Engineered Mutations in Bacterial Rhodopsin Allow Light-Stimulated Molecule to Transport Cesium; Pump Proteins May Be Used to Speed Up Decontamination Efforts for Fukushima Nuclear Disaster

A novel cesium-transporting bacterial pump developed by researchers at the Nagoya Institute of Technology (NITech), with colleagues at the University of Tokyo, may prove beneficial in radioactivity decontamination efforts. These findings were reported online on December 14, 2015 in The Journal of Physical Chemistry Letters. The article is titled “Mutant of a Light-Driven Sodium Ion Pump Can Transport Cesium Ions.” The research team successfully induced a molecular pump found in bacteria to transport cesium. The process simply requires the presence of light to make it function. The finding could pave the way for a new means of extracting cesium from the environment, potentially speeding up decontamination efforts following the radioactive fallout from the Fukushima Daiichi nuclear disaster in 2011. This work focused on rhodopsins, which are light-activated molecules found in the human eye, as well as in bacteria. Rhodopsins have been found capable of pumping anions or cations into or out of cells, respectively--activity important for maintaining various cell functions. In the new study, the research team worked on a rhodopsin from a marine bacterium, which normally pumps sodium, as well as lithium, across the cell membrane. Earlier studies had identified the particular building blocks within the middle of this pump that are vital for it to transport only those ions it is meant to transport. Subsequent works applied this information to induce the pumping of potassium instead of sodium. Further progress along this line of study has now led to production of a cesium pump. This is a major breakthrough as no light-driven cesium pumps have been found in nature.
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