Role of zinc in the structure and toxic activity of botulinum neurotoxin
Abstract
Zn2+-protease activity of botulinum neurotoxin causes the blockage of neurotransmitter release resulting in botulism disease. We have investigated the role of Zn2+ in the biological activity of type A botulinum neurotoxin by removing the bound Zn2+ by EDTA treatment, followed by monitoring its structure in terms of secondary and tertiary folding (second derivative UV, FT-IR, and circular dichroism spectroscopy) and function in terms of its effect on the release of norepinephrine from PC12 cells. The single Zn2+ bound to each neurotoxin molecule was reversibly removed by EDTA treatment, whereas the biological activity of the neurotoxin was irreversibly lost. Based on the Amide III IR spectral analysis, the alpha-helical content of neurotoxin increased from 29% to 42% upon removal of Zn2+, which reverted to 31% upon treatment with 1:5 molar excess of exogenous Zn2+. Second derivative UV spectroscopy revealed no change in surface topography of Tyr residues with removal of Zn2+. However, near-UV circular dichroism signals suggested significant alterations in the topography of Phe and Tyr residues that could be buried in the protein matrix. Thermal unfolding experiments suggested that removal of Zn2+ results in the formation of the ...Continue Reading
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Molecular basis of immunogenicity to botulinum neurotoxins and uses of the defined antigenic regions
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Botulism (ASM)
Botulism is a rare but serious paralytic illness caused by a nerve toxin that is produced by the bacterium clostridium botulinum. Discover the latest research on botulism here.
Botulism
Botulism is a rare but serious paralytic illness caused by a nerve toxin that is produced by the bacterium clostridium botulinum. Discover the latest research on botulism here.