The RelA Nuclear Localization Signal Folds upon Binding to IκBα

JOURNAL OF MOLECULAR BIOLOGY

卷:405

Article

Cervantes, Carla F.¹  Bergqvist, Simon¹  Kjaergaard, Magnus¹  Kroon, Gerard²  Sue, Shih-Che³  Dyson, H. Jane²  Komives, Elizabeth A.¹ 

[1] Univ Calif San Diego, Dept Chem & Biochem, La Jolla, CA 92092 USA

[2] Scripps Res Inst, Dept Mol Biol, La Jolla, CA 92037 USA

[3] Natl Tsing Hua Univ, Inst Bioinformat & Struct Biol, Hsinchu 30013, Taiwan

关键词: nuclear localization;    ankyrin repeat;    NMR;    intrinsically disordered protein;    coupled folding and binding;   

DOI  :  10.1016/j.jmb.2010.10.055

来源: Elsevier

【 摘 要 】

The nuclear localization signal (NLS) polypeptide of RelA, the canonical nuclear factor-kappa B family member, is responsible for regulating the nuclear localization of RelA-containing nuclear factor-kappa B 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 I kappa B alpha, 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 I kappa B alpha under solution conditions, we conducted NMR and isothermal titration calorimetry studies using a truncated form of I kappa B alpha 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 I kappa B alpha, the resonance dispersion in the NMR spectrum is significantly greater, providing definitive evidence that the RelA NLS polypeptide folds upon binding I kappa B alpha. 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 I kappa B alpha-bound RelA NLS polypeptide, is critical for the binding of the RelA NLS polypeptide to I kappa B alpha. These results help to explain the role of helix 4 in mediating the high affinity of RelA for I kappa B alpha. (C) 2010 Elsevier Ltd. All rights reserved.

【 授权许可】

Free