Convergent evolution among immunoglobulin G-binding bacterial proteins

Research output: Contribution to journalArticle


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.


  • Inga-Maria Frick
  • M Wikström
  • S Forsen
  • Torbjörn Drakenberg
  • H Gomi
  • U Sjöbring
  • L Björck
Research areas and keywords

Subject classification (UKÄ)

  • Infectious Medicine
Original languageEnglish
Pages (from-to)8532-8536
JournalProceedings of the National Academy of Sciences
Issue number18
Publication statusPublished - 1992
Publication categoryResearch