title: Characterization of the interaction between L-ficolin/p35 and mannan-binding lectin-associated serine proteases-1 and -2.
abstract: Ficolins are oligomeric lectins comprising a collagen-like and a fibrinogen-like domain, with a binding specificity for N-acetylglucosamine. It has been reported recently that L-ficolin/P35 associates with mannan-binding lectin (MBL)-associated serine proteases (MASP-1 and -2) and MBL-associated protein 19 (MAp19) in serum and forms complexes able to activate complement. Using surface plasmon resonance spectroscopy we have shown that recombinant MASP-1 and -2, their N-terminal CUB1 (module originally found in complement proteins C1r/C1s, Uegf, and bone morphogenetic protein-1)-epidermal growth factor (EGF)-CUB2 and CUB1-EGF segments, and MAp19 bind to immobilized L-ficolin/P35 in the presence of Ca(2+) ions. Comparable K(d) values were obtained for the full-length proteases and their CUB1-EGF-CUB2 segments (9.2 and 10 nM for MASP-1 and 4.6 and 5.4 nM for MASP-2, respectively), whereas higher values were obtained for the CUB1-EGF segments (26.7, 15.6, and 14.3 nM for MASP-1, MASP-2, and MAp19). These values are in the same range as those determined for the interaction of these proteins with MBL. Binding was Ca(2+) dependent and was only partly sensitive to EDTA for MASP-1, MASP-2, and MASP-2 CUB1-EGF-CUB2. Half-maximal binding was obtained at comparable Ca(2+) concentrations for MASP-1 and MASP-2 (0.45 and 0.47 micro M, respectively), their CUB1-EGF-CUB2 segments (0.37 and 0.72 micro M), and their CUB1-EGF segments (0.31 and 0.79 micro M). These values are lower than those determined in the case of MBL, indicating a difference between MBL and L-ficolin/P35 with respect to the Ca(2+) dependence of their interaction with the MASPs. Preincubation of the MASPs with soluble MBL inhibited subsequent binding to immobilized L-ficolin/P35 and, conversely, suggesting that these lectins compete with each other for binding to the MASPs in vivo.
authors.affiliation: Laboratoire d'Enzymologie Moléculaire, Institut de Biologie Structurale Jean-Pierre Ebel (Commissariat à l'Energie Atomique-Centre National de la Recherche Scientifique-Université Joseph Fourier), 41 rue Jules Horowitz, 38027 Grenoble Cedex 1, France.
authors.forename: Sandor
authors.initials: S
authors.lastname: Cseh
authors.forename: Loanys
authors.initials: L
authors.lastname: Vera
authors.forename: Misao
authors.initials: M
authors.lastname: Matsushita
authors.forename: Teizo
authors.initials: T
authors.lastname: Fujita
authors.forename: Gérard J
authors.initials: GJ
authors.lastname: Arlaud
authors.forename: Nicole M
authors.initials: NM
authors.lastname: Thielens
mesh_terms: D020816:Amino Acid Motifs / Q000235:genetics; D000818:Animals; D001667:Binding, Competitive / Q000235:genetics; D002118:Calcium / Q000737:chemistry / Q000378:metabolism; D002352:Carrier Proteins / Q000737:chemistry / Q000378:metabolism*; D015923:Complement C1r / Q000235:genetics; D003173:Complement C1s / Q000235:genetics; D004815:Epidermal Growth Factor / Q000235:genetics; D006801:Humans; D037102:Lectins / Q000737:chemistry / Q000378:metabolism*; D037601:Mannose-Binding Lectin / Q000378:metabolism*; D050606:Mannose-Binding Protein-Associated Serine Proteases; D010446:Peptide Fragments / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding / Q000235:genetics; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000378:metabolism; D012697:Serine Endopeptidases / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018411:Spodoptera / Q000235:genetics; D020349:Surface Plasmon Resonance; D000097604:Ficolins
chemical_list: D002118:Calcium; D002352:Carrier Proteins; D015923:Complement C1r; D003173:Complement C1s; D004815:Epidermal Growth Factor; D037102:Lectins; D037601:Mannose-Binding Lectin; D050606:Mannose-Binding Protein-Associated Serine Proteases; D010446:Peptide Fragments; D011994:Recombinant Proteins; D012697:Serine Endopeptidases; D000097604:Ficolins; C105296:MASP2 protein, human