Structural analysis of Clostridium botulinum neurotoxin type D as a platform for the development of targeted secretion inhibitors

• Published in: Scientific reports Vol. 5; no. 1; p. 13397
• Main Authors: Masuyer, Geoffrey, Davies, Jonathan R., Moore, Kevin, Chaddock, John A., Ravi Acharya, K.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.09.2015; Nature Publishing Group
• Subjects: 631/45; 631/535; Animals; Botulinum toxin type D; Botulinum Toxins - chemistry; Botulinum Toxins - genetics; Botulinum Toxins - metabolism; CHO Cells; Cholinergic nerves; Clostridium botulinum; Clostridium botulinum - classification; Clostridium botulinum - metabolism; Cricetinae; Cricetulus; Crystallography, X-Ray; Growth hormone; Growth hormones; Hormone release; Humanities and Social Sciences; Humans; multidisciplinary; Nerve endings; Neurotransmission; Pituitary; Protein Structure, Tertiary; Receptors, Neuropeptide - genetics; Receptors, Neuropeptide - metabolism; Receptors, Pituitary Hormone-Regulating Hormone - genetics; Receptors, Pituitary Hormone-Regulating Hormone - metabolism; Recombinant Proteins - biosynthesis; Recombinant Proteins - chemistry; Recombinant Proteins - isolation & purification; Scattering, Small Angle; Science; Secretion; Serogroup; Serotypes; X-Ray Diffraction; X-ray scattering
• ISSN: 2045-2322; 2045-2322
• DOI: 10.1038/srep13397

The botulinum neurotoxin type D is one of seven highly potent toxins produced by Clostridium botulinum which inhibit neurotransmission at cholinergic nerve terminals. A functional fragment derived from the toxin, LHn, consisting of the catalytic and translocation domains, has been heralded as a platform for the development of targeted secretion inhibitors. These secretion inhibitors are aimed at retargeting the toxin towards a specific cell type to inhibit vesicular secretion. Here we report crystal structures of LHn from serotype D at 2.3?Å and that of SXN101959 at 3.1?Å resolution. SXN101959, a derivative that combines LHn from serotype D with a fragment of the growth hormone releasing hormone, has previously revealed promising results in inhibiting growth hormone release in pituitary somatotrophs. These structures offer for the first time insights into the translocation domain interaction with the catalytic domain in serotype D. Furthermore, structural information from small-angle X-ray scattering of LHn/D is compared among serotypes A, B and D. Taken together, these results demonstrate the robustness of the ‘LHn fold’ across serotypes and its use in engineering additional polypeptide components with added functionality. Our study demonstrates the suitability of botulinum neurotoxin and serotype D in particular, as a basis for engineering novel secretion inhibitors.