Genome complexity: RNA copies and is turned on and off (Introduction)

by David Turell , Saturday, November 28, 2020, 21:13 (1455 days ago) @ David Turell

A new method of study finds out how:

https://www.sciencedaily.com/releases/2020/11/201127085440.htm

"During transcription, an enzyme called RNA polymerase wraps itself around the double helix of DNA, using one strand to match nucleotides to make a copy of genetic material -- resulting in a newly synthesized strand of RNA that breaks off when transcription is complete. That RNA enables production of proteins, which are essential to all life and perform most of the work inside cells.

"Just as with any coherent message, RNA needs to start and stop in the right place to make sense. A bacterial protein called Rho was discovered more than 50 years ago because of its ability to stop, or terminate, transcription. In every textbook, Rho is used as a model terminator that, using its very strong motor force, binds to the RNA and pulls it out of RNA polymerase. But a closer look by these scientists showed that Rho wouldn't be able to find the RNAs it needs to release using the textbook mechanism.

***

"The research, published online by the journal Science today, Nov. 26, 2020, determined that instead of attaching to a specific piece of RNA near the end of transcription and helping it unwind from DNA, Rho actually "hitchhikes" on RNA polymerase for the duration of transcription. Rho cooperates with other proteins to eventually coax the enzyme through a series of structural changes that end with an inactive state enabling release of the RNA.

***

"'It answers a fundamental question -- transcription is fundamental to life, but if it were not controlled, nothing would work. RNA polymerase by itself has to be completely neutral. It has to be able to make any RNA, including those that are damaged or could harm the cell. While traveling with RNA polymerase, Rho can tell if the synthesized RNA is worth making -- and if not, Rho releases it."

***

"'RNA polymerase moves along, matching hundreds of thousands of nucleotides in bacteria. The complex is extremely stable because it has to be -- if the RNA is released, it is lost," Artsimovitch said. "Yet Rho is able to make the complex fall apart in a matter of minutes, if not seconds.

***

"Though the study was conducted in bacteria, Artsimovitch said this termination process is likely to occur in other forms of life.

"'It appears to be common," she said. "In general, cells use similar working mechanisms from a common ancestor. They all learned the same tricks as long as these tricks were useful.'"

Comment: The last comment above makes sense given common descent. The mechanisms that control these molecular dances is not known, but my guess is that there are designed electrical forces that control The electrical parts of the molecules. The decision making must follow instruction al information in the genome.