What if a tiny shift in the way DNA fragments is connected could make genetic engineering dramatically more efficient? A new study suggests that a surprising approach could open the door to faster and more precise DNA construction.
A group of Japanese researchers has developed a new technique that could overcome some of the limitations of traditional DNA assembly, which relies on restriction enzymes that cut only at specific sequences and typically produce very short “sticky ends,” usually four bases long.
The new method builds on a chemical reaction involving the strong affinity between silver and sulfur. By using silver nanoparticles with modified DNA, researchers can cut DNA at customized sites.
A collaborative team led by Professor Hiroshi Abe and Assistant Professor Masahito Inagaki at Nagoya University, alongside Professor Natsuhisa Oka at Gifu University, published their findings in Nucleic Acids Research, detailing the chemical technique and its potential for improving DNA assembly.
Early attempts using loose silver ions caused random binding and precipitation, resulting in a DNA recovery rate of just 14%.
To overcome this problem, the researchers coated the silver nanoparticles with polyethylene glycol (PEG), stabilizing the particles in water and allowing the DNA cleavage process to work at mild temperatures.
Unwanted DNA fragments remained attached to the nanoparticle surfaces and could then be removed through centrifugation. This left the desired fragments in solution, increasing the final DNA recovery rate from 14% to 98%.
The silver nanoparticle approach also makes it possible to generate much longer overhangs, ranging from 10 to 18 bases, compared with the four-base sticky ends typically produced by conventional methods.
When joined using standard DNA ligase, an 18-base overhang achieved a 44% joining efficiency, compared with just 8% for a traditional four-base overhang—roughly a 5x improvement.
To demonstrate that the technique could work in living cells, the researchers successfully assembled a gene encoding green fluorescent protein (GFP) and introduced it into human cells, which subsequently expressed the protein.
