Feature-Based Molecular Networking for the Targeted Identification of Gq-Inhibiting FR900359 Derivatives.

Abstract

Both the soil bacterium Chromobacterium vaccinii and the bacterial endosymbiont Candidatus Burkholderia crenata of the plant Ardisia crenata are producers of FR900359 (FR). This cyclic depsipeptide is a potent and selective Gq protein inhibitor used extensively to investigate the intracellular signaling of G protein coupled receptors (GPCRs). In this study, the metabolomes of both FR producers were investigated and compared using feature-based molecular networking (FBMN). As a result, 30 previously unknown FR derivatives were identified, one-third being unique to C. vaccinii. Guided by MS, a novel FR derivative, FR-6 (compound 1), was isolated, and its structure unambiguously established. In a whole-cell biosensing assay based on detection of dynamic mass redistribution (DMR) as readout for Gq inhibition, FR-6 suppressed Gq signaling with micromolar potency (pIC50 = 5.56). This functional activity was confirmed in radioligand binding assays (pKi = 7.50). This work demonstrates the power of molecular networking, guiding the way to a novel Gq-inhibiting FR derivative and underlining the potency of FR as a Gq inhibitor.