Sinister DNA

18 May 2016

A team from Tsinghua University of Beijing has managed to synthesise an enzyme capable of replicating mirrored DNA.

Molecules are often constructed to favour one side or another, like a pair of gloves their shape is identical, but you can’t wear them on the wrong hand. In chemistry, this property is known as chirality. Amongst organic molecules, the DNA in cells is right handed and amino acids are usually left handed.

Mirror images are of interest because the reflected molecules should work the same, but could be resistant to attack from viruses or enzymes which only work with the original not its mirror image. Short strands of mirror DNA have already been constructed using chemical methods, but the process is extremely slow.

To try and speed up the process, a team of Chinese scientists took the approach of creating a left handed version of a polymerase, the enzymes responsible for replication and transcription of DNA. Due to the complexity of the task, the team used the African swine fever virus Polymerase X, the smallest, comprised of 174 amino acids. Once successful, it could be used to extend the length of a mirrored DNA strand from twelve nucleotides to eighteen, and then to 56 nucleotides within 36 hours.

Although the pace of replication is slow, the team hopes that having proven their concept, they can move on to a more complex polymerase, constructed from more amino acids, which would work faster. They hope that this is a significant step towards more complex mirror image machinery, capable of self-replication.

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