Department of Life Sciences, National Chung Hsing University, Taichung, 402, Taiwan.
Appl Microbiol Biotechnol. 2010 Jun;87(2):561-9. doi: 10.1007/s00253-010-2466-x. Epub 2010 Feb 20.
Recombinant tilapia (Oreochromis mossambicus) fish metallothionein (MT) was used as a surface biosorbent for mercury removal in Escherichia coli. Fish MT conferred better resistance than did mouse or human MT. When tilapia MT (tMT) was fused with an outer-membrane protein, outer membrane protein C (OmpC), the membrane-targeted fusion protein, OmpC-tMT, gave enhanced resistance compared with cytoplasmic tMT expressed in the same host cell. The cytoplasmically expressed tMT showed high mercury adsorption (4.3 +/- 0.4 mg/g cell dry weight). The cell surface that expressed E. coli showed about 25% higher adsorption ability (5.6 +/- 0.4 mg/g) than the cells expressing cytoplasmic MT, attaining almost twice the level of adsorption of the control plasmid (3.0 +/- 0.4 mg/g). As MTs are also known for their ability to scavenge hydroxyl-free radicals, it was also shown that tMT exhibited better radical-scavenging activities than glutathione. These results suggest that fish MT has potential for the development of a bioremediation system for mercury removal that protects the harboring E. coli host by free-radical scavenging.
重组罗非鱼（Oreochromis mossambicus）鱼金属硫蛋白（MT）被用作大肠杆菌中汞去除的表面生物吸附剂。鱼 MT 比鼠或人 MT 具有更好的抗性。当罗非鱼 MT（tMT）与外膜蛋白，外膜蛋白 C（OmpC）融合时，与在相同宿主细胞中表达的细胞质 tMT 相比，靶向膜的融合蛋白 OmpC-tMT 表现出增强的抗性。细胞质表达的 tMT 显示出高的汞吸附（4.3 +/- 0.4 mg/g 细胞干重）。表达 E. coli 的细胞表面的吸附能力比表达细胞质 MT 的细胞高约 25％（5.6 +/- 0.4 mg/g），达到对照质粒（3.0 +/- 0.4 mg/g）吸附水平的近两倍。由于 MT 也因其清除羟基自由基的能力而闻名，因此还表明 tMT 表现出比谷胱甘肽更好的自由基清除活性。这些结果表明，鱼 MT 具有开发用于汞去除的生物修复系统的潜力，该系统通过清除自由基来保护携带的 E. coli 宿主。
