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Updated: Mar 7, 2026

A Guide to Production, Crystallization, and Structure Determination of Human IKK1/α
Published on: November 2, 2018
Functional importance of stripping in NFκB signaling revealed by a stripping-impaired IκBα mutant
Holly E Dembinski1, Kevin Wismer1, Jesse D Vargas2,3
1Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093-0378.
Abstract:
Stress-response transcription factors such as NFκB turn on hundreds of genes and must have a mechanism for rapid cessation of transcriptional activation. We recently showed that the inhibitor of NFκB signaling, IκBα, dramatically accelerates the dissociation of NFκB from transcription sites, a process we have called "stripping." To test the role of the IκBα C-terminal PEST (rich in proline, glutamic acid, serine, and threonine residues) sequence in NFκB stripping, a mutant IκBα was generated in which five acidic PEST residues were mutated to their neutral analogs. This IκBα(5xPEST) mutant was impaired in stripping NFκB from DNA and formed a more stable intermediate ternary complex than that formed from IκBα(WT) because DNA dissociated more slowly. NMR and amide hydrogen-deuterium exchange mass spectrometry showed that the IκBα(5xPEST) appears to be "caught in the act of stripping" because it is not yet completely in the folded and NFκB-bound state. When the mutant was introduced into cells, the rate of postinduction IκBα-mediated export of NFκB from the nucleus decreased markedly.
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