Botulinum neurotoxin type F - P30996 (BXF_CLOBO)

 

Protein Feature View of PDB entries mapped to a UniProtKB sequence  

  • Number of PDB entries for P30996: 4
 
Function
Botulinum neurotoxin type F: Botulinum toxin causes flaccid paralysis by inhibiting neurotransmitter (acetylcholine) release from the presynaptic membranes of nerve terminals of the eukaryotic host skeletal and autonomic nervous system, with frequent heart or respiratory failure. Precursor of botulinum neurotoxin F which may have 2 coreceptors; complex polysialylated gangliosides found on neural tissue and specific membrane-anchored proteins found in synaptic vesicles. Receptor proteins are exposed on host presynaptic cell membrane during neurotransmitter release, when the toxin heavy chain (HC) binds to them. Upon synaptic vesicle recycling the toxin is taken up via the endocytic pathway. When the pH of the toxin-containing endosome drops a structural rearrangement occurs so that the N-terminus of the HC forms pores that allows the light chain (LC) to translocate into the cytosol. Once in the cytosol the disulfide bond linking the 2 subunits is reduced and LC cleaves its target protein on synaptic vesicles, preventing their fusion with the cytoplasmic membrane and thus neurotransmitter release (By similarity). Whole toxin only has protease activity after reduction, which releases LC (PubMed:8505288). Requires complex eukaryotic host polysialogangliosides for full neurotoxicity (By similarity). It is not clear whether a synaptic vesicle protein acts as its receptor; there is evidence for and against SV2 fulfilling this function. UniProt
Catalytic Activity
Limited hydrolysis of proteins of the neuroexocytosis apparatus, synaptobrevins, SNAP25 or syntaxin. No detected action on small molecule substrates. UniProt
Pathway Maps
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Subunit Structure
Heterodimer; disulfide-linked heterodimer of a light chain (LC) and a heavy chain (HC). The LC has the proteolytic/pharmacological activity, while the N- and C-terminal of the HC mediate channel formation and toxin binding, respectively. Interacts with host synaptic vesicle glycoproteins SV2A, SV2B and SV2C. UniProt
Domain
Botulinum neurotoxin F heavy chain: Has 3 functional domains; the translocation domain (TD) and the receptor-binding domain (RBD) which is further subdivided into N- and C-terminal domains (N-RBD and C-RBD) (By similarity). The N-terminus of the TD wraps an extended belt around the perimeter of the LC, protecting Zn(2+) in the active site and may be a pseudosubstrate inhibitor which serves as an intramolecular chaperone for the LC prior to its translocation into the host cytosol (By similarity). The RBD binds transiently exposed coreceptors on the host presynaptic cell membrane. UniProt
  • Other Gene names: botF
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Data in blue originates from PDB
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The PDB to UniProt mapping is based on the data provided by the EBI SIFTS project. See also Velankar et al., Nucleic Acids Research 33, D262-265 (2005).
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