Junk DNA goodbye!: helps extremophiles survive (Introduction)

by David Turell , Saturday, March 03, 2018, 19:57 (2240 days ago) @ David Turell

Protection is from non-coding RNA's activities. They are part of so-called junk DNA, since they don't code for proteins:

https://www.sciencedaily.com/releases/2018/03/180302124842.htm

"Thousands of molecules of ribonucleic acid make salt-loving microbes known as "extremophiles" highly resistant to the phenomenon oxidative stress -- the uncontrollable production of unstable forms of oxygen called "free radicals," which can negatively affect DNA, proteins, and lipids in cells.

"In a study published recently in the Journal of Bacteriology, Johns Hopkins University scientists found that a group of RNAs -- that do not form protein -- orchestrate this resilience in extremophiles requiring high salt concentrations called Haloarchaea, to grow without signs of damage.

***

"To understand the extremophile's resistance to oxidative stress, Gelsinger examined its ribonucleic acid profile under hydrogen peroxide as an agent of the stress. Along with messenger RNA, which is needed to create proteins, he observed large quantities of something surprising -- small noncoding RNA. Unlike messenger RNA, which acts as the go-between for DNA and proteins, noncoding RNAs do not seem to turn into protein.

"'My findings strongly suggest that the [noncoding RNA] actually causes the messenger RNA to degrade and be cut up," Gelsinger said. By effectively blocking the production of protein or breaking down the messenger RNA, the proteins that play a role in oxidative stress were simply not made.

"Moreover, Gelsinger said, these noncoding RNAs affect multiple targets, having a large-scale effect. Pieces of DNA that are jumpy, particularly in times of stress, and hop around in the genome of organisms, called transposons, are targets for such regulatory small RNAs. By disrupting the disruptors, these RNAs possibly keep in check further damage caused by transposons, allowing extremophiles to repair the damage caused by oxidative stress.

"'What we found is that a lot of these noncoding RNAs are causing the degradation of those transposons, so they are essentially silencing them," said Gelsinger. With fewer transposons hopping around, damage to the DNA is reduced.

"Among other targets of the small noncoding RNAs were messenger RNAs that aid in guiding microbes towards or away from food or other chemical agents, as well as those that reign in damaged proteins and prevent injured cells from growing. These noncoding RNAs also targeted a class of molecules that decide which proteins -- and how many of them -- are formed. "If you can regulate the regulator, you can get a much faster, larger effect than just directly regulating your target," said Gelsinger. The enveloping effect of these noncoding RNAs appears to contribute heavily to the oxidative stress resistance found within Haloarchaea.'

Comment: More evidence that much so-called junk DNA isn't junk. According to Darwin current theory junk DNA is useless stuff produced by chance mutations during purposeless evolution, but 80% of it has been found to have function, small and large effects.