Enzyme regulation by allo-targeting: A strategic initiative for chemical biology and molecular therapeutics.

A few enzyme families, including protein kinases and ubiquitin ligases, mediate most vital cellular processes. The ability to selectively inhibit them using small molecules is fundamental both to the design of chemical tools to dissect human physiology, and the development of new therapies for disease. Enzyme active sites are often well-conserved within and between enzyme families, making selectivity difficult to achieve using current strategies. This initiative aims to establish a new str ategy for selective enzyme inhibition by using small molecules to target the protein-protein interactions that regulate enzyme activity. We term this strategy allo-targeting , because it bypasses the active site. We will: develop allo-inhibitors against four example enzymes using fragment-based methods. Each example represents an important target class. Each exemplifies one of three different conceptual approaches to allo-targeting allosteric modulation, adaptor inhibition or scaffol d disruption. validate the use of allo-inhibitors as chemical tools or therapeutic leads using somatic cell genetics combined with fluorescence imaging and spectroscopy. We will explore the cellular mechanism of allo-inhibitors, determine their phenotypic selectivity, and estimate the potency of allo-inhibition required to trigger desired phenotypic consequences. Our work could potentially transform existing tools and approaches for fundamental chemical biology as well as molecular ther apeutics.