Protein Engineering, Vol. 13, No. 5, 345-351,
May 2000
© 2000 Oxford University Press
Structure of the M
2-3 toxin
antibodyantigen complex: combination of modelling with functional mapping experimental results
1 Section de Biophysique des Protéines et des Membranes, DBCM, CEN-Saclay, 91191 Gif-sur-Yvette, France and 3 Lehrstuhl für Biocomputing, IWR, Universität Heidelberg, Im Neuenheimer Feld 368, D-69120 Heidelberg, Germany
Modelled structures of the acetylcholine receptor-mimicking antibody, M
2-3, both free and bound to its antigen, toxin
, are assessed in the light of new experimental mutational data from functional mapping of the paratopic region of M
2-3. The experimental results are consistent with the previously-predicted structure of the free antibody, and also demonstrate that structural particularities of the M
2-3 combining site that were identified in the models play a role in the protein association. The modelled conformations of the hypervariable loops are discussed in the context of recent new data and analyses. The new mutational data allow several previously-considered modelled structures of the complex to be rejected. Two quite similar models now remain.