Scientists Just Created Chromosomes From Scratch—'Huge'

In a milestone achievement, a whole chromosome has been created from scratch by scientists for the first time ever.

The tRNA Neochromosome is a man-made chromosome of the common baker's yeast Saccharomyces cerevisiae. It may soon allow for the creation of synthetic and superior yeast cells, according to a collection of new papers in the scientific journals Cell and Cell Genomics.

This discovery is the newest in an international project called Sc2.0, which has also synthesized all 16 of the yeast's chromosomes with an aim to combine them into a functional cell that might help make yeast faster, more resilient and more productive.

The tRNA Neochromosome is special, as it is entirely synthetic, not made based on one of the original chromosomes of the yeast.

"It is the world's first de novo synthetic chromosome," Patrick Cai, the chair in synthetic genomics at the University of Manchester, international coordinator of the Sc2.0 project, and co-author of the Cell paper, told Newsweek.

"Unlike the other 16 'syn' chromosomes, the tRNA Neochromosome is not modeled on an existing natural chromosome but was literally designed piece by piece, on a computer, the pieces [coming] from at least 9 different species of microorganisms," Cai said.

"There is nothing like it in nature. The fact that it can function by producing tRNAs like a natural genome does is pretty amazing. It is also designed to avoid 'head-on collisions' between RNA polymerase and DNA polymerase, which can lead to DNA breaks and other challenges for the cell."

Thus far, six and a half of the synthetic chromosomes have been combined in a yeast cell at Sc2.0. The project hopes that these synthetic yeast cells may be able to work faster, yield greater results, and be more tolerant to environmental changes when used to make bread or in the production of biofuels, pharmaceuticals, flavors and fragrances.

"These synthetic yeast cells are as normal as the natural cells under normal conditions, but they can transform into 'super-yeast' when the times become tough (e.g., high temperature, high pH)," Cai said. "Amazingly, these synthetic chromosomes are functional like their natural counterparts in the yeast cells, but they have been endowed with new functions which allow them to on-demand rearrange themselves to adapt to different environments like transformers."

This newest synthetic tRNA Neochromosome was designed with the help of artificial intelligence, adding in genes from other organisms to optimize the qualities of the yeast. It will eventually be added to the synthetic yeast cells.

"We designed these synthetic chromosomes using computer-assisted designers, which are used to design buildings and cars; then we synthesize these synthetic chromosomes chunk by chunk in the cell by replacing the wild type sequences, similar to you take a book chapter and re-write it paragraph by paragraph until you get a new chapter," Cai said.

"Now, all these 16 chromosomes (or chapters if you like) are written, and we are in the final push the bring all of them into a book, the ultimate code of life."

This research may also one day be applicable to humans and open new doors to swapping and changing genetic mutations.

"This will have huge impact on human health, in ways to direct test driver mutations for diseases and pave the way for better gene therapies," Cai said.

The researchers hope to soon complete the final Sc2.0 strain, containing all the synthetic yeast chromosomes and the tRNA Neochromosome, marking the first synthetic eukaryote ever created.

"These synthetic yeast cells allow us to think about how genome could have been organized," Cai said. "We were given a yeast genome by nature after billions of years of evolution and random selections (which may not be here anymore). Our understanding of genomes is largely based on the observation of these natural genomes. The ability to build synthetic genomes will lead us to much deeper understanding of the first principles of life."

Do you have a tip on a science story that Newsweek should be covering? Do you have a question about chromosomes? Let us know via science@newsweek.com.