Kyoungtae Kim

Title : Interaction between actin and quantum dots

Abstract:

Quantum dots (QDs) are fluorescent nanoparticles with a broad emission range. As such, QDs are high sought after for optical-based biomedical applications. Recently, studies have shown the toxicity of quantum dots, which raised concerns regarding the use of QDs in biomedical technologies. In particular, there is still a lack of research on the cytotoxicity of quantum dots when exposed to cells due to random interactions with surrounding macromolecules.. In our study, we investigated the direct interaction between QDs and a cytosolic protein to determine if modification of biomolecule upon interaction is one of the factors behind QDs’ toxicity. Using Saccharomyces cerevisiae as a model organism, we performed Shotgun Proteomics to identify QD binding proteins. These identified proteins are associated with translation, mitochondria, vesicular trafficking, and the actin cytoskeleton. As our in vitro culture study showed that QDs caused abnormal actin cytoskeleton organization in yeast, we decided further to study the interaction between QDs and actin using a series of biochemical experiments. Through native polyacrylamide gel electrophoresis, we confirmed the binding of G-actin with QDs. Furthermore, we observed a temperature-dependent quenching of actin’s intrinsic fluorescence by QDs, which suggests a static interaction. In addition, our data revealed an altered absorption spectrum in G-actin protein upon interaction with QDs. This further verifies the static interaction between G-actin and QDs as well as suggests actin-QDs complex formation. Using Circular Dichroism spectroscopy, we also found that QDs induced significant changes to the secondary structure of G-actin. Overall, our research characterized the interaction between QDs and G-actin, and proposed protein structure alteration resulting from direct interaction as a possible mechanism for QDs toxicity. The potential impact of QD binding to G-actin on actin polymerization and disassembly will be assessed.

Audience Take away:

• Quantum dot chemical and physical properties
• Assessment of Quantum-dot interaction with proteins
• Assessment of QD-mediated protein assembly and disassembly

Biography:

Dr. Kyoungtae Kim is a professor at Missouri State University (MSU) in Springfield, MO. He received his Ph.D. in Biology at Florida State University and completed his post-doc at Washington University in St. Louis, MO, where he studied cell biology and physiology. His current research focuses on cellular trafficking and nanomaterial-based nanotoxicology. His work has been published in the following international peer-reviewed journals: Cells, International Journal of Molecular Sciences, European Polymer Journal, FEMS Yeast Research, Cell Biology International, Biology of the Cell, European Journal of Cell Biology, Genes, Nanomaterials, and Biomolecules. Overall, his research results were disseminated in 241 presentations at internal and external scientific meetings, including many invited and keynote presentations. It is noteworthy that he was invited to several international conferences to present the results of his research as a keynote speaker or main presenter. For example, at the sixteenth International Conference on the Science and Application of Nanotube held in Japan in 2015, he presented his results with the theme of "Carbon Nanomaterials Negatively Affect Cell Viability and Gene Expression". In 2018 two other topics "Membrane Trafficking" and "Quantum dot-mediated Cell Toxicity" were presented by him as a keynote speaker in Montreal, Canada. He also served as a conference session moderator at the American Society for Cell Biology and was invited to serve as the World Yeast Congress Organizing Committee and Worlds Yeast Congress Session Chair. In 2019, his research was presented at the German-American Science Slam held in St. Louis, MO with the title “What doesn't kill you makes you...develop acute health problems down the road”. In 2020, he was invited to give his research talk at the EFIGIE Talks held virtually in Brazil with the title “Study of Intracellular Traffics and Assessment of anticancer therapeutics and engineered nanoparticles on cells”.