Clostridium botulinum properties

Blocker, D., Bachmeyer, C., Benz, R., Aktories, K. and Barth, H., Channel formation by the binding component of Clostridium botulinum C2 toxin glutamate 307 of C2II affects channel properties in vitro and pH-dependent C2I translocation in vivo, Biochem., 42, 5368-5377, 2003. 

Tabita, K., Sakaguchi, S., Kozaki, S. and Sakaguchi, G., Distinction between Clostridium botulinum type A strains associated with food-bome botulism and those with infant botulism in Japan in intraintestinal toxin production in infant mice and some other properties, FEMS Microbiol. Lett., 63, 2-3, 251-256,1999. 

Reuner KH, Schlegel K, Just I, et al. (1991) Autoregulatory control of actin synthesis in cultured rat hepatocytes. In FEBS Letters. 286 100-4 Schmid A, Benz R, Just I, et al. (1994) Interaction of Olostridium botulinum 02 toxin with lipid bilayer membranes. Formation of cation-selective channels and inhibition of channel function by chloroquine. In J Biol Chem. 269 16706-11 Simpson LL (1982) A comparison of the pharmacological properties of Clostridium botulinum type 01 and 02 toxins. In J Pharmacol Exp Then 223 695-701 Simpson LL (1989a) Botulinum Neurotoxin andTetanus Toxin, pp 1 -422, San Diego Academic Press... 

Classical bacterial exotoxins, such as diphtheria toxin, cholera toxin, clostridial neurotoxins, and the anthrax toxins are enzymes that modify their substrates within the cytosol of mammalian cells. To reach the cytosol, these toxins must first bind to different cell-surface receptors and become subsequently internalized by the cells. To this end, many bacterial exotoxins contain two functionally different domains. The binding (B-) domain binds to a cellular receptor and mediates uptake of the enzymatically active (A-) domain into the cytosol, where the A-domain modifies its specific substrate (see Figure 1). Thus, three important properties characterize the mode of action for any AB-type toxin selectivity, specificity, and potency. Because of their selectivity toward certain cell types and their specificity for cellular substrate molecules, most of the individual exotoxins are associated with a distinct disease. Because of their enzymatic nature, placement of very few A-domain molecules in the cytosol will normally cause a cytopathic effect. Therefore, bacterial AB-type exotoxins which include the potent neurotoxins from Clostridium tetani and C. botulinum are the most toxic substances known today. However, the individual AB-type toxins can greatly vary in terms of subunit composition and enzyme activity (see Table 2). 

There is some evidence that inhibition of C. botulinum outgrowth in nitrite-cured meat products is mainly due to iron binding in such a way that this is no longer available for outgrowth of Clostridium spores. This strong binding also explains the antioxidative properties of nitrite in these products (Grever and Ruiter, 2001). 

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