Browsing by Author "Sjölund, Amanda"

Botulism is a potentially fatal flaccid paralysis in animals and humans. The disease is caused by botulinum neurotoxins (BoNTs) produced by endospore-forming bacteria of Clostridium botulinum Groups I-IV, or occasionally by Clostridium baratii and Clostridium butyricum. C. botulinum spores prevail in the environment and can contaminate food raw materials. BoNT production may occur in anaerobically stored foods, in the gastrointestinal tract, or in deep wounds. Here we take a novel insight into the regulation of BoNT synthesis through epigenetic control. Epigenetic studies in bacteria focus mostly on DNA methylation catalysed by enzymes called methyltransferases (MTases), which recognize specific DNA sequence motifs and methylate either an adenine or a cytosine base. While most MTases are part of restriction-modification systems involved in defending the cells from foreign mobile DNA elements, there are orphan MTases that methylate DNA to control gene expression. Here we characterized the role of a conserved orphan MTase, M.CboAII, in C. botulinum Group I. In order to unravel the biological role of M.CboAII, a m.cboAII deletion mutant of the proteolytic C. botulinum model strain ATCC 19397 was characterized. The growth, sporulation, cell morphology and neurotoxin production in the Δm.cboAII mutant and its parental strain were compared by measuring the culture density, vegetative cell and spore counts, microscopy, and toxin quantification using an immunological in vitro assay. The mutant showed decreased toxin synthesis and attenuation of sporulation, whereas culture density and cell numbers were similar compared to the parental strain. Further, irregularly shaped mutant cells were detected, which may suggest membrane alterations. Our results suggest that M.CboAII plays a positive role in toxin synthesis and in sporulation. Transcriptomic analysis of ATCC 19397 and Δm.cboAII mutant strains at different stages of growth will help us to uncover the cellular processes controlled by M.CboAII in more detail. Here we take the first glance into epigenetic regulation of cellular processes in C. botulinum. We report a potentially novel regulatory mechanism involved in C. botulinum toxinogenesis and sporulation. Better understanding of these fundamental processes controlling the pathogenicity of C. botulinum may help to develop novel strategies in food and health management in the future.