Alzheimer’s disease and other serious neurodegenerative disorders have been the subject of a tremendous research effort in recent decades. Much of the work, however, has gone into understanding the formation of the signature amyloid deposits—proteins that fold the wrong way. Chemistry graduate student Beatrice Markiewicz wants to tackle it from another angle, and study how they might disassemble.
In order to achieve this, Markiewicz plans to use light-sensitive molecules to break up preformed amyloids. Misfolded proteins contain highly hydrophobic regions—strings of amino acids that don’t like water—which attract each other and hold the amyloids together. “We know that a driving force behind the formation of these misfolded structures is hydrophobic interaction, and we wanted to implement a technique that could disrupt this and break them apart,” Markiewicz says.
Working in the lab of Feng Gai, the Edmund J. and Louise W. Kahn Endowed Term Professor of Chemistry, Markiewicz attaches a molecule—composed of a natural amino acid, lysine, with an additional piece that is photosensitive—to the amyloid. When ultraviolet light is shined on it, that extra component splits off, leaving only the amino acid. This process generates a positive charge, which the hydrophobic regions have an aversion to.
Gai says these experiments are based on what he called a “naïve” idea: to blow up amyloids using a sort of molecular bomb. “Beatrice succeeded in testing this idea,” he says, calling Markiewicz one of the best graduate students he has encountered at Penn. “In order to use this approach to disassemble fibrils that do not naturally contain this bomb, she needed to find novel ways to incorporate it”—the light-sensitive, add-on molecule. Markiewicz will continue to explore the potential applications of this idea through the support of the National Institutes of Health via a Ruth L. Kirschstein National Research Service Award Predoctoral Fellowship.
Markiewicz, who recently received a Graduate Research Award from Penn’s Nano/Bio Interface Center, stressed that the method is far removed from clinical applications. “It’s not a way to combat the disease; it is a proof of principal study to show the ability to control and manipulate these highly ordered protein assemblies,” she said. She has also been working with this technique to generate other light-sensitive biological molecules that self-assemble similarly to amyloids. These include materials known as hydrogels, which could be very useful in medical applications like drug delivery and regenerative medicine.
These are only a few of the projects Markiewicz is involved in that focus on the folding and misfolding of proteins. Along with Gai and another graduate student, Robert Culik, she recently published a review on various ways to manipulate these processes, including the light-based techniques. Another project uses infrared light to monitor changes around a single amino acid on a protein that helps the influenza A virus replicate itself.
“Working in the Gai lab, we have opportunities to do interdisciplinary research in a collaborative environment,” she said. “We have access to numerous biophysical techniques so that we can approach biological problems from physical and quantitative perspectives, which I think is essential to understand these questions.”