Biologists have engineered a synthetic life cell. This simplest cell contains only the bare minimum number of genes necessary for survival and reproduction in the laboratory.
“We have an organism that is as simple as anything that can live on the planet at the moment,” said John Glass, a synthetic biology professor at the J. Craig Venter Institute in California. Glass was the principal investigator on the study, which was published in the journal Cell.
The feat is comparable to stripping a car down to its frame and reassembling only the components required to drive the vehicle, with no air conditioning, windshield wipers, or windows.
The synthetic life cell contains only 480 genes, a tiny fraction of the approximately 4,000 genes found in an E. coli bacteria cell or the 30,000 genes found in our cells.
The discovery will aid scientists in deciphering what specific genes do. It will also have practical applications, such as determining how pharmaceuticals affect cell function.
Additionally, these minuscule synthetic life cells can be used to test novel genetic pathways. One example is that one of Glass’s collaborators is already investigating whether combining different genes can improve carbon fixation, the process of removing carbon dioxide from the atmosphere.
“I believe that over the next decade, we will make significant progress in understanding the fundamental principles of cellular life,” he told Bob McDonald of Quirks & Quarks.
The team was tasked with developing new science. Scientists discovered over 350 years ago that cells comprise all living things. However, it wasn’t until the 1930s that they considered synthesizing life cells as a way to tease apart the fundamental principles of cellular life.
Scientists built a perfectly self-replicating synthetic life cell
When Glass and his colleagues first began developing a synthetic life cell that contained only the genes necessary for survival in a laboratory environment that provided food and nutrients, he stated that the scientific techniques to accomplish this were not yet available.
In 2016, his team announced the development of synthetic life cells derived from a common bacterial pathogen found in goats, Mycoplasma mycoides. They reduced the bacterium’s 901 genes to approximately half, leaving only 473 genes.
To the naked eye, these original minimal cells appeared normal. However, they were challenging to work with and, when reproduced in microscopic time-lapse videos, they did not divide normally.
According to Glass, some of the cells formed spaghetti string shapes dense with cytoplasm and extra chromosomes, “as if there was no control over produced amount of cell membrane.”
“We simply said, ‘What the hell?’ when we saw these time lapse videos. What is occurring here?'”
Return to the drawing board in terms of cellular design
They had created synthetic life cells with good genes to survive but lacked some critical genes required for reproduction. Glass and his colleagues revisited all other cells they had created that contained a few more genes than the minimal 473 genes.
They knew the answer they were looking for was in one or more of these genes. A cell with 19 additional genes reproduced commonly, dividing into viable daughter cells. “When we examined these 19 genes, we exclaimed, ‘Aha! It all makes sense. We categorized these genes as components of bacterial cell division machinery, ” Glass clarified. The bacteria contained the majority of these mysterious genes. Additionally, a significant proportion of them is an ingredient to all life forms on the planet. However, we have no idea what they do. – J. Craig Venter Institute’s Prof. John Glass
When they reintroduced those two genes into their minimal synthetic life cell, there was no improvement. As a result, cells started to divide abnormally. They still needed one or more of the additional genes to reach the improvement.
The researchers then went through the laborious process of adding genes one by one and still came up empty. It wasn’t until they began experimenting with different combinations of these 19 genes. They discovered that the restoration of minimal cells to normal cells requires the restoration of seven genes.
“This means that while all seven of these genes are required for normal cell division, they are not required for life,” Glass explained.
Identifying life’s necessities in the perspective of synthetic life cell
This work resulted in the creation of a new synthetic organism capable of reproduction, containing 480 genes. The chromosome maintenance and protein synthesis involve Approximately half of the 480 genes in their new minimal cell. In contrast, cell metabolism production requires roughly a quarter of them. However, the final quarter of this cell’s genome remains a mystery.
I believe that we will make significant progress toward understanding the fundamental principles of cellular life over the next decade.
– J. Craig Venter Institute’s Prof. John Glass
“The majority of these genes are found in all bacteria, and a significant fraction are found in all life forms on the planet, and yet we have no idea what they do,” Glass explained.
Understanding what these genes do could significantly impact our ability to comprehend life. Since cellular biology and the fundamental processes of life entirely.
“There has never been a more exciting time to be a biologist,” Glass stated.
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