title: Structural elucidation and genomic scrutiny of the C60-C100 mycolic acids of Segniliparus rotundus.
abstract: Mycolic acids, very long-chain α-alkyl, β-hydroxylated fatty acids, occur in the members of the order Corynebacteriales where their chain lengths (C(26)-C(88)) and structural features (oxygen functions, cis or trans double bonds, cyclopropane rings and methyl branches) are genus- and species-specific. The molecular composition and structures of the mycolic acids of two species belonging to the genus Segniliparus were determined by a combination of modern analytical chemical techniques, which include MS and NMR. They consist of mono-ethylenic C(62-)C(64) (α'), di-ethylenic C(77)-C(79) (α) and extremely long-chain mycolic acids (α(+)) ranging from 92 to 98 carbon atoms and containing three unsaturations, cis and/or trans double bonds and/or cyclopropanes. The double bonds in each class of mycolic acids were positioned by oxidative cleavage and exhibit locations similar to those of α- and α'-mycolic acids of mycobacteria. For the ultralong chain α-mycolic acids, the three double bonds were located at equally spaced carbon intervals (C(13)-C(16)), with the methyl branches adjacent to the proximal and distal trans double bonds. Examination of the Segniliparus rotundus genome compared with those of other members of the Corynebacteriales indicated two obvious differences in genes encoding the elongation fatty acid (FAS-II) enzymes involved in the biosynthesis of mycolic acids: the organization of 3-ketoacyl-ACP synthases (KasA and KasB) and (3R)-hydroxyacyl-ACP dehydratases (HadAB/BC), on one hand, and the presence of two copies of the hadB gene encoding the catalytic domain of the latter enzyme type, on the other. This observation is discussed in light of the most recent data accumulated on the biosynthesis of this hallmark of Corynebacteriales.
authors.affiliation: Université de Toulouse (Université Paul Sabatier, Toulouse III), IPBS, 205 Route de Narbonne, BP 64182, F-31077 Toulouse, France.|Centre National de la Recherche Scientifique (CNRS), Institut de Pharmacologie et de Biologie Structurale (IPBS, Unité Mixte de Recherche 5089) Département Mécanismes Moléculaires des Infections Mycobactériennes, 205 Route de Narbonne, BP 64182, F-31077 Toulouse, France.
authors.forename: Marie-Antoinette
authors.initials: MA
authors.lastname: Lanéelle
authors.affiliation: Université de Toulouse (Université Paul Sabatier, Toulouse III), IPBS, 205 Route de Narbonne, BP 64182, F-31077 Toulouse, France.|Centre National de la Recherche Scientifique (CNRS), Institut de Pharmacologie et de Biologie Structurale (IPBS, Unité Mixte de Recherche 5089) Département Mécanismes Moléculaires des Infections Mycobactériennes, 205 Route de Narbonne, BP 64182, F-31077 Toulouse, France.
authors.forename: Nathalie
authors.initials: N
authors.lastname: Eynard
authors.affiliation: Université de Toulouse (Université Paul Sabatier, Toulouse III), IPBS, 205 Route de Narbonne, BP 64182, F-31077 Toulouse, France.|Centre National de la Recherche Scientifique (CNRS), Institut de Pharmacologie et de Biologie Structurale (IPBS, Unité Mixte de Recherche 5089) Département Mécanismes Moléculaires des Infections Mycobactériennes, 205 Route de Narbonne, BP 64182, F-31077 Toulouse, France.
authors.forename: Lucie
authors.initials: L
authors.lastname: Spina
authors.affiliation: Université de Toulouse (Université Paul Sabatier, Toulouse III), IPBS, 205 Route de Narbonne, BP 64182, F-31077 Toulouse, France.|Centre National de la Recherche Scientifique (CNRS), Institut de Pharmacologie et de Biologie Structurale (IPBS, Unité Mixte de Recherche 5089) Département Mécanismes Moléculaires des Infections Mycobactériennes, 205 Route de Narbonne, BP 64182, F-31077 Toulouse, France.
authors.forename: Anne
authors.initials: A
authors.lastname: Lemassu
authors.affiliation: Université de Toulouse (Université Paul Sabatier, Toulouse III), IPBS, 205 Route de Narbonne, BP 64182, F-31077 Toulouse, France.|Centre National de la Recherche Scientifique (CNRS), Institut de Pharmacologie et de Biologie Structurale (IPBS, Unité Mixte de Recherche 5089) Département Mécanismes Moléculaires des Infections Mycobactériennes, 205 Route de Narbonne, BP 64182, F-31077 Toulouse, France.
authors.forename: Françoise
authors.initials: F
authors.lastname: Laval
authors.affiliation: Université de Toulouse (Université Paul Sabatier, Toulouse III), IPBS, 205 Route de Narbonne, BP 64182, F-31077 Toulouse, France.|Centre National de la Recherche Scientifique (CNRS), Institut de Pharmacologie et de Biologie Structurale (IPBS, Unité Mixte de Recherche 5089) Département Mécanismes Moléculaires des Infections Mycobactériennes, 205 Route de Narbonne, BP 64182, F-31077 Toulouse, France.
authors.forename: Emilie
authors.initials: E
authors.lastname: Huc
authors.affiliation: Université de Toulouse (Université Paul Sabatier, Toulouse III), IPBS, 205 Route de Narbonne, BP 64182, F-31077 Toulouse, France.|Centre National de la Recherche Scientifique (CNRS), Institut de Pharmacologie et de Biologie Structurale (IPBS, Unité Mixte de Recherche 5089) Département Mécanismes Moléculaires des Infections Mycobactériennes, 205 Route de Narbonne, BP 64182, F-31077 Toulouse, France.
authors.forename: Gilles
authors.initials: G
authors.lastname: Etienne
authors.affiliation: Université de Toulouse (Université Paul Sabatier, Toulouse III), IPBS, 205 Route de Narbonne, BP 64182, F-31077 Toulouse, France.|Centre National de la Recherche Scientifique (CNRS), Institut de Pharmacologie et de Biologie Structurale (IPBS, Unité Mixte de Recherche 5089) Département Mécanismes Moléculaires des Infections Mycobactériennes, 205 Route de Narbonne, BP 64182, F-31077 Toulouse, France.
authors.forename: Hedia
authors.initials: H
authors.lastname: Marrakchi
authors.affiliation: Université de Toulouse (Université Paul Sabatier, Toulouse III), IPBS, 205 Route de Narbonne, BP 64182, F-31077 Toulouse, France.|Centre National de la Recherche Scientifique (CNRS), Institut de Pharmacologie et de Biologie Structurale (IPBS, Unité Mixte de Recherche 5089) Département Mécanismes Moléculaires des Infections Mycobactériennes, 205 Route de Narbonne, BP 64182, F-31077 Toulouse, France.
authors.forename: Mamadou
authors.initials: M
authors.lastname: Daffé
mesh_terms: D000192:Actinomycetales / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism; D053898:Biosynthetic Pathways / Q000235:genetics*; D004798:Enzymes / Q000235:genetics; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D009171:Mycolic Acids / Q000737:chemistry* / Q000378:metabolism*
chemical_list: D004798:Enzymes; D009171:Mycolic Acids