Researchers demonstrate how 'interfering' RNA can block bacterial evolution

August 31, 2012
Researchers demonstrate how 'interfering' RNA can block bacterial evolution
Colonies and capsules. Experiments in mice show how colonies of bacteria that would typically become encapsulated (left) fail to acquire the necessary gene because of CRISPR interference (right).

(Phys.org)—Bacteria may be simple creatures, but unlike "higher" organisms they have a neat evolutionary trick. When the going gets tough, they can simply pick up and incorporate a loose bit of genetic material from their environment. It's instant evolution, no time-consuming mutations required. This process, known as horizontal gene transfer, is an important reason why nasty bacteria like pneumococci are often able to evade immune system attacks and antibiotic drugs.

A Rockefeller has now uncovered a mechanism by which bacteria can be forced to accept or reject the foreign DNA that they incorporate into their genomes through a process known as transformation. The researchers say that harnessing this mechanism could be a new way to restrict or manipulate bacterial evolution in ways that might be medically useful.

"Transformation is something that bacteria use as a last resort," says Luciano Marraffini, head of Rockefeller's Laboratory of Bacteriology. "In a desperate attempt to stay alive under hostile conditions, they start incorporating whatever genes they can find into their chromosome in the hopes that they can quickly evolve out of trouble."

"Our work shows that an mechanism known as CRISPR can be used to block transformation in pneumococci."

Marraffini and his team, including Rockefeller postdoc David Bikard, conducted a series of experiments inspired by the original research on transformation performed by Rockefeller microbiologists Oswald Avery and Maclyn McCarty in the 1940s. They injected mice with pneumococci containing CRISPR sequences engineered to prevent the bacteria from acquiring the genes that produce a polysaccharide-based "capsule" on its surface that is necessary for the bacteria to establish infection. They also injected the mice with heat-killed pneumococcal bacteria containing genes that code for this encapsulation.

"Normally the mice will develop a and die under these conditions, because the genes that encode for the capsules will successfully transfer to the live bacteria," says Marraffini. "But our experiments showed that when we used the engineered CRISPR-containing bacteria, the mice lived, proving that our CRISPR intervention successfully blocked the bacteria's ability to acquire the necessary sequences via transformation."

The researchers say their work shows that CRISPR has the potential to be an efficient means of targeting specific bacterial cells, such as those with antibiotic resistance or virulence genes, in order to kill them.

Explore further: Flu jab for bacteria

More information: Bikard, D. et al. CRISPR Interference Can Prevent Natural Transformation and Virulence Acquisition during In Vivo Bacterial Infection. Cell Host & Microbe, Volume 12, Issue 2, 177-186, 16 August 2012.

Related Stories

Flu jab for bacteria

March 31, 2010

Viruses can wreak havoc on bacteria as well as humans and, just like us, bacteria have their own defence system in place, explains Professor John van der Oost, at the Society for General Microbiology's spring meeting. Uncovering ...

New study examines how bacteria acquire immunity

September 15, 2010

In a new study this week, Rice University scientists bring the latest tools of computational biology to bear in examining how the processes of natural selection and evolution influence the way bacteria acquire immunity from ...

Researchers unlock the secret of bacteria's immune system

November 4, 2010

A team of Université Laval and Danisco researchers has just unlocked the secret of bacteria's immune system. The details of the discovery, which may eventually make it possible to prevent certain bacteria from developing ...

Understanding a bacterial immune system one step at a time

May 17, 2011

Researchers at the University of Alberta have taken an important step in understanding an immune system of bacteria, a finding that could have implications for medical care and both the pharmaceutical and dairy industries.

Researchers clarify bacterial resistance

June 24, 2011

Just like plants and animals, bacteria have a range of defence mechanisms against viruses and other threats. Dutch researchers at the Wageningen Laboratory for Microbiology and their American and Russian colleagues have largely ...

Recommended for you

Plastic in 99 percent of seabirds by 2050

August 31, 2015

Researchers from CSIRO and Imperial College London have assessed how widespread the threat of plastic is for the world's seabirds, including albatrosses, shearwaters and penguins, and found the majority of seabird species ...

Researchers unveil DNA-guided 3-D printing of human tissue

August 31, 2015

A UCSF-led team has developed a technique to build tiny models of human tissues, called organoids, more precisely than ever before using a process that turns human cells into a biological equivalent of LEGO bricks. These ...

Study shows female frogs susceptible to 'decoy effect'

August 28, 2015

(Phys.org)—A pair of researchers has found that female túngaras, frogs that live in parts of Mexico and Central and South America, appear to be susceptible to the "decoy effect." In their paper published in the journal ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.