Scientists Create Rewritable DNA
May 22, 2012

Scientists Create Rewritable DNA

Scientists have found a way to create rewritable digital data storage in DNA through means similar to binary coding.

The researchers worked to reapply natural enzymes adapted from bacteria to flip specific genetic sequences of DNA back and forth at will.

The scientists, who all work in the Department of Bioengineering at Stanford University Medical Center, said their method essentially works like that of binary computer coding.

"Essentially, if the DNA section points in one direction, it's a zero. If it points the other way, it's a one," graduate student Pakpoom Subsoontorn said in a press release.

Assistant professor Dr. Drew Endy said that programmable data storage within the DNA of living cells could potentially be a powerful tool for studying cancer, aging, and organismal development.

The scientists could count how many times a cell divides, which could someday gives researchers the ability to turn off cells before they turn cancerous.

Their work is known as recombinase-mediated DNA inversion, which is the enzymatic process used to cut, flip and recombine DNA within the cell.

During the research, the team used a device known as a "recombinase addressable data" module, or RAD for short.  They used RAD to modify a particular section of DNA within microbes that determine how the one-celled organisms will fluoresce under UV light.

The microbes glow red or green, depending upon the orientation of the section of DNA.  The scientists can then flip the section back and forth at will.

They said they had to control the precise dynamics of two opposing proteins within the microbes in order to make their system work.

"Previous work had shown how to flip the genetic sequence – albeit irreversibly – in one direction through the expression of a single enzyme," Jerome Bonnet, postdoctoral scholar at Stanford, said. "But we needed to reliably flip the sequence back and forth, over and over, in order to create a fully reusable binary data register, so we needed something different."

The researchers found it easy to flip a section of DNA in either direction, but Endy said they discovered that most of their designs failed when the two proteins were used together within the same cell.

Bonnet has tested RAD modules in single microbes that have doubled more than 100 times, and the switch has held up.  He has also switched the DNA and watched a cell double 90 times, and then set it back.  The latch will even store information when the enzymes are not present.

Endy said his goal is to go from the single bit he has now to eight bits of programmable genetic data storage.

"I'm not even really concerned with the ways genetic data storage might be useful down the road, only in creating scalable and reliable biological bits as soon as possible. Then we'll put them in the hands of other scientists to show the world how they might be used," Endy said.

The research was published in the Proceedings of the National Academy of Sciences on May 21.