Enhancement and destruction of antibody function by somatic mutation: Unequal occurrence is controlled by V gene combinatorial associations

C. Chen, V. A. Roberts, S. Stevens, M. Brown, M. P. Stenzel-Poore, M. B. Rittenberg*

*Corresponding author for this work

Research output: Contribution to journalArticle

40 Scopus citations

Abstract

We examined the positive and negative effects of somatic mutation on antibody function using saturation mutagenesis in vitro to mimic the potential of the in vivo process to diversify antibodies. Identical mutations were introduced into the second complementarity determining region of two anti-phosphocholine antibodies, T15 and D16, which share the same germline VH gene sequence. T15 predominates in primary responses and does not undergo affinity maturation. D16 is representative of antibodies that co-dominate in memory responses and do undergo affinity maturation. We previously reported that > 50% of T15 mutants had decreased antigen binding capacity. To test if this high frequency of binding loss was unique to T15 or a consequence of random point mutations applicable to other combining sites, we analyzed the same mutations in D16. We show that D16 suffers a similar loss of function, indicating an equally high potential for B-cell wastage. However, only D16 displayed the capacity for somatic mutation to improve antigen binding, which should enhance its persistence in memory responses. Mutation of residues contacting the haptenic group, as determined by molecular modeling, did not improve binding. Instead, productive mutations occurred in residues that either contacted carrier protein or were distant from the antigen binding site, possibly increasing binding site flexibility through long-range effects. Targeting such residues for mutation should aid in the rational design of improved antibodies.

Original languageEnglish (US)
Pages (from-to)2784-2794
Number of pages11
JournalEMBO Journal
Volume14
Issue number12
DOIs
StatePublished - 1995

Keywords

  • Affinity maturation
  • Antibody
  • Molecular Modeling
  • Saturation mutagenesis
  • Somatic mutation

ASJC Scopus subject areas

  • Neuroscience(all)
  • Molecular Biology
  • Biochemistry, Genetics and Molecular Biology(all)
  • Immunology and Microbiology(all)

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