Playing with Proteins

A closer look into the team researching Biohubs

Lauren Holly (writer)

UMN researchers genetically modify proteins to mitigate the effects of harmful pollutants through self-cleaning Biohubs

Can we engineer our environment to clean itself? A team of University of Minnesota scientists hopes to find out. Working with structures that already exist in nature and redesigning them to serve new purposes — these researchers are genetically engineering new proteins capable of breaking down heavy metals to clean harmful mercury run-off from mine drainage.

Northern Minnesota is a major part of the Iron Range, a large iron-mining district that crosses through the United States and Canada. These mining sites produce runoff that contain heavy metals and other organic pollutants. If left untreated, these pollutants flow into our environment and poison living organisms. In Minnesota, mercury and lead, along with other heavy metals accumulate in water and soil. Build up of these toxic materials causes detrimental health effects. Heavy metals render fish unsafe for consumption — when ingested heavy metals poison humans and damage to the nervous system.

The team is currently working to establish proof of their design, the Biohub, using mercury. “A Biohub will be engineered to sequester the toxic, ionic mercury on the interior, while two enzymes known as mercury reductase and organomercurial lyase work in sync to convert the harmful, ionic mercury to its elemental form, which is safe,” lead researcher, Claudia SchmidtDannert, explains.

Proteins have naturally self-organizing properties, using this to their advantage the team will create shell-like structures from these proteins capable of self-assembly. The porous surface allows for organic material to flow freely through the protein. These new proteins, Biohubs, will contain target enzymes that perform catalytic reactions to convert harmful metals and organic pollutants into non-toxic components.

The first goal is to establish proof they can engineer specific surfaces to target specific pollutants. Researchers will modify the surfaces of proteins so they bind to a targeted metal. The enzyme within the Biohub interacts with the metal, and the reaction that follows converts the harmful version to a non-toxic form. The non-toxic material is released safely into the environment, and the enzyme patiently waits inside the protein until it encounters the next metal, restarting the process.

This catalytic reaction lends itself well to bioremediation efforts as Biohubs would require no further cleanup once placed on site. Biohubs in glass or metal column-like structures can be placed at locations in need of remediation. Similar to a water filtration system found in a refrigerator, water containing pollutants enters through one end of the column and as the pollutants interact with the Biohubs the enzymes begin their reactions. After, the water exits through the opposite end of the column, free of pollutants.

The enzymatic reaction makes the protein versatile because of its non-toxic end product. However, enzymes found in nature are not always stable. The team needed a way to stabilize the protein through the entire reaction. Calling on the expertise of Minnepura, a biotechnical startup company at the University of Minnesota specializing in the development of biocomposite materials, a silica material is being designed to surround the protein.

Alptekin Aksan, co-founder of Minnepura, works alongside Schmidt-Dannert throughout this project, in addition to fellow researcher, Maureen Quin. “The Biohubs will be encased in silica to create a robust material as an easily adaptable and portable mitigation system,” Quin explains. The silica will help contain enzymes and their reactions, and allow the Biohub to maintain its structural integrity for a long period of time.

Enzymes can act on a range of compounds, so if this method proves successful the potential applications are extensive. “Initial studies will focus on remediation of heavy metals from mine drainage,” Quin says, “but the system could also be applied to clean up of pesticide contaminated soil or water near agricultural land.” Schmidt-Dannert hopes to establish a platform with Biohubs, to serve as a model so other proteins can be modified to pick up several types of organic material. “If we can get this to work with organic compounds this solution could be very versatile, and able to convert a variety of different pollutants,” she says.

Few efforts to bioremediate have been initiated in the state of Minnesota. Schmidt-Dannert believes this is one of the reasons MnDRIVE targeted the project. Her engineered proteins hold potential to provide new, long-term sustainable bioremediation techniques. For states like Minnesota dealing with multiple lands and water supplies in need of remediation, Biohubs offer an exciting future solution.