title: MG2 and lactoferrin form a heterotypic complex in salivary secretions.
abstract: Protein-protein interactions are necessary for homeostasis to be maintained and for biological systems to be integrated. Heterotypic complexes occur in saliva, and a complex between MG2 and SIgA has been suggested to promote microbial clearance from the oral cavity. In this study, we used a peptide display library to investigate previously unrecognized heterotypic complexes involving MG2 and other proteins. The library was panned with MG2 12 times, and analyses of clones identified the sequence Ala-Leu-Leu-Cys-, which occurs in salivary lactoferrin. Blotting experiments confirmed that MG2 and lactoferrin form a heterotypic complex in vitro and in vivo. Periodate treatment of MG2 did not affect the interaction. A synthetic lactoferrin peptide containing the motif Ala-Leu-Leu-Cys-blocked the interaction between MG2 and lactoferrin, confirming the specificity of the interaction identified by panning. This complex may enhance the properties of these salivary components in the oral environment.
authors.affiliation: Department of Periodontology and Oral Biology, Boston University Medical Center, 02118, USA.
authors.forename: R V
authors.initials: RV
authors.lastname: Soares
authors.forename: C C
authors.initials: CC
authors.lastname: Siqueira
authors.forename: L S
authors.initials: LS
authors.lastname: Bruno
authors.forename: F G
authors.initials: FG
authors.lastname: Oppenheim
authors.forename: G D
authors.initials: GD
authors.lastname: Offner
authors.forename: R F
authors.initials: RF
authors.lastname: Troxler
mesh_terms: D000328:Adult; D000409:Alanine; D003545:Cysteine; D006801:Humans; D007071:Immunoglobulin A, Secretory / Q000378:metabolism; D007781:Lactoferrin / Q000378:metabolism*; D007930:Leucine; D009077:Mucins / Q000378:metabolism*; D009842:Oligopeptides / Q000737:chemistry; D016877:Oxidants / Q000494:pharmacology; D010504:Periodic Acid / Q000494:pharmacology; D011485:Protein Binding / Q000187:drug effects; D025941:Protein Interaction Mapping; D012471:Salivary Proteins and Peptides / Q000378:metabolism*; D020539:Sequence Analysis, Protein; D013045:Species Specificity
chemical_list: D007071:Immunoglobulin A, Secretory; C083238:MUC7 protein, human; D009077:Mucins; D009842:Oligopeptides; D016877:Oxidants; D012471:Salivary Proteins and Peptides; D010504:Periodic Acid; C009288:metaperiodate; D007781:Lactoferrin; D007930:Leucine; D003545:Cysteine; D000409:Alanine