Mutational analysis of the interaction between albumin-binding domain from streptococcal protein G and human serum albumin.
Streptococcal protein G (SpG) is a bacterial cell surface receptor exhibiting affinity to both human immunoglobulin (IgG) and human serum albumin (HSA). Interestingly, the serum albumin and immunoglobulin-binding activities have been shown to reside at functionally and structurally separated receptor domains. The binding domain of the HSA-binding part has been shown to be a 46-residue triple alpha-helical structure, but the binding site to HSA has not yet been determined. Here, we have investigated the precise binding region of this bacterial receptor by protein engineering applying an alanine-scanning procedure followed by binding studies by surface plasmon resonance (SPR). The secondary structure as well as the HSA binding of the resulting albumin-binding domain (ABD) variants were analyzed using circular dichroism (CD) and affinity blotting. The analysis shows that the HSA binding involves residues mainly in the second alpha-helix.
Linhult
Martin
M
Department of Biotechnology, Royal Institute of Technology (KTH), SCFAB, S-106 91 Stockholm, Sweden.
Binz
Hans Kaspar
HK
Uhlén
Mathias
M
Hober
Sophia
S
D001426:Bacterial Proteins / Q000378:metabolism*; D001665:Binding Sites / Q000235:genetics; D002942:Circular Dichroism; D006801:Humans; D007074:Immunoglobulin G / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D011485:Protein Binding; D011487:Protein Conformation; D011994:Recombinant Proteins / Q000378:metabolism; D012709:Serum Albumin / Q000378:metabolism*; D013329:Structure-Activity Relationship; D020349:Surface Plasmon Resonance
D001426:Bacterial Proteins; C034284:IgG Fc-binding protein, Streptococcus; D007074:Immunoglobulin G; D011994:Recombinant Proteins; D012709:Serum Albumin