With this award, the Chemistry of Life Processes program is supporting Professor Rudi Fasan at the University of Rochester to investigate the design, synthesis, and functional selection of macrocyclic organo-peptide hybrids (MOrPHs) as chemical agents for selectively targeting protein interfaces. This research will investigate and implement this new methodology for generating organo-peptide macrocycles via a chemoselective reaction between synthetic precursors and genetically encoded polypeptides. Library diversity will benefit from the inclusion of both synthetic organic and encoded peptidyl elements of structural variation. This versatile strategy for ligand assembly and diversification will be coupled to a display system in E. coli and a high throughput screening system for the macrocycle libraries. As a platform to test this approach to chemical biology, the hydrid cyclic peptide libraries will be screened for the selective modulation of protein complex formation between the tumor suppressor protein, p53, and its repressors HdmX and Hdm2.

This approach to modular organo-peptide library generation and screening, if successful, could find broad application in the field of Chemical Biology. Moreover, if selective Hdm2/HdmX-targeting molecules are identified these would likely serve as useful chemical biological tools for the study of regulation/signal transduction in the p53 pathway in cell physiology and cancer biology. This cross-disciplinary research project will expose graduate and undergraduate students to techniques in organic chemistry, biology, and biophysics. The project will also engage members of traditionally underrepresented groups in scientific research at the chemistry-biology interface.

Project Report

Protein-protein interactions play a central role in the control and regulation of cellular processes. Chemical agents capable of modulating protein-protein interactions constitute key assets for the study of protein function in the context of physiological and pathological processes in the cell but developing such compounds has been notoriously difficult. Peptide-based macrocycles are a class of compounds which have recently attracted significant interest for their potential utility toward modulating protein-protein interactions. As part of this NSF-funded project, novel and efficient methodologies for the construction of macrocyclic molecules featuring a peptidic/non-peptidic hybrid backbone were developed. These studies have also contributed valuable insights into the scope, structure-reactivity relationships, and mechanisms of these macrocyclization methods. Unique features of these strategies include the possibility of diversifying these structures by varying the basic modules composing the macrocycle as well as that of exploiting genetic mutagenesis in order to generate large libraries of these compounds. In a specific application, macrocyclic inhibitors of a key protein-protein interaction controlling apoptosis in normal and cancer cells were developed. Altogether, the methods and tools developed in the course of this project are expected to expand current opportunities in the discovery of selective and potent chemical modulators of protein-protein interactions. This project has provided important opportunities for interdisciplinary training and professional development for two graduate students, one master student, and ten undergraduate students. These students have received training in synthetic organic chemistry, protein chemistry, and molecular biology and acquired hands-on experience with sophisticated instrumentation for the physico-chemical and biophysical characterization of the macrocyclic compounds developed during the course of the project. Professional training for both graduate and undergraduate students participating in this project has been further realized through attendance and presentation of their research findings at local and national scientific meetings. Participation in this project have also helped these undergraduate students in their pursuit of careers in science and medical sciences, which include graduate studies in chemistry, chemical biology, and biochemistry and careers in medicine.

National Science Foundation (NSF)
Division of Chemistry (CHE)
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Colby A. Foss
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University of Rochester
United States
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