title: Structural analysis of the recognition mechanism of poly-N-acetyllactosamine by the human galectin-9 N-terminal carbohydrate recognition domain.
abstract: Galectins are a family of beta-galactoside-specific lectins bearing a conserved carbohydrate recognition domain. Interactions between galectins and poly-N-acetyllactosamine sequences are critical in a variety of biological processes. Galectin-9, a member of the galectin family, has two carbohydrate recognition domains at both the N- and C-terminal regions. Here we report the crystal structure of the human galectin-9 N-terminal carbohydrate recognition domain in complex with N-acetyllactosamine dimers and trimers. These complex structures revealed that the galectin-9 N-terminal carbohydrate recognition domain can recognize internal N-acetyllactosamine units within poly-N-acetyllactosamine chains. Based on these complex structures, we propose two putative recognition modes for poly-N-acetyllactosamine binding by galectins.
authors.affiliation: Structural Biology Research Center, Photon Factory, Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki, Japan.
authors.forename: Masamichi
authors.initials: M
authors.lastname: Nagae
authors.forename: Nozomu
authors.initials: N
authors.lastname: Nishi
authors.forename: Takeomi
authors.initials: T
authors.lastname: Murata
authors.forename: Taichi
authors.initials: T
authors.lastname: Usui
authors.forename: Takanori
authors.initials: T
authors.lastname: Nakamura
authors.forename: Soichi
authors.initials: S
authors.lastname: Wakatsuki
authors.forename: Ryuichi
authors.initials: R
authors.lastname: Kato
mesh_terms: D001665:Binding Sites; D018360:Crystallography, X-Ray; D037161:Galectins / Q000737:chemistry* / Q000378:metabolism*; D006801:Humans; D008958:Models, Molecular; D011134:Polysaccharides / Q000737:chemistry* / Q000378:metabolism*; D011487:Protein Conformation; D017434:Protein Structure, Tertiary
chemical_list: D037161:Galectins; C105032:LGALS9 protein, human; D011134:Polysaccharides; C037199:poly-N-acetyllactosamine