Engineered Syn57 Bacteria Redefine the Genetic Code Rule with 57 Codons
Rules are meant to be broken!
Likewise, what if life could run on a different set of biological rules? In a bold leap towards the future of synthetic biologyscientists have engineered a living organism with a radically streamlined genetic code. This actually proves that life can thrive on far fewer instructions than nature provides.
A team of genetic engineers in Cambridge has engineered Syn57 bacteria. They created a new strain of They exhibited chilldubbed Syn57, that functions with just 57 codons, instead of the standard 64 that all known life forms use. This is the most condensed genetic code ever built, and it’s shaking the foundations of what we thought we knew about life’s fundamental blueprint.
The Universal Language of Life—and Its Redundancy
All life on Earth, from humans to mushrooms to microbes, shares a nearly identical genetic code. DNA sequences are composed of four bases: Adenine (A), Thymine (T), Guanine (G), and Cytosine (C). These bases are read in triplets, called codons, each specifying one of the 20 amino acids used to build proteins.
But the code is redundant. Multiple codons can encode the same amino acid
. For instance, serine is represented by six different codons. Out of the 64 possible codons, only 61 specify amino acids; the remaining three act as stop signals to end protein synthesis.
For decades, biologists have debated whether this redundancy is biologically necessary or merely a quirk of evolution.
Genetic Minimalism: Putting the Code to the Test
Thanks to all these advanced tools in genome synthesis, researchers can now rewrite entire genomes and ask a fundamental question: How much of the genetic code is essential for life?
Dr. Wesley Robertson and his team at the Medical Research Council Laboratory of Molecular Biology in the UK, alongside parallel efforts by Dr. Akos Nyerges at Harvard, have taken up this challenge. Their goal is to reduce the number of codons and observe how life copes.
In 2019, the UK team successfully created Syn61, a strain of E. coli that operates without three of the standard 64 codons. Building on that success, they set their sights on a bolder target: Syn57, a bacterium with just 57 codons.
Building Life from Scratch
Creating Syn57 required editing over 100,000 codon positions. This was a monumental engineering feat. Some codon changes caused no issues, while others disrupted overlapping genes or essential functions, threatening the microbe’s viability.
Dr. Robertson mentioned how tricky it was to develop the engineered Syn57 bacteria. There were multiple trials going on; every time they made these changes, they would think whether it would be a dead end or if they could build something. But glitch by glitch, repair by repair, the team succeeded.
Alive, But Barely
Syn57 is barely alive and not exactly thriving. It reproduces four times slower than natural E. coli. But the fact that it’s alive at all is a testament to the plasticity of life.
Dr. Yonatan Chemla, a synthetic biologist at MIT who was not a part of the project, stated that this was a technically demanding tour de force.
Meanwhile, the Harvard team is assembling its own 57-codon genome, still in fragmented stages, but confident it will catch up.
Why Shrink the Genetic Code?
Creating simplified genetic codes isn’t just a biological curiosity. It opens doors to entirely new realms of synthetic biology.
By freeing up redundant codons, scientists can reassign them to unnatural amino acids, chemically engineered building blocks not found in nature. This could allow engineered bacteria to manufacture novel drugs, biomaterials, or industrial catalysts that conventional organisms can’t produce.
It also presents a solution to a primary biosafety concern. Engineered microbes could accidentally transfer genes to wild species in the environment. But if those genes use a synthetic code, natural organisms wouldn’t be able to read them.
Dr. Robertson stated that with the advanced technology, we could build the engineered Syn57 bacteria, and with this, we can prevent the escape of information from the synthetic organisms designed in laboratories.
“We can prevent the escape of information from our synthetic organism,” said
Revisiting Crick’s “Frozen Accident”
This work also lends weight to a long-standing theory by Francis Crick, one of the co-discoverers of DNA. In 1968, Crick proposed that the genetic code might be a “frozen accident”, not the result of intelligent optimization, but simply the outcome of random early events in evolutionary history.
The fact that Syn57 survives without seven of the supposedly “essential” codons supports this view. There may be nothing sacred about the current code, but it is just legacy decisions, locked in by time and complexity.
The Future of Rewritten Life
The creation of Syn57 is a milestone in the quest to design life from the ground up. As scientists continue to refine these synthetic genomes, we may soon unlock organisms capable of solving challenges in medicine, materials science, and environmental sustainability.
“Life still works,” Dr. Robertson remarked. And now, it works on entirely new terms.
Key Takeaways:
- Syn57 is a new strain of E. coli engineered with only 57 codons, the most minimal genetic code ever used by a living organism.
- The project offers insights into the evolution of the genetic code, supports Francis Crick’s “frozen accident” hypothesis, and paves the way for biosafety, biotechnological innovation, and the discovery of new biological functions.
- Future applications may include custom microbes for producing synthetic materials or detecting environmental hazards, with built-in safeguards against gene transfer.
