大豆PM1蛋白抗氧化作用及提高酵母对铜耐受力

深圳大学生命与海洋科学学院,深圳市微生物基因工程重点实验室,广东深圳518060

大豆; GmPM1蛋白; 组氨酸; Cu2+胁迫; 清除羟基自由基; 酵母重组子

Characteristics of antioxidant activity of soybean PM1 protein and enhancement of tolerance of recombinant yeast to copper stress
Li Chengna, Gao Yang, Liu Ziming, Liu Guobao, and Zheng Yizhi

College of Life Sciences and Oceanography, Shenzhen University, Shenzhen Key Laboratory of Microbiology and Gene Engineering, Shenzhen 518060, Guangdong Province, P.R.China

soybean; GmPM1 protein; histidine; Cu2+ stress; scavenging hydroxyl radicals; recombinant yeast

DOI: 10.3724/SP.J.1249.2017.05457

备注

Cu2+是植物生长必需的微量元素之一,但土壤中过量的Cu2+会对植物细胞产生毒害作用.大豆GmPM1蛋白属于第4组的胚胎晚期富集(late embroygenesis abundant, LEA)蛋白,该组蛋白序列中富含组氨酸残基. 研究大豆GmPM1蛋白在提高植物耐Cu2+胁迫方面的保护作用及其机理. 对大豆幼苗进行150 μmol/L CuSO4胁迫实验. 结果表明,Cu2+胁迫会造成大豆幼苗叶片失水萎蔫; 在胁迫3 h和24 h时,幼叶内GmPM1基因表达上调. 构建了酵母表达载体pYES2-GmPM1,转化Cu2+敏感型酵母(ΔYAP1)得到重组菌ΔYAP1-GmPM1. 检测结果表明,表达GmPM1蛋白的酵母重组子对Cu2+胁迫耐受力得到提高. 采用Cu抗坏血酸体系,在体外检测出GmPM1及富含组氨酸残基的GmPM1-C端蛋白具有清除羟基自由基能力. 研究表明,大豆GmPM1蛋白可通过其C端的组氨酸残基结合过多的Cu2+,清除由Cu2+胁迫造成的细胞内产生的过量羟基自由基,提高植物及其细胞对Cu2+胁迫的耐受性.

Cu2+ is an essential micronutrient for plant growth, but it is toxic when plant growth under excess copper stress. Soybean GmPM1 protein belongs to late embryogenesis abundant(LEA)group 4(LEA4)proteins, which has a high proportion of histidine residues in the protein sequence. Firstly, we investigate the protective function and mechanisms of GmPM1 protein in plant under Cu2+ stress. The leaves of soybean seedling are withered under 150 μmol/L CuSO4 stress, and at the meantime the expression of GmPM1 gene in the young leaves was up-regulated in 3 h and 24 h of the stress. Secondly, the yeast expression plasmid of pYES2-GmPM1 is constructed and then transformed into the copper-sensitive yeast mutant ΔYAP1 to create recombinants of ΔYAP1-GmPM1. The recombinant yeast expressing GmPM1 protein could enhance the tolerance to Cu2+ stress. Then, the activities of scavenging hydroxyl radicals of GmPM1 and GmPM1-C protein in vitro are determined by using Cu-ascorbic acid system, which is rich in histidine residual in their sequence. The results show that GmPM1 could chelate Cu2+ through histidine residual in the C-terminal of GmPM1 protein and exert the activity of scavenge hydroxyl radicals, thus could improve the tolerance of plants to Cu2+ stress.

·