Angelov Dimitar, Bondarenko Vladimir A, Almagro Sébastien, Menoni Hervé, Mongélard Fabien, Hans Fabienne, Mietton Flore, Studitsky Vasily M, Hamiche Ali, Dimitrov Stefan, Bouvet Philippe
Ecole Normale Supérieure de Lyon, CNRS-UMR 5161/INRA 1237/IFR128 Biosciences, Lyon-Gerland, France.
EMBO J. 2006 Apr 19;25(8):1669-79. doi: 10.1038/sj.emboj.7601046. Epub 2006 Apr 6.
Remodeling machines play an essential role in the control of gene expression, but how their activity is regulated is not known. Here we report that the nuclear protein nucleolin possesses a histone chaperone activity and that this factor greatly enhances the activity of the chromatin remodeling machineries SWI/SNF and ACF. Interestingly, nucleolin is able to induce the remodeling by SWI/SNF of macroH2A, but not of H2ABbd nucleosomes, which are otherwise resistant to remodeling. This new histone chaperone promotes the destabilization of the histone octamer, helping the dissociation of a H2A-H2B dimer, and stimulates the SWI/SNF-mediated transfer of H2A-H2B dimers. Furthermore, nucleolin facilitates transcription through the nucleosome, which is reminiscent of the activity of the FACT complex. This work defines new functions for histone chaperones in chromatin remodeling and regulation of transcription and explains how nucleolin could act on transcription.
重塑机器在基因表达调控中发挥着至关重要的作用，但其活性是如何被调节的尚不清楚。在此我们报告，核蛋白核仁素具有组蛋白伴侣活性，并且该因子极大地增强了染色质重塑机器SWI/SNF和ACF的活性。有趣的是，核仁素能够诱导SWI/SNF对macroH2A进行重塑，但不能对H2ABbd核小体进行重塑，否则H2ABbd核小体对重塑具有抗性。这种新的组蛋白伴侣促进组蛋白八聚体的不稳定，帮助H2A-H2B二聚体解离，并刺激SWI/SNF介导的H2A-H2B二聚体转移。此外，核仁素促进转录通过核小体，这让人联想到FACT复合物的活性。这项工作定义了组蛋白伴侣在染色质重塑和转录调控中的新功能，并解释了核仁素如何作用于转录。
