The following text describes a protein:
Function:
[Botulinum neurotoxin type E]: Botulinum toxin causes flaccid paralysis by inhibiting neurotransmitter (acetylcholine) release from the presynaptic membranes of nerve terminals of eukaryotic host skeletal and autonomic nervous system, with frequent heart or respiratory failure. Precursor of botulinum neurotoxin E which has 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); [Botulinum neurotoxin E light chain]: Has proteolytic activity. After translocation into the eukaryotic host cytosol, LC hydrolyzes the '180-Arg-|-Ile-181' bond in SNAP25, blocking neurotransmitter release (By similarity); [Botulinum neurotoxin E heavy chain]: Responsible for host epithelial cell transcytosis, host nerve cell targeting and translocation of light chain (LC) into host cytosol. Composed of 3 subdomains; the translocation domain (TD), and N-terminus and C-terminus of the receptor-binding domain (RBD). The RBD is responsible for the adherence of the toxin to the cell surface. It simultaneously recognizes 2 coreceptors; host polysialated gangliosides and the receptor proteins SV2A and SV2B in close proximity on host synaptic vesicles. Interaction with SV2 proteins requires SV2 glycosylation. The N-terminus of the TD wraps an extended belt around the perimeter of the LC, protecting Zn(2+) in the active site; it may also prevent premature LC dissociation from the translocation channel and protect toxin prior to translocation (By similarity). The TD inserts into synaptic vesicle membrane to allow translocation into the host cytosol (By similarity). Binds ganglioside GD1a in vitro.
Miscellaneous:
MISCELLANEOUS: There are seven antigenically distinct forms of botulinum neurotoxin: Types A, B, C, D, E, F, and G; new subtypes are quite frequent; MISCELLANEOUS: Botulism poisoning is usually food-borne, either by ingesting toxin or bacterial-contaminated food, or less frequently by inhalation poisoning. In both cases the neurotoxin binds to the apical surface of epithelial cells in the gut or airway. Toxin undergoes receptor-mediated endocytosis (using a different receptor than on target nerve cells), transcytosis across the epithelial cells and release into the general circulation. Once in the general circulation it binds to its target cells; MISCELLANEOUS: Unlike botulinum neurotoxin type A, type E is released from bacteria as a single chain and cleaved by host proteases into the active dichain (Probable); MISCELLANEOUS: Types A, B and E are the most frequent cause of adult human foodborne botulism; type A is the most severe, while type E has the shortest incubation period (By similarity). Type E neurotoxin from C.butyricum strains ATCC 43181, ATCC 43775 and BL6340 were all isolated from cases of human infant botulism.
Subcellular Localization:
[Botulinum neurotoxin type E]: Secreted; [Botulinum neurotoxin E light chain]: Secreted. Host cytoplasm, host cytosol; [Botulinum neurotoxin E heavy chain]: Secreted. Host synapse, host presynaptic cell membrane. Host cytoplasmic vesicle, host secretory vesicle, host synaptic vesicle membrane; Multi-pass membrane protein.
Domain:
[Botulinum neurotoxin E light chain]: Has protease activity (By similarity); [Botulinum neurotoxin E 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). In BoNT/E the domains are arranged differently than BoNT/A and BoNT/B; in BoNT/E the LC and RBD are on the same side of the TD and are in contact, whereas in BoNT/A and BoNT/B the LC is separated from the RBD by the TD (By similarity). The putative transmembrane region is closer to the receptor-binding regions in this toxin, which may explain why it acts faster than BoNT/A and BoNT/B (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 (By similarity).
Sequence:
MPTINSFNYNDPVNNRTILYIKPGGCQQFYKSFNIMKNIWIIPERNVIGTIPQDFLPPTSLKNGDSSYYDPNYLQSDQEKDKFLKIVTKIFNRINDNLSGRILLEELSKANPYLGNDNTPDGDFIINDASAVPIQFSNGSQSILLPNVIIMGAEPDLFETNSSNISLRNNYMPSNHGFGSIAIVTFSPEYSFRFKDNSMNEFIQDPALTLMHELIHSLHGLYGAKGITTKYTITQKQNPLITNIRGTNIEEFLTFGGTDLNIITSAQSNDIYTNLLADYKKIASKLSKVQVSNPLLNPYKDVFEAKYGLDKDASGIYSVNINKFNDIFKKLYSFTEFDLATKFQVKCRQTYIGQYKYFKLSNLLNDSIYNISEGYNINNLKVNFRGQNANLNPRIITPITGRGLVKKIIRFCKNIVSVKGIRKSICIEINNGELFFVASENSYNDDNINTPKEIDDTVTSNNNYENDLDQVILNFNSESAPGLSDEKLNLTIQNDAYIPKYDSNGTSDIEQHDVNELNVFFYLDAQKVPEGENNVNLTSSIDTALLEQPKIYTFFSSEFINNVNKPVQAALFVGWIQQVLVDFTTEANQKSTVDKIADISIVVPYIGLALNIGNEAQKGNFKDALELLGAGILLEFEPELLIPTILVFTIKSFLGSSDNKNKVIKAINNALKERDEKWKEVYSFIVSNWMTKINTQFNKRKEQMYQALQNQVNALKAIIESKYNSYTLEEKNELTNKYDIEQIENELNQKVSIAMNNIDRFLTESSISYLMKLINEVKINKLREYDENVKTYLLDYIIKHGSILGESQQELNSMVIDTLNNSIPFKLSSYTDDKILISYFNKFFKRIKSSSVLNMRYKNDKYVDTSGYDSNININGDVYKYPTNKNQFGIYNDKLSEVNISQNDYIIYDNKYKNFSISFWVRIPNYDNKIVNVNNEYTIINCMRDNNSGWKVSLNHNEIIWTLQDNSGINQKLAFNYGNANGISDYINKWIFVTITNDRLGDSKLYINGNLIDKKSILNLGNIHVSDNILFKIVNCSYTRYIGIRYFNIFDKELDETEIQTLYNNEPNANILKDFWGNYLLYDKEYYLLNVLKPNNFINRRTDSTLSINNIRSTILLANRLYSGIKVKIQRVNNSSTNDNLVRKNDQVYINFVASKTHLLPLYADTATTNKEKTIKISSSGNRFNQVVVMNSVGNCTMNFKNNNGNNIGLLGFKADTVVASTWYYTHMRDNTNSNGFFWNFISEEHGWQEK