通过 HIV-1 核小体的转录：PBAF 复合物对 Tat 激活转录的影响。
Transcription through the HIV-1 nucleosomes: effects of the PBAF complex in Tat activated transcription.
机构信息
National Center for Biodefense and Infectious Diseases, George Mason University, Manassas, VA 20110, USA.
出版信息
Virology. 2010 Sep 30;405(2):322-33. doi: 10.1016/j.virol.2010.06.009.
The SWI/SNF complex remodels nucleosomes, allowing RNA Polymerase II access to the HIV-1 proviral DNA. It has not been determined which SWI/SNF complex (BAF or PBAF) remodels nucleosomes at the transcription start site. These complexes differ in only three subunits and determining which subunit(s) is required could explain the regulation of Tat activated transcription. We show that PBAF is required for chromatin remodeling at the nuc-1 start site and transcriptional elongation. We find that Baf200 is required to ensure activation at the LTR level and for viral production. Interestingly, the BAF complex was observed on the LTR whereas PBAF was present on both LTR and Env regions. We found that Tat activated transcription facilitates removal of histones H2A and H2B at the LTR, and that the FACT complex may be responsible for their removal. Finally, the BAF complex may play an important role in regulating splicing of the HIV-1 genome.
SWI/SNF 复合物重塑核小体，使 RNA 聚合酶 II 能够接近 HIV-1 前病毒 DNA。目前还不清楚哪种 SWI/SNF 复合物（BAF 或 PBAF）在转录起始位点重塑核小体。这两种复合物仅在三个亚基上存在差异，确定需要哪种（哪些）亚基可以解释 Tat 激活转录的调控。我们表明，PBAF 是核-1 起始位点染色质重塑和转录延伸所必需的。我们发现 Baf200 对于 LTR 水平的激活和病毒产生是必需的。有趣的是，BAF 复合物存在于 LTR 上，而 PBAF 存在于 LTR 和 Env 区域。我们发现 Tat 激活转录促进了 LTR 处组蛋白 H2A 和 H2B 的去除，而 FACT 复合物可能负责其去除。最后，BAF 复合物可能在调节 HIV-1 基因组的剪接中发挥重要作用。
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