Scientists from The University of Texas at Austin, the Stanford
University School of Medicine and
The research appears online Feb. 25 in the journal Science.
Both RNA and DNA are critical for life. In humans and many other
organisms, DNA molecules act as the body's blueprints, while RNA
molecules act as the construction crew—reading the blueprints, building
the body and maintaining the functions of life.
The research team found for the first time that bacteria can snatch bits
of RNA from invaders such as viruses and incorporate the RNA into their
own genomes, using this information as something akin to mug shots.
They then help the bacteria recognize and disrupt dangerous viruses in
the future.
"This mechanism serves a defensive purpose in bacteria," says Alan
Lambowitz, director of the Institute for cellular and molecular biology
at UT Austin and co-senior author of the paper. "You could imagine
transplanting it into other organisms and using it as a kind of virus
detector."
The newly discovered mechanism stores both DNA and RNA mug shots from
viruses in a bacterium's genome. That makes sense from an evolutionary
standpoint, the researchers say, given that some viruses are DNA-based
and some are RNA-based.
Lambowitz says that as a next step, researchers can examine how to
genetically engineer a crop such as tomatoes so that each of their cells
would carry this virus detector. Then the researchers could do
controlled laboratory experiments in which they alter environmental
conditions to see what effects the changes have on the transmission of
pathogens.
"Combining these plants with the environment that they face, be it
natural or involving the application of herbicides, insecticides or
fungicides, could lead to the discovery of how pathogens are getting to
these plants and what potential vectors could be," says Georg Mohr, a
research associate at UT Austin and co-first author of the paper.
Another application might be in the dairy industry, where viruses
routinely infect the bacteria that produce cheese and yogurt, causing
the production process to slow down or even preventing it from going to
completion. Currently, preventing infections is complicated and costly.
Lambowitz and Mohr say dairy bacteria could be engineered to record
their virus interactions and defend against subsequent infections.
This RNA-based defense mechanism is closely related to a previously
discovered mechanism, called CRISPR/Cas, in which bacteria snatch bits
of DNA and store them as mug shots. That method has inspired a new way
of editing the genomes of virtually any living organism, launching a
revolution in biological research and sparking a patent war, but the
researchers say they do not anticipate this new discovery will play a
role in that sort of gene-editing. However, the enzymatic mechanism used
to incorporate RNA segments into the genome is novel and has potential
biotechnological applications.
Researchers discovered this novel defense mechanism in a type of
bacteria commonly found in the ocean called Marinomonas mediterranea.
It's part of a class of microbes called Gammaproteobacteria, which
include many human pathogens such as those that cause cholera, plague,
lung infections and food poisoning.
two other institutions have discovered
that bacteria have a system that can recognize and disrupt dangerous
viruses using a newly identified mechanism involving ribonucleic acid
(RNA). It is similar to the CRISPR/Cas system that captures foreign DNA.
The discovery might lead to better ways to thwart viruses that kill
agricultural crops and interfere with the production of dairy products
such as cheese and yogurt.
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