Receptor Binding Enables Botulinum Neurotoxin B to Sense Low pH for Translocation Channel Assembly

Sun, Shihu; Suresh, Swetha; Liu, Huisheng; Tepp, William H.; Johnson, Eric A.; Edwardson, J. Michael; Chapman, Edwin R.

doi:10.1016/j.chom.2011.06.012

Cited by 65 publications

(93 citation statements)

References 52 publications

(71 reference statements)

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“…Similar results were recently reported for BoNT/B (Sun et al, 2011). For BoNT/A, LC translocation is observed as a time-dependent increase in Na + conductance through the HC channel; the initial 14 pS channel activity rapidly transitions through several intermediate before reaching a stable approximately 68 pS Montal, 2007a, 2007b).…”

Section: Minimal Protein Translocation Unitsupporting

confidence: 74%

“…3) (Fischer et al, 2008). A similar requirement for BoNT/B has recently been presented by Sun et al (2011). Sun et al (2011) further suggested that, for BoNT/B, RBD association with its ganglioside receptor promotes channel formation through oligomerization.…”

Section: Productive Intoxication Requires Several Steps Of Interdomaimentioning

confidence: 83%

“…A similar requirement for BoNT/B has recently been presented by Sun et al (2011). Sun et al (2011) further suggested that, for BoNT/B, RBD association with its ganglioside receptor promotes channel formation through oligomerization. The LC chaperones the HC by maintaining it in a soluble conformation at neutral pH until residence within the acidic endosome where the LC serves to gate the TD channel in order to initiate LC translocation (Fischer and Montal, 2007b).…”

Section: Productive Intoxication Requires Several Steps Of Interdomaimentioning

confidence: 90%

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Molecular dissection of botulinum neurotoxin reveals interdomain chaperone function

Fischer

Mushrush

Sambashivan

et al. 2013

Toxicon

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Clostridium botulinum neurotoxin (BoNT) is a multi-domain protein made up of the approximately 100 kDa heavy chain (HC) and the approximately 50 kDa light chain (LC). The HC can be further subdivided into two halves: the N-terminal translocation domain (TD) and the Cterminal Receptor Binding Domain (RBD). We have investigated the minimal requirements for channel activity and LC translocation. We utilize a cellular protection assay and a single channel/ single molecule LC translocation assay to characterize in real time the channel and chaperone activities of BoNT/A truncation constructs in Neuro 2A cells. The unstructured, elongated belt region of the TD is demonstrated to be dispensable for channel activity, although may be required for productive LC translocation. We show that the RBD is not necessary for channel activity or LC translocation, however it dictates the pH threshold of channel insertion into the membrane. These findings indicate that each domain functions as a chaperone for the others in addition to their individual functions, working in concert to achieve productive intoxication.

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Section: Minimal Protein Translocation Unitsupporting

confidence: 74%

Section: Productive Intoxication Requires Several Steps Of Interdomaimentioning

confidence: 83%

Section: Productive Intoxication Requires Several Steps Of Interdomaimentioning

confidence: 90%

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Molecular dissection of botulinum neurotoxin reveals interdomain chaperone function

Fischer

Mushrush

Sambashivan

et al. 2013

Toxicon

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“…TeNT Undergoes Secondary Structural Changes in the Presence of Polysialogangliosides at Low pH-Recent studies demonstrated that interaction of ganglioside GT1b with BoNT/B and BoNT/E triggers conformational changes within the two proteins that facilitates transformation into hydrophobic proteins at low pH (34,35). To test whether gangliosides trigger a similar conformational change in TeNT, CD spectroscopy was performed at neutral and acidic pH in the absence and presence of GT1b.…”

Section: Functional Entry Of Recombinant Tetanus Toxin and Proteinmentioning

confidence: 99%

Tetanus Neurotoxin Utilizes Two Sequential Membrane Interactions for Channel Formation

Burns

Baldwin

2014

Journal of Biological Chemistry

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Background: Tetanus neurotoxin enters the neuronal cytosol to block the release of neurotransmitters. Results: Channel formation is enhanced by receptor binding and dependent on acidic lipids. Conclusion: A two-step sequential process takes place: ganglioside-mediated membrane anchorage, followed by pH-triggered channel formation modulated by the membrane environment. Significance: This represents a new paradigm for how A-B toxins translocate enzymatic domains across cellular membranes.

