The TALE technology, with which scientists have achieved a number of high-quality medical and biotechnological applications, recently clouded the CRISPR technology, which provides the same applications as the TALE proteins, but is easier to use. But TALE proteins are capable of some additional tricks that can help them return to the center of attention, they say at the Institute of Chemistry.
A team of Slovenian scientists discovered that when two TALE proteins are linked to adjacent sites, this protein, which is located on the left, with DNA, displaces the TALE protein, which is linked to the right, but not vice versa.
“Imagine a series of small chairs with a man sitting in the same chair. If you are sitting in a chair to the left of a person who is already sitting, this chair is too small for you, so you are protecting a neighbor who must stand up. Usually this person can bounce back and you have to get up, and in the case of TALE it only works in one direction. The fusion protein on the left can force out the one that is bound to the DNA to the right of it. This is an example of the molecular displacement structure, which was discovered in our research and showed that it can be used for other interesting purposes, ”the drawing explained. Roman GeralHead of the Department of Synthetic Biology and Immunology at the Institute of Chemistry in Ljubljana, who led the study, published in the scientific journal Nature Chemical Biology,
Dr. Tina Lebar takes her research very seriously and thus tattoos TALE, CRISPR and logical functions. PHOTO: Chemical Institute
In addition to clarifying the mechanism of polarized movement, researchers have shown that this property of TALE proteins can be very useful for regulating gene expression. Tina Lebar, the first author of the study and doctoral researcher in the group of prof. Jeral added: “We found that we can take another step. Adding the third TALE protein to the left leads to the displacement of the right neighbor, which allows the TALE protein to move to the extreme right position. Like dominance of dominoes, only one of the other dominoes falls. We showed that it works even with the five neighboring TALE, which was unexpected and very interesting. We found that this mechanism can be used to encode logical functions, such as OR, AND, or NAND, which can control the response of human cells to external signals and the processing of information in cells. ”
The action based on targeted movement is more efficient and fast, the research team of the Institute of Chemistry, which a few years ago demonstrated the implementation of logical functions in human cells, emphasized. An important additional advantage is that this type of gene control is very accurate. Unlike some other methods used so far with the bias-bias mechanism, only the selected gene can be silenced, while neighboring genes remain active, they explained.
An animation of how TALE works:
“It appears that polarized bias is unique to TALE proteins, and the researchers also used it to displace other DNA proteins, in particular, to prevent the formation of the CRISPR complex. CRISPR technology is a powerful tool in molecular biology, which scientists mainly use to separate target DNA and outbreak of gene cells. An important problem with this technology is DNA vaccination in unwanted sites. The shift mechanism with TALE proteins can also be used to protect the genome from unwanted cleavage using CRISPR technology, which would greatly contribute to a safer and more reliable gene therapy, ”the researchers wrote in a press release.
Separating molecular complexes by binding other molecules is one of the most important natural principles, and this study is probably the first time that molecular displacement has been designed and used for a completely new purpose. Researchers believe that this discovery is important both for understanding the mechanism of the rearrangement of molecular complexes in nature, and for improving the accuracy, safety and efficiency of cell therapy or for biotechnological use.
What is a TALE?
The properties of cells and whole organisms largely determine the genome containing the DNA program. The activity of thousands of genes is controlled by proteins that bind to DNA in their immediate vicinity. Using synthesis biology, they can regulate gene expression using putative proteins that target the selected target DNA sequence. Ten years ago, scientists unloaded a DNA recognition code for proteins called TALE (abbreviated for a transcription activator, similar to the effect) found in bacteria that attack plants. Understanding this code has allowed scientists to develop and prepare TALE proteins that bind to virtually any selected DNA sequence. Adding a suitable protein domain, TALE proteins can be transformed into activators or inhibitors of any gene, which makes them very useful for medical therapy and biotechnology, explained the Chemical Institute.
The study was supported by the Slovenian research agency.