of DNA with oxidants
such as peroxynitrite and bleomycin. The most reactive base propenal,
adenine propenal, is mutagenic in Escherichia coli and reacts with DNA to form covalent adducts; however, the reaction
of adenine propenal with protein has not yet been investigated. A
survey of the reaction of adenine propenal with amino acids revealed
that lysine and cysteine form adducts, whereas histidine and arginine
do not. Nε-Oxopropenyllysine, a
lysine–lysine cross-link, and S-oxopropenyl
cysteine are the major products. Comprehensive profiling of the reaction
of adenine propenal with human serum albumin and the DNA repair protein,
XPA, revealed that the only stable adduct is Nε-oxopropenyllysine. The most reactive sites for modification
in human albumin are K190 and K351. Three sites of modification of
XPA are in the DNA-binding domain, and two sites are subject to regulatory
acetylation. Modification by adenine propenal dramatically reduces
XPA’s ability to bind to a DNA substrate.
Collapse
Affiliation(s)
- Sarah C Shuck
- A. B. Hancock Jr. Memorial Laboratory for Cancer Research, Departments of Biochemistry, ‡Chemistry, and §Pharmacology, ∥Mass Spectrometry Research Center, ⊥Center in Molecular Toxicology, #Center for Structural Biology, ∇Department of Medicine, Vanderbilt Institute of Chemical Biology, and Vanderbilt-Ingram Cancer Center, Vanderbilt University School of Medicine , Nashville, Tennessee 37232-0146, United States
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
2
|
Nishiyama Y, Taguchi H, Hara M, Planque SA, Mitsuda Y, Paul S. Metal-dependent amyloid β-degrading catalytic antibody construct. J Biotechnol 2014; 180:17-22. [PMID: 24698848 DOI: 10.1016/j.jbiotec.2014.03.026] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2013] [Revised: 03/05/2014] [Accepted: 03/21/2014] [Indexed: 01/29/2023]
Abstract
Catalytic antibodies (catabodies) that degrade target antigens rapidly are rare. We describe the metal-dependence of catabody construct 2E6, an engineered heterodimer of immunoglobulin light chain variable domains that hydrolyzes amyloid β peptides (Aβ) specifically. In addition to the electrophilic phosphonate inhibitor of serine proteases, the metal chelators ethylenediaminetetraacetic acid (EDTA) and 1,10-phenanthroline completely inhibited the hydrolysis of Aβ by catabody 2E6. Formation of catabody-electrophilic phosphonate inhibitor adducts was unaffected by EDTA, suggesting that the metal exerts a favorable effect on a catalytic step after the initial catabody nucleophilic attack on Aβ. The EDTA inactivated catabody failed to disaggregate fibrillar Aβ, indicating the functional importance of the Aβ hydrolytic activity. Treating the EDTA-inactivated catabody with Zn(2+) or Co(2+) restored the Aβ hydrolytic activity, and Zn(2+)-induced catabody conformational transitions were evident by fluorescence emission spectroscopy. The studies reveal the absolute catabody dependence on a metal cofactor.
Collapse
Affiliation(s)
- Yasuhiro Nishiyama
- Chemical Immunology Research Center, Department of Pathology and Laboratory Medicine, University of Texas-Houston Medical School, Houston, TX 77030, USA
| | - Hiroaki Taguchi
- Chemical Immunology Research Center, Department of Pathology and Laboratory Medicine, University of Texas-Houston Medical School, Houston, TX 77030, USA
| | - Mariko Hara
- Chemical Immunology Research Center, Department of Pathology and Laboratory Medicine, University of Texas-Houston Medical School, Houston, TX 77030, USA
| | - Stephanie A Planque
- Chemical Immunology Research Center, Department of Pathology and Laboratory Medicine, University of Texas-Houston Medical School, Houston, TX 77030, USA
| | - Yukie Mitsuda
- Chemical Immunology Research Center, Department of Pathology and Laboratory Medicine, University of Texas-Houston Medical School, Houston, TX 77030, USA
| | - Sudhir Paul
- Chemical Immunology Research Center, Department of Pathology and Laboratory Medicine, University of Texas-Houston Medical School, Houston, TX 77030, USA.
