Structural and functional insight into the effect of AFF4 dimerization on activation of HIV-1 proviral transcription
Structural and functional insight into the effect of AFF4 dimerization on activation of HIV-1 proviral transcription
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从结构和功能角度深入了解 AFF4 二聚化对 HIV-1 前病毒转录激活的影响
DOI：
10.1038/s41421-020-0142-6
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发表时间：
2020-02-18
期刊：
影响因子：
33.5
通讯作者：
Qi, Shiqian
中科院分区：
文献类型：
--
作者：
Tang, Dan;Chen, Chunjing;Qi, Shiqian
超延伸复合体（SEC）是HIV-1前病毒转录所必需的RNA聚合酶II的正调节因子。AFF1/4是一种支架蛋白，通过其THD结构域（TPRL with Handle Region Dimerization domain）募集SEC的其他组分并形成二聚体。在这里，我们报告了人类AFF4-THD的晶体结构，分辨率为2.4 Å。一个AFF4-THD的α4、α5和α6介导二聚体的形成，并与AFF4-THD二聚体中第二个分子的等效部分紧密结合。诱变分析表明，AFF4的Phe1014或Tyr1096突变对丙氨酸的形成都有影响。此外，转激活实验还表明，AFF4的Phe1014和Tyr1096对AFF4的转激活活性至关重要。有趣的是，AFF1中相应的残基Phe1063和Tyr1145对HIV-1前病毒的转激活有影响。然而，AFF1/4的这种突变对AFF1/4与SEC其他亚基的相互作用没有影响。总之，我们的数据表明，AFF1/4的二聚化对于HIV-1前病毒的转激活是必不可少的。
Super elongation complex (SEC) is a positive regulator of RNA polymerase II, which is required for HIV-1 proviral transcription. AFF1/4 is the scaffold protein that recruits other components of SEC and forms dimer depending on its THD domain (TPRL with Handle Region Dimerization Domain). Here we report the crystal structure of the human AFF4-THD at the resolution of 2.4 Å. The α4, α5, and α6 of one AFF4-THD mediate the formation of a dimer and pack tightly against the equivalent part of the second molecule in the dimer of AFF-THD. Mutagenesis analysis revealed that single mutations of either Phe1014 or Tyr1096 of AFF4 to alanine impair the formation of the AFF4 dimer. In addition, transactivation assay also indicated that Phe1014 and Tyr1096 of AFF4 are critical to the transactivation activity of AFF4. Interestingly, the corresponding residues Phe1063 and Tyr1145 in AFF1 have an effect on the transactivation of HIV-1 provirus. However, such mutations of AFF1/4 have no effect on the interaction of AFF1/4 with other subunits of the SEC. Together, our data demonstrated that the dimerization of AFF1/4 is essential to transactivation of HIV-1 provirus.