5VGV

Structure of the C. botulinum neurotoxin serotype A with Cu bound

Summary for 5VGV

• Entry DOI: 10.2210/pdb5vgv/pdb
• Related: 5VGX
• Descriptor: Botulinum neurotoxin type A, COPPER (II) ION, ACETATE ION, ... (4 entities in total)
• Functional Keywords: botulinum, neurotoxin, metalloprotease, toxin
• Biological source: Clostridium botulinum
• Total number of polymer chains: 1
• Total formula weight: 50788.18

Authors

Carolan, J.P.,Allen, K.N. (deposition date: 2017-04-11, release date: 2017-05-31, Last modification date: 2023-10-04)

Primary citation

Bremer, P.T.,Pellett, S.,Carolan, J.P.,Tepp, W.H.,Eubanks, L.M.,Allen, K.N.,Johnson, E.A.,Janda, K.D.
Metal Ions Effectively Ablate the Action of Botulinum Neurotoxin A.
J. Am. Chem. Soc., 139:7264-7272, 2017

PubMed Abstract: Botulinum neurotoxin serotype A (BoNT/A) causes a debilitating and potentially fatal illness known as botulism. The toxin is also a bioterrorism threat, yet no pharmacological antagonist to counteract its effects has reached clinical approval. Existing strategies to negate BoNT/A intoxication have looked to antibodies, peptides, or organic small molecules as potential therapeutics. In this work, a departure from the traditional drug discovery mindset was pursued, in which the enzyme's susceptibility to metal ions was exploited. A screen of a series of metal salts showed marked inhibitory activity of group 11 and 12 metals against the BoNT/A light chain (LC) protease. Enzyme kinetics revealed that copper (I) and (II) cations displayed noncompetitive inhibition of the LC (K ≈ 1 μM), while mercury (II) cations were 10-fold more potent. Crystallographic and mutagenesis studies elucidated a key binding interaction between Cys165 on BoNT/A LC and the inhibitory metals. As potential copper prodrugs, ligand-copper complexes were examined in a cell-based model and were found to prevent BoNT/A cleavage of the endogenous protein substrate, SNAP-25, even at low μM concentrations of complexes. Further investigation of the complexes suggested a bioreductive mechanism causing intracellular release of copper, which directly inhibited the BoNT/A protease. In vivo experiments demonstrated that copper (II) dithiocarbamate and bis(thiosemicarbazone) complexes could delay BoNT/A-mediated lethality in a rodent model, indicating their potential for treating the harmful effects of BoNT/A intoxication. Our studies illustrate that metals can be therapeutically viable enzyme inhibitors; moreover, enzymes that share homology with BoNT LCs may be similarly targeted with metals.

PubMed: 28475321
DOI: 10.1021/jacs.7b01084

Experimental method

X-RAY DIFFRACTION (2.6 Å)