黄羽扇豆翻译延伸因子2的序列分析

Sequencing of Elongation Factor 2 from Lupinus luteus

利用Sanger双脱氧链终止法对黄羽扇豆（Lupinusluteus）翻译延伸因子2（EF2）的全长cDNA克隆进行了序列分析。该cDNA长度为2794bp,其中包括5’末端的80bp非翻译区,3’末端185bp非翻译区和2529bp长编码序列,3’末端为一18bp poly（A）尾。与其它GTP结合蛋白比较其编译的843aa（氨基酸）序列,发现它们具有显著的同源性;黄羽扇豆EF2与甜菜EF2的氨基酸序列90％相同。其差异主要存在于序列的中部;而与肽基tRNA和核糖体作用部位、与GTP结合部位和GTP酶活性有关的部位具有很高的保守性。黄羽扇豆EF2第700个氨基酸残基组氨酸是白喉毒素的ADP-核糖基化部位。

A full-length cDNA clone encoding Lupinus luteus elongation factor 2 (EF2) involved in the elongation step of protein synthesis was sequenced. The cDNA insert contains a 80-bp 5'-untranslated region,a 2529-bp long coding sequence and a 185-bp 3'-untranslated region. The deduced amino acid sequence (843 residues) from this 2794 bp nucleotide sequence shares 90% homology with that from Beta vulgaris. The sequence analysis supports that diphthamide {2-[3-carboxyamido-3-(trimethylammonio) propyl] histidine( , the site of ADP-ribosylation by diphtheria toxin (DT), is produced by post-translational modification of a histidine residue in the primary translational product. Sequence comparision with other EF2s and GTP-binding protein typa shows that the domains, which are likely to be involved in GTP binding and GTPase activity, and interaction with ribosome and toxins,are highly conserved.