title: Interaction of human, rat, and mouse immunoglobulin A (IgA) with Staphylococcal superantigen-like 7 (SSL7) decoy protein and leukocyte IgA receptor.
abstract: 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.
authors.affiliation: Centre for Immunology, The Burnet Institute, Melbourne 3004, Australia.
authors.forename: Bruce D
authors.initials: BD
authors.lastname: Wines
authors.forename: Paul A
authors.initials: PA
authors.lastname: Ramsland
authors.forename: Halina M
authors.initials: HM
authors.lastname: Trist
authors.forename: Sandra
authors.initials: S
authors.lastname: Gardam
authors.forename: Robert
authors.initials: R
authors.lastname: Brink
authors.forename: John D
authors.initials: JD
authors.lastname: Fraser
authors.forename: P Mark
authors.initials: PM
authors.lastname: Hogarth
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D015703:Antigens, CD / Q000378:metabolism; D005098:Exotoxins / Q000378:metabolism*; D006031:Glycosylation; D006801:Humans; D007070:Immunoglobulin A / Q000737:chemistry / Q000378:metabolism*; D007962:Leukocytes / Q000378:metabolism*; D051379:Mice; D008958:Models, Molecular; D008969:Molecular Sequence Data; D050505:Mutant Proteins / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding; D051381:Rats; D011961:Receptors, Fc / Q000378:metabolism*; D016415:Sequence Alignment
chemical_list: D015703:Antigens, CD; D005098:Exotoxins; C036832:Fc(alpha) receptor; C045281:IgA receptor; D007070:Immunoglobulin A; D050505:Mutant Proteins; D011961:Receptors, Fc; C416085:staphylococcal exotoxin 1