Document Detail

The effect of zinc oxide nanoparticles on the structure of the periplasmic domain of the Vibrio cholerae ToxR protein.
MedLine Citation:
PMID:  20825484     Owner:  NLM     Status:  MEDLINE    
Proteins adsorbed on nanoparticles (NPs) are being used as biosensors and in drug delivery. However, our understanding of the effect of NPs on the structure of proteins is still in a nascent state. In this work we report the unfolding behavior of the periplasmic domain of the ToxR protein (ToxRp) of Vibrio cholerae on zinc oxide (ZnO) nanoparticles with a diameter of 2.5 nm. This protein plays a crucial role in regulating the expression of several virulence factors in the pathogenesis of cholera. Thermodynamic analysis of the equilibrium of unfolding, induced both by urea and by guanidine hydrochloride (GdnHCl), and measured by fluorescence spectroscopy, revealed a two-state process. NPs increased the susceptibility of the protein to denaturation. The midpoints of transitions for the free and the NP-bound ToxRp in the presence of GdnHCl were 1.5 and 0.5 m respectively, whereas for urea denaturation, the values were 3.3 and 2.4 m, respectively. Far-UV CD spectra showed a significant change in the protein conformation upon binding to ZnO NPs, which was characterized by a substantial decrease in the α-helical content of the free protein. Isothermal titration calorimetry, used to quantify the thermodynamics of binding of ToxRp with ZnO NPs, showed an exothermic binding isotherm (ΔH = -9.8 kcal·mol(-1) and ΔS = -5.17 cal·mol(-1)·K(-1)).
Tanaya Chatterjee; Soumyananda Chakraborti; Prachi Joshi; Surinder P Singh; Vinay Gupta; Pinak Chakrabarti
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2010-09-06
Journal Detail:
Title:  The FEBS journal     Volume:  277     ISSN:  1742-4658     ISO Abbreviation:  FEBS J.     Publication Date:  2010 Oct 
Date Detail:
Created Date:  2010-10-07     Completed Date:  2010-11-02     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  101229646     Medline TA:  FEBS J     Country:  England    
Other Details:
Languages:  eng     Pagination:  4184-94     Citation Subset:  IM    
Copyright Information:
© 2010 The Authors Journal compilation © 2010 FEBS.
Department of Biochemistry, Bose Institute, Kolkata, India.
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MeSH Terms
Bacterial Proteins / chemistry*
Circular Dichroism
DNA-Binding Proteins / chemistry*
Guanidine / pharmacology
Nanoparticles / chemistry,  therapeutic use
Periplasm / chemistry*
Protein Conformation / drug effects
Protein Denaturation / drug effects*
Transcription Factors / chemistry*
Urea / pharmacology
Zinc Oxide / pharmacology*
Reg. No./Substance:
0/Bacterial Proteins; 0/DNA-Binding Proteins; 0/Transcription Factors; 0/toxR protein, Vibrio cholerae; 113-00-8/Guanidine; 1314-13-2/Zinc Oxide; 57-13-6/Urea

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