Biochemie-Zentrum der Universität Heidelberg, Im Neuenheimer Feld 328, Heidelberg 69120, Germany.
Biochemie-Zentrum der Universität Heidelberg, Im Neuenheimer Feld 328, Heidelberg 69120, Germany.
Cell. 2015 Aug 27;162(5):1029-38. doi: 10.1016/j.cell.2015.07.060.
The exosome regulates the processing, degradation, and surveillance of a plethora of RNA species. However, little is known about how the exosome recognizes and is recruited to its diverse substrates. We report the identification of adaptor proteins that recruit the exosome-associated helicase, Mtr4, to unique RNA substrates. Nop53, the yeast homolog of the tumor suppressor PICT1, targets Mtr4 to pre-ribosomal particles for exosome-mediated processing, while a second adaptor Utp18 recruits Mtr4 to cleaved rRNA fragments destined for degradation by the exosome. Both Nop53 and Utp18 contain the same consensus motif, through which they dock to the "arch" domain of Mtr4 and target it to specific substrates. These findings show that the exosome employs a general mechanism of recruitment to defined substrates and that this process is regulated through adaptor proteins.
外核体调节大量 RNA 种类的加工、降解和监控。然而，对于外核体如何识别和被招募到其不同的底物上，人们知之甚少。我们报告了识别衔接蛋白的方法，这些衔接蛋白将外核体相关解旋酶 Mtr4 招募到独特的 RNA 底物上。酵母肿瘤抑制因子 PICT1 的同源物 Nop53 将 Mtr4 靶向到前核糖体颗粒，以便在外核体介导的加工中进行处理，而第二个衔接蛋白 Utp18 将 Mtr4 招募到注定要被外核体降解的切割 rRNA 片段。Nop53 和 Utp18 都包含相同的共识基序，通过该基序与 Mtr4 的“拱”结构域结合，并将其靶向特定的底物。这些发现表明，外核体采用了一种针对特定底物的通用招募机制，并且该过程通过衔接蛋白进行调节。
