Maturation of an antibody response is governed by modulations in flexibility of the antigen-combining site.

Although affinity maturation constitutes an integral part of T-dependent humoral responses, its structural basis is less well understood. We compared the physicochemical properties of antigen binding of several independent antibody panels derived from both germline and secondary responses. We found that antibody maturation essentially reflects modulations in entropy-control of the association, but not dissociation, step of the binding. This influence stems from variations in conformational heterogeneity of the antigen-combining site, which in turn regulates both the affinity and specificity for antigen. Thus, the simple device of manipulating conformational flexibility of paratope provides a mechanism wherein the transition from a degenerate recognition capability to a high-fidelity effector response is readily achieved, with the minimum of somatic mutations.

[1]  I. Wilson,et al.  Structural analysis of antibody specificity. Detailed comparison of five Fab'-steroid complexes. , 1994, Journal of molecular biology.

[2]  G. Kelsoe In situ studies of the germinal center reaction. , 1995, Advances in immunology.

[3]  R. Poljak,et al.  Crystal structure of the complex of the variable domain of antibody D1.3 and turkey egg white lysozyme: a novel conformational change in antibody CDR-L3 selects for antigen. , 1996, Journal of molecular biology.

[4]  M. Weigert,et al.  Fixing Mismatches , 1998, Science.

[5]  N. Maizels,et al.  Somatic hypermutation: How many mechanisms diversify V region sequences? , 1995, Cell.

[6]  Christopher Lee Calculating binding energies , 1992, Current Biology.

[7]  R. P. Roy,et al.  B cell responses to a peptide epitope. V. Kinetic regulation of repertoire discrimination and antibody optimization for epitope. , 1998, Journal of immunology.

[8]  B K Jakobsen,et al.  TCR binding to peptide-MHC stabilizes a flexible recognition interface. , 1999, Immunity.

[9]  A M Lesk,et al.  Structural repertoire of the human VH segments. , 1992, Journal of molecular biology.

[10]  D. F. Waugh,et al.  Protein-protein interactions. , 1954, Advances in protein chemistry.

[11]  G. Petsko,et al.  Three-dimensional structure of murine anti-p-azophenylarsonate Fab 36-71. 2. Structural basis of hapten binding and idiotypy. , 1991, Biochemistry.

[12]  J. Foote,et al.  Kinetic and affinity limits on antibodies produced during immune responses. , 1995, Proceedings of the National Academy of Sciences of the United States of America.

[13]  E L Sonnhammer,et al.  The imprint of somatic hypermutation on the repertoire of human germline V genes. , 1996, Journal of molecular biology.

[14]  P. Schultz,et al.  Mutational analysis of the affinity maturation of antibody 48G7. , 1999, Journal of Molecular Biology.

[15]  Y. Pewzner‐Jung,et al.  Structural elements controlling anti-DNA antibody affinity and their relationship to anti-phosphorylcholine activity. , 1996, Journal of immunology.

[16]  M. Schumacher,et al.  The Structural Basis of Repertoire Shift in an Immune Response to Phosphocholine , 2000, The Journal of experimental medicine.

[17]  R. Vishwakarma,et al.  B Cell Responses to a Peptide Epitope. X. Epitope Selection in a Primary Response Is Thermodynamically Regulated1 , 2000, The Journal of Immunology.

[18]  R C Stevens,et al.  Structural insights into the evolution of an antibody combining site. , 1997, Science.

[19]  L. Wysocki,et al.  Clustered H chain somatic mutations shared by anti-p-azophenylarsonate antibodies confer enhanced affinity and ablate the cross-reactive idiotype. , 1990, Journal of immunology.

[20]  P. Nakra,et al.  B cell responses to a peptide epitope , 2000 .

[21]  A. Agarwal,et al.  B cell responses to a peptide epitope. I. The cellular basis for restricted recognition. , 1996, Journal of immunology.

[22]  L R Pease,et al.  Structural basis of plasticity in T cell receptor recognition of a self peptide-MHC antigen. , 1998, Science.

