The structural foundation in the ability to turn off the light of fluorescent protein

University of Oregon scientists have identified the molecular characteristics that make green fluorescent proteins capable of glowing and by adding a single oxygen atom skillfully, they can keep the light it is off for 65 hours.

Mr. S. James Remington, a professor of physics and a member of the University of Oregon's Institute of Molecular Biology, said the finding could be applied to most fluorescent proteins that can turn off light (photoswitchable )

'This new model offers specific predictions and can improve the quality of protein into a signal to turn off the light,' Remington said. 'It gives us the first picture of how molecules can be turned on and off. This allows us to create new variants to make these proteins more useful. '

Over more than a decade, the fluorescent protein - the protein that was first separated in jellyfish and has since been discovered in many colors from algae living on coral reefs - has been revolutionized. chemistry of molecular biology, allowing scientists to use them as a marker for gene expression, molecular positioning and observation of cell activity.

The model of the structure column alignment turns on and off of a fluorescent protein capable of turning on and off the light.(Photo: S. James Remington)

Recent discoveries of fluorescent proteins that are able to turn off light - work that can be done with laser technology - have had significant development in cell research.

'Fluorescent protein capable of turning off light has extremely good applications for passive proteins,' said Remington. 'You can identify all molecules if you use laser technology under a microscope, you can only activate a small group of them. That allows you to track the movements of the subset of molecules. We look forward to understanding this process so that we can regularly turn them off or change the interval between the on and off states ".

However, he said: The mechanism of light switching is still unknown, and in many cases, the protein changes to its fixed state automatically and automatically.

By applying the combination of gene mutation techniques and directed evolution, the University of Oregon doctoral trainee, J. Nathan Henderson, identified the crystal structure. High resolution of both on and off states of a fluorescent protein extracted from an anemone.

In the steady state or fluorescence of the molecule, the two side chains of the atom are aligned in a uniform fashion, on a plane and in order. When impacted by bright laser light, the researchers observed that the protein rapidly darkened when the rotation was about 180 degrees and reversed to about 45 degrees, and moved to stand still according to the column alignment. uniform and unstable. These two structures give scientists an opportunity to observe changes in the interaction between neighboring groups.

Remington said: In the dark state, the molecule absorbs ultraviolet light and does not emit light. However, when the chromophore (a group of atoms and electrons forms a part of the molecule) absorbs ultraviolet light, it will sometimes ionize and become negatively charged. This makes the island turn around in the fluorescent form.

Controlling the emission of light will allow for more accurate studies in cells, he added.

Earlier, Mr. Nathan Henderson studied structures, he noticed that, in the dark state, there was an unfavorable interaction, where carbon and oxygen atoms were adjacent. 'Nathan watched and wondered what would happen if the oxygen atom was added in the correct place.' By relying on this structure, Mr. Henderson created a single mutation capable of extending the turn-on time from 5 minutes to 65 hours.

Finally, he concluded: The ability to control the state of switching on and off, in addition to supporting microscopic studies and molecular identification, can also bring about improvements in optical memory. learn, for example, single-molecule information storage.

Thanh Van