银杏GbGGPS基因的克隆及序列分析

Cloning and characterization of the geranylgeranyl pyrophosphate synthase gene from Ginkgo biloba Linn.

利用RACE技术克隆并获得了银杏牻牛儿基牻牛儿基焦磷酸合成酶基因(GbGGPS基因)。银杏GbGGPS基因的cDNA全长为1 641 bp,含有1个1 176 bp的可读框,编码391个氨基酸序列。生物信息学预测GbGGPS蛋白的分子质量为42.51 ku,理论等电点为5.98,N端有叶绿体信号肽,其二级结构主要由α-螺旋和无规则卷曲组成。蛋白质同源分析表明,GbGGPS含有多聚异戊二烯基合成酶家族中保守的5个特征性结构域和2个富含天冬氨酸的区域。同源建模分析显示GbGGPS序列与薄荷GGPS蛋白的三维结构及活性位点高度相似。系统进化分析表明,银杏GGPS蛋白归属植物进化支,且与加拿大红豆杉、挪威云杉、北美冷杉的GGPS蛋白归为同一分支。

In this study, we cloned and characterized a geranylgeranyl pyrophosphate synthase （GGPS） gene from Gink- go biloba Linn. The full-length eDNA sequence of GbGGPS was 1 641 bp containing an open reading frame （ORF） of 1 176 bp, which encoded a 391 amino acids with a predicted molecular mass of 42. 51 ku and the theoretical isoelectrie point （PI） of 5.98. GbGGPS was an intro-free gene, and its deduced polypeptide contained a chloroplast-targeting sig- nal peptide of 79 amino acids in the N terminal. The secondary structure of GbGGPS was mainly composed of alpha helix and random coil. Comparative analysis showed that GbGGPS had a high similarity to other plant GGPS proteins, and contained all the five conserved domains and functional aspartate-rieh motifs of the polyprenyl synthetase family. The ho- mology-based structural modeling showed that GbGGPS has the typical structure of Menthax piperita GGPS. Phylogenetic tree revealed that GbGGPS, TcGGDS, PaGGDS5 and AgGGDS were assigned to the same clade.