| |
Collapse
|
3
|
Nishiyama Y, Planque S, Hanson CV, Massey RJ, Paul S. CD4 binding determinant mimicry for HIV vaccine design. Front Immunol 2012; 3:383. [PMID: 23251137 PMCID: PMC3523313 DOI: 10.3389/fimmu.2012.00383] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2012] [Accepted: 11/29/2012] [Indexed: 11/24/2022] Open
Abstract
The immunodominant epitopes expressed by the HIV-1 envelope protein gp120 are hypermutable, defeating attempts to develop an effective HIV vaccine. Targeting the structurally conserved gp120 determinant that binds host CD4 receptors (CD4BD) and initiates infection is a more promising route to vaccination, but this has proved difficult because of the conformational flexibility of gp120 and immune evasion mechanisms used by the virus. Mimicking the outer CD4BD conformational epitopes is difficult because of their discontinuous nature. The CD4BD region composed of residues 421–433 (CD4BDcore) is a linear epitope, but this region possesses B cell superantigenic character. While superantigen epitopes are vulnerable to a small subset of spontaneously produced neutralizing antibodies present in humans without infection (innate antibodies), their non-covalent binding to B cell receptors (BCRs) does not stimulate an effective adaptive response from B cells. Covalent binding at naturally occurring nucleophilic sites of the BCRs by an electrophilic gp120 (E-gp120) analog is a promising solution. E-gp120 induces the synthesis of neutralizing antibodies the CD4BDcore. The highly energetic covalent reaction is hypothesized to convert the abortive superantigens–BCR interaction into a stimulatory signal, and the binding of a spatially distinct epitope at the traditional combining site of the BCRs may furnish a second stimulatory signal. Flexible synthetic peptides can detect pre-existing CD4BDcore-specific neutralizing antibodies. However, induced-fit conformational transitions of the peptides dictated by the antibody combining site structure may induce the synthesis of non-neutralizing antibodies. Successful vaccine targeting of the CD4BD will require a sufficiently rigid immunogen that mimics the native epitope conformation and bypasses B cell checkpoints restricting synthesis of the neutralizing antibodies.
Collapse
Affiliation(s)
- Yasuhiro Nishiyama
- Chemical Immunology Research Center, Department of Pathology and Laboratory Medicine, University of Texas-Houston Medical School Houston, TX, USA
| | | | | | | | | |
Collapse
|
4
|
Sapparapu G, Planque S, Mitsuda Y, McLean G, Nishiyama Y, Paul S. Constant domain-regulated antibody catalysis. J Biol Chem 2012; 287:36096-104. [PMID: 22948159 DOI: 10.1074/jbc.m112.401075] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Some antibodies contain variable (V) domain catalytic sites. We report the superior amide and peptide bond-hydrolyzing activity of the same heavy and light chain V domains expressed in the IgM constant domain scaffold compared with the IgG scaffold. The superior catalytic activity of recombinant IgM was evident using two substrates, a small model peptide that is hydrolyzed without involvement of high affinity epitope binding, and HIV gp120, which is recognized specifically by noncovalent means prior to the hydrolytic reaction. The catalytic activity was inhibited by an electrophilic phosphonate diester, consistent with a nucleophilic catalytic mechanism. All 13 monoclonal IgMs tested displayed robust hydrolytic activities varying over a 91-fold range, consistent with expression of the catalytic functions at distinct levels by different V domains. The catalytic activity of polyclonal IgM was superior to polyclonal IgG from the same sera, indicating that on average IgMs express the catalytic function at levels greater than IgGs. The findings indicate a favorable effect of the remote IgM constant domain scaffold on the integrity of the V-domain catalytic site and provide a structural basis for conceiving antibody catalysis as a first line immune function expressed at high levels prior to development of mature IgG class antibodies.
