Genetically Encoded Fluorescent Biosensors For Intracellular Metal Ions

It is well known that a number of metal ions are essential to life. A major determinant of their functional in live cell is that a substantial fraction of protein requires metals for their biological function. Conversely, metal ions in live cells should be kept in a narrow range. Careful regulation of metal ion is critical for cells because disorder of metals may result in many kinds of disease. Taking copper for an example, deregulation of this metal may cause Wilson disease, Menkes disease and neurodegeneration. Traditional methods like atomic absorption and chemical sensors have been used to detect trace levels of metal in aqueous media. But they cannot fill the need of dynamic metal imaging in live cells. It is essential for researchers to realize the importance for a well detection method for intracellular metal. We developed two genetically encoded fluorescent metal ion sensors basing on YFP and a metalloregulatory protein CueR. With protein engineering and molecular biology technology, we construct a series of fusion protein varieties as sensor candidates. The final biosensor was gotten by utilizing high-throughput screening. This sensor expressing in Escherichia coli and mammalian cells performed a dramatic fluorescent changing towards Cu+ and Ag+ binding respectively. With high sensitivity and selectivity, both sensors will be used in metal detection in live cell.