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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。
In spermidine biosynthesis, spermidine synthase is responsible for the catalytic transfer of propylamine from S-adenosylmethionine to putrescine, which plays an important role in the biological growth and development. In this study, a new spermidine synthase gene was obtained from rice by rapid amplification of 3-terminal cDNA and named as OsSPDS3. OsSPDS3 contains a 1 194 bp open reading frame encoding 397 amino acids. Domain prediction results show that spermidine synthase contains a complete spermine synthase domain, two putative low-complexity segments and multiple S-adenosylmethionine binding sites. Three-dimensional structure prediction showed that OsSPDS3 contains α-helix, β-sheet and curly structure. Phylogenetic analysis showed that OsSPDS3 belonged to the plant spermidine synthase gene family and was divided into a subgroup with Arabidopsis spermidine synthase 3 and rice spermidine synthase 2. Salt treatment significantly increased OsSPDS3 expression, but rice spermidine synthase 1 and 2 did not respond to salt treatment. In addition, both drought and low temperature treatments could not change the gene expression of three rice spermidine synthase genes. These results suggest that OsSPDS3 may play a unique role in rice salt reaction.