Collapse
Affiliation(s)
- Gopal Sapparapu
- Chemical Immunology Research Center, Department of Pathology and Laboratory Medicine, University of Texas Houston Medical School, Houston, Texas 77030, USA
| | | | | | | | | | | |
Collapse
|
5
|
Koutsopoulos S, Zhang S. Two-layered injectable self-assembling peptide scaffold hydrogels for long-term sustained release of human antibodies. J Control Release 2012; 160:451-8. [PMID: 22465676 DOI: 10.1016/j.jconrel.2012.03.014] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2012] [Revised: 03/15/2012] [Accepted: 03/15/2012] [Indexed: 10/28/2022]
Abstract
The release kinetics for human immunoglobulin (IgG) through the permeable structure of nanofiber scaffold hydrogels consisting of the ac-(RADA)(4)-CONH(2) and ac-(KLDL)(3)-CONH(2) self-assembling peptides were studied during a period of 3 months. Self assembling peptides are a class of stimuli-responsive materials which undergo sol-gel transition in the presence of an electrolyte solution such as biological fluids and salts. IgG diffusivities decreased with increasing hydrogel nanofiber density providing a means to control the release kinetics. Two-layered hydrogel structures were created consisting of concentric spheres of ac-(RADA)(4)-CONH(2) core and ac-(KLDL)(3)-CONH(2) shell and the antibody diffusion profile was determined through the 'onion-like' architecture. Secondary and tertiary structure analyses as well as biological assays using single molecule analyses and quartz crystal microbalance of the released IgG showed that encapsulation and release did not affect the conformation of the antibody and the biological activity even after 3 months inside the hydrogel. The functionality of polyclonal human IgG to the phosphocholine antigen was determined and showed that IgG encapsulation and release did not affect the antibody binding efficacy to the antigen. Our experimental protocol allows for 100% IgG loading efficiency inside the hydrogel while the maximum amount of antibody loading depends solely on the solubility of the antibody in water because the peptide hydrogel consists of water up to 99.5%. Our results show that this fully biocompatible and injectable peptide hydrogel system may be used for controlled release applications as a carrier for therapeutic antibodies.
Collapse
Affiliation(s)
- Sotirios Koutsopoulos
- Center for Biomedical Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA.
| | | |
Collapse
|
6
|
Brown EL, Nishiyama Y, Dunkle JW, Aggarwal S, Planque S, Watanabe K, Csencsits-Smith K, Bowden MG, Kaplan SL, Paul S. Constitutive production of catalytic antibodies to a Staphylococcus aureus virulence factor and effect of infection. J Biol Chem 2012; 287:9940-9951. [PMID: 22303018 DOI: 10.1074/jbc.m111.330043] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Antibodies that recognize microbial B lymphocyte superantigenic epitopes are produced constitutively with no requirement for adaptive immune maturation. We report cleavage of the Staphylococcus aureus virulence factor extracellular fibrinogen-binding protein (Efb) by catalytic antibodies produced with no exposure to the bacterium and reduction of the catalytic antibody activity following infection. IgG catalytic antibodies that specifically hydrolyzed Efb via a nucleophilic catalytic mechanism were found in the blood of healthy humans and aseptic mice free of S. aureus infection. IgG hydrolyzed peptide bonds on the C-terminal side of basic amino acids, including a bond located within the C3b-binding domain of Efb. Efb digested with the IgG lost its ability to bind C3b and inhibit complement-dependent antibody-mediated red blood cell lysis. In addition to catalysis, the IgG expressed saturable Efb binding activity. IgG from S. aureus-infected mice displayed reduced Efb cleaving activity and increased Efb binding activity compared with uninfected controls, suggesting differing effects of the infection on the antibody subsets responsible for the two activities. IgG from children hospitalized for S. aureus infection also displayed reduced Efb cleavage compared with healthy children. These data suggest a potential defense function for constitutively produced catalytic antibodies to a putative superantigenic site of Efb, but an adaptive catalytic response appears to be proscribed.
Collapse
Affiliation(s)
- Eric L Brown
- Center for Infectious Diseases, University of Texas School of Public Health, Houston, Texas 77030,; Department of Extracellular Matrix Biology, The Texas A&M University Institute of Biosciences and Technology, Houston, Texas 77030, and.
| | - Yasuhiro Nishiyama
- Department of Pathology and Laboratory Medicine, Chemical Immunology Research Center, University of Texas-Houston Medical School, Houston, Texas 77030
| | - Jesse W Dunkle
- Center for Infectious Diseases, University of Texas School of Public Health, Houston, Texas 77030
| | - Shreya Aggarwal
- Department of Pathology and Laboratory Medicine, Chemical Immunology Research Center, University of Texas-Houston Medical School, Houston, Texas 77030
| | - Stephanie Planque
- Department of Pathology and Laboratory Medicine, Chemical Immunology Research Center, University of Texas-Houston Medical School, Houston, Texas 77030
| | - Kenji Watanabe
- Department of Pathology and Laboratory Medicine, Chemical Immunology Research Center, University of Texas-Houston Medical School, Houston, Texas 77030
| | - Keri Csencsits-Smith
- Department of Pathology and Laboratory Medicine, Chemical Immunology Research Center, University of Texas-Houston Medical School, Houston, Texas 77030
| | - M Gabriela Bowden
- Department of Pathology and Laboratory Medicine, Chemical Immunology Research Center, University of Texas-Houston Medical School, Houston, Texas 77030
| | - Sheldon L Kaplan
- Department of Pediatrics, Baylor College of Medicine and the Texas Children's Hospital, Houston, Texas 77030
| | - Sudhir Paul
- Department of Pathology and Laboratory Medicine, Chemical Immunology Research Center, University of Texas-Houston Medical School, Houston, Texas 77030,.
