With support from the Chemical Measurement and Imaging Program in the Division of Chemistry, Dr. Wenwan Zhong and her group at the University of California - Riverside are working to improve our fundamental understanding of how proteins work. Proteins are the workhorses of all living systems. Their functions are regulated by diverse modifications of protein structures. Identifying and understanding these modifications can benefit many areas of research, including such diverse work as probing the chemical mechanisms of life, energy production, and environmental remediation. The Zhong group seeks to enhance this knowledge by developing selective recognition tools that can accurately assess changes in protein modification in response to external stimulation of living cells. Specifically, they are developing a series of sensors for specific types of protein modification. The recognition element is a judiciously designed molecule that acts like a lock's "keyhole," fitting only a correctly sized "key" - the right type of modification on a protein. Inserting the "key" into the "lock" generates a large optical signal, allowing simple and rapid detection of protein modifications. The work targets improved understanding of protein modification, thereby advancing strategies for controlling processes in living systems. In addition to these technical impacts, the work is enhancing the diversity of the scientific workforce via engagement of both graduate and undergraduate students, especially those from underrepresented groups.
The Zhong group is developing synthetic receptor-based arrays for detection of post-translational modifications (PTMs) in proteins. Selective host-guest interactions between modified side chains and synthetic receptors (cavitands) allows highly selective recognition of modified proteins, and can discriminate for example among proteins with different methylation levels, sites, and numbers. The technique will be valuable in rapid profiling of methylation alterations in cells under external stimulation and in situ monitoring of PTM enzyme activities. Initial targets include hosts that bind selectively to trimethylated lysine, with an aim of enabling array-based PTM profiling. Cavitand hosts are being synthesized and used in fluorescence displacement assays (FDA) for selective detection and discrimination of PTM peptides. Characterization of cavitand-guest interactions will enhance understanding of how cavitand structures affect binding strength and kinetics, supporting new designs with improved FDA performance. In a specific model application, cavitand-based arrays are being applied to study histone methylation in stimulated cells. It is expected that the highly selective and versatile PTM sensing arrays enabled by cavitands can greatly improve the detection of peptides carrying modifications, and enhance the efficacy of PTM study. Discovery of hosts with high affinity and selectivity for diverse PTM types will boost understanding of PTM functions.
