How can a cell repair broken DNA?

And how can the correct sequences of DNA be found to use as a template in the crowded interior of the cell?

These two questions have puzzled researchers for many years, and recently researchers from Uppsala University in Sweden have provided answers.

A group of Swedish researchers headed by Professor Johan Elf finally reached a solution to the mystery, and presented their findings in a study published in the journal Nature at the beginning of September.

Crystal structure of the protein "Rica" necessary for DNA repair (networking sites)

DNA repair mechanisms

Over the past half century, biologists have studied the mechanisms involved in making DNA repairs, yet an essential part of the process has remained unclear.

But by tagging key enzymes and DNA with fluorescent markers and monitoring the repair process in real time in an E. coli model, the researchers bridged this knowledge gap about how bacteria find the templates they depend on for genetic repair.

When a DNA molecule splits into two parts, the fate of the cell becomes threatened, so repairing the break quickly is a matter of life or death for the cell, but repairing DNA without introducing errors in the sequence is a great challenge, as the repair machine needs to Find a template.

The process of repairing broken DNA using a template from a sister chromosome is known as "homologous recombination", yet the description usually ignores the tedious task of finding a matching template among all other genome sequences, because it is quite clear that simple diffusion in 3D will not be rapid enough.

Scientists have succeeded in monitoring the repair in real time in the bacteria 'Escherichia coli' (Pixabi)

The Rica molecule has been implicated in the research

Homologous recombination has been a mystery for at least 50 years, and through previous studies it appears that the RecA molecule is involved in the search for a matching template within genome sequences, but this has been the limit to our understanding of this process.

Rica is a protein responsible for the repair and maintenance of DNA, and its analogue in structural and functional structure has been found in all types of microorganisms, so it served as the ideal model for this class of proteins involved in DNA repair, and this ideal and identical model is present in all Of eukaryotic and prokaryotic organisms.

The Rica protein has several functions all relevant to DNA repair, for example in microorganisms such as bacteria it activates the auto-mitotic cleavage process of some inhibitors.

Researchers bridge the knowledge gap about how bacteria find gene repair templates (Pixabi)

Using CRISPR technology

The researchers used CRISPR-based technology to make controlled DNA breaks in bacteria. By culturing cells in a microfluidic culture chip and tracking RecA particles with a fluorescence microscope, the researchers were able to image the process of homologous recombination from start to finish.

"The chip allows us to simultaneously follow the fate of thousands of individual bacteria and to control CRISPR-induced DNA breaks in a timely manner," Jacob Wiktor, one of the researchers who conducted the study, said in an Uppsala University press release.

"It's very precise, almost like having a pair of tiny DNA scissors," he added.

Using microscopy, Professor Johann Elf and his team also found that the cell responds by rearranging the Reca molecule to form thin filaments that extend the length of the cell. They concluded that the entire repair was completed in an average of 15 minutes, and that the form was completed in only about 9 minutes.

"We can see the formation of a thin, flexible structure that protrudes from the fracture site immediately after DNA damage," Arvid Gina, who worked on the project throughout his PhD, says in the same press release.

This research may help understand the causes of tumor growth (Pixabe)

What is the importance of this research?

The honorable reader may ask: What is the importance of such research?

The answer in short: it may help us understand the causes of tumor growth, because the process of symmetry repair is nearly identical for all organisms, including humans.

DNA damage occurs frequently in our bodies, and without the ability to heal broken DNA, we are more likely to develop cancer, because most oncogenes are associated with DNA repair, and new mechanistic insights may help us understand the causes of tumor growth.

Repairing broken genes quickly and completely can be a matter of life or death for most organisms, as even the simplest changes in the sequence risk catastrophe, especially if the altered code is responsible for a critical function.

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