WHY THIS MATTERS IN BRIEF
DNA is the universes’ most advanced programming language, and we might have just given it a boost of infinite proportions.
DNA is wonderful. And powerful. After all, it gave us everything from the dinosaurs and dolphins, to us, and, of course, the world’s first biological computers, designer babies, DNA micro-robots that could one day create the world’s first molecular assemblers, and the technology to turn humans into supercomputers and the ability to store all the world’s information in a small shoebox, among other millions of other things, like ultra-hardy cockroaches. And all that was created with just four DNA letters – A, C, G, T. So now imagine what we could do with eight DNA letters – and the answer, just in case you were wondering, is the universe, not the sky, is the limit. Both literally and figuratively.
A couple billion years ago, four molecules combined together to form the elegant DNA double helix, the biological code for all life on Earth. But was this just fluke, and were these four players really fundamental to the appearance of life, or could other molecules have also given rise to our genetic code?
A new study, published this week in the journal Science, supports the latter proposition, and scientists have already used this information to create a new kind of DNA double helix with eight DNA letters, not four. And they aren’t the first scientists to use this thinking to create a new form of Synthetic DNA – last year scientists elsewhere managed to create the world’s first utterly alien organism, biologically speaking, built using six base pair DNA.
In the former’s case the researchers crafted the synthetic DNA using four additional molecules, so that the resulting product had a code made up from eight letters rather than four. With the increase in letters, this DNA had a much greater capacity to store information, whether that is the “information of life” that could be used to create almost God like superhumans, or store data, in the form of computer data, which would let us shrink our small shoebox to just a pinhead.
Scientists called the new DNA “Hachimoji,” which is Japanese for “eight letters,” and as you’d expect their work expanded on the previous work from the teams involved in creating the six letter synthetic DNA experiment.
Natural DNA is composed of four molecules, called nitrogenous bases, that pair up with each other to form the code for life on Earth – A binds with T, and G binds with C. The Hachimoji DNA includes these four natural bases, plus four more synthetically made nucleotide bases which the researchers called P, B, Z and S.
The team, which included several different teams across the US, created hundreds of these Hachimoji double helixes with different combinations of the natural and synthetic nucleotide base pairs. Then, they conducted a series of experiments to see if the various double helixes had properties needed to create and support life.
Natural DNA has a hallmark property that no other genetic molecule seems to have – it’s stable and predictable. That means that researchers can calculate exactly how it will behave in certain temperatures and environments, including when it will degrade. But it turns out that the researchers were also able to do this with the Hachimoji DNA – they could come up with a set of rules that can predict the DNA’s stability when it is exposed to different temperatures.
But what about using the new synthetic DNA to create life I hear you ask…
“The finding that it’s possible to add the four synthetic bases and still get a [DNA] code that’s predictable and programmable … that’s just unprecedented,” said Floyd Romesberg, a chemistry professor at Scripps Research in California, who was not a part of the study but who previously published research on an earlier six letter code. “This landmark paper suggests indeed that G, C, A and T are not unique,” added Romesberg.
Senior author of the paper Steven Benner, a distinguished fellow at the Foundation for Applied Molecular Evolution in Florida, agreed.
“If somewhere else in the universe, life is also coded in DNA, it’s not going to be exactly like what we have here on Earth,” said Benner. “It’s very useful to have these kinds of experiments in the laboratory to understand what alternative structures [might exist].” And speaking of seeding life through the universe, fear not, Earth bound scientists have already drawn up those plans, so if you’ve ever watched the movie Prometheus and loved it then remember this article, and of course the scientists hard work, and revel in being one of the first people to know that this is where it all began. Hashtag awesome.
But creating DNA that stores information isn’t enough, Benner noted. It also has to have the ability to transfer that information to its sister molecule RNA, so that RNA can then instruct proteins to carry out all the business in an organism.
With that in mind, the researchers developed synthetic enzymes, proteins that facilitate a reaction, that successfully copied Hachimoji DNA into Hachimoji RNA. Furthermore, they found that the RNA molecule was able to fold into a sort of L shape that would be necessary for it to further transfer information. And in addition to that, the DNA strands must be able to twist into the same 3D structure — the famous DNA double helix.
The team created three crystal structures of Hachimoji DNA, each with different sequences of the eight base pairs, and found that indeed, each formed the classic double helix.
Still, in order for the Hachimoji DNA to support life, there’s a fifth requirement, Benner said. That is, it needs to be self-sustaining or have the ability to survive on its own. However, the researchers stopped short of investigating this step, in order to prevent the molecule from becoming a biohazard that could one day work its way into the genomes of organisms on Earth. Phew. But I’m sure it won’t be long before some scientist somewhere gets “too curious” at which point we need to make sure the Hazmat teams are on standby just in case.
Aside from glimpsing alternatives for life in the cosmos, this eight letter DNA strand also has applications here on our home planet. An eight letter genetic alphabet will store more information and bind to certain targets more specifically, Benner said. For example, Hachimoji DNA might be used to bind to liver cancer cells or anthrax toxins, or be used to speed up chemical reactions, again, all for starters.
“By increasing the number of letters from four to six to eight, the diversity of DNA sequences is greatly increased,” said Ichiro Hirao, a synthetic molecular biologist at the Institute of Bioengineering and Nanotechnology, A*STAR in Singapore whose team was also involved in the previous research to create the six letter DNA organism.
In fact he’s under selling the technology because the combinations become almost infinite… and that’s one of the main reasons why this technology would be so powerful if we ever decided to really push the boundaries with it and make stuff with it, like awesome aliens, superhumans, and even, bringing things down to Earth again, new computers, drugs, materials and other bio-products.
Of course, “this is just a first demonstration” of an eight letter DNA double helix, and for practical use, we need to improve the accuracy and efficiency of replication and transcription into RNA, said Hirao, who now believes that eventually they might be able to build up to even more letters.
