Functional interaction between the HIV transactivator Tat and the transcriptional coactivator PC4 in T cells
Functional interaction between the HIV transactivator Tat and the transcriptional coactivator PC4 in T cells
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DOI：
10.1074/jbc.m909058199
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发表时间：
2000-07-14
影响因子：
4.8
通讯作者：
Shannon, MF
中科院分区：
文献类型：
--
作者：
Holloway, AF;Occhiodoro, F;Shannon, MF
人类免疫缺陷病毒（HIV）反式激活因子达特（Tat）是HIV长末端重复序列转录的有效激活因子，对于有效的病毒基因表达和复制至关重要。达特已显示与基础转录机制和转录激活因子的组分相互作用。在这里，我们确定了细胞辅激活因子PC 4作为一个Tat相互作用的蛋白质，使用酵母双杂交系统，并证实了这种相互作用在体外和体内的免疫共沉淀。我们发现，这种相互作用有一个功能的结果，PC 4过表达增强激活的HIV长末端重复在瞬时转染研究中的Tat依赖性的方式。对相互作用所需的PC 4和达特的结构域进行了定位。体外结合研究表明，达特的基本反式激活响应结合结构域是与PC 4相互作用所必需的。PC 4结合达特所需的最小区域是氨基酸22-91，而氨基酸22和43之间的富含赖氨酸的结构域的突变阻止了与达特的相互作用。Tat-PC 4相互作用可能受磷酸化控制，因为酪蛋白激酶II对PC 4的磷酸化抑制了与达特的体内和体外相互作用。我们认为PC 4可能参与将达特与基础转录机制连接起来。
The human immunodeficiency virus (HIV) transactivator Tat is a potent activator of transcription from the HIV long terminal repeat and is essential for efficient viral gene expression and replication. Tat has been shown to interact with components of the basal transcription machinery and transcriptional activators. Here we identify the cellular coactivator PC4 as a Tat-interacting protein using the yeast two-hybrid system and confirmed this interaction both in vitro and in vivo by coimmunoprecipitation. We found that this interaction has a functional outcome in that PC4 overexpression enhanced activation of the HIV long terminal repeat in transient transfection studies in a Tat-dependent manner. The domains of PC4 and Tat required for the interaction were mapped. In vitro binding studies showed that the basic transactivation-responsive binding domain of Tat is required for the interaction with PC4. The minimum region of PC4 required for Tat binding was amino acids 22-91, whereas mutation of the lysine-rich domain between amino acids 22 and 43 prevented interaction with Tat. Tat-PC4 interactions may be controlled by phosphorylation, because phosphorylation of PC4 by casein kinase II inhibited interactions with Tat both in vivo and in vitro. We propose that PC4 may be involved in linking Tat to the basal transcription machinery.