Ultimate magazine theme for WordPress.

The mystery of the molecule that reads the genetic information is solved


RIKEN scientists explain how RNA polymerase moves through nucleosomes on DNA strands

Japanese scientists at the RIKEN Biosystems Dynamics Research Center have unraveled a mystery related to gene activity in the cell nucleus. For the first time, he explained how RNA polymerase molecules, which synthesize messenger RNA, pass through the nuclear proteins that package the DNA chain without being destroyed. research results, Published In the journal Science.

In the nucleus of a eukaryotic cell, DNA is wrapped around histone proteins to form nucleosomes, the basic units of chromatin (segregated material) that resemble “beads on a string.” Nucleosomes, which each contain eight histones (an octamer), allow DNA to be packaged in a more compact form, but at the same time they are a physical barrier for the DNA-dependent RNA polymerase II enzyme, which is responsible for reading. Genetic information is stored in DNA. RNA polymerase II must pass through nucleosomes, preserving their structure, but how this happens was not known until now.

It is known that RNA polymerase II, while moving along the DNA, binds to several accessory proteins. One of them is a specific protein that facilitates chromatin transcription (FAT), which is involved in the disassembly of the nucleosome before the polymerase and promotes its reassembly behind the polymerase. This process also requires the presence of transcription factors Spt6, Spn1, Spt4/5, Elf1, TFIIS and Paf1, which contribute to the continuous function of RNA polymerase.

Photograph: science.org

In the new work, the researchers visualized the passage of RNA polymerase II through the nucleosome using cryoelectron microscopy, which reveals the size of the molecules with atomic resolution. To do this, they created several DNA samples with nucleosomes, during the transcription of which the polymerase stopped at different points, where its leading edge was close to twisted sections of DNA. In total, six different conformations were visualized as a result of interactions between nucleosomes, polymerases, FACT and transcription factors.

It turns out that transcription factors cover almost the entire surface of RNA polymerase, forming a kind of nuclear factory with a tunnel through which the DNA strand passes. As this complex approaches the nucleosome, DNA unwinds and FACT and transcription factors interact with histones. When the complex approaches the center of the nucleosome, only one-third of the octamer surface is covered with DNA, then the nucleosome separates into two parts – a hexamer (six histones) and a dimer (two histones).

In the next step, FACT binds to both fragments and transfers them to the DNA strand left behind by the polymerase. First, the hexamer, and then the dimer, binds to the DNA, and as the complex progresses, it turns, causing the nucleosome to reassemble. An important role in this is played by the factors Spt4, Spt5, Spt6 and Paf1, which form a “cradle” at the DNA exit site – a structural recess where FACT associated with histones is located.

According to the authors, the results of the study will help to study the mechanisms of diseases such as cancer and to develop new treatments.

Source: lenta.ru/

*The article has been translated based on the content of lenta.ru/. If there is any problem regarding the content, copyright, please leave a report below the article. We will try to process as quickly as possible to protect the rights of the author. Thank you very much!

*We just want readers to access information more quickly and easily with other multilingual content, instead of information only available in a certain language.

*We always respect the copyright of the content of the author and always include the original link of the source article.If the author disagrees, just leave the report below the article, the article will be edited or deleted at the request of the author. Thanks very much! Best regards!

For all the latest news click here

Denial of responsibility! WHICHLEDLIGHT.COM is an automatic aggregator around the global media. All the content are available free on Internet. We have just arranged it in one platform for educational purpose only. In each content, the hyperlink to the primary source is specified. All trademarks belong to their rightful owners, all materials to their authors. If you are the owner of the content and do not want us to publish your materials on our website, please contact us by email – at amritpaljha@gmail.com The content will be deleted within 24 hours.

Leave A Reply

Your email address will not be published.