Poster abstracts
Poster number 119 submitted by Johann Roque
Covalent Ligand Discovery for Selectively Targeting Homologous RNA Binding Protiens: hnRNP H and F
JOHANN ROQUE (Department of Chemistry and Biochemistry University of Notre Dame), Julia Haas (Department of Chemistry and Biochemistry University of Notre Dame), Ariel Thelander (Department of Chemistry and Biochemistry University of Notre Dame), Dr. Blanton Tolbert (Department of Biochemistry and Biophysics, Unviersity of Pennsylvania ), Dr. Brittany S. Morgan (Department of Chemistry and Biochemistry University of Notre Dame)
Abstract:
Dynamic and/or disordered proteins have historically been difficult to target by conventional, non-covalent small molecule methods. This is largely due to their lack of classical binding pockets and lack of protein structural information for rational design. One class of unligandable, dynamic and/or disordered proteins is RNA-binding proteins (RBPs). RBPs are master regulators of RNA biology and are the protein family with the most disease associated mutations. Despite their therapeutic potential, RBPs lack selective, potent small molecule probes, hindering RBP structure, function, and therapeutic studies. This is due in part to their structural conservation, where the sites of greatest diversity are in unligandable dynamic loops and linkers. Utilizing heterogeneous nuclear RiboNucleoProtein (hnRNP H/F) as a model system, we hypothesized that covalent ligands could selectively target loop structures and differential loop sequence and dynamics could be exploited for ligand selectivity. To begin, lead ligands were identified through literature reported cell lysate screenings. The ligands were re-screened in vitro, which identified F4 as two-fold selective for hnRNP H. By commercial and synthetic structure-activity relationships (SAR), an analog has been discovered with ten-fold selectivity for hnRNP H. Furthermore, the SAR revealed: i) the reaction mechanism of the covalent warhead significantly alters selectivity; ii) elimination of a single amide bond leads to a dramatic decrease in potency; and iii) isosteres of adamantane lead to higher selectivity. This work corroborates the potential of covalent ligands to selectively target dynamic and/or disordered proteins, particularly in systems with high sequence and structural conservation. Further, it has the potential to revolutionize our understanding of RBPs, leading to potent and selective probes for these “unligandable” proteins.
Keywords: Proteins, Covalent , Dynamic