Pesticide chemical leads inhibiting protein-protein interactions

Abstract

Pesticides, especially herbicides, have revolutionized agriculture by providing energy-efficient solutions for pest control that replaces labor-intensive cultivation methods. However, the widespread evolution of pesticide resistance poses a significant challenge to current agriculture. Most pesticides function by binding to specific pockets on target enzymes, enabling a single mutation to confer resistance. An alternative approach is the disruption of protein-protein interactions (PPI), thus for resistance to occur, it requires complementary mutations on both interacting partners. Despite extensive efforts, no herbicides with new modes of action have been commercialized for decades. Thus, we focused on the discovery and design of small molecule inhibitors that target the interface of the PPI complex of O-acetylserine sulfhydrylase (OASS) and serine acetyltransferase (SAT), key plant enzymes involved in the biosynthesis of the essential amino acid cysteine. Using in silico filtering techniques on a virtual library of 30 million small molecules, we identified initial hits capable of binding OASS and interfering with its interaction with a peptide derived from SAT. Subsequently, we conducted chemical optimizations to evaluate biophysical enzyme disruption, followed by cellular and in-planta activity in plants. These new compounds described herein can serve as promising starting points for further optimization as herbicides acting on a new mode of action.