TY - JOUR
T1 - Significant structural and functional change of an antigen-binding site by a distant amino acid substitution
T2 - Proposal of a structural mechanism
AU - Chien, N. C.
AU - Roberts, V. A.
AU - Giusti, A. M.
AU - Scharff, M. D.
AU - Getzoff, E. D.
PY - 1989
Y1 - 1989
N2 - To study the molecular basis for antibody diversity and the structural basis for antigen binding, we have characterized the loss of phosphocholine (P-Cho) binding both experimentally and computationally in U10, a somatic mutant of the antibody S107. Nucleotide sequencing of U10 shows a single base change in J(H)1, substituting Asp-101 with Ala, over 9 Å distant from the P-Cho-binding pocket. Probing with anti-idiotypic antibodies suggests local, not global, conformational changes. Computational results support a specific structural mechanism for the loss of P-Cho binding. The U10 mutation eliminates the charged interaction between Asp-101 and Arg-94, which allows the Arg-94 side chain to disrupt P-Cho binding sterically and electrostatically by folding into the P-Cho-binding site. These results specifically show the importance of the Arg-94 to Asp-101 side chain salt bridge in the heavy-chain CDR3 conformation and suggest that residues distant from the binding site play an important role in antibody diversity and inducible complementarity.
AB - To study the molecular basis for antibody diversity and the structural basis for antigen binding, we have characterized the loss of phosphocholine (P-Cho) binding both experimentally and computationally in U10, a somatic mutant of the antibody S107. Nucleotide sequencing of U10 shows a single base change in J(H)1, substituting Asp-101 with Ala, over 9 Å distant from the P-Cho-binding pocket. Probing with anti-idiotypic antibodies suggests local, not global, conformational changes. Computational results support a specific structural mechanism for the loss of P-Cho binding. The U10 mutation eliminates the charged interaction between Asp-101 and Arg-94, which allows the Arg-94 side chain to disrupt P-Cho binding sterically and electrostatically by folding into the P-Cho-binding site. These results specifically show the importance of the Arg-94 to Asp-101 side chain salt bridge in the heavy-chain CDR3 conformation and suggest that residues distant from the binding site play an important role in antibody diversity and inducible complementarity.
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U2 - 10.1073/pnas.86.14.5532
DO - 10.1073/pnas.86.14.5532
M3 - Article
C2 - 2748602
AN - SCOPUS:0024368992
SN - 0027-8424
VL - 86
SP - 5532
EP - 5536
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
IS - 14
ER -