Publication: Investigation of the unfolding pathway of Bacillus thuringiensis Cyt2Aa2 toxin reveals an unfolding intermediate
Issued Date
2009-05-20
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ISSN
01681656
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2-s2.0-67349086916
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Mahidol University
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SCOPUS
Bibliographic Citation
Journal of Biotechnology. Vol.141, No.3-4 (2009), 137-141
Suggested Citation
Anchanee Sangcharoen, Weerachon Tepanant, Somruathai Kidsanguan, Boonhiang Promdonkoy, Chartchai Krittanai Investigation of the unfolding pathway of Bacillus thuringiensis Cyt2Aa2 toxin reveals an unfolding intermediate. Journal of Biotechnology. Vol.141, No.3-4 (2009), 137-141. doi:10.1016/j.jbiotec.2009.03.012 Retrieved from: https://repository.li.mahidol.ac.th/handle/20.500.14594/27226
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Title
Investigation of the unfolding pathway of Bacillus thuringiensis Cyt2Aa2 toxin reveals an unfolding intermediate
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Abstract
Cyt2Aa2 is a cytolytic toxin from Bacillus thuringiensis subsp. darmstadiensis. Its active form has a lethal activity against specific mosquito larvae. We characterized an unfolding pathway of Cyt2Aa2 using a guanidinium hydrochloride denaturation. The results revealed three-state transition with a detectable intermediate in a condition with 3-4 M of GuHCl. The conformational free energies for native and intermediate state unfolding were 5.82 ± 0.47 and 16.85 ± 1.47 kcal/mol, respectively. Kinetic analysis suggested that the activation energy of both transitions was around 23-25 kcal/mol, with a rate-limiting step in the second transition. These results have established an energy profile of the Cyt2Aa2 toxin in various conformations involved in the unfolding/refolding pathway. Further characterization of the intermediate state by dye-binding assay, intrinsic fluorescence, and circular dichroism spectroscopy demonstrated characteristics of a molten globule state. This revealed intermediate could play an active role in the structural folding and biological activity of the toxin. © 2009 Elsevier B.V. All rights reserved.
