One of the main tools in the research is the "laser tweezers" developed at the Technion and allows the DNA strands to be unraveled in order to examine the connections between them and important molecules that help organize them in the cell nucleus
![The optical tweezers on the right begin to unravel the DNA into its two strands. When the primer reaches the chromosome, it will be stopped by contacts between the histones [in yellow, pink and blue] and the DNA, and thus it will be possible to check whether it is an open (bottom right) or tight (bottom left) chromosome.](https://www.hayadan.org.il/images/content3/2021/07/2-2.png)
Research conducted at the Technion sheds light on the chromosome - one of the critical components in the process of translating DNA into important physiological processes in health and disease. The study published in the journal Molecular cells Held at the Faculty of Biology by Dr. Sergey Rodnitsky under the direction of Professors Ariel Kaplan and Filipa Melamed.
One of the main tools in the research is the "laser tweezers" developed at the Technion and which allows the DNA strands to be unraveled in order to examine the connections between them and important molecules that help organize them in the cell nucleus. Each of the cells in our body contains DNA that provides the necessary instructions for the development of the cell and its functioning and hence also for our health as a whole organism. The DNA, a kind of thread about two meters long, is compressed in the cell nucleus - a tiny micron-sized organelle. This compression is made possible thanks to the packaging of DNA around proteins called histones in a compact structure called chromatin. An important subgroup of the histones are "linker histones" that connect the DNA strands in a structure called Chromosome.
The role of the chromosome
Chromatin and the chromatosome, therefore, have an essential role in keeping the DNA compacted in the cell nucleus. The problem is that the same compression hides the DNA from those components in the cell that are responsible for reading it and implementing the instructions written in it. Therefore, chromatin also has a central role inMonitoring of these processes by Controlled DNA access. how? Kaplan and Malamed laboratories have been dealing with this for many years. These studies are of great clinical importance since malfunctions in chromatin and chromosome function are associated with the development of serious diseases, including cancer.
The technical research group discovered that the linker histone plays a central role in the accessibility of the DNA. Deciphering the activity of this histone is a difficult challenge because these are dynamic histones, and the conventional methods - analysis of a huge number of molecules at once - do not provide an answer to the aforementioned puzzle.
The breakthrough in the current research is based on the use of a unique tool in Prof. Kaplan's research group: "laser tweezers". This tool allowed the researchers to "unzip" the DNA thread similar to a zipper. When priming reaches the chromosome, and there is a contact point between the histone and the DNA, the zipper gets stuck and a force is required to break the contact point and continue priming. This is how the researchers map the location and strength of all the contacts that are responsible for the formation of the chromosome.
Dr. Rudnicki and his colleagues discovered in the current study that the contacts between the binding histone and DNA are much more extensive than was commonly thought and that the chromosomes are about 50% larger than the estimate that was common in the scientific community. In addition, the researchers discovered that the cell knows how to change the shape of the chromosome between two options: a symmetrical and tight shape in which the DNA Is not readable; and an asymmetrical and open shape that makes it accessible. The transition between the forms is controlled in part by the transcription system itself, which indicates that the cell uses the "game" between the two histone forms to regulate access to DNA. The importance of this discovery is clear given the critical role of the chromosome in maintaining the normal expression of the genome.
The research was supported by the National Science Foundation (ISF).
for the article in the journal Molecular cells
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