| |
Collapse
|
7
|
Paul S, Planque S, Nishiyama Y, Escobar M, Hanson C. Back to the future: covalent epitope-based HIV vaccine development. Expert Rev Vaccines 2010; 9:1027-43. [PMID: 20822346 DOI: 10.1586/erv.10.77] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
Traditional HIV vaccine approaches have proved ineffective because the immunodominant viral epitopes are mutable and the conserved epitopes necessary for infection are not sufficiently immunogenic. The CD4 binding site expressed by the HIV envelope protein of glycoprotein 120 is essential for viral entry into host cells. In this article, we review the B-cell superantigenic character of the CD4 binding site as the cause of its poor immunogenicity. We summarize evidence supporting development of covalent immunization as the first vaccine strategy with the potential to induce an antibody response to a conserved HIV epitope that neutralizes genetically divergent HIV strains.
Collapse
Affiliation(s)
- Sudhir Paul
- Department of Pathology and Laboratory Medicine, Chemical Immunology Research Center, University of Texas-Houston Medical School, 6431 Fannin, MSB 2.230A, Houston, TX 77030, USA.
| | | | | | | | | |
Collapse
|
8
|
Nishiyama Y, Planque S, Mitsuda Y, Nitti G, Taguchi H, Jin L, Symersky J, Boivin S, Sienczyk M, Salas M, Hanson CV, Paul S. Toward effective HIV vaccination: induction of binary epitope reactive antibodies with broad HIV neutralizing activity. J Biol Chem 2009; 284:30627-42. [PMID: 19726674 DOI: 10.1074/jbc.m109.032185] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We describe murine monoclonal antibodies (mAbs) raised by immunization with an electrophilic gp120 analog (E-gp120) expressing the rare ability to neutralize genetically heterologous human immunodeficiency virus (HIV) strains. Unlike gp120, E-gp120 formed covalent oligomers. The reactivity of gp120 and E-gp120 with mAbs to reference neutralizing epitopes was markedly different, indicating their divergent structures. Epitope mapping with synthetic peptides and electrophilic peptide analogs indicated binary recognition of two distinct gp120 regions by anti-E-gp120 mAbs, the 421-433 and 288-306 peptide regions. Univalent Fab and single chain Fv fragments expressed the ability to recognize both peptides. X-ray crystallography of an anti-E-gp120 Fab fragment revealed two neighboring cavities, the typical antigen-binding cavity formed by the complementarity determining regions (CDRs) and another cavity dominated by antibody heavy chain variable (V(H)) domain framework (FR) residues. Substitution of the FR cavity V(H) Lys-19 residue by an Ala residue resulted in attenuated binding of the 421-433 region peptide probe. The CDRs and V(H) FR replacement/silent mutation ratios exceeded the ratio for a random mutation process, suggesting adaptive development of both putative binding sites. All mAbs studied were derived from V(H)1 family genes, suggesting biased recruitment of the V gene germ line repertoire by E-gp120. The conserved 421-433 region of gp120 is essential for HIV binding to host CD4 receptors. This region is recognized weakly by the FR of antibodies produced without exposure to HIV, but it usually fails to induce adaptive synthesis of neutralizing antibodies. We present models accounting for improved CD4-binding site recognition and broad HIV neutralizing activity of the mAbs, long sought goals in HIV vaccine development.
