Highlight the cell
Russian scientists have created a glowing protein with unique properties
Biophysicists from MIPT and European countries have created an "ideal" luminous molecule that will allow monitoring the life of cancer cells or microbes, as well as studying other biological processes at the nanoscale. Its description was presented in the journal Photochemical & Photobiological Sciences (Nazarenko et al., A thermostable flavin-based fluorescent protein from Chloroflexus aggregans: a framework for ultra-high resolution structural studies).
"These dyes can be used to study the mechanisms of tumor development. For example, scientists can grow a certain type of cancer tissue, insert our tags into its proteins and plant it in mice. After that, the biochemical processes in the cells become an open book, and the smallest details can be seen in the microscope," says Vera Nazarenko from the Moscow Physics Department in Dolgoprudny.
According to the researchers, today biologists use a whole lot of luminous labels, for example, the red pigment rhodamine, which can attach to DNA molecules, proteins and other components of cells and "highlight" them. This allows scientists to study the internal structure of the microcosm at the nanoscale.
To do this, biologists simply inject a similar dye into the studied samples, bombard them with laser beams or ultraviolet light at a certain wavelength. Their photons cause the tags to produce beams of light at a different frequency, which allows you to see the contents of a cell or other bodies with ultra-high resolution, inaccessible to conventional microscopes.
All these fluorescent labels have several big drawbacks – they quickly disintegrate under prolonged illumination, do not tolerate heating and are extremely difficult to use for observations of living cells due to their high toxicity. In addition, many of them are too large to attach to any protein molecules and almost all such substances cannot produce light without oxygen.
Nazarenko and her colleagues found an ideal replacement for all such substances by referring to the arsenal of fluorescent proteins that nature has developed over many hundreds of millions of years of evolution of various animals and microbes.
According to the MIPT press service, Russian and foreign biophysicists were interested in special proteins that cyanobacteria and other microbes use as a kind of light sensors that help them either avoid its rays, or vice versa, get the maximum amount of solar energy.
The attention of scientists was attracted by the bacterium Chloroflexus aggregans, discovered by Japanese naturalists in hot geothermal lakes and springs on Honshu Island at the end of the last century. This microbe can feed on both "ready-made" organic matter and has the ability to photosynthesize.
Colonies of these bacteria, as biophysicists have noticed, grow well in hot water even without the presence of oxygen, which prompted them to think that their protein "light sensors" can be used to create a new generation of fluorescent labels.
Guided by this idea, the scientists studied the structure of the protein Cagg_3753, which plays a similar role in the cells of Japanese bacteria, and cut off all the "extra" parts of this molecule that are not related to its ability to absorb and emit light. After that, they inserted the CagFbFP gene encoding a shortened version of this substance into the genome of an ordinary E. coli and checked whether it would glow when irradiated with blue light.
Spatial structure of the CagFbF protein (figure from an article in Photochemical & Photobiological Sciences).
"Our protein turned out to be more thermally stable compared to its analogues – it breaks down only at 68 degrees Celsius. Secondly, it is much more miniature compared to the majority of bulky fluorescent proteins currently used, and it can really glow in oxygen–free conditions," Nazarenko continues.
The same sequence of amino acids, as noted, can be attached to virtually any protein in human or other cells, which will allow you to monitor the movements of these molecules and their role in the life of the body.
Scientists hope that their brainchild will quickly find its place in science and medicine and will help doctors and molecular biologists find new drugs for cancer and other diseases.
The MIPT emblem, "painted" by E. coli bacteria with the built-in CagFbF gene.
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