Role of the C-terminal tail region in the self-assembly of λ-repressor

Bandyopadhyay, Sumita ; Banik, Utpal ; Bhattacharyya, Bhabatarak ; Mandal, Nitai C. ; Roy, Siddhartha (1995) Role of the C-terminal tail region in the self-assembly of λ-repressor Biochemistry, 34 (15). pp. 5090-5097. ISSN 0006-2960

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Acrylamide quenching of the tryptophan fluorescence of the λ-repressor at different protein concentrations indicates that one of the three tryptophan residues, W129, W142, and W230, undergoes a change in environment upon self-assembly, from dimer to associated species. Quenching data suggest that this tryptophan residue is inaccessible to low concentrations of acrylamide and is blue-shifted in the associated form. In the dimer, this tryptophan residue is highly accessible to acrylamide and is red-shifted. NBS oxidation, at protein concentrations which favor the associated form, showed that this tryptophan is also significantly protected from NBS oxidation. HPLC peptide mapping of NBS-oxidized λ-repressor, amino acid analysis, and sequencing indicate that the protected, blue-shifted tryptophan is tryptophan 230. A mutant repressor (F235C) was specifically labeled at Cys 235 with an environment-sensitive probe, acrylodan. The acrylodan fluorescence of the labeled F235C λ -repressor undergoes a significant blue-shift, accompanied by fluorescence enhancement, upon protein association. Along with other genetic evidence, these results suggest involvement of the C-terminal tail region in the self-assembly of the λ-repressor.

Item Type:Article
Source:Copyright of this article belongs to American Chemical Society.
ID Code:26168
Deposited On:06 Dec 2010 12:59
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