Scientists Develop Smallest Living Genome Found in Nature

Evolution is the process by which organisms are able to grow and develop over time. It’s what has allowed the peppered moth to survive the industrial revolution, mice to develop an immunity to rat poison, and lizards to grow longer legs to avoid attacks from fire ants. It’s also the process that’s frustrated biological engineers for as long as such a field has existed.

“Evolution has given us a real mess,” said Chris Voigt, a biological engineer from MIT. “We’ve been trying to do genetic and biological engineering, (and) it’s really just bubble gum and sticks, piecing together whatever work,” Voigt continued.

After decades of work, biologists may be closer than ever to a solution. Craig Venter, Founder, Chairman, and Chief Executive Officer of the J. Craig Venter Institute, and his colleagues have created a new organism with the smallest genome of any known cellular life form. It’s the closest that scientists have come to creating a cell in which every gene and protein is fully understood. That is a good start, but there is still room to improve.

According to Clyde Hutchison, the lead author of the story, “We want to understand at a mechanistic level how a living cell grows and divides.”

As of now, according to Hutchison, there’s “no cell that exists where the function of every gene is known.” That understanding is the point of the research.

“(We’d be) in a better position to engineer cells to make specific products,” Hutchison continued.

Here’s a brief outline of the preliminary work as discussed in The Scientist.

The team’s starting point was the bacterium Mycoplasma genitalium, which has the smallest known genome of any living cell with just 525 genes. However, it also has a very slow growth rate, making it difficult to work with. To practice synthesizing genomes and building new organisms, the team therefore turned to M. genitalium’s cousins, M. mycoides and M. capricolum, which have bigger genomes and faster growth rates. In 2010, Venter’s team successfully synthesized a version of the M. mycoides genome (JCVI-syn1.0) and placed it into the cell of a M. capricolum that had had its own genome removed. This was the first cell to contain a fully synthetic genome capable of supporting replicative life.

Once this was accomplished, the team needed to make the genome smaller. The team decided to try and speed through the process by designing their own genome, building it and installing it inside the cell; however, that didn’t work out the way the team had planned.

“We thought we knew enough, that it would be that much faster,” said Hutchison. “We weren’t completely right about that (and) it took quite a bit longer than we thought.”

After a number of additional rounds of consideration and testing, the team had a genome that was able to successfully support life. Even though they still don’t understand each gene’s function, they’re further along now, than they were.

Leroy Hood, the president of the Institute for Systems Biology in Seattle, had thoughts on the research.

“This is a really pioneering next step in the use of synthetic biology,” Hood said.

That doesn’t mean they’re done yet though. More than a third of the genes the researchers removed have purposes that remain unknown.

“I also think we kid ourselves about how much we know about the genomes of organisms. There’s still an enormous amount of dark matter,” Hood continued.

It’s that kind of work that the researchers find most fascinating.

“(The ones we don’t understand), in a way, are the most exciting,” Hutchison said, “because they might represent some new undescribed function that has spread through other life forms.”

As research continues to prove new findings, the field becomes more equipped to genetically engineer bacteria that can produce fuel, pharmaceuticals or even remove toxins to help strengthen your assets. It’s the foundation necessary to keep the field from relying on bubble gum and sticks.