Cloning and characterization of the Drosophila U7 small nuclear RNA
Cloning and characterization of the Drosophila U7 small nuclear RNA
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DOI：
10.1073/pnas.1533509100
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发表时间：
2003-08-05
影响因子：
11.1
通讯作者：
Marzluff, WF
中科院分区：
文献类型：
--
作者：
Dominski, Z;Yang, XC;Marzluff, WF
U7 小核 RNA (snRNA) 5' 端与复制依赖性组蛋白前体 mRNA 中的组蛋白下游元件 (HIDE) 之间的碱基配对是 3' 端加工中导致成熟组蛋白 mRNA 生成的关键事件。我们克隆了果蝇 U7 snRNA，并证明它是果蝇核提取物中组蛋白前体 mRNA T 末端加工所必需的。 71-nt 果蝇 U7 snRNA 由单个基因编码，该基因直接嵌入 Eip63E 基因内含子中。 U7 snRNA基因含有其他果蝇snRNA基因典型的保守启动子元件，编码序列后面有一个3'框，表明果蝇U7 snRNA基因是一个独立的转录单位。果蝇 U7 snRNA 在 S' 端包含一个三甲基鸟苷帽和一个假定的 Sm 结合位点，类似于其他 U7 snRNA 中发现的独特 Sm 结合位点。由于 5' 序列延长，果蝇 U7 snRNA 比哺乳动物 U7 snRNA 长约 10 nt，并且在 3' 末端附近形成茎环结构的潜力有限。果蝇 U7 snRNA 的延伸 5' 末端可以与所有五种果蝇组蛋白前 mRNA 中的 HDE 碱基配对。用互补寡核苷酸阻断 U7 snRNA 的 5' 末端可特异性阻断果蝇组蛋白前 mRNA 的加工。 HIDE 的变化会消除或降低处理效率，从而导致将 U7 snRNA 招募到前 mRNA 的能力降低。
Base pairing between the 5' end of U7 small nuclear RNA (snRNA) and the histone downstream element (HIDE) in replication-dependent histone pre-mRNAs is the key event in 3'-end processing that leads to generation of mature histone mRNAs. We have cloned the Drosophila U7 snRNA and demonstrated that it is required for histone pre-mRNA T-end processing in a Drosophila nuclear extract. The 71-nt Drosophila U7 snRNA is encoded by a single gene that is embedded in the direct orientation in an intron of the Eip63E gene. The U7 snRNA gene contains conserved promoter elements typical of other Drosophila snRNA genes, and the coding sequence is followed by a 3' box indicating that the Drosophila U7 snRNA gene is an independent transcription unit. Drosophila U7 snRNA contains a trimethyl-guanosine cap at the S' end and a putative Sm-binding site similar to the unique Sm-binding site found in other U7 snRNAs. Drosophila U7 snRNA is approximate to10 nt longer than mammalian U7 snRNAs because of an extended 5' sequence and has only a limited potential to form a stem-loop structure near the 3' end. The extended 5' end of Drosophila U7 snRNA can base pair with the HDE in all five Drosophila histone pre-mRNAs. Blocking the 5' end of the U7 snRNA with a complementary oligonucleotide specifically blocks processing of a Drosophila histone pre-mRNA. Changes in the HIDE that abolish or decrease processing efficiency result in a reduced ability to recruit U7 snRNA to the pre-mRNA.