一个新的水稻亚精胺合成酶基因克隆、表达及特性分析(英文)

Molecular Cloning,Expression Patterns and Characterization of a New Spermidine Synthase Gene in Oryza sativa

在亚精胺生物合成中,亚精胺合成酶负责从S-腺苷甲硫氨酸到腐胺过程中催化转移丙胺,其在生物生长发育中发挥重要作用。本研究利用3末端cDNA快速扩增技术从水稻中获得一个新的亚精胺合成酶基因,命名为OsSPDS3。OsSPDS3包含一个1 194 bp的开放阅读框,该阅读框编码397个氨基酸。结构域预测结果表明亚精胺合成酶含有一个完整的精胺合成酶结构域,2个推测的低复杂性区段和多个S-腺苷甲硫氨酸结合位点。三维结构预测显示OsSPDS3含有α螺旋,β折叠和卷曲结构。进化分析表明OsSPDS3属于植物类亚精胺合成酶基因家族,与拟南芥亚精胺合成酶3和水稻亚精胺合成酶2划分为一个亚类。盐处理能显著上调OsSPDS3表达,但水稻亚精胺合成酶1和2对盐处理没有响应。此外,干旱和低温处理都不能改变3个水稻亚精胺合成酶基因表达,以上结果暗示OsSPDS3可能在水稻盐反应中发挥独特作用。

Spennidine synthase is an enzyme that catalyzes the transfer of the pmpylamine group from S-adenosylmethionine to putrescine in the biosynthesis of spermidine, and which plays a critical role in a wide range of growth and developmental process. In this research, a new spermidine synthase gene, designated as OsSPDS3, was isolated by 3＇ RACE method in Oryza sativa. The OsSPDS3 contained an 1 194 bp open reading frame encoding 397 amino acids. The OsSPDS3 included a complete spermine_synth domain, two putative low complexity regions and several binding sites of S-adenosylmethionine. The predicted 3-D structure indicated that OsSPDS3 contained α-helices, B-sheets and coils. The phylogenetic analyses revealed that OsSPDS3 belonged to plant spermidine synthase family, in which AtSODS3, OsSPDS3 and OsSPDS2 were clustered into one clade. OsSPDS3 transcripts were significantly up-regulated under high salinity stress. In contrast, no such induction of the OsSPDS1 and OsSPDS2 were observed under high salinity stress. In addition, the expressions of three rice spermidine synthase genes did not change under drought and cold treatments. The results suggested that OsSPDS3 indicated a distinct function in high salinity stress.