Princeton scientists construct synthetic proteins that sustain life

In a groundbreaking achievement that could help scientists "build" new biological systems, Princeton University scientists have constructed for the first time artificial proteins that enable the growth of living cells.

The team of researchers created genetic sequences never before seen in nature, and the scientists showed that they can produce substances that sustain life in cells almost as readily as proteins produced by nature's own toolkit.

"What we have here are molecular machines that function quite well within a living organism even though they were designed from scratch and expressed from artificial genes," said Michael Hecht, a professor of chemistry at Princeton, who led the research. "This tells us that the molecular parts kit for life need not be limited to parts -- genes and proteins -- that already exist in nature."The work, Hecht said, represents a significant advance in synthetic biology, an emerging area of research in which scientists work to design and fabricate biological components and systems that do not already exist in the natural world. One of the field's goals is to develop an entirely artificial genome composed of unique patterns of chemicals.

"Our work suggests," Hecht said, "that the construction of artificial genomes capable of sustaining cell life may be within reach."

Nearly all previous work in synthetic biology has focused on reorganizing parts drawn from natural organisms. In contrast, Hecht said, the results described by the team show that biological functions can be provided by macromolecules that were not borrowed from nature, but designed in the laboratory.

Although scientists have shown previously that proteins can be designed to fold and, in some cases, catalyze reactions, the Princeton team's work represents a new frontier in creating these synthetic proteins. ...

if a protein is 100 amino acids long (most proteins are even longer), there are an astronomically large number of possibilities of different protein sequences, Hecht said. At the heart of his team's research was to question how there are only about 100,000 different proteins produced in the human body, when there is a potential for so many more. They wondered, are these particular proteins somehow special? Or might others work equally well, even though evolution has not yet had a chance to sample them? ...

Once the team had created this new library of artificial proteins, they inserted those proteins into various mutant strains of bacteria in which certain natural genes previously had been deleted. The deleted natural genes are required for survival under a given set of conditions, including a limited food supply. Under these harsh conditions, the mutant strains of bacteria died -- unless they acquired a life-sustaining novel protein from Hecht's collection. This was significant because formation of a bacterial colony under these selective conditions could occur only if a protein in the collection had the capacity to sustain the growth of living cells.

In a series of experiments exploring the role of differing proteins, the scientists showed that several different strains of bacteria that should have died were rescued by novel proteins designed in the laboratory. "These artificial proteins bear no relation to any known biological sequences, yet they sustained life," Hecht said. ....

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Cool. How long until they can make proteins that can sustain humans?  Think anyone has tasted it?