Cargando…

Beltless Translocation Domain of Botulinum Neurotoxin A Embodies a Minimum Ion-conductive Channel

Botulinum neurotoxin, the causative agent of the paralytic disease botulism, is an endopeptidase composed of a catalytic domain (or light chain (LC)) and a heavy chain (HC) encompassing the translocation domain (TD) and receptor-binding domain. Upon receptor-mediated endocytosis, the LC and TD are p...

Descripción completa

Detalles Bibliográficos
Autores principales: Fischer, Audrey, Sambashivan, Shilpa, Brunger, Axel T., Montal, Mauricio
Formato: Online Artículo Texto
Lenguaje:English
Publicado: American Society for Biochemistry and Molecular Biology 2012
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3265847/
https://www.ncbi.nlm.nih.gov/pubmed/22158863
http://dx.doi.org/10.1074/jbc.C111.319400
_version_ 1782222130356682752
author Fischer, Audrey
Sambashivan, Shilpa
Brunger, Axel T.
Montal, Mauricio
author_facet Fischer, Audrey
Sambashivan, Shilpa
Brunger, Axel T.
Montal, Mauricio
author_sort Fischer, Audrey
collection PubMed
description Botulinum neurotoxin, the causative agent of the paralytic disease botulism, is an endopeptidase composed of a catalytic domain (or light chain (LC)) and a heavy chain (HC) encompassing the translocation domain (TD) and receptor-binding domain. Upon receptor-mediated endocytosis, the LC and TD are proposed to undergo conformational changes in the acidic endocytic environment resulting in the formation of an LC protein-conducting TD channel. The mechanism of channel formation and the conformational changes in the toxin upon acidification are important but less well understood aspects of botulinum neurotoxin intoxication. Here, we have identified a minimum channel-forming truncation of the TD, the “beltless” TD, that forms transmembrane channels with ion conduction properties similar to those of the full-length TD. At variance with the holotoxin and the HC, channel formation for both the TD and the beltless TD occurs independent of a transmembrane pH gradient. Furthermore, acidification in solution induces moderate secondary structure changes. The subtle nature of the conformational changes evoked by acidification on the TD suggests that, in the context of the holotoxin, larger structural rearrangements and LC unfolding occur preceding or concurrent to channel formation. This notion is consistent with the hypothesis that although each domain of the holotoxin functions individually, each domain serves as a chaperone for the others.
format Online
Article
Text
id pubmed-3265847
institution National Center for Biotechnology Information
language English
publishDate 2012
publisher American Society for Biochemistry and Molecular Biology
record_format MEDLINE/PubMed
spelling pubmed-32658472012-01-27 Beltless Translocation Domain of Botulinum Neurotoxin A Embodies a Minimum Ion-conductive Channel Fischer, Audrey Sambashivan, Shilpa Brunger, Axel T. Montal, Mauricio J Biol Chem Reports Botulinum neurotoxin, the causative agent of the paralytic disease botulism, is an endopeptidase composed of a catalytic domain (or light chain (LC)) and a heavy chain (HC) encompassing the translocation domain (TD) and receptor-binding domain. Upon receptor-mediated endocytosis, the LC and TD are proposed to undergo conformational changes in the acidic endocytic environment resulting in the formation of an LC protein-conducting TD channel. The mechanism of channel formation and the conformational changes in the toxin upon acidification are important but less well understood aspects of botulinum neurotoxin intoxication. Here, we have identified a minimum channel-forming truncation of the TD, the “beltless” TD, that forms transmembrane channels with ion conduction properties similar to those of the full-length TD. At variance with the holotoxin and the HC, channel formation for both the TD and the beltless TD occurs independent of a transmembrane pH gradient. Furthermore, acidification in solution induces moderate secondary structure changes. The subtle nature of the conformational changes evoked by acidification on the TD suggests that, in the context of the holotoxin, larger structural rearrangements and LC unfolding occur preceding or concurrent to channel formation. This notion is consistent with the hypothesis that although each domain of the holotoxin functions individually, each domain serves as a chaperone for the others. American Society for Biochemistry and Molecular Biology 2012-01-13 2011-12-12 /pmc/articles/PMC3265847/ /pubmed/22158863 http://dx.doi.org/10.1074/jbc.C111.319400 Text en © 2012 by The American Society for Biochemistry and Molecular Biology, Inc. Author's Choice—Final version full access. Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/by-nc/3.0/) applies to Author Choice Articles
spellingShingle Reports
Fischer, Audrey
Sambashivan, Shilpa
Brunger, Axel T.
Montal, Mauricio
Beltless Translocation Domain of Botulinum Neurotoxin A Embodies a Minimum Ion-conductive Channel
title Beltless Translocation Domain of Botulinum Neurotoxin A Embodies a Minimum Ion-conductive Channel
title_full Beltless Translocation Domain of Botulinum Neurotoxin A Embodies a Minimum Ion-conductive Channel
title_fullStr Beltless Translocation Domain of Botulinum Neurotoxin A Embodies a Minimum Ion-conductive Channel
title_full_unstemmed Beltless Translocation Domain of Botulinum Neurotoxin A Embodies a Minimum Ion-conductive Channel
title_short Beltless Translocation Domain of Botulinum Neurotoxin A Embodies a Minimum Ion-conductive Channel
title_sort beltless translocation domain of botulinum neurotoxin a embodies a minimum ion-conductive channel
topic Reports
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3265847/
https://www.ncbi.nlm.nih.gov/pubmed/22158863
http://dx.doi.org/10.1074/jbc.C111.319400
work_keys_str_mv AT fischeraudrey beltlesstranslocationdomainofbotulinumneurotoxinaembodiesaminimumionconductivechannel
AT sambashivanshilpa beltlesstranslocationdomainofbotulinumneurotoxinaembodiesaminimumionconductivechannel
AT brungeraxelt beltlesstranslocationdomainofbotulinumneurotoxinaembodiesaminimumionconductivechannel
AT montalmauricio beltlesstranslocationdomainofbotulinumneurotoxinaembodiesaminimumionconductivechannel