Azetidomonamide and Diazetidomonapyridone Metabolites Control Biofilm Formation and Pigment Synthesis in Pseudomonas aeruginosa

Abstract

Synthesis of azetidine-derived natural products by the opportunistic pathogen Pseudomonas aeruginosa is controlled by quorum sensing, a process involving the production and sensing of diffusible signal molecules that is decisive for virulence regulation. In this study, we engineered P. aeruginosa for the titratable expression of the biosynthetic aze gene cluster, which allowed the purification and identification of two new products, azetidomonamide C and diazetidomonapyridone. Diazetidomonapyridone was shown to have a highly unusual structure with two azetidine rings and an open-chain diimide moiety. Expression of aze genes strongly increased biofilm formation and production of phenazine and alkyl quinolone virulence factors. Further physiological studies revealed that all effects were mainly mediated by azetidomonamide A and diazetidomonapyridone, whereas azetidomonamides B and C had little or no phenotypic impact. The P450 monooxygenase AzeF which catalyzes a challenging, stereoselective hydroxylation of the azetidine ring converting azetidomonamide C into azetidomonamide A is therefore crucial for biological activity. Based on our findings, we propose this group of metabolites to constitute a new class of diffusible regulatory molecules with community-related effects in P. aeruginosa.

Deuterated Modifiers in Sub/Supercritical Fluid Chromatography for Streamlined NMR Structure Elucidation

“…Delivering high purity for NMR analysis from multicomponent reaction mixtures often requires arduous fractionation workloads or multipass column separations. − The evolution of high-field magnets, small-diameter cryogenic NMR probes, and pulse sequences has facilitated the structure elucidation of complex analytes from substantially smaller-scale purifications. − As a result, chromatographic isolation on the analytical scale is now feasible, offering obvious advantages in term of speed, instrumentation, and environmental footprint.…”