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“…Besides, it is not easy to predict the structural and conformational changes induced both in the molecule and at the membrane surface (at various stages), making it difficult to assert any strong assumptions regarding the role of various domains and the receptors involved. This has been proved repeatedly where new receptors and factors influencing toxin internalization are identified (59)(60)(61)(62) with an increased understanding of the toxinhost interaction. It is really necessary to confirm the data obtained from such studies in vivo before making any strong interpretations.…”

Section: Discussionmentioning

confidence: 99%

The C-Terminal Heavy-Chain Domain of Botulinum Neurotoxin A Is Not the Only Site That Binds Neurons, as the N-Terminal Heavy-Chain Domain Also Plays a Very Active Role in Toxin-Cell Binding and Interactions

2015

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c Botulinum neurotoxins (BoNTs) possess unique specificity for nerve terminals. They bind to the presynaptic membrane and then translocate intracellularly, where the light-chain endopeptidase cleaves the SNARE complex proteins, subverting the synaptic exocytosis responsible for acetylcholine release to the synaptic cleft. This inhibits acetylcholine binding to its receptor, causing paralysis. Binding, an obligate event for cell intoxication, is believed to occur through the heavy-chain C-terminal (H C ) domain. It is followed by toxin translocation and entry into the cell cytoplasm, which is thought to be mediated by the heavy- Botulinum neurotoxins (BoNTs) are the most potent toxins and are ranked by the Centers for Disease Control and Prevention (CDC) as bioterrorism threats with the six highest-risk class A agents (1). The potency of the toxin is due to its outstanding specificity to nerve terminals and selective enzymatic activity, resulting in the cleavage of SNARE (soluble N-ethylmaleimidesensitive factor attachment protein receptor) complex proteins. The cleavage of SNARE proteins inhibits the fusion of synaptic vesicles (containing the neurotransmitter) to the plasma membrane, thereby blocking neurotransmitter release and causing paralysis (2, 3).Unraveling the features of the mode of action of BoNTs has permitted numerous applications of the toxins in many therapeutic, pharmaceutical, and cosmetic applications (4-7). However, understanding of the full biochemical mechanism of its action still remains to be elucidated.BoNTs, produced by Gram-positive, obligate anaerobic Clostridium botulinum bacteria, are classified into eight different serotypes (A through H) (8-10). BoNTs are expressed as a single polypeptide chain (ϳ150 kDa) which is posttranslationally cleaved to produce an N-terminal light (L) chain of ϳ50 kDa, which is a Zn 2ϩ metalloprotease, and a heavy (H) chain of ϳ100 kDa. The L and H chains are linked together by a disulfide bond and other noncovalent interactions to form the active toxin. The H chain is further functionally divided into two seemingly independent domains: the N-terminal or translocation (H N ) domain and the Cterminal receptor-binding (H C ) domain (11).The entry of BoNT into neurons and its resultant toxicity are exhibited in a systematic manner, accomplished by a superb molecular partnership between the H and L chains. It is believed that an intricate mechanism involving various low-and high-affinity interactions is involved in intoxication of the cell (12). The difference in pH and redox potential across the endosomes is believed to induce conformational changes in the H chain, which subsequently forms a chaperone and channels the L chain into the cytosol. Once the L chain is translocated, it is subsequently released by disulfide bond reduction, followed by its refolding in the neutral cytosol, where it cleaves the SNARE substrates (13). The current understanding of toxin entry into the cell is that the H C domain binds to the neurons via dual host receptors (gangliosides...

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Receptor Binding Enables Botulinum Neurotoxin B to Sense Low pH for Translocation Channel Assembly

Cited by 65 publications

References 52 publications

Molecular dissection of botulinum neurotoxin reveals interdomain chaperone function

Molecular dissection of botulinum neurotoxin reveals interdomain chaperone function

Tetanus Neurotoxin Utilizes Two Sequential Membrane Interactions for Channel Formation

The C-Terminal Heavy-Chain Domain of Botulinum Neurotoxin A Is Not the Only Site That Binds Neurons, as the N-Terminal Heavy-Chain Domain Also Plays a Very Active Role in Toxin-Cell Binding and Interactions

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