Abstract:

AdoMet plays numerous roles of being the major methyl-group donor in trans-methylation reactions. To gain insight into the possible functions of the AdoMet protein of Suaeda salsa L. in response to salt stress, S-adenosylmethionine synthetase gene (SAMS2) was analyzed. We isolated SAMS2 cDNA clone (AF321001) from a λ-Zap cDNA library constructed from the halophyte S. salsa Pall aerial tissue treated with 400 mmol/L NaCl. SsSAMS2 was found to encode a S-adenolyl-L-methionine synthetase enzyme (AdoMet synthetase). The fragment was 1 531 bp with an open reading frame of 395 amino acids, the calculated molecular weight was about 43 kD. SsSAMS2 showed the highest homology to SAMS2 gene of Catharanthus roseus G. Don., with 93% identity in deduced amino acid sequence. Southern blotting analysis showed that SsSAMS2 might be a two-copy gene in S. salsa genome. Northern blot indicated that the cDNA was up-regulated by salt and other stresses. Enzyme activity assay indicated that the activity of SAMS2 increased under NaCl stress.

硫腺苷甲硫氨酸合成酶基因的克隆及其在盐胁迫条件下的不同表达
马秀灵 王增兰 戚元成 赵彦修 张 慧*
（山东师范大学生命科学学院逆境植物重点实验室，济南 2 5 0 0 1 4）
摘要： 硫腺苷甲硫氨酸作为甲基供体在转甲基反应中起到重要作用。为了解硫腺苷甲硫氨酸在盐地碱蓬(Suaedasalsa (L.) Pall)耐盐中的作用，我们对可能编码硫腺苷甲硫氨酸合成酶的基因(SsSAMS2)进行了分析。该基因在经400 mmol/L NaCl 处理的盐地碱蓬地上部分的λ- Zap cDNA 文库中克隆到，其插入片段全长1 531 bp，包含一个395 个氨基酸的开放阅读框架，该基因推断的分子量约为43 kD。SsSAMS2 与长春花(Catharanthus roseus)的SAMS2 在氨基酸水平上的一致性为93%。Southern 杂交显示，SsSAMS2 在盐地碱蓬基因组中可能是两个拷贝。Northern 分析显示硫腺苷甲硫氨酸合成酶基因受NaCl 等胁迫的正调控。酶活性检测表明，NaCl 胁迫条件下该酶活性增强。
关键词： 硫腺苷甲硫氨酸合成酶；盐地碱蓬；盐胁迫；S A M S 基因；序列；表达

通讯作者。 E-mail: <zhangh@sdnu.edu.cn>。