Research at the Stowers Institute for Medical Research suggests a short polymerase pause at the beginning of transcription mediates the flow of genetic information from DNA into RNA. The study was published in the journal Nature Genetics. According to the researchers, this stop/pause right at the beginning of the path actually helps with the pathway. In essence, it prevents another machine from immediately following the first, presumably to better control the gene traffic.
The research enumerates the positioning of RNA polymerase each time a gene is expressed or turned on. RNA polymerase must position itself at a specific spot and travel down the winding strands of DNA. It transcribes the gene from start to finish. Scientists once thought that as soon as a polymerase is stimulated to begin the process, it would zoom to the finish line. However, this wasn’t the case. Most polymerases pause shortly after they start.
The research showed that a single polymerase pause on the track keeps other polymerases from entering the starting gate. Ironically, the longer the polymerases pause, the faster they mediate the gene expression. Moreover, these polymerases liaise more synchronized gene expression in response to the signals triggered by various stages of development or dysregulated in cancer.
Genetic information flows from DNA to RNA to protein. The first step from “DNA to RNA” is called transcription. It is the first step to making practically everything in the cell. Thus, it has been an intense area of study for decades. A large number of studies have focused on the initiation of transcription i.e. the assembly of polymerase on the DNA. It was during the last ten years of extensive research that scientists found that polymerases pause a short distance down from the starting gate as if delayed by a warning sign.
Findings of the study
The researchers used a method called ChIP-nexus to map the position of polymerases on the DNA. The enzyme was mapped or located both in the presence and absence of transcription-blocking drugs. The scientists found paused polymerases to be more stable than polymerases assembled at the initiation site. In addition, these polymerases kept new polymerases from initiating transcription.
Genes are transcribed with bursts of activity. In particular, a rapid series of numerous transcribing polymerases dispersed by periods of inactivity that can last minutes or even hours. The researchers thought that the paused, more stable polymerases block other polymerases from following them during bursts of transcription. Moreover, they also sit there in between bursts of transcription.
Note that cancer arises when gene expression is allowed to spread out unhindered. Therefore, these basic mechanisms of controlling gene expression can benefit the underlying causes of cancer and related diseases.
Transcription is the first step of gene expression. It allows the copying of the information stored in DNA into RNA. The molecular machine behind the process is RNA polymerase. These polymerases often pause, sometimes for hours, as they travel down the double helix. These paused polymerases keep other polymerases from initiating transcription. Thus, they provide a much-needed interval in between bursts of transcription, making gene expression more controlled and on purpose.