DNA Transcription: New Research Offers New Insight
In order to "read" the information from a gene - for purposes like mapping a human genome - the gene first needs to be copied.
This transcription process uses a factory molecule (RNA polymerase) that works much like a biological jump-drive: it attaches to the DNA at the beginning of a gene, "downloads" the genetic information into the RNA molecule, and then terminates the transcription process at the end of the gene.
Not surprisingly, it is critical to start and stop this transcription process at exactly the correct place or the data (in this case, the RNA transcript) may become corrupted, meaning that it might not make any sense or sometimes may even cause harm.
As ScienceDaily reports, new research published this month in Genes & Development looks at understanding how the transcription process is terminated.
In general, there have been two models that are used to explain how this transcription process stops.
Allosteric Model of Termination
The allosteric model suggests that the properties of RNA polymerase are changed after binding or losing some of its associated proteins, causing it to detach from the DNA. Essentially, termination can be attributed to structural change to the RNA polymerase unit.
Torpedo Model of Termination
The torpedo model proposes that at the ends of genes, a "molecular torpedo" jumps onto the RNA and chases the RNA polymerase, bumping it off the DNA when it catches it.
Looking for Answers with Gene Editing
In this study, the scientists used the approach of gene editing to identify this molecular torpedo.
The team of researchers was then able to eliminate strategic mechanisms in a short time frame, which in turn gave the scientists a better look at what, exactly, was occurring. They then took this modality and combined it with a technique that illustrates the exact position of RNA polymerase on all genes in a cell.
Gene editing technology has been making a lot of news cycles as of late, especially when it comes to the therapeutic potential of such technology. Research like this shows a different side of this progress, however, by using these advances as a biological tool to look more closely at cellular processes. Removing the molecular torpedo demonstrated that the RNA polymerase took much longer to stop, and this result was seen in most genes.
Further Reading & References:
Joshua D. Eaton, Lee Davidson, David L.V. Bauer, Toyoaki Natsume, Masato T. Kanemaki, and Steven West. Xrn2 accelerates termination by RNA polymerase II, which is underpinned by CPSF73 activity. Genes and Development, 2018
University of Exeter. "New insight into workings of building blocks of life." ScienceDaily. ScienceDaily, 12 February 2018. www.sciencedaily.com/releases/2018/02/180212105240.htm.
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