Genomes, neurotoxins and biology of Clostridium botulinum Group I and Group II.
Bottom Line: Recent developments in whole genome sequencing have made a substantial contribution to understanding the genomes, neurotoxins and biology of Clostridium botulinum Group I (proteolytic C. botulinum) and C. botulinum Group II (non-proteolytic C. botulinum).The properties of the different types of neurotoxin formed, and different neurotoxin gene clusters found in C. botulinum Groups I and II are explored.Specific examples of botulinum neurotoxin genes are chosen for an in-depth discussion of neurotoxin gene evolution.
Affiliation: Institute of Food Research, Norwich Research Park, Colney, Norwich, NR4 7UA, UK.Show MeSH
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Mentions: Type B neurotoxin is formed by strains of C. botulinum Groups I and II, and the type B neurotoxin gene sequences are compared (Fig. 6). Considering the large genetic and physiological gap which separates C. botulinum Groups I and II, it is perhaps not surprising that each type B subtype appears to be exclusive to C. botulinum Group I or Group II. Subtype B4 appears to be only found in C. botulinum Group II, while all the other subtypes are solely located in C. botulinum Group I. This may indicate that a window of opportunity for horizontal gene transfer of type B toxin genes between the two C. botulinum Groups in the distant evolutionary past has now closed. (It is noted, however, that while the C. botulinum Group II strain Prevot 59 in our laboratory possessed the type B4 neurotoxin gene, the version of this strain examined by Hill possessed the type B2 neurotoxin gene ). The cluster at top left of Fig. 6, which is designated ‘B?’ contains type B genes that are described as type B1 (M-18/3) and type B2 (Osaka06, CDC 6291, 115B), but in this analysis seem to form a separate group (subtype information for strain 115B was derived from microarray data, GEO accession number GSM402938). This appears to be yet another example of C. botulinum neurotoxin genes which fail to fit into a nicely defined subtype box.
Affiliation: Institute of Food Research, Norwich Research Park, Colney, Norwich, NR4 7UA, UK.