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6xcf

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Structure of the C. botulinum neurotoxin serotype A light chain protease in complex with noncovalent inhibitor 59

Structural highlights

6xcf is a 1 chain structure with sequence from Clostridium botulinum. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Method:	X-ray diffraction, Resolution 1.68Å
Ligands:	,
Resources:	FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT

Function

BXA1_CLOBO Inhibits acetylcholine release. The botulinum toxin binds with high affinity to peripheral neuronal presynaptic membrane to the secretory vesicle protein SV2. It binds directly to the largest luminal loop of SV2A, SV2B and SV2C. It is then internalized by receptor-mediated endocytosis. The C-terminus of the heavy chain (H) is responsible for the adherence of the toxin to the cell surface while the N-terminus mediates transport of the light chain from the endocytic vesicle to the cytosol. After translocation, the light chain (L) hydrolyzes the 197-Gln-|-Arg-198 bond in SNAP-25, thereby blocking neurotransmitter release. Inhibition of acetylcholine release results in flaccid paralysis, with frequent heart or respiratory failure.

Publication Abstract from PubMed

Botulinum neurotoxins have remarkable persistence ( approximately weeks to months in cells), outlasting the small-molecule inhibitors designed to target them. To address this disconnect, inhibitors bearing two pharmacophores-a zinc binding group and a Cys-reactive warhead-were designed to leverage both affinity and reactivity. A series of first-generation bifunctional inhibitors was achieved through structure-based inhibitor design. Through X-ray crystallography, engagement of both the catalytic Zn(2+) and Cys165 was confirmed. A second-generation series improved on affinity by incorporating known reversible inhibitor pharmacophores; the mechanism was confirmed by exhaustive dialysis, mass spectrometry, and in vitro evaluation against the C165S mutant. Finally, a third-generation inhibitor was shown to have good cellular activity and low toxicity. In addition to our findings, an alternative method of modeling time-dependent inhibition that simplifies assay setup and allows comparison of inhibition models is discussed.

Catch and Anchor Approach To Combat Both Toxicity and Longevity of Botulinum Toxin A.,Lin L, Olson ME, Sugane T, Turner LD, Tararina MA, Nielsen AL, Kurbanov EK, Pellett S, Johnson EA, Cohen SM, Allen KN, Janda KD J Med Chem. 2020 Sep 18. doi: 10.1021/acs.jmedchem.0c01006. PMID:32886509^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

References

↑ Lin L, Olson ME, Sugane T, Turner LD, Tararina MA, Nielsen AL, Kurbanov EK, Pellett S, Johnson EA, Cohen SM, Allen KN, Janda KD. Catch and Anchor Approach To Combat Both Toxicity and Longevity of Botulinum Toxin A. J Med Chem. 2020 Sep 18. doi: 10.1021/acs.jmedchem.0c01006. PMID:32886509 doi:http://dx.doi.org/10.1021/acs.jmedchem.0c01006