Zhang, SicaiMasuyer, GeoffreyZhang, JieShen, YiLundin, DanielHenriksson, LindaMiyashita, Shin-IchiroMartínez-Carranza, MarkelDong, MinStenmark, Pål2017-11-212017Zhang, Sicai, Geoffrey Masuyer, Jie Zhang, Yi Shen, Daniel Lundin, Linda Henriksson, Shin-Ichiro Miyashita, Markel Martínez-Carranza, Min Dong, and Pål Stenmark. 2017. “Identification and characterization of a novel botulinum neurotoxin.” Nature Communications 8 (1): 14130. doi:10.1038/ncomms14130. http://dx.doi.org/10.1038/ncomms14130.http://nrs.harvard.edu/urn-3:HUL.InstRepos:34375147Botulinum neurotoxins are known to have seven serotypes (BoNT/A–G). Here we report a new BoNT serotype, tentatively named BoNT/X, which has the lowest sequence identity with other BoNTs and is not recognized by antisera against known BoNTs. Similar to BoNT/B/D/F/G, BoNT/X cleaves vesicle-associated membrane proteins (VAMP) 1, 2 and 3, but at a novel site (Arg66-Ala67 in VAMP2). Remarkably, BoNT/X is the only toxin that also cleaves non-canonical substrates VAMP4, VAMP5 and Ykt6. To validate its activity, a small amount of full-length BoNT/X was assembled by linking two non-toxic fragments using a transpeptidase (sortase). Assembled BoNT/X cleaves VAMP2 and VAMP4 in cultured neurons and causes flaccid paralysis in mice. Thus, BoNT/X is a novel BoNT with a unique substrate profile. Its discovery posts a challenge to develop effective countermeasures, provides a novel tool for studying intracellular membrane trafficking, and presents a new potential therapeutic toxin for modulating secretions in cells.en-USJournal Article2017-11-2110.1038/ncomms14130