Genomic location of flagellin CBO0798 and regions of sequence similarity with CNTs. A) Genomic context of the neurotoxin gene cluster for C. botulinum A. str. Hall. B) Domain structure of CNTs and regions of detected similarity with NTNH (region I) and BoNT/A (region 2) according to SSEARCH. A consensus CNT secondary structure based on a multiple sequence alignment is indicated below the schematic, with black lines representing alpha helices and grey lines representing beta sheets. C) The structure of BoNT/A (PDB ID 3BTA) with region II highlighted in red. D) A Smith-Waterman alignment of region II from C. butyricum BoNT/E and CBO0798.