Abstract: LEA3 (group 3 late embryogenesis abundant proteins) is a type of protein responsed to abiotic stresses and protects cells from damage. Deinococcus gobiensis I-0 was isolated from the Gobi Desert with drought, major temperature difference and strong solar radiation. It possessed highly strong resistance to ultraviolet (UV) radiation, ionizing radiation and desiccation. The protein encoded by Dgo_CA1631 gene in the genome was certain homologous with LEA3, so it was named as Dgl3, and its biological function was investigated in this article. Survival experiments revealed that Dgl3 could significantly enhance resistance of the expression strain BL21 to oxidative and freezing stresses and increase the resistance against to many damages. Likewise, the experiments in vitro demonstrated that the enzymatic activities of malate dehydrogenase and lactate dehydrogenase were effectively maintained due to Dg13 under oxidation and freeze-thaw cycles. Therefore, it was speculated that Dgl3 protein enhanced resistance of host to oxidation and freezing stresses by protecting cellular enzyme activities.

Key words: LEA3 protein, Deinococcus gobiensis I-0, abiotic stress, enzyme activity

摘要： LEA3（group 3 late embryogenesis abundant proteins）是一类非生物胁迫响应蛋白，能够保护细胞免受胁迫损伤。戈壁异常球菌(Deinococcus gobiensis)I-0分离于干旱、温差大及强阳光辐射的戈壁沙漠环境，具有超强的耐受紫外(UV)辐射、电离辐射和干燥等胁迫的能力，其基因组中Dgo_CA1631基因编码蛋白与LEA3具有一定同源性，将该蛋白命名为Dgl3，并对其生物学功能展开研究。非生物胁迫实验表明，Dgl3蛋白能够显著增强表达菌株BL21对氧化和冷冻胁迫的抗性，最大限度地保护宿主菌免受损伤。体外酶活保护实验结果进一步表明，氧化和反复冻融胁迫条件下Dgl3蛋白能够保护苹果酸脱氢酶（MDH）和乳酸脱氢酶（LDH）的活性。因此推测，Dgl3蛋白通过保护细胞体内相关酶类的活性，增强宿主细胞对氧化和冷冻胁迫的抵抗能力。

关键词: LEA3蛋白, 戈壁异常球菌, 非生物胁迫, 酶活