Two 5′-ETS regions implicated in interactions with U3 snoRNA are required for small subunit rRNA maturation in Trypanosoma brucei
Two 5′-ETS regions implicated in interactions with U3 snoRNA are required for small subunit rRNA maturation in Trypanosoma brucei
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DOI：
10.1093/nar/27.16.3300
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发表时间：
1999-08-15
影响因子：
14.9
通讯作者：
Toyofuku, W
中科院分区：
文献类型：
--
作者：
Hartshorne, T;Toyofuku, W
在古老的原生动物寄生虫布氏锥虫（Trypanosoma brucei）中检查了早期前rRNA加工事件，发现其具有独特和保守的特征。出现两个5 '-ETS裂解：A'和新发现的A0。A'和A0似乎分别与脊椎动物和酵母的初级前RNA切割位点相关。然而，锥虫的初级rRNA转录物可以首先在ITS 1/5.8S边界处加工，然后通过在5 '-ETS/SSU rRNA连接处的A'、A0和A1处连续切割去除5 '-ETS序列。使用我们的新标记rRNA系统测试了先前与U3 snoRNA交联的5 '-ETS序列在rRNA加工中的作用。两个不同的A '-相邻序列元件，可以与U3铰链碱基配对，是SSU rRNA产生所特别需要的，作为下游元件。后一个元件似乎与A0、A1和A2切割所需的酵母5 ′-ETS U3结合序列保守，因为它们都与U3铰链序列共有10个互补碱基，并且位于潜在茎环结构中A0和A1位点的上游，假定的锥虫U3结合位点相对于A'和A0切割的独特定位表明不同的U3-从属机制可以指导每个处理事件。
Early pre-rRNA processing events were examined in the ancient protozoan parasite Trypanosoma brucei and found to have both distinctive and conserved features. Two 5'-ETS cleavages occur: A' and the newly discovered A0. A' and A0 appear related to vertebrate and yeast primary pre-RNA cleavage sites, respectively. However, trypanosomatid primary rRNA transcripts can first be processed at the ITS1/5.8S boundary and 5'-ETS sequences then removed by consecutive cleavages at A', A0 and A1 at the 5'-ETS/SSU rRNA junction. 5'-ETS sequences previously crosslinked to U3 snoRNA were tested for their roles in rRNA processing using our new tagged rRNA system. Two distinct A'-adjacent sequence elements, which may pair with U3 hinge bases, were specifically required for SSU rRNA production, as was a downstream element. The latter element appears conserved with the yeast 5'-ETS U3 binding sequence, required for A0, A1 and A2 cleavages, in that they both share 10 bases complementary with U3 hinge sequences and lie upstream from A0 and A1 sites located in a potential stem-loop structure, The distinctive positioning of putative trypanosomatid U3 binding sites with respect to A' and A0 cleavages suggests that different U3-dependent mechanisms may direct each processing event.