RNA Helicase Prp43 and Its Co-factor Pfa1 Promote 20 to 18 S rRNA Processing Catalyzed by the Endonuclease Nob1
RNA Helicase Prp43 and Its Co-factor Pfa1 Promote 20 to 18 S rRNA Processing Catalyzed by the Endonuclease Nob1
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DOI：
10.1074/jbc.m109.040774
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发表时间：
2009-12-11
影响因子：
4.8
通讯作者：
Hurt, Ed
中科院分区：
文献类型：
--
作者：
Pertschy, Brigitte;Schneider, Claudia;Hurt, Ed
许多RNA核酸酶和解旋酶参与核糖体生物合成，但它们如何相互合作在很大程度上是未知的。在这里，我们报告说，在体内切割的酵母pre-rRNA位点D，3 '端的18 S rRNA，需要PIN（PilT N末端）结构域蛋白Nob 1和DEAH盒RNA解旋酶Prp 43之间的功能相互作用。Nob 1在体外显示出对D-位点底物类似物的特异性切割，这被Nob 1 PIN结构域或RNA底物中的突变所废除。遗传分析将Nob 1与晚期前40 S相关因子Ltv 1、RNA解旋酶Prp 43及其辅因子Pfa 1联系起来。在缺乏Ltv 1的菌株中，Prp 43或Pfa 1的突变导致20 S pre-rRNA在细胞质中的显著积累，这是由于位点D切割的抑制。这种表型被野生型Nob 1的剂量增加所抑制，但不被催化位点突变的Nob 1变体所抑制。在ltv 1/pfa 1突变体中，20 S pre-rRNA易被胞质外泌体从3'端降解到5'端。这降解到18 S rRNA的3'区，强烈表明前核糖体是结构缺陷的。
Many RNA nucleases and helicases participate in ribosome biogenesis, but how they cooperate with each other is largely unknown. Here we report that in vivo cleavage of the yeast pre-rRNA at site D, the 3'-end of the 18 S rRNA, requires functional interactions between PIN (PilT N terminus) domain protein Nob1 and the DEAH box RNA helicase Prp43. Nob1 showed specific cleavage on a D-site substrate analogue in vitro, which was abolished by mutations in the Nob1 PIN domain or the RNA substrate. Genetic analyses linked Nob1 to the late pre-40 S-associated factor Ltv1, the RNA helicase Prp43, and its cofactor Pfa1. In strains lacking Ltv1, mutation of Prp43 or Pfa1 led to a striking accumulation of 20 S pre-rRNA in the cytoplasm due to inhibition of site D cleavage. This phenotype was suppressed by increased dosage of wildtype Nob1 but not by Nob1 variants mutated in the catalytic site. In ltv1/pfa1 mutants the 20 S pre-rRNA was susceptible to 3' to 5' degradation by the cytoplasmic exosome. This degraded into the 3' region of the 18 S rRNA, strongly indicating that the pre-ribosomes are structurally defective.