| Autor: |
Carrie A. Hughes, Christopher B. Phelps, Elizabeth A. Komives, Dennis Mishler, Tom Huxford, Lei Lei Sengchanthalangsy, Gourisankar Ghosh, De-Bin Huang, Ryan Reeves |
| Rok vydání: |
2002 |
| Předmět: |
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| Zdroj: |
Journal of Molecular Biology. 324:587-597 |
| ISSN: |
0022-2836 |
| DOI: |
10.1016/s0022-2836(02)01149-x |
| Popis: |
IκBα inhibits transcription factor NF-κB activity by specific binding to NF-κB heterodimers composed of p65 and p50 subunits. It binds with slightly lower affinity to p65 homodimers and with significantly lower affinity to homodimers of p50. We have employed a structure-based mutagenesis approach coupled with protein–protein interaction assays to determine the source of this dimer selectivity exhibited by IκBα. Mutation of amino acid residues in IκBα that contact NF-κB only marginally affects complex binding affinity, indicating a lack of hot spots in NF-κB/IκBα complex formation. Conversion of the weak binding NF-κB p50 homodimer into a high affinity binding partner of IκBα requires transfer of both the NLS polypeptide and amino acid residues Asn202 and Ser203 from the NF-κB p65 subunit. Involvement of Asn202 and Ser203 in complex formation is surprising as these amino acid residues occupy solvent exposed positions at a distance of 20 A from IκBα in the crystal structures. However, the same amino acid residue positions have been genetically isolated as determinants of binding specificity in a homologous system in Drosophila. X-ray crystallographic and solvent accessibility experiments suggest that these solvent-exposed amino acid residues contribute to NF-κB/IκBα complex formation by modulating the NF-κB p65 subunit NLS polypeptide. |
| Databáze: |
OpenAIRE |
| Externí odkaz: |
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