Dynamics of the Large Progenitor Toxin Complex of Clostridium botulinum

Botulinum neurotoxins (BoNTs) and tetanus neurotoxin (TeNT) are the most potent toxins known and cause botulism and tetanus, respectively. BoNTs are also widely utilized as therapeutic toxins. They contain three functional domains responsible for receptor-binding, membrane translocation, and proteolytic cleavage of host proteins required for synaptic vesicle exocytosis. These toxins also have distinct features: BoNTs exist within a progenitor toxin complex (PTC), which protects the toxin and facilitates its absorption in the gastrointestinal tract, whereas TeNT is uniquely transported retrogradely within motor neurons. Our increasing knowledge of these toxins has allowed the development of engineered toxins for medical uses. The discovery of new BoNTs and BoNT-like proteins provides additional tools to understand the evolution of the toxins and to engineer toxin-based therapeutics. This review summarizes the progress on our understanding of BoNTs and TeNT, focusing on the PTC, receptor recognition, new BoNT-like toxins, and therapeutic toxin engineering.

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The complete nucleotide sequence of the gene coding for the nontoxic-nonhemagglutinin component of Clostridium botulinum type C progenitor toxin

Biochemical and Biophysical Research Communications ◽

10.1016/s0006-291x(05)80328-6 ◽

1992 ◽

Vol 183 (3) ◽

pp. 1273-1279 ◽

Cited By ~ 29

Author(s):

K. Tsuzuki ◽

K. Kimura ◽

N. Fujii ◽

N. Yokosawa ◽

K. Oguma

Keyword(s):

Nucleotide Sequence ◽

Complete Nucleotide Sequence ◽

Clostridium Botulinum ◽

Gene Coding ◽

Botulinum Type ◽

Type C ◽

Progenitor Toxin

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Identification of RNA Species in the RNA–Toxin Complex and Structure of the Complex in Clostridium botulinum Type E

Biochemical and Biophysical Research Communications ◽

10.1006/bbrc.2002.6435 ◽

2002 ◽

Vol 291 (1) ◽

pp. 154-157 ◽

Cited By ~ 3

Author(s):

Masaru Kitamura

Keyword(s):

Clostridium Botulinum ◽

Toxin Complex ◽

Botulinum Type ◽

Clostridium Botulinum Type E

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Holotoxin Activity of Botulinum Neurotoxin Subtype A4 Originating from a Nontoxigenic Clostridium botulinum Expression System

Applied and Environmental Microbiology ◽

10.1128/aem.01795-14 ◽

2014 ◽

Vol 80 (23) ◽

pp. 7415-7422 ◽

Cited By ~ 14

Author(s):

Marite Bradshaw ◽

William H. Tepp ◽

Regina C. M. Whitemarsh ◽

Sabine Pellett ◽

Eric A. Johnson

Keyword(s):

Clostridium Botulinum ◽

Botulinum Neurotoxin ◽

Expression System ◽

Single Amino Acid ◽

Content Type ◽

Expression Host ◽

Toxin Complex ◽

Human Neuronal Cells

ABSTRACTClostridium botulinumsubtype A4 neurotoxin (BoNT/A4) is naturally expressed in the dual-toxin-producingC. botulinumstrain 657Ba at 100× lower titers than BoNT/B. In this study, we describe purification of recombinant BoNT/A4 (rBoNT/A4) expressed in a nonsporulating and nontoxigenicC. botulinumexpression host strain. The rBoNT/A4 copurified with nontoxic toxin complex components provided intransby the expression host and was proteolytically cleaved to the active dichain form. Activity of the recombinant BoNT/A4 in mice and in human neuronal cells was about 1,000-fold lower than that of BoNT/A1, and the recombinant BoNT/A4 was effectively neutralized by botulism heptavalent antitoxin. A previous report using recombinant truncated BoNT/A4 light chain (LC) expressed inEscherichia colihas indicated reduced stability and activity of BoNT/A4 LC compared to BoNT/A1 LC, which was surmounted by introduction of a single-amino-acid substitution, I264R. In order to determine whether this mutation would also affect the holotoxin activity of BoNT/A4, a recombinant full-length BoNT/A4 carrying this mutation as well as a second mutation predicted to increase solubility (L260F) was produced in the clostridial expression system. Comparative analyses of thein vitro, cellular, andin vivoactivities of rBoNT/A4 and rBoNT/A4-L260F I264R showed 1,000-fold-lower activity than BoNT/A1 in both the mutated and nonmutated BoNT/A4. This indicates that these mutations do not alter the activity of BoNT/A4 holotoxin. In summary, a recombinant BoNT from a dual-toxin-producing strain was expressed and purified in an endogenous clostridial expression system, allowing analysis of this toxin.

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