Collapse
Affiliation(s)
- Yasuhiro Nishiyama
- Department of Pathology and Laboratory Medicine, Chemical Immunology Research Center, University of Texas-Houston Medical School, Houston, Texas 77030, USA
| | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
9
|
Controlled release of functional proteins through designer self-assembling peptide nanofiber hydrogel scaffold. Proc Natl Acad Sci U S A 2009; 106:4623-8. [PMID: 19273853 DOI: 10.1073/pnas.0807506106] [Citation(s) in RCA: 335] [Impact Index Per Article: 20.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The release kinetics for a variety of proteins of a wide range of molecular mass, hydrodynamic radii, and isoelectric points through a nanofiber hydrogel scaffold consisting of designer self-assembling peptides were studied by using single-molecule fluorescence correlation spectroscopy (FCS). In contrast to classical diffusion experiments, the single-molecule approach allowed for the direct determination of diffusion coefficients for lysozyme, trypsin inhibitor, BSA, and IgG both inside the hydrogel and after being released into the solution. The results of the FCS analyses and the calculated pristine in-gel diffusion coefficients were compared with the values obtained from the Stokes-Einstein equation, Fickian diffusion models, and the literature. The release kinetics suggested that protein diffusion through nanofiber hydrogels depended primarily on the size of the protein. Protein diffusivities decreased, with increasing hydrogel nanofiber density providing a means of controlling the release kinetics. Secondary and tertiary structure analyses and biological assays of the released proteins showed that encapsulation and release did not affect the protein conformation and functionality. Our results show that this biocompatible and injectable designer self-assembling peptide hydrogel system may be useful as a carrier for therapeutic proteins for sustained release applications.
Collapse
|
10
|
Biological Activity of Aminophosphonic Acids and Their Short Peptides. TOPICS IN HETEROCYCLIC CHEMISTRY 2009. [DOI: 10.1007/7081_2008_14] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
|
11
|
Taguchi H, Planque S, Sapparapu G, Boivin S, Hara M, Nishiyama Y, Paul S. Exceptional amyloid beta peptide hydrolyzing activity of nonphysiological immunoglobulin variable domain scaffolds. J Biol Chem 2008; 283:36724-33. [PMID: 18974093 DOI: 10.1074/jbc.m806766200] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Nucleophilic sites in the paired variable domains of the light and heavy chains (VL and VH domains) of Ig can catalyze peptide bond hydrolysis. Amyloid beta (Abeta)-binding Igs are under consideration for immunotherapy of Alzheimer disease. We searched for Abeta-hydrolyzing human IgV domains (IgVs) in a library containing a majority of single chain Fv clones mimicking physiological VL-VH-combining sites and minority IgV populations with nonphysiological structures generated by cloning errors. Random screening and covalent selection of phage-displayed IgVs with an electrophilic Abeta analog identified rare IgVs that hydrolyzed Abeta mainly at His14-Gln15. Inhibition of IgV catalysis and irreversible binding by an electrophilic hapten suggested a nucleophilic catalytic mechanism. Structural analysis indicated that the catalytic IgVs are nonphysiological structures, a two domain heterodimeric VL (IgVL2-t) and single domain VL clones with aberrant polypeptide tags (IgVL-t'). The IgVs hydrolyzed Abeta at rates superior to naturally occurring Igs by 3-4 orders of magnitude. Forced pairing of the single domain VL with VH or VL domains resulted in reduced Abeta hydrolysis, suggesting catalysis by the unpaired VL domain.Angstrom level amino acid displacements evident in molecular models of the two domain and unpaired VL domain clones explain alterations of catalytic activity. In view of their superior catalytic activity, the VL domain IgVs may help attain clearance of medically important antigens more efficiently than natural Igs.
