一种去磷酸化缺陷型IκBα突变体揭示了去磷酸化在NFκB信号传导中的功能重要性。
Functional importance of stripping in NFκB signaling revealed by a stripping-impaired IκBα mutant.
作者信息
Dembinski Holly E, Wismer Kevin, Vargas Jesse D, Suryawanshi Gajendra W, Kern Nadja, Kroon Gerard, Dyson H Jane, Hoffmann Alexander, Komives Elizabeth A
机构信息
Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093-0378.
Department of Microbiology, Immunology and Molecular Genetics, University of California, Los Angeles, CA 90095.
出版信息
Proc Natl Acad Sci U S A. 2017 Feb 21;114(8):1916-1921. doi: 10.1073/pnas.1610192114. Epub 2017 Feb 6.
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.
应激反应转录因子如核因子κB（NFκB）可开启数百个基因，且必须具备快速终止转录激活的机制。我们最近发现，NFκB信号通路的抑制剂IκBα能显著加速NFκB从转录位点的解离，我们将这一过程称为“剥离”。为了测试IκBα C末端富含脯氨酸、谷氨酸、丝氨酸和苏氨酸残基的PEST序列在NFκB剥离中的作用，构建了一个突变型IκBα，其中五个酸性PEST残基被突变为它们的中性类似物。该IκBα（5xPEST）突变体在从DNA上剥离NFκB方面存在缺陷，并且与由IκBα（野生型）形成的中间三元复合物相比，其形成的复合物更稳定，因为DNA解离得更慢。核磁共振（NMR）和酰胺氢-氘交换质谱分析表明，IκBα（5xPEST）似乎“在剥离过程中被捕获”，因为它尚未完全处于折叠且与NFκB结合的状态。当将该突变体导入细胞时，诱导后IκBα介导的NFκB从细胞核输出的速率显著降低。
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