Chemical Affinity Probes for Discovery of Histidine Methylome

Emory University, Atlanta GA

Investigators

Abstract

With the support of the Chemistry of Life Processes program in the Division of Chemistry, Professor Monika Raj of Emory University is studying how chemical modifications of specific amino acids in proteins influences their role in various biological processes and diseases. Modifications to histidine side chains in proteins could potentially activate or deactivate crucial functions inside cells, responsible for cell growth and communication between cells. Understanding histidine modifications deeply and how they affect interactions between proteins could be crucial for developing new molecules that could disrupt those protein-protein interactions and potentially serve as therapeutics for various diseases. However, identifying influential histidine modifications remains a daunting challenge that traditional biochemical strategies have not addressed. Dr. Raj aims to develop new approaches that enable selective chemical labeling of modified histidine side chains and reveal the interconnection with protein partners. These innovative chemical approaches are expected to offer a general strategy for systematically identifying histidine modifications and protein-protein interactions caused by histidine modifications. The project's impact will be further enhanced by efforts to engage underrepresented individuals across various age groups, educational levels, and socioeconomic and cultural backgrounds, encouraging their active interest and retention in STEM (Science, Technology, Engineering, and Mathematics). These efforts focus on assembling a diverse group of graduate and undergraduate students to receive interdisciplinary research training in organic chemistry and biochemistry. Outreach activities targeting high school students, especially women and individuals from underrepresented groups, introduce them to basic concepts of biochemistry and enable them to explore the realm of protein identification through hands-on activities. The goal is to provide them with the necessary social support to pursue a STEM major in college. Chemical strategies that effectively target a specific functional group at a single amino acid site while accounting for reactive amino acid side chains on protein surfaces are rare. Even more rare are organic reactions that can occur under mild conditions to label biomolecules without deleterious effects. To tackle these challenges, this research project seeks to develop chemical probes based on nucleophilic substitution and ring opening. These probes could enable the site-specific incorporation of photoreactive and affinity groups near modified histidine. The method seeks to differentiate between two isomers of methyl histidine (1MeH and 3MeH) by producing different products using the same chemistry. It could be used to selectively label modified histidine residues with various cargoes and to capture proteins responsible for adding and removing these methyl groups. The method also seeks to capture protein-protein interactions mediated by modified histidine residues. Abnormal histidine modification of a protein can lead to unique interactions with other proteins, resulting in various diseases. However, chemical methods for selectively detecting histidine modifications and associated protein-protein interactions are still lacking. This research could provide highly selective chemical probes capable of effectively detecting modified histidine and capturing their protein partners. Thus, the proposed research has the potential to advance our understanding of how these histidine modifications and their aberrations regulate various cellular signaling processes, potentially leading to a better understanding and treatment of various diseases. 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.