家蚕真核翻译起始因子3f基因结构与表达研究

Analysis of Structure and Expression of Eukaryotic Translation Initiation Factor 3f Gene in the Silkworm,Bombyx mori

在对家蚕5龄丝腺cDNA文库测序的过程中,发现一个编码家蚕翻译起始因子基因(eIF3f)的EST序列。利用电子克隆、3′RACE(3′rapid amplification of cDNA ends)方法克隆了家蚕eIF3f基因cDNA序列全长,命名为eIF3f(GenBank登录号为DQ868530)。家蚕eIF3f基因cDNA全长为1 009 bp,由870 bp的开放阅读框序列(openreading frame,ORF)、55 bp的5′端非翻译区序列(5′-UTR)和65 bp的3′端非编码区序列(3′-UTR)组成,编码289个氨基酸。氨基酸序列比较分析显示,家蚕eIF3f与其他物种的eIF3f都具有翻译起始功能所必需的JAB_MPN结构域。家蚕eIF3f基因组结构分析:该基因由5个外显子和4个内含子组成;5′调控序列存在E74A、DFD、DRI等多个潜在的转录因子结合位点,但没有TATA盒启动子序列。家蚕eIF3f基因的表达在不同组织和不同发育时期存在差异,eIF3f是一种负调控翻译起始因子。研究结果有助于进一步研究真核翻译起始因子的相关基因调控规律。

According to silkworm EST generated by the large-scale cDNA sequencing in our lab, we found an EST which is highly homologous to the eIF3f. By using the methods of electronic clone and 3′RACE, a full-length cDNA, named as eIF3f （GenBank accession number DQ868530） was isolated from silkworm, which is 1 009 bp nucleotide long, and contains an ORF（870 bp） encoded 289 amino acids, 55 bp nucleotide sequence in 5′UTR and 65 bp nucleotide sequence in 3＇-UTR. The deduced amino acids showed a high degree of similarity to the previously reported eIF3fs and shared a conserved JAB-MPN domain which is essential for the translation initiation. Genomic structure analysis suggested that eIF3f contains 5 exons and 4 introns. In the 5′upstream, many potential binding sites for the transcription factors were detected, such as E74A, DFD, DRI etc, but no TATA box. The expression level of eIF3f gene at different stages and in different tissues were different. The results implied that eIF3fis a negative regulator of translation initiation. The above results will be helpful to elucidate the regulation principle of expression of genes related to eukaryotic translation initiation factors.