Cloning, expression and purification of botulinum neurotoxin type A heavy chain – crystallographic evidence for a putative tetrameric pore. (6th November 2012)

• Record Type: Journal Article
• Authors: Lakshminarasimhan, Damodharan; Kumaran, Desigan; Agarwal, Rakhi; Singh, Bal Ram; Swaminathan, Subramanyam
• Is Part Of: Botulinum journal. Volume 2:Number 2(2012)
• Page Start: 135
• Page End: 149
• Publication Date: 2012-11-06
• Subjects: botulinum neurotoxin -- BoNT -- translocation -- oligomerisation -- Pore formation -- heavy chain -- HC -- auto induction -- inclusion bodies; Botulinum toxin -- Periodicals; Clostridium botulinum -- Periodicals; Drug development -- Periodicals; 615.9529364
• Languages: English
• ISSNs: 1754-7318

Abstract

Clostridium botulinum produces seven antigenically distinct serotypes of botulinum neurotoxin (BoNTs, A-G) the most potent toxins to humans. They cause paralysis at less than picomolar concentration by blocking neurotransmitter release. BoNT consists of a heavy chain and a light chain. The C-terminal half of the heavy chain allows the toxin to bind to the presynaptic membrane while the N-terminal half helps in forming a channel in the endosomal membrane to allow the light chain to escape into the cytosol. While the binding and catalytic mechanisms are well understood now, the details of translocation still remain a mystery. A full length BoNT/A heavy chain (BAHC) has been cloned, over expressed and purified from inclusion bodies by solubilising with a detergent. Preliminary crystallographic results show that BAHC forms a tetramer in the crystal lending experimental support for tetrameric pore formation for the light chain to pass through the endosomal membrane.