Premium
TCEP treatment reduces proteolytic activity of BoNT/B in human neuronal SHSY‐5Y cells
Author(s) -
Shi Xuerong,
Garcia Gregory E.,
Neill Roger J.,
Gordon Richard K.
Publication year - 2009
Publication title -
journal of cellular biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.028
H-Index - 165
eISSN - 1097-4644
pISSN - 0730-2312
DOI - 10.1002/jcb.22205
Subject(s) - tcep , chemistry , endopeptidase , ricin , biochemistry , endocytosis , toxin , cell , enzyme , phosphine , catalysis
The light chain (LC) of botulinum neurotoxin B (BoNT/B) is unable to enter target neuronal cells by itself. It is brought into the cell in association with the BoNT/B heavy chain (HC) through endocytosis. The BoNT HC‐LC subunits are held together by a single disulfide bond. Intracellular reduction of this bond and separation of the two subunits activates the endopeptidase activity of the LC. This requirement suggests a strategy to prevent uptake by prophylactic reduction to disrupt the disulfide bond prior to endocytosis of the complex. We examined the utility of tris‐(2‐carboxyethyl)‐phosphine hydrochloride (TCEP), a relatively non‐toxic, non‐sulfur containing disulfide bond reducing agent that lacks the undesirable properties of mercapto‐containing reducing agents. We found that TCEP was as effective as DTT with maximal LC endopeptidase activation occurring at 1 mM, a concentration not toxic to the human neuronal cell line, SHSY‐5Y. In these cells, 1 mM TCEP maximally protected against BoNT/B inhibition of [ 3 H]‐NA release, achieving 72% of the release from un‐intoxicated controls. This effect appears to be due to the sparing of SNARE proteins as the levels of VAMP‐2, the specific target of BoNT/B, were protected. These results show that TCEP disrupts the structure of BoNT/B by reduction of the LC and HC bridging disulfide bond and prevents neuronal intoxication. Since disulfide bond coupling between toxin subunits is a general motif for many toxins, e.g., ricin, snake venom, and all BoNT serotypes, this suggests that TCEP is a promising means to protect against these toxins by preventing cell penetration. J. Cell. Biochem. 107: 1021–1030, 2009. Published 2009 Wiley‐Liss, Inc.