title: Structural analysis of botulinum neurotoxin serotype F light chain: implications on substrate binding and inhibitor design.
abstract: The seven serologically distinct Clostridium botulinum neurotoxins (BoNTs A-G) are zinc endopeptidases which block the neurotransmitter release by cleaving one of the three proteins of the soluble N-ethylmaleimide-sensitive-factor attachment protein receptor complex (SNARE complex) essential for the fusion of vesicles containing neurotransmitters with target membranes. These metallopeptidases exhibit unique specificity for the substrates and peptide bonds they cleave. Development of countermeasures and therapeutics for BoNTs is a priority because of their extreme toxicity and potential misuse as biowarfare agents. Though they share sequence homology and structural similarity, the structural information on each one of them is required to understand the mechanism of action of all of them because of their specificity. Unraveling the mechanism will help in the ultimate goal of developing inhibitors as antibotulinum drugs for the toxins. Here, we report the high-resolution structure of active BoNT/F catalytic domain in two crystal forms. The structure was exploited for modeling the substrate binding and identifying the S1' subsite and the putative exosites which are different from BoNT/A or BoNT/B. The orientation of docking of the substrate at the active site is consistent with the experimental BoNT/A-LC:SNAP-25 peptide model and our proposed model for BoNT/E-LC:SNAP-25.
authors.affiliation: Biology Department, Brookhaven National Laboratory, Upton, New York 11973, USA.
authors.forename: Rakhi
authors.initials: R
authors.lastname: Agarwal
authors.forename: Thomas
authors.initials: T
authors.lastname: Binz
authors.forename: Subramanyam
authors.initials: S
authors.lastname: Swaminathan
mesh_terms: D001665:Binding Sites; D001905:Botulinum Toxins / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000302:isolation & purification; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D019281:Dimerization; D015195:Drug Design; D008565:Membrane Proteins / Q000737:chemistry; D017669:Mercury Compounds / Q000494:pharmacology; D008958:Models, Molecular; D011487:Protein Conformation; D017510:Protein Folding; D033921:Vesicular Transport Proteins / Q000737:chemistry
chemical_list: D008565:Membrane Proteins; D017669:Mercury Compounds; C114051:VAPA protein, human; D033921:Vesicular Transport Proteins; D001905:Botulinum Toxins; C096321:botulinum toxin type F