Rewriting the Genetic Alphabet: Synthetic Biology reaches new milestone

Patient DNA dataIn May 2010, for only the second time in the history of life on planet Earth, a life-form was created with no biological parent. Unlike the first of its kind, this organism wasn’t whipped up in some primordial soup; it was formed in a Californian laboratory by a world-renowned biologist by the name of J. Craig Venter.

Venter, one of the first sequencers of the human genome, and his colleagues managed to create a self-replicating life-form out of the memory of a computer, which they would come to call “Mycoplasma mycoides JCVI-syn1.0”. They achieved this by digitally sequencing a whole bacterial genome and introducing it into an empty cell. They even left a code written into its DNA – using the four “letters” of the genetic alphabet – for people to crack, along with an email address to send the code to once it was discovered.

The accomplishment would mark the coming of age of a new, yet highly anticipated, field of science: synthetic biology. Today, pretty much four years later, scientists have added one more notch on the field’s belt by publishing a landmark experiment where they have literally engineered new DNA and created an organism out of it.

Spelling out life with new genetic letters

In a paper published in today’s edition of the journal Nature, researchers in the US describe creating the first ever reported organism containing a man-made DNA makeup. To appreciate this, we need to go back to Genetics 101 and remind ourselves how DNA is formed and what it does (or at least I did).

As mentioned above, there are just four different “letters” in the genetic alphabet, which represent the four different nucleobases (the chemical building blocks of DNA) found in natural life-forms. These four nucleobases combine to form two separate combinations known as “base pairs”, which fold together to form the DNA helix. Cells then read the code spelled out by their DNA (by the way these “letters” are sequenced) in order to do what it is they are meant to do.

Apparently, synthetic biologists have been expanding the genetic alphabet for years by creating new DNA bases in the lab. Previously, they have been unable to place the artificial DNA within a natural cell and then reproduce it, which is how you would bring the DNA to life, so to speak.

However, in today’s study in Nature, the US researchers report having been able to inseminate an E. coli cell with man-made DNA, which was then reproduced effectively (that is, without impacting on cell growth) by the cell’s replication machinery.

The study provides evidence that an organism can house, decode and spread an extended genetic alphabet.

Get your organisms tailor-made

It has long been a goal for the field of synthetic biology to create new organisms with unnatural DNA structures, as they provide a platform for reprogramming cells for a wide range of applications. The authors of the study note that the experiment could lead the way to evolving cells which can produce new proteins with unnatural amino acids.

Now, proteins are amazing at what they do. No matter how advanced our technology is, nothing rivals the efficiency of the biochemical machinery of proteins when it comes to making use of natural resources.

What this study shows is the possibility that we can synthesise our own versions of the chemical building blocks of life to build new kinds of biological machines, tailor-made to work the way we want them to.

This is, of course, still a distant reality for synthetic biologists – and many a biologist would still call it a pipe dream. Not only that, the idea of reinventing, or tailor-making, life-forms to suit our own ends would make a lot of people uncomfortable. (Indeed, in 2012 over 100 environmental and civil society organisations called for a worldwide moratorium on the release and commercial use of synthetic organisms.)

It’s still an exciting time for synthetic biology nevertheless. If scientists have managed to pull off something as brash as successfully rewriting the genetic alphabet, something many would have nigh considered impossible, imagine what kinds of things synthetic biology can achieve in the future.

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