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Dynamics of IkBa Probed by NMR
Author(s) -
Cervantes Carla Fabiola,
Komives Elizabeth Ann,
Dyson Jane,
Sue S C,
Kroon Gerard
Publication year - 2007
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.21.5.a655-c
Subject(s) - ankyrin repeat , ankyrin , chemistry , stereochemistry , biophysics , biology , biochemistry , gene
Although the structure of the transcription factor Nuclear Factor Kappa B (NF‐κB) bound to its inhibitor, the ankyrin repeat protein IκBα, has been solved by x‐ray crystallography, no structure of the free state of IκBα is available. Native state H/D exchange experiments showed that its ankyrin repeat domain possesses significant structural flexibility in the first, fifth and sixth ankyrin repeats. While the secondary structure of IκBα remains the same in the free and NF‐κB‐bound states as shown by CD, the β‐hairpin regions in the fifth and sixth ankyrin repeats are highly solvent accessible and these regions become more structured upon binding NF‐κB. In order to understand the role of the flexibility of IκBα for its function, we are using NMR experiments to investigate the backbone dynamics of free IκBα and to probe the relevance of these motions for the stability and function of IκBα by site‐directed mutagenesis. Full NMR backbone assignments for the C‐terminally truncated IκBα(67‐206) will be presented. We have made various stabilized mutants in which residues are replaced with those corresponding to the consensus sequence for stable ankyrin repeat proteins in order to assign residues 207–287, the fifth and sixth repeats. Results of NMR studies on the binding of the NLS of NF‐κB to IκBα will also be presented.