The research interests of our group lie in the areas of bioorganic chemistry, chemical biology, and biomolecular engineering and evolution. Our laboratory integrates methods and principles of organic chemistry, molecular biology, and molecular evolution to develop novel chemo-biosynthetic and chemo-enzymatic approaches to the discovery of biologically active molecules. Our goal is to investigate and apply these methodologies toward the development of chemical agents useful for probing cell signaling pathways and controlling biomolecular interactions implicated in cancer development.
A major project involves the development of new strategies to direct the synthesis, diversification, and evolution of macrocyclic peptide-based molecules as potent and selective modulators of protein-protein interactions (PPIs). PPIs are implicated in all cellular processes from signal transduction to gene regulation, cell proliferation and apoptosis. Chemical agents capable of targeting PPIs with high potency and selectivity can provide invaluable tools for the study of complex cellular pathways and useful starting points for development of new therapeutics, but the development of such compounds has constituted a major challenge in chemical biology and drug discovery. Our group has pioneered methods to generate Macrocyclic Organo-Peptide Hybrids (MOrPHs) via the modular assembly of synthetic organic moieties with genetically encoded polypeptide precursors. These molecules constitute attractive molecular scaffolds to mediate specific and high-affinity recognition of a target protein as they combine a high degree of chemical complexity with a compact and conformationally rigid architecture. In addition, the MOrPH approach enables to couple the versatility of chemical synthesis with the advantages of genetic encoding and power of genetic mutagenesis, providing unique opportunities for the creation and screening of highly diverse chemical libraries and the molecular evolution of organo-peptide macrocycles with tailored protein-binding selectivity. Our group is exploring the potential of this new class of macrocyclic structures to tackle challenging molecular recognition problems, such as the selective and efficient disruption of protein-protein and protein-DNA complexes of therapeutic relevance and the specific recognition of structural homologues and post-translational isoforms of human proteins. An integral component of these studies is the application of a variety of biophysical techniques (e.g. Surface Plasmon Resonance, NMR and fluorescence spectroscopy) and biological assays for the characterization of the conformational and binding properties and biological activity of these compounds.
Another major area of interest is concerned with the design and development of efficientbiological catalysts for the selective functionalization of aliphatic C—H bonds. The selective functionalization of unactivated C(sp3)—H bonds represents a most valuable but also one of the most challenging transformations in organic chemistry. Our group is investigating the use of engineered cytochrome P450s as well as other heme-containing proteins (e.g. myoglobin) as catalytic platforms for the direct conversion of C(sp3)—H bonds into C—O, C—N, and C—C bonds. With the latter two, we aim at expanding the reactivity scope of these protein-based catalysts beyond that exhibited by naturally occurring enzymes. As part of these projects, we are developing systematic, rationally-driven approaches to predict the reactivity of these P450- and myoglobin-based catalysts via the combination of high-throughput screening methods and computational tools. We are also exploring new protein engineering strategies to enable rapid fine-tuning of the regio- and stereoselectivity of these enzymes. The ultimate goal of these studies is to develop efficient and systematic approaches to expedite the development of C—H functionalization biocatalysts with tailored activity and site-selectivity for synthetic applications. Finally, the scope and synthetic value of these methodologies is being investigated through the synthesis and functional elaboration of complex natural product scaffolds of medical interest via chemoenzymatic synthesis.
All our projects involve the synergistic integration of rational design, chemical synthesis, protein chemistry, and molecular evolution methods toward the development of enabling molecular discovery platforms of practical and broad utility. Members of the Fasan group have thus the opportunity to receive training in these areas and conduct interdisciplinary research at the intersection of chemistry, biology, and biophysics.