Hofmann C J, Marshallsay C, Waibel F, Filipowicz W
Friedrich Miescher-Institut, Basel, Switzerland.
Mol Biol Rep. 1992 Nov;17(1):21-8. doi: 10.1007/BF01006396.
Three genes encoding U4 small nuclear RNA (U4 snRNA) in the higher plant Arabidopsis thaliana have been isolated and characterized. Two of the genes, AtU4.1 and AtU4.2, contain all the transcriptional signals known to be essential for U-snRNA gene activity in dicot plants: the Upstream Sequence Element (USE), the -30 TATA box and the downstream 3' end formation sequence. The USE and TATA elements are centered approximately four helical DNA turns apart, a feature characteristic of RNA polymerase II-transcribed U-snRNA genes of plants. The genes AtU4.1 and AtU4.2 are actively transcribed in transfected plant protoplasts and in Arabidopsis plants. Expression of the third gene, AtU4.3, could not be demonstrated. Since this gene is missing the downstream signal important for RNA 3' end formation, it probably represents a pseudogene. The genes AtU4.1 and AtU4.2 encode 152-153 nt long RNAs which show 85-89% sequence similarity with broad bean and pea U4 RNAs and 60-65% similarity with mammalian U4 RNAs. Arabidopsis U4 and U6 snRNAs can be folded into the base-paired Y-shaped model supporting the importance of the U4/U6 interaction during pre-mRNA splicing in plants as well as animals.
已分离并鉴定了高等植物拟南芥中编码U4小核RNA（U4 snRNA）的三个基因。其中两个基因，AtU4.1和AtU4.2，包含所有已知对双子叶植物U-snRNA基因活性至关重要的转录信号：上游序列元件（USE）、-30 TATA盒和下游3'末端形成序列。USE和TATA元件大约相隔四个螺旋DNA圈居中，这是植物RNA聚合酶II转录的U-snRNA基因的一个特征。基因AtU4.1和AtU4.2在转染的植物原生质体和拟南芥植物中被积极转录。第三个基因AtU4.3的表达未能得到证实。由于该基因缺少对RNA 3'末端形成重要的下游信号，它可能代表一个假基因。基因AtU4.1和AtU4.2编码152-153个核苷酸长的RNA，与蚕豆和豌豆的U4 RNA显示出85-89%的序列相似性，与哺乳动物的U4 RNA显示出60-65%的相似性。拟南芥U4和U6 snRNA可以折叠成碱基配对的Y形模型，这支持了U4/U6相互作用在植物和动物前体mRNA剪接过程中的重要性。
