DNA is a great way to store information – just ask your cells. But while it’s easy for a cell to read information from DNA, the cell can’t rewrite new data into its DNA sequence.
Now, scientists have engineered a rewritable DNA-based memory module that can reliably and reversibly store data in the chromosome of living cells – research that could be used to track cellular events to study aging or cancer.
Rewritable biological memory circuits have been made before, usually as a cellular switch to shut gene expression on or off in a cell. But these systems could write a piece of information only once.
Thus far people have not been able to control flipping back and forth – they flip once and then they’re done, or they flip randomly, Scientific American reports. Writing info onto a blank CD once is not as useful as a rewritable CD.
So, a Stanford team led by Drew Endy developed a new storage module that can cycle the memory element over and over again: record, erase, rewrite over and over again.
To do so, they first got DNA to act like the way an electronic or binary switch can be off or on, 0 or 1. But the real technical advance here is to flip reliably back and forth as many times as you want.
The researchers chose DNA as the stuff of memory and used enzymes called recombinases as the tools to flip it on and off. Those enzymes came from bacteriophages, which are viruses that infect bacteria. These viruses use one enzyme to integrate into the genome of the bacterium they’re infecting.
In the experiment, the enzyme traveled to a particular place on the sequence of DNA that contains genetic information and flipped a small section so that it read backward. Sending a second signal then flipped the sequence back to its original state.
They tested out their memory system the DNA of E. coli. A stretch of DNA is flanked by sites that signal to enzymes made by the bacteriophage, instructing them to cut out the DNA and paste it back into the chromosome in the reverse orientation, Nature explains. Under the influence of 2 different proteins, the bits of DNA sections would glow either green or red, depending on their orientation. Like 1 and 0.
"One of the coolest places for computing is within biological systems," Endy says.
They call it the recombinase addressable data (RAD) module. So far, they’ve got one bit of memory. Next, they hope to scale up to eight bits, or a byte.
The work was published in Proceedings of the National Academy of Sciences yesterday.
Image by ynse via Flickr