大肠杆菌海藻糖的代谢调控

Regulation of Trehalose Metabolism in Escherichia coli

海藻糖是一种重要的抗逆物质。大肠杆菌中otsBA操纵子编码的两种酶负责海藻糖合成。otsBA基因的表达受渗透压诱导和σs 因子的调节。细胞的周质海藻糖酶 (treA)将外源海藻糖分解成两个葡萄糖分子。尽管大肠杆菌中渗透压诱导合成的海藻糖并不能保护细胞抗干燥 ,我们将otsA单个基因通过农杆菌转入烟草时 ,转基因株提高了耐盐和抗干燥特性 ,同时在转基因烟草提取物中检测到海藻糖 ,证明otsA基因在烟草中表达并合成海藻糖。我们认为若将otsA基因转入其它植物 ,可望改善这些植物的抗干旱。

The disaccharide trehalose is an important stress compound in E.coli. Two enzymes encoded by otsBA operon are responsible for the sugar synthesis. otsBA gene expression is induced by osmotic stress and depends on σ s factor.Exogenously provided trehalose is degraded to two glucose molecules by periplasmic trehalase ( treA ).Although osmotic induced trehalose synthesis is not involved in desiccation protection in E.coli ,when we transferred a single E.coli otsA gene into tobacco mediated by Agrobacterium, the transgenic plant exhibited an improved stress tolerance to salt and desiccation,the sugar could be detected in transgenic tobacco extracts by HPLC.It is confirmed that otsA gene is expressed and trehalose synthesized in the plant.We are convinced that engineering otsA gene into other plant species may provide crucial protection against drought and salinity,and confer improved storage properties after harvest.\;