Functional importance of stripping in NF?B signaling revealed by a stripping-impaired I?B? mutant.

ABSTRACT: Stress-response transcription factors such as NF?B turn on hundreds of genes and must have a mechanism for rapid cessation of transcriptional activation. We recently showed that the inhibitor of NF?B signaling, I?B?, dramatically accelerates the dissociation of NF?B from transcription sites, a process we have called "stripping." To test the role of the I?B? C-terminal PEST (rich in proline, glutamic acid, serine, and threonine residues) sequence in NF?B stripping, a mutant I?B? was generated in which five acidic PEST residues were mutated to their neutral analogs. This I?B?(5xPEST) mutant was impaired in stripping NF?B from DNA and formed a more stable intermediate ternary complex than that formed from I?B?(WT) because DNA dissociated more slowly. NMR and amide hydrogen-deuterium exchange mass spectrometry showed that the I?B?(5xPEST) appears to be "caught in the act of stripping" because it is not yet completely in the folded and NF?B-bound state. When the mutant was introduced into cells, the rate of postinduction I?B?-mediated export of NF?B from the nucleus decreased markedly.

SUBMITTER: Dembinski HE 

PROVIDER: S-EPMC5338396 | biostudies-literature | 2017 Feb

REPOSITORIES: biostudies-literature