Del Rosario Brian C, Pemberton Lucy F
Center for Cell Signaling, University of Virginia, Charlottesville, VA 22908, USA.
Mol Cell Biol. 2008 Apr;28(7):2113-24. doi: 10.1128/MCB.02136-07. Epub 2008 Jan 28.
Chromatin remodeling is central to the regulation of transcription elongation. We demonstrate that the conserved Saccharomyces cerevisiae histone chaperone Nap1 associates with chromatin. We show that Nap1 regulates transcription of PHO5, and the increase in transcript level and the higher phosphatase activity plateau observed for Deltanap1 cells suggest that the net function of Nap1 is to facilitate nucleosome reassembly during transcription elongation. To further our understanding of histone chaperones in transcription elongation, we identified factors that regulate the function of Nap1 in this process. One factor investigated is an essential mRNA export and TREX complex component, Yra1. Nap1 interacts directly with Yra1 and genetically with other TREX complex components and the mRNA export factor Mex67. Additionally, we show that the recruitment of Nap1 to the coding region of actively transcribed genes is Yra1 dependent and that its recruitment to promoters is TREX complex independent. These observations suggest that Nap1 functions provide a new connection between transcription elongation, chromatin assembly, and messenger RNP complex biogenesis.
染色质重塑对于转录延伸的调控至关重要。我们证明了保守的酿酒酵母组蛋白伴侣Nap1与染色质相关联。我们表明Nap1调节PHO5的转录，并且在Δnap1细胞中观察到的转录水平增加和更高的磷酸酶活性平台表明，Nap1的净功能是在转录延伸过程中促进核小体重组。为了进一步了解转录延伸中的组蛋白伴侣，我们鉴定了在此过程中调节Nap1功能的因子。研究的一个因子是必需的mRNA输出和TREX复合物组分Yra1。Nap1直接与Yra1相互作用，并在遗传上与其他TREX复合物组分和mRNA输出因子Mex67相互作用。此外，我们表明Nap1募集到活跃转录基因的编码区是Yra1依赖性的，而其募集到启动子是TREX复合物非依赖性的。这些观察结果表明，Nap1的功能在转录延伸、染色质组装和信使核糖核蛋白复合物生物发生之间提供了新的联系。
