Activity-based protein profiling guided new target identification of quinazoline derivatives for expediting bactericide discovery: Activity-based protein profiling derived new target discovery of antibacterial quinazolines

Introduction

The looming antibiotic-resistance problem has imposed an enormous crisis on global public health and agricultural development. Even worse, the evolution and widespread distribution of antibiotic-resistance elements in bacterial pathogens have made the resurgence of diseases that were once easily treatable deadly again. The development of antibiotics with novel mechanisms of action is urgently required.

Objectives

Inspired by charming activity-based protein profiling (ABPP) technology and increasing attention to quinazolines in the development of antibacterial agents, this study engineered a series of new quinazoline derivatives, assessed their antibacterial profiles, and first identified the possible target.

Methods

The target identification and their possible binding sites were verified by ABPP technology, molecular docking, and molecular dynamic simulations. The fatty acid synthesis process was analyzed by gas chromatography, propidium iodide staining, and scanning electron microscopy. The physicochemical properties and fungicide-likeness were evaluated using the Fungicide Physicochemical-properties Analysis Database.

Results

Compound 7a, an acrylamide-functionalized quinazoline derivative, exhibited excellent antibacterial potency against Xanthomonas oryzae pv. oryzae with an EC₅₀ value of 13.20 µM. More importantly, ABPP technology showed that β-ketoacyl-ACP-synthase Ⅱ (FabF) was the first identified quinazolines’ potential target. Compound 7a could selectively bind to the Cys151 residue of FabF through covalent interaction, suppress fatty acid biosynthesis, and damage the cell membrane integrity, thereby killing the bacteria. The pot experiment results showed that compound 7a demonstrated protective and curative values of 49.55 % and 47.46 %, surpassing controls bismerthiazol and thiodiazole copper. Finally, compound 7a exhibited low toxicity towards non-target organisms. These unprecedented performances contributed to excavating new quinazoline-based bactericidal agents.

Conclusion

Our research highlights the superiority of ABPP technology, for the first time, identifies the target of engineered quinazolines in pathogenic bacteria, and their potential target fished by ABPP tools holds great promise for the development of quinazoline-based and/or FabF-targeted bactericides.