Tracking Oxygen Levels In Living Cells

Scientists have developed a genetically-encoded sensor that can be used to monitor changes in oxygen levels in living cells with high sensitivity and in real time.

AsianScientist (Sep. 12, 2018) – In a study published in Scientific Reports, a research group in Japan descibe a fluorescent protein sensor that can provide real-time information on dynamic changes in oxygen levels.

Oxygen is a major player in the biochemical processes that make life on earth possible. Being able to rapidly and accurately measure oxygen levels inside living cells could be useful in several areas of biology, including physiology, medicine and bioengineering. For example, oxygen levels in cancer cells can affect their response to anti-cancer therapies, while oxygen levels in tissues following a stroke or heart attack can influence treatment and recovery.

In the present study, researchers led by Assistant Professor Jiro Nomata and Professor Toru Hisabori at Tokyo Institute of Technology, Japan, have found a way to detect changes in cellular oxygen levels with high sensitivity and in real time. The researchers used a protein called the direct oxygen sensor protein, or DosP, from the bacterium Escherichia coli. The protein has the ability to either bind or release oxygen depending on the oxygen levels inside the cell.

Importantly, the researchers isolated the part of the protein that can bind oxygen and linked it to a fluorescent protein. They then evaluated the fluorescence intensity of the resulting product, which they named ANA sensor (anaerobic/aerobic sensing fluorescence protein), under different oxygen levels.

The researchers found that the fluorescence of their novel protein increased in the presence of oxygen and decreased in the absence of oxygen, thereby successfully tracking the dynamic changes in oxygen content. Further development allowed them to fine-tune the protein to enable more accurate quantification of oxygen levels.

By using the ANA sensor, oxygen production by photosynthesis in cyanobacteria (a type of photosynthetic microbe) could be monitored. The researchers highlighted that their findings have the potential to be applied to the development of other protein sensor probes, possibly allowing the detection of other cellular changes at the molecular level.

“Almost all current sensor protein probes are based on conformational changes,” said Nomata. “In contrast, the fluorescence quenching mechanism used in this study expands the possibilities for the development of novel protein sensor probes.”



The article can be found at: Nomata & Hisabori (2018) Development of Heme Protein Based Oxygen Sensing Indicators.

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Source: Tokyo Institute of Technology; Photo: Shutterstock.
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