Datta, Ajit B. ; Roy, Siddhartha ; Parrack, Pradeep (2003) Disorder-order transition of λ CII promoted by low concentrations of guanidine hydrochloride suggests a stable core and a flexible C-terminus European Journal of Biochemistry, 270 (22). pp. 4439-4446. ISSN 0014-2956
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Official URL: http://onlinelibrary.wiley.com/doi/10.1046/j.1432-...
Related URL: http://dx.doi.org/10.1046/j.1432-1033.2003.03835.x
Abstract
The CII protein of bacteriophage λ, which activates the synthesis of the λ repressor, plays a key role in the lysis-lysogeny switch. CII has a small in vivo half-life due to its proteolytic susceptibility, and this instability is a key component for its regulatory role. The structural basis of this instability is not known. While studying guanidine hydrochloride-assisted unfolding of CII, we found that low concentrations of the chaotrope (50-500 mm) have a considerable effect on the structure of this protein. This effect is manifest in an increase in molar ellipticity, an enhancement of intrinsic tryptophan fluorescence intensity and a reduction in ANS binding. At low concentrations of guanidine hydrochloride CII is stabilized, as reflected in a significant decrease in the rate of proteolysis by trypsin and resistance to thermal aggregation, while the tetrameric nature of the protein is retained. Thus low concentrations of guanidine hydrochloride promote a more structured conformation of the CII protein. On the basis of these observations, a model has been proposed for the structure of CII wherein the protein equilibrates between a compact form and a proteolytically accessible form, in which the C-terminal region assumes different structures.
Item Type: | Article |
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Source: | Copyright of this article belongs to John Wiley and Sons. |
Keywords: | Bacteriophage λ HflB Protein; Proteolysis; Genetic Switch; Lysogeny |
ID Code: | 43189 |
Deposited On: | 10 Jun 2011 08:16 |
Last Modified: | 18 May 2016 00:16 |
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