Scientific Tinkering Leads To New Cell Insight

Scientists in England have found a way to trick bacterial cells into making compounds that aren't found in nature. Those compounds are proteins, and proteins are the basic building blocks of everything a living organism needs to survive.

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Scientists in England have found a way to trick bacterial cells into making compounds that are not found in nature. These compounds are new kinds of proteins, and proteins, of course, are the building blocks a living organism needs to survive. NPR's Joe Palca has more.

JOE PALCA: Okay, we're not talking about the proteins you get from meat. In biology, just about everything is made up of proteins. Enzymes are proteins. Hormones are proteins. So tinkering with proteins can have fundamental consequences on anything that's alive. And now there's a new way to tinker with them. The technique involves changing the way protein factories inside living cells work.

Before we go on, here's the world's shortest lesson in molecular biology. Proteins are made of amino acids. The instructions for which amino acids to use to make a particular protein are contained in DNA. DNA is made up of long strings of what you can think of as the letters A, T, C and G. So to make a protein, you need something that can read the instructions in the DNA letters.

Dr. JIM COLLINS (Biologist, Boston University): And what you have are molecular machines within the cell that can read the letters in groups of three.

PALCA: Jim Collins is a biologist at Boston University. These molecular machines are called ribosomes. Not only do the ribosomes read the letters and find the right amino acids, but they also string them together - amazing things, those ribosomes.

But for protein tinkerers, this system is limited. The three-letter code only allows you to specify 20 amino acids or so. If you had a ribosome that could read letters in groups of four, you could have over 200 amino acids to choose from in making your protein.

Dr. COLLINS: The challenge there is that the molecular machines that read out these codes are naturally designed - at least here on earth - to read only the triplets.

PALCA: But Collins says Jason Chin may have found a way around that limitation. Chin is at the Medical Research Council Laboratory of Molecular Biology in Cambridge, England.

Dr. COLLINS: And what Jason Chin's group just did was to reengineer ribosomes so that they would read quadruplets.

PALCA: Or four letters at a time instead of three. Chin says from a scientific perspective, this is pretty cool stuff. Tinkering with basic cell machinery almost always leads to new insights about how cells work. But Chin also sees practical applications. Cells can be turned into protein factories, and cells make happy factories - no surly bosses or grumpy employees, just feed the cells and stand back.

Chin says it should be possible to use his new system to insert new amino acids that will make proteins heartier.

Dr. JASON CHIN (Medical Research Council Laboratory of Molecular Biology, Cambridge England): So for certain therapeutic proteins, you want to be able to do this to increase their efficacy, to increase the amount of time they're available in the body without getting degraded.

PALCA: In recent years, biologists have gotten pretty good at designing new proteins. Bioengineer Farren Isaacs of Harvard Medical School says Jason Chin has given them a new way to actually make the proteins they've designed.

Dr. FARREN ISAACS (Bioengineer, Harvard Medical School): I imagine that you're just going to see a lot of collaboration between people like Jason and protein design engineers to really enhance the power of this technology.

PALCA: A description of this new technology appears in the online edition of the journal Nature.

Joe Palca, NPR News, Washington.

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