Collapse
Affiliation(s)
- Hiroaki Taguchi
- Chemical Immunology Research Center, Department of Pathology and Laboratory Medicine, University of Texas Houston Medical School, Houston, Texas 77030, USA
| | | | | | | | | | | | | |
Collapse
|
12
|
Planque S, Escobar MA, Smith KC, Taguchi H, Nishiyama Y, Donnachie E, Pratt KP, Paul S. Covalent inactivation of factor VIII antibodies from hemophilia A patients by an electrophilic FVIII Analog. J Biol Chem 2008; 283:11876-86. [PMID: 18337255 PMCID: PMC2335366 DOI: 10.1074/jbc.m800589200] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/23/2008] [Revised: 03/05/2008] [Indexed: 11/06/2022] Open
Abstract
The antigen-binding sites of antibodies (Abs) can express enzyme-like nucleophiles that react covalently with electrophilic compounds. We examined the irreversible and specific inactivation of antibodies (Abs) to Factor VIII (FVIII) responsible for failure of FVIII replacement therapy in hemophilia A (HA) patients. Electrophilic analogs of FVIII (E-FVIII) and its C2 domain (E-C2) were prepared by placing the strongly electrophilic phosphonate groups at surface-exposed Lys side chains of diverse antigenic epitopes. IgG Abs to FVIII from HA patients formed stable immune complexes with E-FVIII and E-C2 that were refractory to dissociation by SDS treatment and boiling, procedures that dissociate noncovalent Ab-antigen complexes. The rate-limiting step in the reaction was formation of the initial noncovalent complexes. Conversion of the initial complexes to the irreversible state occurred rapidly. The antigenic epitopes of E-FVIII were largely intact, and most of the Abs were consumed covalently. E-FVIII expressed poor FVIII cofactor activity in clotting factor assays. Nonspecific interference by E-FVIII in clotting factor function was not evident. Treatment with E-FVIII, and to a lesser extent E-C2, irreversibly relieved the FVIII inhibitory effect of HA IgG in clotting factor assays. Small FVIII peptides did not display useful reactivity, highlighting the diverse epitope specificities of the Abs and the conformational character of FVIII epitopes. E-FVIII is a prototype reagent able to attain irreversible and specific inactivation of pathogenic Abs.
Collapse
Affiliation(s)
- Stephanie Planque
- Chemical Immunology Research Center, Department of Pathology, University of Texas-Houston Medical School, Houston, Texas 77030, USA
| | | | | | | | | | | | | | | |
Collapse
|
13
|
Nishiyama Y, Mitsuda Y, Taguchi H, Planque S, Salas M, Hanson CV, Paul S. Towards Covalent Vaccination. J Biol Chem 2007; 282:31250-6. [PMID: 17728243 DOI: 10.1074/jbc.m706471200] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023] Open
Abstract
Rare monoclonal antibodies (Abs) can form irreversible complexes with antigens by enzyme-like covalent nucleophile-electrophile pairing. To determine the feasibility of applying irreversible antigen inactivation by Abs as the basis of vaccination against microbes, we studied the polyclonal nucleophilic Ab response induced by the electrophilic analog of a synthetic peptide corresponding to the principal neutralizing determinant (PND) of human immunodeficiency virus type-1 (HIV) gp120 located in the V3 domain. Abs from mice immunized with the PND analog containing electrophilic phosphonates (E-PND) neutralized a homologous HIV strain (MN) approximately 50-fold more potently than control Abs from mice immunized with PND. The IgG fractions displayed binding to intact HIV particles. HIV complexes formed by anti-E-PND IgG dissociated noticeably more slowly than the complexes formed by anti-PND IgG. The slower dissociation kinetics are predicted to maintain long-lasting blockade of host cell receptor recognition by gp120. Pretreatment of the anti-PND IgG with a haptenic electrophilic phosphonate compound resulted in more rapid dissociation of the HIV-IgG complexes, consistent with the hypothesis that enhanced Ab nucleophilic reactivity induced by electrophilic immunization imparts irreversible character to the complexes. These results suggest that electrophilic immunization induces a sufficiently robust nucleophilic Ab response to enhance the anti-microbial efficacy of candidate polypeptide vaccines.
Collapse
Affiliation(s)
- Yasuhiro Nishiyama
- Chemical Immunology Research Center, Department of Pathology and Laboratory Medicine, University of Texas--Houston Medical School, Houston, Texas 77030, USA.
| | | | | | | | | | | | | |
Collapse
|
14
|
Koen YM, Gogichaeva NV, Alterman MA, Hanzlik RP. A proteomic analysis of bromobenzene reactive metabolite targets in rat liver cytosol in vivo. Chem Res Toxicol 2007; 20:511-9. [PMID: 17305373 DOI: 10.1021/tx6003166] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Metabolic activation and protein covalent binding are early and apparently obligatory events in the cytotoxicity of many simple organic chemicals including drugs and natural products. Although much has been learned about the chemistry of reactive metabolite formation and reactivity toward protein nucleophiles, progress in identifying specific protein targets for reactive metabolites of various protoxins has been much slower. We previously reported nine microsomal and three cytosolic proteins as targets for reactive metabolites of bromobenzene in rat liver. These results, and contemporary work by others, indicate that protein covalent binding is not totally random in cells. Moreover, as protein targets for other protoxins were identified, little commonality of target proteins became apparent. In the present work, we used two-dimensional gel electrophoresis to separate liver cytosolic proteins from rats treated with 14C-bromobenzene; 110 of the 836 observed spots contained measurable radioactivity that varied over a 600-fold range of adduct density. Of these 110 spots, in-gel digestion coupled with mass spectrometry identified apparently single proteins in 57 spots. A few other spots clearly contained more than one identifiable protein, and in several cases, the same protein was identified in several spots having different apparent molecular masses and/or pI. Altogether, 33 unique new protein targets for bromobenzene metabolites were identified and compared to those known for acetaminophen, naphthalene, butylated hydroxytoluene, benzene, thiobenzamide, and halothane via a target protein database available at http://tpdb.medchem.ku.edu:8080/protein_database/. With increasing numbers of target proteins becoming known, more commonality in targeting by reactive metabolites from diverse chemical agents may be seen. Such commonality may help to separate toxicologically significant covalent binding events from a background of covalent binding that is toxicologically inconsequential.