[23]  Christopher Lee Calculating binding energies: Current Opinion in Structural Biology 1992, 2:217–222 , 1992 .

[24]  L Wang,et al.  Molecular dynamics and free-energy calculations applied to affinity maturation in antibody 48G7. , 1999, Proceedings of the National Academy of Sciences of the United States of America.

[25]  C. Arpin,et al.  Germinal center development , 1997, Immunological reviews.

[26]  I. Wilson,et al.  Structural evidence for induced fit as a mechanism for antibody-antigen recognition. , 1994, Science.

[27]  C. Slaughter,et al.  The cross-reactive idiotype of A-strain mice Serological and structural analyses. , 1982, Immunology today.

[28]  Z Reich,et al.  Thermodynamics of T cell receptor binding to peptide-MHC: evidence for a general mechanism of molecular scanning. , 1999, Proceedings of the National Academy of Sciences of the United States of America.

[29]  W. Stites,et al.  Protein−Protein Interactions: Interface Structure, Binding Thermodynamics, and Mutational Analysis , 1997 .

[30]  A. Agarwal,et al.  B cell responses to a peptide epitope: III. Differential T helper cell thresholds in recruitment of B cell fine specificities. , 1997, Journal of immunology.

[31]  A. Sarai,et al.  The Affinity Maturation of Anti-4-hydroxy-3-nitrophenylacetyl Mouse Monoclonal Antibody , 1995, The Journal of Biological Chemistry.

[32]  R L Stanfield,et al.  Antibody-antigen interactions: new structures and new conformational changes. , 1994, Current opinion in structural biology.

[33]  J. Janin,et al.  Principles of protein-protein recognition from structure to thermodynamics. , 1995, Biochimie.

[34]  P. Kussie,et al.  Modulation of antibody affinity by an engineered amino acid substitution. , 1995, Journal of immunology.

[35]  C. Milstein,et al.  Conformational isomerism and the diversity of antibodies. , 1994, Proceedings of the National Academy of Sciences of the United States of America.

[36]  Kanury Rao,et al.  Selection in a T‐dependent primary humoral response: new insight from polypeptide models: , 1999, APMIS : acta pathologica, microbiologica, et immunologica Scandinavica.

[37]  I. Wilson,et al.  Antibody-antigen interactions , 1993 .

[38]  S. Smith‐Gill,et al.  Patterns of antibody specificity during the BALB/c immune response to hen eggwhite lysozyme. , 1992, Journal of immunology.

[39]  K N Houk,et al.  Evolution of shape complementarity and catalytic efficiency from a primordial antibody template. , 1999, Science.

[40]  K. Tsumoto,et al.  Role of Salt Bridge Formation in Antigen-Antibody Interaction , 1996, The Journal of Biological Chemistry.

[41]  H. Nakamura,et al.  Junctional amino acids determine the maturation pathway of an antibody. , 1999, Immunity.

[42]  G. F. Joyce Evolutionary Chemistry: Getting There from Here , 1997, Science.

[43]  R M Zinkernagel,et al.  Early high-affinity neutralizing anti-viral IgG responses without further overall improvements of affinity. , 1995, Proceedings of the National Academy of Sciences of the United States of America.

[44]  T. Manser,et al.  Altering the antibody repertoire via transgene homologous recombination: evidence for global and clone-autonomous regulation of antigen-driven B cell differentiation , 1995, The Journal of experimental medicine.

[45]  T. Manser,et al.  Evaluation of loss and change of specificity resulting from random mutagenesis of an antibody VH region. , 1995, Journal of immunology.

[46]  T. Manser,et al.  Amplified follicular immune complex deposition in mice lacking the Fc receptor gamma-chain does not alter maturation of the B cell response. , 1997, Journal of immunology.

[47]  D. Mason,et al.  A very high level of crossreactivity is an essential feature of the T-cell receptor. , 1998, Immunology today.