September 4, 2015

Making Nanowires from Protein and DNA


Co-crystal structure of protein-DNA nanowires. The protein-DNA nanowire
design is experimentally verified by X-ray crystallography.
Credit: Yun (Kurt) Mou, Jiun-Yann Yu, Timothy M. Wannier, Chin-Lin Guo
and Stephen L. Mayo/Caltech

(September 4, 2015)  The ability to custom design biological materials such as protein and DNA opens up technological possibilities that were unimaginable just a few decades ago. For example, synthetic structures made of DNA could one day be used to deliver cancer drugs directly to tumor cells, and customized proteins could be designed to specifically attack a certain kind of virus. Although researchers have already made such structures out of DNA or protein alone, a Caltech team recently created—for the first time—a synthetic structure made of both protein and DNA. Combining the two molecule types into one biomaterial opens the door to numerous applications.

A paper describing the so-called hybridized, or multiple component, materials appears in the September 2 issue of the journal Nature.

Design strategy of protein-DNA nanowires. The protein-DNA nanowire is
self-assembled with a computationally designed protein homodimer and
a double-stranded DNA with the protein binding sites properly arranged.
Credit: Yun (Kurt) Mou, Jiun-Yann Yu, Timothy M. Wannier, Chin-Lin Guo
and Stephen L. Mayo/Caltech

There are many advantages to multiple component materials, says Yun (Kurt) Mou (PhD '15), first author of the Nature study. "If your material is made up of several different kinds of components, it can have more functionality. For example, protein is very versatile; it can be used for many things, such as protein–protein interactions or as an enzyme to speed up a reaction. And DNA is easily programmed into nanostructures of a variety of sizes and shapes."

But how do you begin to create something like a protein–DNA nanowire—a material that no one has seen before?

Mou and his colleagues in the laboratory of Stephen Mayo, Bren Professor of Biology and Chemistry and the William K. Bowes Jr. Leadership Chair of Caltech's Division of Biology and Biological Engineering, began with a computer program to design the type of protein and DNA that would work best as part of their hybrid material. "Materials can be formed using just a trial-and-error method of combining things to see what results, but it's better and more efficient if you can first predict what the structure is like and then design a protein to form that kind of material," he says.

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