Identification of the contact surface of a streptococcal protein G domain complexed with a human Fc fragment.
The B1 domain of streptococcal protein G interacts with the C-terminal fragment of the heavy chain of immunoglobulin G (IgGFc). The binding site for the protein G domain on the antibody fragment is in close proximity or overlapping with that determined for staphylococcal protein A. The interaction of the B1 domain with IgGFc was investigated by 1H-15N correlation spectroscopy. The major interaction site on the B1 domain comprises parts of beta-strand 3 as well as the alpha-helix. Comparison with the crystal structure of the protein A/IgGFc complex suggests that the mode of interaction in the two complexes is analogous, despite the lack of sequence or structural similarity between two antibody binding proteins.
Gronenborn
A M
AM
Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, MD 20814.
Clore
G M
GM
D001426:Bacterial Proteins / Q000737:chemistry*; D006801:Humans; D007141:Immunoglobulin Fc Fragments / Q000737:chemistry*; D007074:Immunoglobulin G / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D011487:Protein Conformation
D001426:Bacterial Proteins; C034284:IgG Fc-binding protein, Streptococcus; D007141:Immunoglobulin Fc Fragments; D007074:Immunoglobulin G