Degenerate interfaces in antigen-antibody complexes.
In most of the work dealing with the analysis of protein-protein interfaces, a single X-ray structure is available or selected, and implicitly it is assumed that this structure corresponds to the optimal complex for this pair of proteins. However, we have found a degenerate interface in a high-affinity antibody-antigen complex: the two independent complexes of the camel variable domain antibody fragment cAb-Lys3 and its antigen hen egg white lysozyme present in the asymmetric unit of our crystals show a difference in relative orientation between antibody and antigen, leading to important differences at the protein-protein interface. A third cAb-Lys3-hen lysozyme complex in a different crystal form adopts yet another relative orientation. Our results show that protein-protein interface characteristics can vary significantly between different specimens of the same high-affinity antibody-protein antigen complex. Consideration should be given to this type of observation when trying to establish general protein-protein interface characteristics.
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Vrije Universiteit Brussel Dienst Ultrastructuur, Vlaams Instituut voor Biotechnologie, Paardenstraat 65, B-1640 St.-Genesius Rode, Belgium. klaas@ultr.vub.ac.be
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Desmyter
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Maes
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Muyldermans
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Wyns
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D000818:Animals; D000936:Antigen-Antibody Complex / Q000737:chemistry* / Q000276:immunology*; D001666:Binding Sites, Antibody; D002162:Camelus; D002645:Chickens / Q000276:immunology; D018360:Crystallography, X-Ray; D004529:Egg White; D005260:Female; D007135:Immunoglobulin Variable Region / Q000737:chemistry / Q000276:immunology; D008958:Models, Molecular; D009113:Muramidase / Q000737:chemistry* / Q000276:immunology*; D010446:Peptide Fragments / Q000737:chemistry / Q000276:immunology; D011487:Protein Conformation
D000936:Antigen-Antibody Complex; D007135:Immunoglobulin Variable Region; D010446:Peptide Fragments; D009113:Muramidase