Impact of the Deletion of Genes of the Nitrogen Metabolism on Triacylglycerol, Cardiolipin and Actinorhodin Biosynthesis in .

Since nitrogen limitation is known to be an important trigger of triacylglycerol (TAG) accumulation in most microorganisms, we first assessed the global lipid content of 21 strains derived from M145 deleted for genes involved in nitrogen metabolism. Seven of these strains deleted for genes encoding proteins involved in polyamine (GlnA2/SCO2241, GlnA3/SCO6962, GlnA4/SCO1613), or protein (Pup/SCO1646) degradation, in the regulation of nitrogen metabolism (GlnE/SCO2234 and GlnK/SCO5584), or the global regulator DasR/SCO5231 that controls negatively the degradation of N-acetylglucosamine, a constituent of peptidoglycan, had a higher TAG content than the original strain, whereas five of these strains (except the and mutants) had a lower cardiolipin (CL) content. The production of the blue polyketide actinorhodin (ACT) was totally abolished in the mutant in both Pi conditions, whereas the deletion of , , , and was correlated with a significant increase in total ACT production, but mainly in Pi limitation.

Consequences of the deletion of the major specialized metabolite biosynthetic pathways of Streptomyces coelicolor on the metabolome and lipidome of this strain.

Chassis strains, derived from Streptomyces coelicolor M145, deleted for one or more of its four main specialized metabolites biosynthetic pathways (CPK, CDA, RED and ACT), in various combinations, were constructed for the heterologous expression of specialized metabolites biosynthetic pathways of various types and origins. To determine consequences of these deletions on the metabolism of the deleted strains comparative lipidomic and metabolomic analyses of these strains and of the original strain were carried out. These studies unexpectedly revealed that the deletion of the peptidic clusters, RED and/or CDA, in a strain deleted for the ACT cluster, resulted into a great increase in the triacylglycerol (TAG) content, whereas the deletion of polyketide clusters, ACT and CPK had no impact on TAG content.

Comprehensive analysis of oxylipins using reverse phase liquid chromatography and data dependent acquisition workflow on LTQ-Orbitrap® Velos Pro.

Oxylipins - involved in inflammatory processes - are reported in several diseases, in biological, pharmacological, and physiological fields. To face the structural complexity of oxylipins, the study of isomers and isobars species relied on Selected Reaction Monitoring (SRM) and Multiple Reaction Monitoring (MRM) in tandem mass spectrometry such as triple quadrupole, quadrupole-Time of Flight (TOF). Unfortunately, false positive signals in cellular matrix could occur using MRM or SRM mode since the MS/MS spectrum of each molecule is not acquired with the previous mode to help molecule confirmation.

Modulation of release and pharmacokinetics from nanoscale lipid prodrugs of dexamethasone with variable linkage chemistry.

In an attempt to tune drug release and subsequent pharmacokinetics once administered intravenously, we have synthesized three lipid-drug conjugates (LDCs) of dexamethasone (DXM) each possessing a different lipid-drug chemical linkage: namely ester, carbamate and carbonate. These LDCs were thoroughly characterized before being turned into nanoscale particles by an emulsion-evaporation process using DSPE-PEG (Distearoyl-sn-Glycero-3-Phosphoethanolamine-N-(methoxy(polyethylene glycol)-2000) as the only excipient. Spherical nanoparticles (NPs) of about 140-170 nm, with a negative zeta potential, were obtained for each LDC and exhibited good stability upon storage at 4 °C for 45 days with no recrystallization of LDCs observed.

Genome Analysis of a Variant of M145 with High Lipid Content and Poor Ability to Synthetize Antibiotics.

M145 is a model strain extensively studied to elucidate the regulation of antibiotic biosynthesis in species. This strain abundantly produces the blue polyketide antibiotic, actinorhodin (ACT), and has a low lipid content. In a process designed to delete the gene encoding the isocitrate lyase () of the glyoxylate cycle, an unexpected variant of was obtained besides deletion mutants.