New source of world’s deadliest toxin discovered
Researchers from the Quadram Institute in Norwich have identified genes encoding a previously undiscovered version of the botulinum neurotoxin in bacteria from a cow’s gut.
It is the first time an intact cluster of genes for making botulinum neurotoxin have been found outside of the bacterium Clostridium botulinum or its close relatives and only the second report of a new botulinum toxin in the past 40 years.
Clostridium botulinum is a dangerous pathogen that forms the highly potent botulinum toxin, which when ingested causes botulism, a deadly neuroparalytic disease. But botulinum neurotoxin is now also used in a range of medical procedures, as well as for cosmetic purposes. The discovery of this new type from an unexpected source has the potential to widen the range of medical uses even further.
The genes that encode the botulinum toxin protein along with accessory proteins that protect the botulinum toxin and ensure it functions, are organised as a gene cluster.
In new research, published in the journal FEBS Letters, scientists at the Quadram Institute carried out a search of the National Centre for Biotechnology Information’s Whole Genome Sequence database.
Using bioinformatics techniques, Dr Jason Brunt and Dr Andrew Carter, working with Professor Mike Peck and Dr Sandra Stringer, screened this database for other entries that were similar to the predicted proteins that the botulinum toxin gene would produce. The study was funded by the Biotechnology and Biological Sciences Research Council.
This search identified a previously undiscovered gene cluster encoding a new botulinum neurotoxin and accessory proteins in the genome of a species of Enterococcus bacteria isolated from cow faeces.
As well as understanding the implications of finding this new variant of the botulism gene cluster in a non-clostridial species of gut bacterium, the team are interested in exploring how it might help in developing new treatments for diseases.
The researchers have found indications from 3D structure modelling that this new version of the toxin may possess a novel targeting mechanism, which could enable it to treat a wider range of conditions.
• PHOTOGRAPH SHOWS: Dr Jason Brunt