Arabidopsis FLL2 promotes liquid-liquid phase separation of polyadenylation complexes
Arabidopsis FLL2 promotes liquid-liquid phase separation of polyadenylation complexes
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DOI：
10.1038/s41586-019-1165-8
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发表时间：
2019-05-09
期刊：
影响因子：
64.8
通讯作者：
Dean, Caroline
中科院分区：
文献类型：
--
作者：
Fang, Xiaofeng;Wang, Liang;Dean, Caroline
细胞生物化学的一个重要组成部分是非膜区室中蛋白质和核酸的浓度（1，2）。这些生物分子缩合物由包括液-液相分离的过程形成。液-液相分离所需的多价相互作用已在体外进行了广泛研究（1，3）。然而，这一过程在体内的调控知之甚少。在这里，我们确定了在体内调节液-液相分离，通过基因筛选靶向拟南芥RNA结合蛋白FCA功能所需的因素。FCA含有朊病毒样结构域，其在体外发生相分离，并在体内表现出与相分离一致的行为。突变体筛选确定了FCA核体形成中FLL 2（一种卷曲螺旋蛋白）的功能需求。FCA通过促进拟南芥基因组中许多位点的近端聚腺苷酸化来减少转录通读（3，4）。需要FLL 2来促进这种近端聚腺苷酸化，但不需要FCA与靶RNA的结合。FLL 2的异位表达增加FCA核体的大小和数量。用甲醛交联捕获FLL 2、FCA和RNA 3 '端加工机器的聚合酶和核酸酶模块之间的体内相互作用。这些3'RNA加工组分与FCA在体内共定位于核体中，这表明FCA核体将3'末端加工因子区室化以增强特定位点的聚腺苷酸化。我们的研究结果表明，卷曲螺旋蛋白可以促进液-液相分离，这扩大了我们对类液体体体内动力学原理的理解。
An important component of cellular biochemistry is the concentration of proteins and nucleic acids in non-membranous compartments(1,2). These biomolecular condensates are formed from processes that include liquid-liquid phase separation. The multivalent interactions necessary for liquid-liquid phase separation have been extensively studied in vitro(1,3). However, the regulation of this process in vivo is poorly understood. Here we identify an in vivo regulator of liquid-liquid phase separation through a genetic screen targeting factors required for Arabidopsis RNA-binding protein FCA function. FCA contains prion-like domains that phase-separate in vitro, and exhibits behaviour in vivo that is consistent with phase separation. The mutant screen identified a functional requirement for FLL2, a coiled-coil protein, in the formation of FCA nuclear bodies. FCA reduces transcriptional read-through by promoting proximal polyadenylation at many sites in the Arabidopsis genome(3,4). FLL2 was required to promote this proximal polyadenylation, but not the binding of FCA to target RNA. Ectopic expression of FLL2 increased the size and number of FCA nuclear bodies. Crosslinking with formaldehyde captured in vivo interactions between FLL2, FCA and the polymerase and nuclease modules of the RNA 3'-end processing machinery. These 3' RNA-processing components colocalized with FCA in the nuclear bodies in vivo, which indicates that FCA nuclear bodies compartmentalize 3'-end processing factors to enhance polyadenylation at specific sites. Our findings show that coiled-coil proteins can promote liquid-liquid phase separation, which expands our understanding of the principles that govern the in vivo dynamics of liquid-like bodies.