Making Microcircuits with Yeast Proteins

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Sometimes serendipity, not necessity, can be the mother of invention. Case in point: the chance discovery of a new way to fabricate tiny electrical circuits from yeast proteins.

Susan Lindquist, Ph.D., a molecular biologist at the Whitehead Institute for Biomedical Research, is a leader in the study of prions. These misfolded forms of normal cellular proteins can cause serious illnesses, such as mad cow disease, in humans and animals. While studying prions in common brewer's yeast, she unexpectedly found one particular molecule called NM that can assemble itself into very thin fibers with surprising precision.

The prion fibers, which are quite similar to those found in the tangles within brains of people with Alzheimer's s disease, turned out to have some rather unusual—and potentially quite useful—properties. The fibers are exceptionally durable and have very specific sizes, nanometers wide and up to several hundred micrometers long. The physical properties of the fibers suggest that they might be used to create extremely small "biotemplated" devices such as electric circuits.

Teaming with materials scientists, Lindquist and her collaborators then decided to see if they could genetically modify NM proteins to bind tiny particles of gold. The resulting gold-coated fibers formed stable electrical wires with ideal characteristics: very high conductivity and low resistance. In addition, the team found that NM proteins can be fused with other proteins, creating hybrid molecules that potentially could form complex circuits with special chemical and biological functions, such as those of enzymes. Lindquist speculates that this technology may lead to a wide variety of nanodevices with applications in both the electronics and medical industries.