Collapse
Affiliation(s)
- Yakov M Koen
- Department of Medicinal Chemistry, University of Kansas, Lawrence, Kansas 66045-7582, USA
| | | | | | | |
Collapse
|
15
|
Nishiyama Y, Karle S, Mitsuda Y, Taguchi H, Planque S, Salas M, Hanson C, Paul S. Towards irreversible HIV inactivation: stable gp120 binding by nucleophilic antibodies. J Mol Recognit 2007; 19:423-31. [PMID: 16838382 DOI: 10.1002/jmr.795] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
Conventional antibodies react with antigens reversibly. We report the formation of unusually stable complexes of HIV gp120 and nucleophilic antibodies raised by immunization with an electrophilic HIV gp120 analog (E-gp120). The stability of the complexes was evident from their very slow dissociation in a nondenaturing solvent (approximate t(1/2) 18.5 days) and their resistance to dissociation by a denaturant commonly employed to disrupt noncovalent protein-protein binding (sodium dodecyl sulfate). Kinetic studies indicated time-dependent and virtually complete progression of the antibody-gp120 complexes from the initial noncovalent state to a poorly dissociable state. The antibodies to E-gp120 displayed improved covalent reactivity with an electrophilic phosphonate probe compared to control antibodies, suggesting their enhanced nucleophilicity. One of the stably binding antibodies neutralized the infectivity of CCR5-dependent primary HIV strains belonging to clades B and C. These findings suggest the feasibility of raising antibodies capable of long-lasting inactivation of antigens by electrophilic immunization.
Collapse
Affiliation(s)
- Yasuhiro Nishiyama
- Chemical Immunology and Therapeutics Research Center, Department of Pathology and Laboratory Medicine, University of Texas-Houston Medical School, Houston, Texas 77030, USA
| | | | | | | | | | | | | | | |
Collapse
|
16
|
Paul S, Nishiyama Y, Planque S, Taguchi H. Theory of proteolytic antibody occurrence. Immunol Lett 2006; 103:8-16. [PMID: 16290203 DOI: 10.1016/j.imlet.2005.10.003] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2005] [Revised: 10/09/2005] [Accepted: 10/09/2005] [Indexed: 11/22/2022]
Abstract
Antibodies (Abs) with proteolytic and other catalytic activities have been characterized in the blood and mucosal secretions of humans and experimental animals. The catalytic activity can be traced to nucleophilic sites of innate origin located in Ab germline variable regions. Discoveries of the natural chemical reactivity of Abs were initially met with bewilderment, as the notion had taken hold that catalytic activities can be introduced into Abs by artificial means, but somatically operative selection pressures are designed only to adapt non-covalent Ab binding to antigen ground states. Unsurprisingly, initial efforts to engineer Abs with catalytic activity were oriented towards improving the non-covalent binding at the atoms immediately within the transition state reaction center. Slowly, however, dogmatic approaches to Ab catalysis have given way to the realization that efficient and specific catalytic Abs can be prepared by improving the natural nucleophilic reactivity combined with non-covalent recognition of epitope regions remote from the reaction center. The field remains beset, however, with controversy. This article attempts to provide a rational basis for natural Ab catalysis, in the hope that understanding this phenomenon will stimulate medical and basic science advances in the field.
Collapse
Affiliation(s)
- Sudhir Paul
- Chemical Immunology and Therapeutics Research Center, Department of Pathology and Laboratory Medicine, University of Texas-Houston Medical School, 6431 Fannin, 77030, USA.
| | | | | | | |
Collapse
|