title: MAB_3551c encodes the primary triacylglycerol synthase involved in lipid accumulation in Mycobacterium abscessus.
abstract: Slow growing pathogenic mycobacteria utilize host-derived lipids and accumulate large amounts of triacylglycerol (TAG) in the form of intracytoplasmic lipid inclusions (ILI), serving as a source of carbon and energy during prolonged infection. Mycobacterium abscessus is an emerging and rapidly growing species capable to induce severe and chronic pulmonary infections. However, whether M. abscessus, like Mycobacterium tuberculosis, possesses the machinery to acquire and store host lipids, remains unaddressed. Herein, we aimed at deciphering the contribution of the seven putative M. abscessus TAG synthases (Tgs) in TAG synthesis/accumulation thanks to a combination of genetic and biochemical techniques and a well-defined foamy macrophage (FM) model along with electron microscopy. Targeted gene deletion and functional complementation studies identified the MAB_3551c product, Tgs1, as the major Tgs involved in TAG production. Tgs1 exhibits a preference for long acyl-CoA substrates and site-directed mutagenesis demonstrated that His144 and Gln145 are essential for enzymatic activity. Importantly, in the lipid-rich intracellular context of FM, M. abscessus formed large ILI in a Tgs1-dependent manner. This supports the ability of M. abscessus to assimilate host lipids and the crucial role of Tgs1 in intramycobacterial TAG production, which may represent important mechanisms for long-term storage of a rich energy supply.
authors: Centre National de la Recherche Scientifique FRE3689, Centre d'études d'agents Pathogènes et Biotechnologies pour la Santé, Université de Montpellier, 1919 route de Mende, Montpellier, 34293, France.|Centre d'Immunologie de Marseille-Luminy, Aix Marseille Université UM2, Inserm, U1104, CNRS UMR7280, Marseille, 13288, France.
authors: Albertus
authors: A
authors: Viljoen
authors: Centre National de la Recherche Scientifique FRE3689, Centre d'études d'agents Pathogènes et Biotechnologies pour la Santé, Université de Montpellier, 1919 route de Mende, Montpellier, 34293, France.
authors: Mickael
authors: M
authors: Blaise
authors: Centre d'Immunologie de Marseille-Luminy, Aix Marseille Université UM2, Inserm, U1104, CNRS UMR7280, Marseille, 13288, France.
authors: Chantal
authors: C
authors: de Chastellier
authors: Centre National de la Recherche Scientifique FRE3689, Centre d'études d'agents Pathogènes et Biotechnologies pour la Santé, Université de Montpellier, 1919 route de Mende, Montpellier, 34293, France.|INSERM, CPBS, Montpellier, 34293, France.
authors: Laurent
authors: L
authors: Kremer
mesh_terms: D000595:Amino Acid Sequence; D064429:Fatty Acid Synthases / Q000235:genetics* / Q000378:metabolism; D050356:Lipid Metabolism / Q000235:genetics; D016297:Mutagenesis, Site-Directed; D009170:Nontuberculous Mycobacteria / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D014280:Triglycerides / Q000096:biosynthesis* / Q000378:metabolism
chemical_list: D014280:Triglycerides; D064429:Fatty Acid Synthases