title: Conformational divergence in the HA-33/HA-17 trimer of serotype C and D botulinum toxin complex.
abstract: Clostridium botulinum produces a large toxin complex (L-TC) comprising botulinum neurotoxin associated with auxiliary nontoxic proteins. A complex of 33- and 17-kDa hemagglutinins (an HA-33/HA-17 trimer) enhances L-TC transport across the intestinal epithelial cell layer via binding HA-33 to a sugar on the cell surface. At least two subtypes of serotype C/D HA-33 exhibit differing preferences for the sugars sialic acid and galactose. Here, we compared the three-dimensional structures of the galactose-binding HA-33 and HA-33/HA-17 trimers produced by the C-Yoichi strain. Comparisons of serotype C/D HA-33 sequences reveal a variable region with relatively low sequence similarity across the C. botulinum strains; the variability of this region may influence the manner of sugar-recognition by HA-33. Crystal structures of sialic acid- and galactose-binding HA-33 are broadly similar in appearance. However, small-angle X-ray scattering revealed distinct solution structures for HA-33/HA-17 trimers. A structural change in the C-terminal variable region of HA-33 might cause a dramatic shift in the conformation and sugar-recognition mode of HA-33/HA-17 trimer.
authors.affiliation: Department of Food and Cosmetic Science, Faculty of Bioindustry, Tokyo University of Agriculture, 196 Yasaka, Abashiri 099-2493, Japan. Electronic address: y3sagane@bioindustry.nodai.ac.jp.
authors.forename: Yoshimasa
authors.initials: Y
authors.lastname: Sagane
authors.affiliation: Department of Food and Cosmetic Science, Faculty of Bioindustry, Tokyo University of Agriculture, 196 Yasaka, Abashiri 099-2493, Japan.
authors.forename: Shintaro
authors.initials: S
authors.lastname: Hayashi
authors.affiliation: Department of Bioscience, Faculty of Applied Bioscience, Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya-ku, Tokyo 156-8502, Japan.
authors.forename: Tomonori
authors.initials: T
authors.lastname: Akiyama
authors.affiliation: Rigaku Corporation, 3-9-12 Matsubara-Cho, Akishima 196-8666, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Matsumoto
authors.affiliation: Rigaku Corporation, 3-9-12 Matsubara-Cho, Akishima 196-8666, Japan.
authors.forename: Kimiko
authors.initials: K
authors.lastname: Hasegawa
authors.affiliation: Rigaku Corporation, 3-9-12 Matsubara-Cho, Akishima 196-8666, Japan.
authors.forename: Akihito
authors.initials: A
authors.lastname: Yamano
authors.affiliation: Department of Nutritional Science and Food Safety, Faculty of Applied Bioscience, Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya-ku, Tokyo 156-8502, Japan.
authors.forename: Tomonori
authors.initials: T
authors.lastname: Suzuki
authors.affiliation: Department of Food and Cosmetic Science, Faculty of Bioindustry, Tokyo University of Agriculture, 196 Yasaka, Abashiri 099-2493, Japan.
authors.forename: Koichi
authors.initials: K
authors.lastname: Niwa
authors.affiliation: Department of Food and Cosmetic Science, Faculty of Bioindustry, Tokyo University of Agriculture, 196 Yasaka, Abashiri 099-2493, Japan.
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Watanabe
authors.affiliation: Department of Bioscience, Faculty of Applied Bioscience, Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya-ku, Tokyo 156-8502, Japan. Electronic address: yshun@nodai.ac.jp.
authors.forename: Shunsuke
authors.initials: S
authors.lastname: Yajima
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry* / Q000378:metabolism; D001905:Botulinum Toxins / Q000737:chemistry* / Q000378:metabolism; D001906:Botulism / Q000382:microbiology; D003014:Clostridium botulinum / Q000737:chemistry* / Q000378:metabolism; D005690:Galactose / Q000378:metabolism; D006388:Hemagglutinins / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D008958:Models, Molecular; D019158:N-Acetylneuraminic Acid / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D055503:Protein Multimerization; D053838:Scattering, Small Angle; D014961:X-Ray Diffraction
chemical_list: D001426:Bacterial Proteins; D006388:Hemagglutinins; D001905:Botulinum Toxins; D019158:N-Acetylneuraminic Acid; D005690:Galactose
keywords: Clostridium botulinum; Crystallography; Galactose; Hemagglutinin; Protein conformation; Small-angle X-ray scattering