The RelA nuclear localization signal folds upon binding to IκBα.

Autor: Cervantes CF; Department of Chemistry and Biochemistry, University of California, San Diego, 9500 Gilman Drive, La Jolla, CA 92092-0378, USA., Bergqvist S, Kjaergaard M, Kroon G, Sue SC, Dyson HJ, Komives EA
Jazyk: angličtina
Zdroj: Journal of molecular biology [J Mol Biol] 2011 Jan 21; Vol. 405 (3), pp. 754-64. Date of Electronic Publication: 2010 Nov 19.
DOI: 10.1016/j.jmb.2010.10.055
Abstrakt: The nuclear localization signal (NLS) polypeptide of RelA, the canonical nuclear factor-κB family member, is responsible for regulating the nuclear localization of RelA-containing nuclear factor-κB dimers. The RelA NLS polypeptide also plays a crucial role in mediating the high affinity and specificity of the interaction of RelA-containing dimers with the inhibitor IκBα, forming two helical motifs according to the published X-ray crystal structure. In order to define the nature of the interaction between the RelA NLS and IκBα under solution conditions, we conducted NMR and isothermal titration calorimetry studies using a truncated form of IκBα containing residues 67-206 and a peptide spanning residues 293-321 of RelA. The NLS peptide, although largely unfolded, has a weak tendency toward helical structure when free in solution. Upon addition of the labeled peptide to unlabeled IκBα, the resonance dispersion in the NMR spectrum is significantly greater, providing definitive evidence that the RelA NLS polypeptide folds upon binding IκBα. Isothermal titration calorimetry studies of single-point mutants reveal that residue F309, which is located in the middle of the more C-terminal of the two helices (helix 4) in the IκBα-bound RelA NLS polypeptide, is critical for the binding of the RelA NLS polypeptide to IκBα. These results help to explain the role of helix 4 in mediating the high affinity of RelA for IκBα.
(Copyright © 2010 Elsevier Ltd. All rights reserved.)
Databáze: MEDLINE
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