Abstract:

The integration plasmid pKSB was constructed by inserting a special recombination target, psbB, into multiple cloning site (MCS) of pBluescript KS. The fragment psbB is part of psbB gene (from #693 bp to #2563 bp) from Synechocystis sp.PCC 6803. Human liver metallothionein mutant gene ββ chemically synthesized was inserted into downstream of the promoter PpsbA on the intermediary vector pRL-439. The expression vector pKSB-ββ was constructed by inserting PpsbA as well as ββ gene into MCS of pKSB and was transferred into Synechocystis sp. PCC 6803. The stable transgenic strain has been obtained by raising concentration of ampicillin gradually in the process of selection. The results of PCR analysis indicated that ββ gene has been integrated in the Synechocystis sp. PCC 6803 chromosome DNA by single-crossover events. Western blotting and ELISA analysis showed that the ββgene was expressed in the transgenic strain with an amount of 0.739 mg/g fresh cells. Cu2+ tolerance experiments proved that the transgenic strain had higher Cu2+-resistance. Atomic absorption demonstrated that 82% of Cu2+could be removed by the transgenic strain when cultured in BG11 medium containing 10 μmol/L Cu2+ for 3 d.

用同源重组法将人肝金属硫蛋白突变体ββ 基因
整合在集胞藻6803中表达
宋凌云^1,2施定基²  宁叶¹  罗娜¹ 邵宁² 俞梅敏¹ 茹炳根¹

（1. 北京大学生命科学学院，北京100871；2. 中国科学院植物研究所，北京100093）

摘要：将集胞藻 (Synechocystis sp .)PCC 6 80 3上psbB的一段序列 (从 # 6 93bp到 # 2 5 6 3bp)插入pBluescript KS的多克隆位点 ,构建带有整合平台的载体pKSB。再将人工合成的 ββ基因插入中间载体pRL-439上启动子PpsbA的下游 ,并将pRL-ββ上PpsbA和 ββ基因插入pKSB构建成整合表达载体pKSB-ββ。利用自然转化将整合表达载体导入集胞藻 6 80 3,并通过单交换同源重组使 ββ基因整合到集胞藻 6 80 3基因组DNA上。逐步提高氨苄青霉素浓度 ,筛选得到遗传性状稳定的转基因集胞藻 6 80 3。PCR检测转基因集胞藻 6 80 3,结果证实 ββ基因已整合到集胞藻 6 80 3的染色体上 ;Westernblotting结果表明 ,ββ基因在转基因集胞藻 6 80 3细胞中得到表达 ,ELISA测定表明在 5 0 μmol/L的Zn^{2 +}诱导下 ββ在新鲜集胞藻 6 80 3中的蛋白表达量为 0 .739mg/g ;重金属耐受性实验表明 ,得到能耐受Cu^{2 +}的转基因集胞藻 6 80 3。经原子吸收光谱法测定 ,转基因集胞藻6803在含低浓度Cu²⁺ (10umol/L)的培养液中对Cu²⁺的去除率可达到82%

关键词： 人肝金属硫蛋白ββ突变体；集胞藻6803；单交换；同源重组；蓝藻基因工程；铜去除

Key words: ββ mutant gene of human liver metallothionein, Synechocystis sp. PCC 6803, single-crossover, homology recombination, genetic engineering of cyanobacteria, Cu2+-removal