Trafficking pathways of mycolic acids: structures, origin, mechanism of formation, and storage form of mycobacteric acids

• Published in: Journal of lipid research Vol. 50; no. 3; pp. 477 - 490
• Main Authors: Rafidinarivo, Elie, Lanéelle, Marie-Antoinette, Montrozier, Henri, Valero-Guillén, Pedro, Astola, José, Luquin, Marina, Promé, Jean-Claude, Daffé, Mamadou
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 01.03.2009; American Society for Biochemistry and Molecular Biology; Elsevier
• Subjects: Baeyer-Villiger reaction; biosynthesis; catabolism; Energy Metabolism; Fatty Acids - chemistry; Magnetic Resonance Spectroscopy; Models, Biological; Molecular Structure; mycobacteria; Mycobacterium - growth & development; Mycobacterium - metabolism; Mycolic Acids - chemistry; Mycolic Acids - metabolism; oxidation; Oxygen Isotopes; Spectrometry, Mass, Electrospray Ionization; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; oxidation; catabolism; mycobacteria; Baeyer-Villiger reaction; biosynthesis
• ISSN: 0022-2275; 1539-7262
• DOI: 10.1194/jlr.M800384-JLR200

Mycolic acids, the hallmark of mycobacteria and related bacteria, are major and specific components of their cell envelope and essential for the mycobacterial survival. Mycobacteria contain structurally related long-chain lipids, but the metabolic relationships between these various classes of compounds remain obscure. To address this question a series of C35 to C54 nonhydroxylated fatty acids (mycobacteric acids), ketones, and alcohols structurally related to the C70–80 dicyclopropanated or diethylenic mycolic acids were characterized in three mycobacterial strains and their structures compared. The relationships between these long-chain acids and mycolic acids were established by following the in vivo traffic of 14C labeled α-mycolic acids purified from the same mycobacterial species. The labeling was exclusively found in mycobacteric acids. The mechanism of this degradation was established by incorporation of 18O2 into long-chain lipids and shown to consist in the rupture of mycolic acids between carbon 3 and 4 by a Baeyer-Villiger-like reaction. We also demonstrated that mycobacteric acids occur exclusively in the triacylglycerol (TAG) fraction where one molecule of these acids esterifies one of the three hydroxyl groups of glycerol. Altogether, these data suggest that these compounds represent a pathway of metabolic energy that would be used by mycobacteria in particular circumstances.