title: Identification of the missing trans-acting enoyl reductase required for phthiocerol dimycocerosate and phenolglycolipid biosynthesis in Mycobacterium tuberculosis.
abstract: Phthiocerol dimycocerosates (DIM) and phenolglycolipids (PGL) are functionally important surface-exposed lipids of Mycobacterium tuberculosis. Their biosynthesis involves the products of several genes clustered in a 70-kb region of the M. tuberculosis chromosome. Among these products is PpsD, one of the modular type I polyketide synthases responsible for the synthesis of the lipid core common to DIM and PGL. Bioinformatic analyses have suggested that this protein lacks a functional enoyl reductase activity domain required for the synthesis of these lipids. We have identified a gene, Rv2953, that putatively encodes an enoyl reductase. Mutation in Rv2953 prevents conventional DIM formation and leads to the accumulation of a novel DIM-like product. This product is unsaturated between C-4 and C-5 of phthiocerol. Consistently, complementation of the mutant with a functional pks15/1 gene from Mycobacterium bovis BCG resulted in the accumulation of an unsaturated PGL-like substance. When an intact Rv2953 gene was reintroduced into the mutant strain, the phenotype reverted to the wild type. These findings indicate that Rv2953 encodes a trans-acting enoyl reductase that acts with PpsD in phthiocerol and phenolphthiocerol biosynthesis.
authors.affiliation: Institut de Pharmacologie et Biologie Structurale, Centre National de la Recherche Scientifique, 205 route de Narbonne, 31077 Toulouse Cedex, France.
authors.forename: Roxane
authors.initials: R
authors.lastname: Siméone
authors.forename: Patricia
authors.initials: P
authors.lastname: Constant
authors.forename: Christophe
authors.initials: C
authors.lastname: Guilhot
authors.forename: Mamadou
authors.initials: M
authors.lastname: Daffé
authors.forename: Christian
authors.initials: C
authors.lastname: Chalut
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002855:Chromatography, Thin Layer; D019295:Computational Biology; D050753:Enoyl-(Acyl-Carrier-Protein) Reductase (NADH) / Q000235:genetics / Q000378:metabolism*; D006017:Glycolipids / Q000096:biosynthesis* / Q000737:chemistry; D008055:Lipids / Q000096:biosynthesis* / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D009154:Mutation; D009169:Mycobacterium tuberculosis / Q000201:enzymology / Q000235:genetics / Q000378:metabolism*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D001426:Bacterial Proteins; D006017:Glycolipids; D008055:Lipids; C008901:phthiocerol dimycocerosate; D050753:Enoyl-(Acyl-Carrier-Protein) Reductase (NADH)