title: Insights into Substrate Modification by Dehydratases from Type I Polyketide Synthases.
abstract: Dehydration reactions play a crucial role in the de novo biosynthesis of fatty acids and a wide range of pharmacologically active polyketide natural products with strong emphasis on human medicine. The type I polyketide synthase PpsC from Mycobacterium tuberculosis catalyzes key biosynthetic steps of lipid virulence factors phthiocerol dimycocerosates and phenolic glycolipids. Given the insolubility of the natural C28-C30fatty acyl substrate of the PpsC dehydratase (DH) domain, we investigated its structure-function relationships in the presence of shorter surrogate substrates. Since most enzymes belonging to the (R)-specific enoyl hydratase/hydroxyacyl dehydratase family conduct the reverse hydration reaction in vitro, we have determined the X-ray structures of the PpsC DH domain, both unliganded (apo) and in complex with trans-but-2-enoyl-CoA or trans-dodec-2-enoyl-CoA derivatives. This study provides for the first time a snapshot of dehydratase-ligand interactions following a hydration reaction. Our structural analysis allowed us to identify residues essential for substrate binding and activity. The structural comparison of the two complexes also sheds light on the need for long acyl chains for this dehydratase to carry out its function, consistent with both its in vitro catalytic behavior and the physiological role of the PpsC enzyme.
authors.affiliation: Institut de Pharmacologie et de Biologie Structurale, Université de Toulouse, CNRS, UPS, 31077 Toulouse Cedex 04, France.
authors.forename: Alexandre
authors.initials: A
authors.lastname: Faille
authors.affiliation: Institut de Pharmacologie et de Biologie Structurale, Université de Toulouse, CNRS, UPS, 31077 Toulouse Cedex 04, France.
authors.forename: Sabine
authors.initials: S
authors.lastname: Gavalda
authors.affiliation: Institut de Pharmacologie et de Biologie Structurale, Université de Toulouse, CNRS, UPS, 31077 Toulouse Cedex 04, France.
authors.forename: Nawel
authors.initials: N
authors.lastname: Slama
authors.affiliation: ITAV USR 3505, 31106 Toulouse Cedex 1, France.
authors.forename: Christian
authors.initials: C
authors.lastname: Lherbet
authors.affiliation: Institut de Pharmacologie et de Biologie Structurale, Université de Toulouse, CNRS, UPS, 31077 Toulouse Cedex 04, France.
authors.forename: Laurent
authors.initials: L
authors.lastname: Maveyraud
authors.affiliation: Institut de Pharmacologie et de Biologie Structurale, Université de Toulouse, CNRS, UPS, 31077 Toulouse Cedex 04, France.
authors.forename: Valérie
authors.initials: V
authors.lastname: Guillet
authors.affiliation: Institut de Pharmacologie et de Biologie Structurale, Université de Toulouse, CNRS, UPS, 31077 Toulouse Cedex 04, France.
authors.forename: Françoise
authors.initials: F
authors.lastname: Laval
authors.affiliation: Institut de Pharmacologie et de Biologie Structurale, Université de Toulouse, CNRS, UPS, 31077 Toulouse Cedex 04, France.
authors.forename: Annaïk
authors.initials: A
authors.lastname: Quémard
authors.affiliation: Institut de Pharmacologie et de Biologie Structurale, Université de Toulouse, CNRS, UPS, 31077 Toulouse Cedex 04, France. Electronic address: Lionel.Mourey@ipbs.fr.
authors.forename: Lionel
authors.initials: L
authors.lastname: Mourey
authors.affiliation: Institut de Pharmacologie et de Biologie Structurale, Université de Toulouse, CNRS, UPS, 31077 Toulouse Cedex 04, France. Electronic address: Jean-Denis.Pedelacq@ipbs.fr.
authors.forename: Jean-Denis
authors.initials: JD
authors.lastname: Pedelacq
mesh_terms: D000214:Acyl Coenzyme A / Q000737:chemistry* / Q000378:metabolism*; D018360:Crystallography, X-Ray; D006836:Hydro-Lyases / Q000737:chemistry* / Q000378:metabolism*; D008958:Models, Molecular; D009169:Mycobacterium tuberculosis / Q000201:enzymology*; D048630:Polyketide Synthases / Q000737:chemistry* / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation
chemical_list: D000214:Acyl Coenzyme A; D048630:Polyketide Synthases; D006836:Hydro-Lyases
keywords: Mycobacterium tuberculosis; X-ray structure; dehydratase; metabolizable ligand; polyketide synthase