Casañal Ana, Kumar Ananthanarayanan, Hill Chris H, Easter Ashley D, Emsley Paul, Degliesposti Gianluca, Gordiyenko Yuliya, Santhanam Balaji, Wolf Jana, Wiederhold Katrin, Dornan Gillian L, Skehel Mark, Robinson Carol V, Passmore Lori A
MRC Laboratory of Molecular Biology, Cambridge, UK.
Chemistry Research Laboratory, University of Oxford, Oxford, UK.
Science. 2017 Nov 24;358(6366):1056-1059. doi: 10.1126/science.aao6535. Epub 2017 Oct 26.
Newly transcribed eukaryotic precursor messenger RNAs (pre-mRNAs) are processed at their 3' ends by the ~1-megadalton multiprotein cleavage and polyadenylation factor (CPF). CPF cleaves pre-mRNAs, adds a polyadenylate tail, and triggers transcription termination, but it is unclear how its various enzymes are coordinated and assembled. Here, we show that the nuclease, polymerase, and phosphatase activities of yeast CPF are organized into three modules. Using electron cryomicroscopy, we determined a 3.5-angstrom-resolution structure of the ~200-kilodalton polymerase module. This revealed four β propellers, in an assembly markedly similar to those of other protein complexes that bind nucleic acid. Combined with in vitro reconstitution experiments, our data show that the polymerase module brings together factors required for specific and efficient polyadenylation, to help coordinate mRNA 3'-end processing.
新转录的真核生物前体信使核糖核酸（前体mRNA）在其3'端由约1兆道尔顿的多蛋白切割和聚腺苷酸化因子（CPF）进行加工。CPF切割前体mRNA，添加聚腺苷酸尾巴，并触发转录终止，但目前尚不清楚其各种酶是如何协调和组装的。在这里，我们表明酵母CPF的核酸酶、聚合酶和磷酸酶活性被组织成三个模块。使用电子冷冻显微镜，我们确定了约200千道尔顿聚合酶模块的3.5埃分辨率结构。这揭示了四个β螺旋桨，其组装与其他结合核酸的蛋白质复合物的组装明显相似。结合体外重组实验，我们的数据表明聚合酶模块汇集了特异性和高效聚腺苷酸化所需的因子，以帮助协调mRNA 3'端加工。
