For the first time, scientists made synthetic DNA with 4 additional letters


The Earth may have a dizzying array of life forms, but our biology is still a solitary data point – we simply have no reference to life based on a different DNA than ours. Now scientists have taken matters into their own hands to push the boundaries of what life could be like.

A NASA-funded research led by the Foundation for Applied Molecular Evolution in the United States led to the creation of a new flavor of the double-helix DNA, at four additional nucleotide bases.

It is called hachimoji DNA (Japanese words "eight letters") and includes two new pairs to add to existing partnerships of adenine (A) coupled with thymine (T) and guanine (G) to cytosine (C).

This work to develop the genetic recipe of nature may seem a little familiar. The same scientists have already managed to insert two new letters in 2011. Last year, last year, another version of an extended alphabet, also comprising six letters, was designed to work at inside a living organism.

Now, in what may seem like a case of outperformance, researchers have returned to the drawing board to develop even more nonstandard nucleotides.

However, they are intended to double the number of codes in the cookbook.

"By carefully analyzing the roles of shape, size, and structure in hachimoji DNA, this work helps to better understand the types of molecules that can store information in extraterrestrial life on extraterrestrial worlds," he says. chemist Steven Benner.

We already know a lot about the stability and functionality of "natural" DNA under various environmental conditions, and we are gradually deconstructing possible scenarios describing its evolution from simple organic matter to living chemistry.

However, to fully understand how a genetic system might evolve, we need to test the limits of its underlying chemistry.

The DNA of Hachimoji certainly allows it. The new codes, named P, B, Z and S, are based on the same type of nitrogen molecules as the existing molecules, classified as purines and pyrimidines.

Similarly, they bind with hydrogen bonds to form their own base pairs – bond S with B and P with Z.

It is there that the similarities fade. These new "letters" introduce dozens of new chemical parameters into the double-helix structure that can potentially affect how they zap and twist.

By designing models that predict the stability of the molecule and then observing the actual structures made up of this "foreign" DNA, researchers are better equipped for what is really important with respect to the fundamentals of a model. genetic.

The researchers constructed hundreds of hachimoji propellers composed of different natural and synthetic base configurations, and then subjected them to various conditions to check their resistance.

Although there are some minor differences in the behavior of the new letters, there was no reason to believe that the hachimoji DNA would not work well as a support model. information that can mutate and evolve.

The team not only showed that their synthetic letters could contribute to new codes without disintegrating quickly, but the sequences were also translated into synthetic RNA versions.

Their work is far from a second genesis. But a new DNA format like this is a step forward in determining what living chemistry might look like – and could not – look like that of the universe.

"The detection of life is an increasingly important goal of NASA's global science missions, and this new work will help us develop effective instruments and experiments that will expand the reach of what we are looking for," he said. Lori Glaze, Acting Director, NASA Planetary Science Division.

The design of new databases that can work alongside our own DNA also has applications closer to home, not only as a means of reprogramming life with a different code base, but also in our efforts to build new types of nanostructures .

The sky is really not the limit with synthetic DNA. This will take us to the stars and to the back.

This research was published in Science.


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