番茄中一个LSm1蛋白同源基因LeLSm1的克隆及表达分析

Cloning and expression analysis of tomato LeLSm1,a LSm1 protein-encoding gene

从番茄品种超级大明星中克隆LSm1蛋白同源基因LeLSm1。LeLSm1基因全长cDNA共有1 038个核苷酸,包含一个387个核苷酸的编码区,以及318个核苷酸的5′非编码区和333个核苷酸的3′非编码区,编码一个含128个氨基酸的蛋白质,分子质量为14.5 ku,等电点为4.94。LeLSm1编码的氨基酸序列包含LSm1蛋白的保守功能域,与截形苜蓿、拟南芥和水稻等植物的类似LSm蛋白具有高度的同源性,在氨基酸水平上的一致性依次为82.8%、82.0%和72.1%。用PCR方法克隆了LeLSm1基因,其全长转录区共4 751 bp,其中包含5个外显子和4个内含子。Southern杂交结果显示,LeLSm1是单拷贝基因。半定量RT-PCR分析表明,LeLSm1在番茄五叶期和结果期的根、茎、叶以及花和果实中均有表达,且表达量无明显差异,是一个组成型表达基因。

A homolog of LSm1 encoding gene, designed LeLSm1, was cloned from tomato （Lycopersicum esculentum ） cultivar Chaojidamingxing . The full-length cDNA of LeLSm1 was 1038 nt, containing an ORF of 387 nt encoding a 128 aa protein with a calculated molecular mass of 14. 5 kDa and isoelectric point at pH 4.94, a 318 nt 5＇- and a 333 nt 3＇-untranslated regions. The deduced amino acid sequence of the LeLSm1 protein contains domains conserved among LSm1 proteins. LeLSm1 shares high homology to the presumed LSm1 proteins of Medicago truncatula, Arabidopsis thaliana and Oryza sativa with identities of 82.8%, 82.0% and 72.1%, respectively. A genomic fragment of 4751 bp in length that contained the full-length transcribed region of LeLSm1 was isolated by PCR. As revealed by comparison with full-length cDNA, the LeLSml is composed of 5 exons and 4 introns. Southern blotting analysis indicated that LeLSm1 was a single copy gene in tomato genome. Semi-quantitative RT-PCR analysis revealed that LeLSm1 might be constitutively expressed in tomato roots, stems, leaves, flowers, and fruits.