Interaction of human, rat, and mouse immunoglobulin A (IgA) with Staphylococcal superantigen-like 7 (SSL7) decoy protein and leukocyte IgA receptor

J Biol Chem. 2011 Sep 23;286(38):33118-24. doi: 10.1074/jbc.M111.272252. Epub 2011 Jul 22.


Host survival depends on an effective immune system and pathogen survival on the effectiveness of immune evasion mechanisms. Staphylococcus aureus utilizes a number of molecules to modulate host immunity, including the SSL family of which SSL7 binds IgA and inhibits Fcα receptor I (FcαRI)-mediated function. Other Gram-positive bacterial pathogens produce IgA binding proteins, which, similar to SSL7, also bind the Fc at the CH2/CH3 interface (the junction between constant domains 2 and 3 of the heavy chain). The opposing activities of the host FcαRI-IgA receptor ligand pair and the pathogen decoy proteins select for host and pathogen variants, which exert stronger protection or evasion, respectively. Curiously, mouse but not rat IgA contains a putative N-linked glycosylation site in the center of this host receptor and pathogen-binding site. Here, we demonstrate that this site is glycosylated and that the effect of amino acid changes and glycosylation of the CH2/CH3 interface inhibits interaction with the pathogen IgA binding protein SSL7, while maintaining binding of pIgR, essential to the biosynthesis and transport of SIgA.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Antigens, CD / metabolism
  • Exotoxins / metabolism*
  • Glycosylation
  • Humans
  • Immunoglobulin A / chemistry
  • Immunoglobulin A / metabolism*
  • Leukocytes / metabolism*
  • Mice
  • Models, Molecular
  • Molecular Sequence Data
  • Mutant Proteins / chemistry
  • Mutant Proteins / metabolism
  • Protein Binding
  • Rats
  • Receptors, Fc / metabolism*
  • Sequence Alignment


  • Antigens, CD
  • Exotoxins
  • Fc(alpha) receptor
  • IgA receptor
  • Immunoglobulin A
  • Mutant Proteins
  • Receptors, Fc
  • staphylococcal exotoxin 1