Characterization of beta-glucan recognition site on C-type lectin, dectin 1.
Dectin 1 is a mammalian cell surface receptor for (1-->3)-beta-d-glucans. Since (1-->3)-beta-d-glucans are commonly present on fungal cell walls, it has been suggested that dectin 1 is important for recognizing fungal invasion. In this study we tried to deduce the amino acid residues in dectin 1 responsible for beta-glucan recognition. HEK293 cells transfected with mouse dectin 1 cDNA could bind to a gel-forming (1-->3)-beta-d-glucan, schizophyllan (SPG). The binding of SPG to a dectin 1 transfectant was inhibited by pretreatment with other beta-glucans having a (1-->3)-beta-d-glucosyl linkage but not by pretreatment with alpha-glucans. Dectin 1 has a carbohydrate recognition domain (CRD) consisting of six cysteine residues that are highly conserved in C-type lectins. We prepared 32 point mutants with mutations in the CRD and analyzed their binding to SPG. Mutations at Trp(221) and His(223) resulted in decreased binding to beta-glucan. Monoclonal antibody 4B2, a dectin- 1 monoclonal antibody which had a blocking effect on the beta-glucan interaction, completely failed to bind the dectin-1 mutant W221A. A mutant with mutations in Trp(221) and His(223) did not have a collaborative effect on Toll-like receptor 2-mediated cellular activation in response to zymosan. These amino acid residues are distinct from residues in other sugar-recognizing peptide sequences of typical C-type lectins. These results suggest that the amino acid sequence W221-I222-H223 is critical for formation of a beta-glucan binding site in the CRD of dectin 1.
Adachi
Yoshiyuki
Y
Laboratory for Immunopharmacology of Microbial Products, School of Pharmacy, Tokyo University of Pharmacy and Life Science, 1432-1 Horinouchi, Hachioji, Tokyo, 192-0392, Japan. adachiyo@ps.toyaku.ac.jp
Ishii
Takashi
T
Ikeda
Yoshihiko
Y
Hoshino
Akiyoshi
A
Tamura
Hiroshi
H
Aketagawa
Jun
J
Tanaka
Shigenori
S
Ohno
Naohito
N
D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000276:immunology; D001665:Binding Sites; D001710:Biotin / Q000378:metabolism; D005936:Glucans / Q000737:chemistry / Q000378:metabolism*; D037181:Lectins, C-Type / Q000737:chemistry / Q000378:metabolism*; D008565:Membrane Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation; D016328:NF-kappa B / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D012567:Schizophyllum / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D020539:Sequence Analysis, Protein; D000099181:Dectin-1
D000911:Antibodies, Monoclonal; D001710:Biotin; D005936:Glucans; D037181:Lectins, C-Type; D008565:Membrane Proteins; D016328:NF-kappa B; D009419:Nerve Tissue Proteins; D000099181:Dectin-1