Dez Christophe, Dlakić Mensur, Tollervey David
Wellcome Trust Centre for Cell Biology, University of Edinburgh, Scotland.
RNA. 2007 Sep;13(9):1516-27. doi: 10.1261/rna.609807. Epub 2007 Jul 24.
A family of HEAT-repeat containing ribosome synthesis factors was previously identified in Saccharomyces cerevisiae. We report the detailed characterization of two of these factors, Utp10 and Utp20, which were initially identified as components of the small subunit processome. Coprecipitation analyses confirmed the association of Utp10 and Utp20 with U3 snoRNA and the early pre-rRNA processing intermediates. Particularly strong association was seen with aberrant processing intermediates, which may help target these RNAs for degradation. Genetic depletion of either protein inhibited the early pre-rRNA processing steps in 18S rRNA maturation but had little effect on pre-rRNA transcription or synthesis of the 25S or 5.8S rRNAs. The absence of the poly(A) polymerase Trf5, a component of the TRAMP5 complex and exosome cofactor, led to stabilization of the aberrant 23S RNA in strains depleted of Utp10 or Utp20. In the case of Utp10, 20S pre-rRNA synthesis was also modestly increased by this loss of surveillance activity.
之前在酿酒酵母中鉴定出了一个包含HEAT重复序列的核糖体合成因子家族。我们报告了其中两个因子Utp10和Utp20的详细特征，它们最初被鉴定为小亚基加工体的组成部分。共沉淀分析证实了Utp10和Utp20与U3 snoRNA以及早期前体rRNA加工中间体的关联。在异常加工中间体中观察到了特别强的关联，这可能有助于将这些RNA靶向降解。任一蛋白质的基因缺失都抑制了18S rRNA成熟过程中的早期前体rRNA加工步骤，但对前体rRNA转录或25S或5.8S rRNAs的合成影响很小。聚腺苷酸聚合酶Trf5（TRAMP5复合物和外切体辅因子的一个组成部分）的缺失导致在缺失Utp10或Utp20的菌株中异常23S RNA的稳定。就Utp10而言，这种监测活性的丧失也适度增加了20S前体rRNA的合成。
