The proteasome regulates HIV-1 transcription by both proteolytic and nonproteolytic mechanisms
The proteasome regulates HIV-1 transcription by both proteolytic and nonproteolytic mechanisms
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DOI：
10.1016/j.molcel.2006.12.020
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发表时间：
2007-02-09
期刊：
影响因子：
16
通讯作者：
Kiernan, Rosemary E.
中科院分区：
文献类型：
--
作者：
Lassot, Irina;Latreille, Daniel;Kiernan, Rosemary E.
虽然蛋白酶体促进从几个酵母启动子的转录，但尚不清楚它的作用是否是蛋白水解或涉及哪些亚基。我们发现，蛋白酶体调节HIV-1启动子的蛋白水解和非蛋白水解模式。在没有转录因子达特的情况下，蛋白酶体与启动子和编码区相关，其蛋白水解活性调节来自启动子的基础转录水平。达特通过招募蛋白酶体相关蛋白PAAF 1将蛋白酶体转换为非蛋白水解模式，PAAF 1有利于蛋白酶体解离成19 S和20 S颗粒。凝胶过滤层析显示，达特和PAAF 1的表达增强了核提取物中19 S样复合物的丰度。19 S亚基，而不是20 S亚基，在达特和PAAF 1的存在下被强烈募集到启动子中，并共激活Tat依赖性转录。19 S组分促进转录延伸，并可能参与从启动子中清除暂停的转录延伸复合物。
Although the proteasome facilitates transcription from several yeast promoters, it is unclear if its role is proteolytic or which subunits are involved. We show that the proteasome regulates the HIV-1 promoter in both proteolytic and nonproteolytic modes. In the absence of transcription factor, Tat, proteasome was associated with promoter and coding regions, and its proteolytic activity regulated the level of basal transcription emanating from the promoter. Tat switched the proteasome to a nonproteolytic mode by recruiting a proteasome-associated protein, PAAF1, which favors proteasome dissociation into 19S and 20S particles. Gel filtration chromatography showed that expression of both Tat and PAAF1 enhanced the abundance of a 19S-like complex in nuclear extracts. 19S, but not 20S, subunits were strongly recruited to the promoter in the presence of Tat and PAAF1 and coactivated Tat-dependent transcription. 19S components facilitated transcriptional elongation and may be involved in clearance of paused transcriptional elongation complexes from the promoter.