All individual domains of staphylococcal protein A show Fab binding.
The interactions between the individual domains (E, D, A, B and C) of staphylococcal protein A (SPA) and Fc and Fab regions of human immunoglobulins were studied using real-time biospecific interaction analysis. An engineered domain Z, similar to fragment B but with a single glycine to alanine amino acid substitution, was also included in the study. The domains were expressed in Escherichia coli, affinity purified and immobilised onto sensor chip surfaces in a directed manner using a unique C-terminal cysteine residue engineered into the recombinant proteins. All domains bound to a recombinant human IgG1 Fc fragment with similar strength. For the first time, binding to human Fab was demonstrated for all native SPA domains, using both polyclonal F(ab')2 and a recombinant scFv fragment as reagents. Interestingly, the engineered Z domain showed a considerably lower affinity for Fab as compared to the native domains.
Jansson
B
B
Department of Biochemistry and Biotechnology, Royal Institute of Technology, Stockholm, Sweden.
Uhlén
M
M
Nygren
P A
PA
D000595:Amino Acid Sequence; D000937:Antigen-Antibody Reactions; D002846:Chromatography, Affinity; D005822:Genetic Vectors; D007140:Immunoglobulin Fab Fragments / Q000276:immunology* / Q000378:metabolism; D007141:Immunoglobulin Fc Fragments / Q000276:immunology / Q000378:metabolism; D007128:Immunoglobulin Fragments / Q000276:immunology / Q000378:metabolism; D008969:Molecular Sequence Data; D011485:Protein Binding; D011993:Recombinant Fusion Proteins / Q000276:immunology / Q000378:metabolism; D013205:Staphylococcal Protein A / Q000737:chemistry / Q000235:genetics / Q000276:immunology* / Q000378:metabolism
D007140:Immunoglobulin Fab Fragments; D007141:Immunoglobulin Fc Fragments; D007128:Immunoglobulin Fragments; D011993:Recombinant Fusion Proteins; D013205:Staphylococcal Protein A; C055966:immunoglobulin Fv