title: Effect of nicking the C-terminal region of the Clostridium botulinum serotype D neurotoxin heavy chain on its toxicity and molecular properties.
abstract: A unique strain of Clostridium botulinum serotype D 4947 produces toxin complexes that are composed of un-nicked components, including a neurotoxin (BoNT) and auxiliary proteins. This BoNT showed aberrant elution upon Superdex gel filtration, indicating a much lower molecular weight, due to hydrophobic interaction with the column. Limited trypsin proteolysis of BoNT produces two nicks; first nick yielded a BoNT 50 kDa light chain disulfide linked to a 100 kDa heavy chain (Hc), and a second nick arose in Hc C-terminal 10 kDa. The second nick occurred in the putative binding domain of the BoNT molecule and induced alterations in its secondary structure, leading to a significant reduction of mouse toxicity in comparison with that of the fully-activated singly nicked BoNT. These results help to clarify the role of the C-terminal half of the Hc in the oral toxicity of single-chain and more complex forms of BoNT.
authors.affiliation: Department of Food Science and Technology, Faculty of Bioindustry, Tokyo University of Agriculture, 196 Yasaka, Abashiri 099-2493, Japan.
authors.forename: Tomonori
authors.initials: T
authors.lastname: Suzuki
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Kouguchi
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Watanabe
authors.forename: Kimiko
authors.initials: K
authors.lastname: Hasegawa
authors.forename: Tohru
authors.initials: T
authors.lastname: Yoneyama
authors.forename: Koichi
authors.initials: K
authors.lastname: Niwa
authors.forename: Atsushi
authors.initials: A
authors.lastname: Nishikawa
authors.forename: Jae-Chul
authors.initials: JC
authors.lastname: Lee
authors.forename: Keiji
authors.initials: K
authors.lastname: Oguma
authors.forename: Tohru
authors.initials: T
authors.lastname: Ohyama
mesh_terms: D000818:Animals; D001905:Botulinum Toxins / Q000737:chemistry* / Q000633:toxicity*; D002850:Chromatography, Gel; D002942:Circular Dichroism; D047968:Clostridium botulinum type C / Q000737:chemistry / Q000378:metabolism; D047969:Clostridium botulinum type D / Q000737:chemistry* / Q000378:metabolism; D051379:Mice; D008958:Models, Molecular; D008970:Molecular Weight; D009498:Neurotoxins / Q000737:chemistry / Q000633:toxicity; D011487:Protein Conformation
chemical_list: D009498:Neurotoxins; D001905:Botulinum Toxins