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Access to the cyclic depsipeptide FR900359 (FR), a selective Gq/11 protein inhibitor of high pharmacological interest and a potential lead molecule for targeted therapy of cancers with oncogenic GNAQ or GNA11 mutations (encoding Gq and G11 respectively), has been challenging ever since its initial discovery more than three decades ago. The recent discovery of Chromobacterium vaccinii as a cultivable FR producer enables the development of approaches leading to a high‐yielding, scalable and sustainable biotechnological process for production of FR, thereby removing this bottleneck. Here we characterize different promoters in exchange of the native promoter of the FR assembly line, resulting in an overexpression mutant with significantly increased production of FR. Thereby, the isolation and structure elucidation of novel FR analogs of low abundance is enabled. Further, we explore the antiproliferative activities of fifteen chromodepsins against uveal melanoma cell lines harboring Gq/11 mutations and characterize the major metabolite of FR formed in plasma. [ABSTRACT FROM AUTHOR]

G proteins are key mediators of G protein‐coupled receptor (GPCR) signaling, facilitating a plethora of important physiological processes. The role of G proteins is much less understood than other aspects of GPCR function, which is largely due to the shortage of potent and selective G protein inhibitors. The natural cyclic depsipeptides YM‐254890 and FR900359 are two of the very few known selective inhibitors of the Gq subfamily, and are used as unique pharmacological tools in the study of G q‐mediated signaling. Moreover, a peptide‐based G protein antagonist‐2A (GP‐2A), a 27‐residue peptide (27mer(I860A)) derived from phospholipase C‐β3 (PLC‐β3), and the small molecule BIM‐46187 have also been characterized as selective G q inhibitors within the past 5 years. In this review, we highlight the recent development in chemical syntheses, characterization, and mechanism of action of these selective G q inhibitors. The development and application of G q‐selective inhibitors will expand our knowledge of the structure and function of G protein‐mediated signaling, shed light on the development of inhibitors for other G protein classes, and feed in to drug discovery for diseases where G proteins are implicated, including various forms of cancer. [ABSTRACT FROM AUTHOR]

Abstract: Das cyclische Depsipeptid FR900359 (FR), isoliert aus der tropischen Pflanze Ardisia crenata, zeigt starke und selektive Inhibierung von Gq‐Proteinen. Dadurch ist es sowohl für die Erforschung Gq‐abhängiger Prozesse interessant als auch ein vielversprechender Arzneimittelkandidat. Gq‐Inhibierung ist ein neuer Wirkmechanismus für Abwehrstoffe und entscheidend für die ökologische Funktion von FR, wie durch In‐vivo‐Experimente an Mäusen, Affinität zu Gq‐Proteinen von Insekten und Toxizitätsstudien an Insekten gezeigt wurde. Die Sequenzierung des unkultivierten Endosymbionten von A. crenata führte zur Entdeckung des nichtribosomalen Peptidsynthetasegenclusters von FR (frs). Wir präsentieren hier ein Modell der Biosynthese von FR, unterstützt durch bioinformatische und In‐vitro‐Enzymstudien und das neue Derivat AC‐1, welches Flexibilität der Starter‐Kondensierungsdomänen von FR beweist. Expression der frs‐Gene in E. coli führte erstmals zu heterologen Produktion von FR in einem kultivierbaren bakteriellen Wirt. [ABSTRACT FROM AUTHOR]

Abstract: The cyclic depsipeptide FR900359 (FR), isolated from the tropical plant Ardisia crenata, is a strong and selective inhibitor of Gq proteins, making it an indispensable pharmacological tool to study Gq‐related processes, as well as a promising drug candidate. Gq inhibition is a novel mode of action for defense chemicals and crucial for the ecological function of FR, as shown by in vivo experiments in mice, its affinity to insect Gq proteins, and insect toxicity studies. The uncultured endosymbiont of A. crenata was sequenced, revealing the FR nonribosomal peptide synthetase (frs) gene cluster. We here provide a detailed model of FR biosynthesis, supported by in vitro enzymatic and bioinformatic studies, and the novel analogue AC‐1, which demonstrates the flexibility of the FR starter condensation domains. Finally, expression of the frs genes in E. coli led to heterologous FR production in a cultivable, bacterial host for the first time. [ABSTRACT FROM AUTHOR]