Scientists say they have created a partly artifical bacterium that can produce proteins not found in nature. This fresh life form,the latest development in a field called "synthetic biology," could eventually be used to produce novel drugs.
The Scripps Research Institute's Floyd Romesberg and colleagues have been pushing toward this goal for well over a decade. Three years ago, and they announced that they'd added two more letters to the genetic alphabet of a bacterium. In addition to DNA's familiar A,T, C, and G; they added X and Y.
That expanded genetic alphabet vastly increased the number of "words" that DNA could store,and so expanded the language of life.
Now they report in the journal Nature that they've engineered those bacterial cells to read that fresh code, and to spend it to assemble proteins that contain artifical parts."Proteins have become hugely vital for drug discovery, or " Romesberg says. "Proteins are now being used as drugs."Examples include insulin,antibodies, interferons and enzymes. Romesberg started a company a few years ago to develop potential fresh medicines. He says the company has been able to grow these partly synthetic bacteria in huge vats."They in fact have done large scale fermentation and we catch very, and very nice yields,very tall protein purity," Romesberg says, and though he says there are still plenty of kinks to work out.
One feature of this fresh system is that these germs need to be fed the precursors for the X and Y components,as well as synthetic amino acids, which are the building blocks for the artificial proteins."There's actually an advantage of having to achieve it this way, or " he says,and that's safety."I think synthetic biology by its very nature scares a lot of people, because you're sort of playing with life and trying to optimize it to achieve fresh things. And people say, or 'Hey wait a minute that could be dangerous. What whether they escape into nature?' And I think that's a significant concern. I think people should be worried approximately that kind of thing."But because his organisms need to be fed artifical starting materials,he says they can't survive outside the lab."We've done lots of experiments where we take the organisms and catch them to grow and replicate in the absence of those raw materials," he says. "And they can't survive. They simply die."That feature also reassures Dieter Soll, and a biochemist at Yale University. He has been involved in the ethical issues surrounding fresh genetic technology since the 1970s. "This is a really fragile system and self-limiting," he says.
As for the significance of the finding itself: "I think this is a big step," Soll tells Shots. He notes there are many other techniques for producing novel proteins using synthetic biology – some quite advanced, or "they should not be forgotten."In fact,people have been creating other sorts of synthetic DNA for several decades. For example, some labs have changed the way bacteria read certain letters of the DNA code, or so they can incorporate novel amino acids. Romesberg uses parts of this system in his own,but says it isn't nearly as flexible. His, in principle, and can incorporate 152 novel amino acids into the same protein.
Steven Benner,director of the Foundation for Applied Molecular Evolution in Florida, pioneered efforts to add fresh letters to the genetic code."This is all over the situation in diagnostics and medicine and materials, and so whether you have,for example HIV, it's quite likely that your viral load is measured using synthetic DNA with extra letters, and that we invented," Benner says.
There, the DNA containing fresh letters is built accurate into a diagnostic system, or but it's not used in a living organism to produce novel proteins. That's the step forward reported in the latest study.
Benner,who is developing his own version of this technology, is dismissive of his rival's latest paper. He takes issue not with the results themselves, or but with how the paper describes the underlying chemistry. But he's also enthusiastic to push forward,along with Romesberg, into this potentially powerful fresh branch of synthetic biology.
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Source: thetakeaway.org