title: Electron density projection map of the botulinum neurotoxin 900-kilodalton complex by electron crystallography.
abstract: The 900-kDa botulinum neurotoxin complex serotype A has been crystallized by the lipid-layer two-dimensional crystallization technique. Based on the binding characteristics of the hemagglutinating portion of the complex, a number of ganglioside/ lipid mixtures were tested but only lactosyl ceramide/1-palmityl-2-oleoyl-sn-glycero-3-phosphocholine was found to crystallize the complex. The optimum lipid mixture contained 75 mass % lactosyl ceramide and 25 mass % 1-palmityl-2-oleoyl-sn-glycero-3-phosphocholine. Using protein concentrations from 5 to 500 micrograms/ml and pH and 5 acetate buffer, we have obtained crystals that diffract to better than 15 A when prepared in negative stain. A projection map with a resolution of 30 A was calculated with unit cell dimensions of a = b = 157 A and P3 symmetry. The complex is triangular in shape with six distinct lobes observed. Additionally, six smaller structures protrude from the triangular core.
authors.affiliation: Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
authors.forename: F
authors.initials: F
authors.lastname: Burkard
authors.forename: F
authors.initials: F
authors.lastname: Chen
authors.forename: G M
authors.initials: GM
authors.lastname: Kuziemko
authors.forename: R C
authors.initials: RC
authors.lastname: Stevens
mesh_terms: D001905:Botulinum Toxins / Q000737:chemistry* / Q000302:isolation & purification; D003460:Crystallization; D003461:Crystallography / Q000379:methods; D007091:Image Processing, Computer-Assisted; D008854:Microscopy, Electron / Q000379:methods; D008961:Models, Structural; D008970:Molecular Weight; D009498:Neurotoxins
chemical_list: D009498:Neurotoxins; D001905:Botulinum Toxins