Convergent evolution among immunoglobulin G-binding bacterial proteins.
Protein G, a bacterial cell-wall protein with high affinity for the constant region of IgG (IgGFc) antibodies, contains homologous repeats responsible for the interaction with IgGFc. A synthetic peptide corresponding to an 11-amino acid-long sequence in the COOH-terminal region of the repeats was found to bind to IgGFc and block the interaction with protein G. Moreover, two other IgGFc-binding bacterial proteins (proteins A and H), which do not contain any sequences homologous to the peptide, were also inhibited in their interactions with IgGFc by the peptide. Finally, a decapeptide based on a sequence in IgGFc blocked the binding of all three proteins to IgGFc. This unusually clear example of convergent evolution emphasizes the complexity of protein-protein interactions and suggests that bacterial surface-protein interaction with host protein adds selective advantages to the microorganism.
Frick
I M
IM
Department of Medical, University of Lund, Sweden.
Wikström
M
M
Forsén
S
S
Drakenberg
T
T
Gomi
H
H
Sjöbring
U
U
Björck
L
L
D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism*; D002352:Carrier Proteins; D007141:Immunoglobulin Fc Fragments / Q000737:chemistry / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D008565:Membrane Proteins; D008958:Models, Molecular; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry / Q000378:metabolism; D013205:Staphylococcal Protein A / Q000737:chemistry / Q000378:metabolism; D013291:Streptococcus / Q000276:immunology*
D001426:Bacterial Proteins; D002352:Carrier Proteins; C034284:IgG Fc-binding protein, Streptococcus; D007141:Immunoglobulin Fc Fragments; D008565:Membrane Proteins; D010455:Peptides; D013205:Staphylococcal Protein A; C064006:protein H, Streptococcus