Illuminating protein interactions one molecule at a time
Roy Teeuwen defended his PhD thesis at the Department of Applied Physics and Science Education on July 2.
Roy Teeuwen has developed advanced microscopy methods to study how proteins interact at the level of individual molecules. By combining single-molecule fluorescence microscopy with gold nanoparticles, his research provides new ways to observe protein behavior that often remains hidden in conventional measurements, helping scientists gain a deeper understanding of processes linked to health and disease.
Why protein interactions matter
Proteins are the molecular machines that drive most processes inside living cells. They continuously interact with one another, forming complex networks that regulate everything from cell growth to protein folding. When these interactions go wrong, a wide range of diseases can arise.
Traditional techniques for studying protein-protein interactions typically measure the average behavior of millions of molecules at once. While powerful, these methods can miss rare but important events. Teeuwen鈥檚 work focuses on single-molecule measurements, allowing researchers to observe individual protein interactions rather than population averages.
Investigating the molecular chaperone DnaK
A central part of the thesis examines DnaK, a molecular chaperone that helps other proteins fold into their correct shapes. Problems in protein folding are associated with various neurological and other diseases.
Using single-molecule fluorescence microscopy, Teeuwen studied how individual DnaK molecules interact with different binding partners. The experiments revealed that DnaK does not interact with all clients in the same way, uncovering client-specific binding behavior that would not be visible in ensemble-average measurements. These findings demonstrate the value of single-molecule techniques for understanding complex biological systems.
Boosting signals with gold nanoparticles
One of the challenges in single-molecule microscopy is that fluorescent labels emit only small amounts of light, limiting measurement speed and sensitivity. To overcome this limitation, Teeuwen incorporated plasmonic gold nanoparticles, which act as nanoantennas that amplify fluorescence signals.
The enhanced brightness enables measurements on much shorter timescales and improves detection accuracy. Because the enhancement occurs only within a highly confined region around the nanoparticle, the technique also allows protein interactions to be studied at concentrations that are much closer to those found in living systems.
Building new tools for protein research
The thesis also introduces methods to attach proteins to gold nanoparticles in a controlled orientation using DNA linkers, creating well-defined experimental systems for studying protein behavior. Teeuwen demonstrated how these plasmon-enhanced microscopy approaches can be used not only to monitor protein interactions, but also to investigate protein folding and unfolding processes with high precision.
Towards a deeper understanding of cellular processes
By combining single-molecule resolution with plasmon-enhanced fluorescence microscopy, Teeuwen鈥檚 work establishes a powerful new toolkit for studying protein-protein interactions. The methods make it possible to reveal molecular heterogeneity that is invisible to conventional approaches, offering fresh insights into the mechanisms that govern protein function.
Ultimately, these advances could help researchers better understand the molecular origins of disease and guide the development of future diagnostic and therapeutic strategies.
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Supervisors
Peter Zijlstra & Maarten Merkx