Dataset Information

The RelA nuclear localization signal folds upon binding to I?B?.

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

SUBMITTER: Cervantes CF

PROVIDER: S-EPMC3056351 | biostudies-literature | 2011 Jan

REPOSITORIES: biostudies-literature

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Publications

The RelA nuclear localization signal folds upon binding to IκBα.

Cervantes Carla F CF Bergqvist Simon S Kjaergaard Magnus M Kroon Gerard G Sue Shih-Che SC Dyson H Jane HJ Komives Elizabeth A EA

Journal of molecular biology 20101119 3

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 interactio ...[more]

PMID: 21094161

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Project description:Histone deacetylase 5 (HDAC5), a class IIa deacetylase, is a prominent regulator of cellular and epigenetic processes that underlie the progression of human disease, ranging from cardiac hypertrophy to cancer. Although it is established that phosphorylation mediates 14-3-3 protein binding and provides the essential link between HDAC5 nucleo-cytoplasmic shuttling and transcriptional repression, thus far only four phospho-acceptor sites have been functionally characterized. Here, using a combinatorial proteomics approach and phosphomutant screening, we present the first evidence that HDAC5 has at least 17 in vivo phosphorylation sites within functional domains, including Ser278 and Ser279 within the nuclear localization signal (NLS), Ser1108 within the nuclear export signal, and Ser755 in deacetylase domain. Global and targeted MS/MS analyses of NLS peptides demonstrated the presence of single (Ser278 and Ser279) and double (Ser278/Ser279) phosphorylations. The double S278/279A mutation showed reduced association with HDAC3, slightly decreased deacetylation activity, and significantly increased cytoplasmic localization compared with wild type HDAC5, whereas the S278A and S1108A phosphomutants were not altered. Live cell imaging revealed a deficiency in nuclear import of S278/279A HDAC5. Phosphomutant stable cell lines confirmed the cellular redistribution of NLS mutants and revealed a more pronounced cytoplasmic localization for the single S279A mutant. Proteomic analysis of immunoisolated S278/279A, S279A, and S259/498A mutants linked altered cellular localization to changes in protein interactions. S278/279A and S279A HDAC5 showed reduced association with the NCoR-HDAC3 nuclear corepressor complex as well as protein kinase D enzymes, which were potentiated in the S259/498A mutant. These results provide the first link between phosphorylation outside the known 14-3-3 sites and downstream changes in protein interactions. Together these studies identify Ser279 as a critical phosphorylation within the NLS involved in the nuclear import of HDAC5, providing a regulatory point in nucleo-cytoplasmic shuttling that may be conserved in other class IIa HDACs-HDAC4 and HDAC9.

Dataset Information

The RelA nuclear localization signal folds upon binding to I?B?.

Publications

The RelA nuclear localization signal folds upon binding to IκBα.

Similar Datasets

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