Structural insights into the evolution of an antibody combining site

GJ Wedemayer, PA Patten, LH Wang, PG Schultz… - Science, 1997 - science.org
GJ Wedemayer, PA Patten, LH Wang, PG Schultz, RC Stevens
Science, 1997science.org
The crystal structures of a germline antibody Fab fragment and its complex with hapten have
been solved at 2.1 Å resolution. These structures are compared with the corresponding
crystal structures of the affinity-matured antibody, 48G7, which has a 30,000 times higher
affinity for hapten as a result of nine replacement somatic mutations. Significant changes in
the configuration of the combining site occur upon binding of hapten to the germline
antibody, whereas hapten binds to the mature antibody by a lock-and-key fit mechanism …
The crystal structures of a germline antibody Fab fragment and its complex with hapten have been solved at 2.1 Å resolution. These structures are compared with the corresponding crystal structures of the affinity-matured antibody, 48G7, which has a 30,000 times higher affinity for hapten as a result of nine replacement somatic mutations. Significant changes in the configuration of the combining site occur upon binding of hapten to the germline antibody, whereas hapten binds to the mature antibody by a lock-and-key fit mechanism. The reorganization of the combining site that was nucleated by hapten binding is further optimized by somatic mutations that occur up to 15 Å from bound hapten. These results suggest that the binding potential of the primary antibody repertoire may be significantly expanded by the ability of germline antibodies to adopt more than one combining-site configuration, with both antigen binding and somatic mutation stabilizing the configuration with optimal hapten complementarity.
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