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 a-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.

Subject headings

TEKNIK OCH TEKNOLOGIER  -- Industriell bioteknik (hsv//swe)

ENGINEERING AND TECHNOLOGY  -- Industrial Biotechnology (hsv//eng)

Keyword

binding

affinity

human serum albumin (HSA)

albumin-binding domain (ABD)

mutational analysis

functional epitope

receptor

mutagenesis

interface

affinity

reveals

ligand

region

Publication and Content Type

ref (subject category)

art (subject category)