银杏锰型超氧化物歧化酶GbMnSOD基因的克隆与表达

Molecular Cloning,Characterization and Expression of A Manganese Superoxide Dismutase Gene From Ginkgo biloba

利用RACE技术首次从银杏中克隆到锰型超氧化物歧化酶基因(GbMnSOD)的cDNA全长。GbMnSOD的cDNA全长965bp(GenBank accession number:EF633506)。生物信息学分析GbMnSOD cDNA序列含有一个681bp最大读码框,编码一个226氨基酸多肽链,通过软件预测分子量为25.5kD,等电点为8.97。三维结构预测结果显示,GbMnSOD含有12个α螺旋和3个β折叠构成一个篮子状的活性中心。GbMnSOD氨基酸序列与其它植物的MnSOD具有很高的相似性。进化树分析结果表明GbMnSOD和其他物种的MnSOD源自于相同的祖先。Southern杂交显示,GbMnSOD属于一个小的多基因家族。Northern杂交表明GbMnSOD在银杏的根、茎、叶和果中都有表达,在叶中的表达量最高,GbMnSOD的转录受到ABA、IAA、蔗糖、甘露醇、NaCl和低温的诱导。

The full-length cDNA sequence of Ginkgo biloba manganese superoxide dismutase gene （ designated as GbMnSOD EF633506） were isolated from G. biloba for the first time. The full-length cDNA of GbMnSOD contained a 681 bp open reading frame （ORF） encoding a 226-amino-acid protein. The deduced protein have a predicted molecular weight of 25.5 kD and a calculated pI of 8.97. 3D structure modeling showed that GbMnSOD contain 12 helixes and 3 sheets and have a basketry motif in the enzyme core. Phylogenetic tree analysis revealed that GbMnSOD shared the same ancestor with other MnSOD. The result of southern analysis show that the MnSOD genes is encoded by a small gene family in the G. biloba. Northern hybridization analysis show that GbMnSOD expressed in leaves, stem, root and fruit and have the highest expression in leaves. The expression of MnSOD could be induced by ABA, IAA, sucrose, mannitol, NaCI and low temperature.