A segment of DNA (center) can be read both forwards and backwards. Reading in one direction successfully decodes the yellow sequence (left), while reading in the other direction successfully decodes the blue sequence (right).

Nicolas Lapique and Yaakov Benenson

Biological research involving transporting DNA into living cells is physically limited in how much genetic information can be moved—current transport methods can only carry a set amount of DNA. Taking a cue from the world of computing, researchers have demonstrated a way to compress, or zip, genetic information for more efficient transmission into living cells. Once inside the cell, the compressed DNA can then be decompressed and read. Such a process makes it possible to move far greater amounts of genetic information.  

Nicolas Lapique and Yaakov Benenson of ETH Zurich’s Department of Biosystems Science and Engineering in Basel, Switzerland have developed a novel technique for compressing DNA by taking advantage of its redundancy. A segment of DNA can be read both forwards and backwards. Thus, researchers can cleverly select chunks of reversible DNA that encode one piece of information in the forward direction and a different piece of information in the backward direction. 

Additionally, the researchers noted that DNA often contains many recurring elements in its coded sequence. For example, the same “promoter” region on the DNA, where individual genes are expressed and activated, can be used by multiple genes. “This presented a clear opportunity to reduce the size,” says Benenson, “just like a file can be compressed if it contains a repeated element, like an image file with lots of white pixels.” Rather than having each gene carry its own copy of its promoter, the researchers engineered compressed DNA strands that carried one shared promoter, which would then work for each gene once the DNA was uncompressed and reassembled. Through these techniques, the same amount of genetic information can be carried in as little as a quarter of the original DNA file size. 

Benenson and Lapique successfully put their system through its paces by showing that human embryonic kidney cells could produce a protein from compressed genetic instructions. In its current early stages, the project uses loops of DNA, called plasmids, as the vehicles for delivering engineered genetic material into cells. The researchers plan to expand their compression technique to viral vectors, which take advantage of virus’ honed abilities to worm their way into cells as infectious agents. These engineered viruses cannot store as much genetic information as plasmids, which makes viral vectors the ideal application for compacted, information-loaded DNA. (Nature Nanotechnology