The trypanosomatid signal recognition particle consists of two RNA molecules, a 7SL RNA homologue and a novel tRNA-like molecule
The trypanosomatid signal recognition particle consists of two RNA molecules, a 7SL RNA homologue and a novel tRNA-like molecule
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DOI：
10.1074/jbc.m209215200
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发表时间：
2003-05-16
影响因子：
4.8
通讯作者：
Michaeli, S
中科院分区：
文献类型：
--
作者：
Liu, L;Ben-Shlomo, H;Michaeli, S
锥虫是一种影响人类和牲畜的古老的真核寄生虫。在这里，我们报告了锥虫信号识别颗粒(SRP)，与自然界中所有其他已知的SRP不同，除了7SL RNA同源物外，还含有一个短的RNA分子，称为SRNA-85。用常规层析，我们发现了一个85个核苷酸的小RNA分子，它与Leptomonas collosoma 7SL RNA共同迁移。该RNA分子被分离、测序，并用于克隆相应的基因。SRNA-85被鉴定为一种tRNA样分子，它偏离了标准的tRNA结构。通过使用针对sRNA-85的反义寡核苷酸的亲和力选择，证实了这些RNA在单个复合体中共存。这两个核糖核酸分子存在于一个类似S的颗粒中，该颗粒短暂地与核糖体结合。在sRNA-85中引入了突变，破坏了其通过碱基配对与7SL RNA相互作用的可能性；这些突变体无法与7SL RNA和核糖体结合，并在细胞内异常分布。我们推测，sRNA-85可能在功能上取代了7SL RNA的Alu结构域。SRNA-85的发现提出了一种耐人寻味的可能性，即sRNA-85功能同源物可能存在于其他缺乏Alu结构域的低等真核生物和真细菌中。
Trypanosomatids are ancient eukaryotic parasites affecting humans and livestock. Here we report that the trypanosomatid signal recognition particle (SRP), unlike all other known SRPs in nature, contains, in addition to the 7SL RNA homologue, a short RNA molecule, termed sRNA-85. Using conventional chromatography, we discovered a small RNA molecule of 85 nucleotides co-migrating with the Leptomonas collosoma 7SL RNA. This RNA molecule was isolated, sequenced, and used to clone the corresponding gene. sRNA-85 was identified as a tRNA-like molecule that deviates from the canonical tRNA structure. The co-existence of these RNAs in a single complex was confirmed by affinity selection using an antisense oligonucleotide to sRNA-85. The two RNA molecules exist in a particle of similar to14 S that binds transiently to ribosomes. Mutations were introduced in sRNA-85 that disrupted its putative potential to interact with 7SL RNA by base pairing; such mutants were unable to bind to 7SL RNA and to ribosomes and were aberrantly distributed within the cell. We postulate that sRNA-85 may functionally replace the truncated Alu domain of 7SL RNA. The discovery of sRNA-85 raises the intriguing possibility that sRNA-85 functional homologues may exist in other lower eukaryotes and eubacteria that lack the Alu domain.