CAREER: Quantification of Cellular Proteome Stress and Recovery Using Chemical Methods

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With this award, the Chemistry of Life Processes Program in the Chemistry Division is funding Dr. Xin Zhang from Pennsylvania State University to develop new tools examining the effects of stresses on proteins in live cells, in real time. The proteins in cells must be maintained in a delicate balance between a folded state that is dissolved in water (soluble folded) and an solid state that does not dissolve in water (insoluble aggregated state). Excessive aggregation is bad for the cells but this phenomenon occurs when cells are exposed to stresses such as aging, heat and certain chemicals. To understand how protein stress relates to cellular function, Dr. Zhang focuses develops a new class of fluorescent sensors that light up when they come into contact with unfolded proteins in cells. This project provides a variety of new tools for real-time determinations of cellular protein stresses and recovery. The interdisciplinary nature of the program allows graduate and undergraduate students to gain training and expertise in modern chemical biology research. The project also includes an education plan called "Seeking Protein Aggregates Detectors". The central theme of this education plan is to integrate K-12 and undergraduate students in research and public engagement programs that discover new chemical detectors for protein aggregates from unexplored natural dyes and their interactions with egg white proteins. As existing proteome stress sensors are insufficient to enable quantitative studies on the dynamics of proteome stress and recovery, Dr. Zhang is developing a novel class of fluorogenic sensors, represented by the AgHalo sensor. This sensor uses changes in fluorescence intensity as a direct readout to quantify stress-induced protein aggregation. Building on this foundation, Dr. Zhang is developing a second fluorogenic proteome stress sensor, AgSNAP, which is orthogonal to AgHalo, thus enabling a set of two-color sensors. To detect protein refolding as a post-stress event, a fluorogenic proteome recovery sensor is being developed using anti-solvatochromic fluorophores. These sensors are used to quantify intracellular protein aggregation and refolding in cells that are subjected to chronic stresses. Mutant proteins that can form either soluble or insoluble aggregates are also targeted. Results of these experiments test the hypothesis that the soluble aggregates of mutant proteins cause a more severe proteome stress than the insoluble aggregates. These research goals enable a set of novel proteome stress and recovery sensors for the protein biochemistry community and provide quantitative knowledge of proteome aggregation and refolding in chronically stressed cells.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.