Molecular evolution of antibody cross-reactivity for two subtypes of type A botulinum neurotoxin


GARCIA-RODRIGUEZ C., LEVY R., ARNDT J. W. , FORSYTH C. M. , RAZAI A., LOU J., et al.

NATURE BIOTECHNOLOGY, cilt.25, ss.107-116, 2007 (SCI İndekslerine Giren Dergi)

  • Cilt numarası: 25 Konu: 1
  • Basım Tarihi: 2007
  • Doi Numarası: 10.1038/nbt1269
  • Dergi Adı: NATURE BIOTECHNOLOGY
  • Sayfa Sayısı: ss.107-116

Özet

Broadening antibody specificity without compromising affinity should facilitate detection and neutralization of toxin and viral subtypes. We used yeast display and a co-selection strategy to increase cross-reactivity of a single chain (sc) Fv antibody to botulinum neurotoxin type A (BoNT/A). Starting with a scFv that binds the BoNT/A1 subtype with high affinity (136 pM) and the BoNT/A2 subtype with low affinity (109 nM), we increased its affinity for BoNT/A2 1,250-fold, to 87 pM, while maintaining high-affinity binding to BoNT/A1 (115 pM). To find the molecular basis for improved cross-reactivity, we determined the X-ray co-crystal structures of wild-type and cross-reactive antibodies complexed to BoNT/A1 at resolutions up to 2.6 angstrom, and measured the thermodynamic contribution of BoNT/A1 and A2 amino acids to wild-type and cross-reactive antibody binding. The results show how an antibody can be engineered to bind two different antigens despite structural differences in the antigen-antibody interface and may provide a general strategy for tuning antibody specificity and cross-reactivity.