title: The structure of Enterococcus faecalis thymidylate synthase provides clues about folate bacterial metabolism.
abstract: Drug resistance to therapeutic antibiotics poses a challenge to the identification of novel targets and drugs for the treatment of infectious diseases. Infections caused by Enterococcus faecalis are a major health problem. Thymidylate synthase (TS) from E. faecalis is a potential target for antibacterial therapy. The X-ray crystallographic structure of E. faecalis thymidylate synthase (EfTS), which was obtained as a native binary complex composed of EfTS and 5-formyltetrahydrofolate (5-FTHF), has been determined. The structure provides evidence that EfTS is a half-of-the-sites reactive enzyme, as 5-FTHF is bound to two of the four independent subunits present in the crystal asymmetric unit. 5-FTHF is a metabolite of the one-carbon transfer reaction catalysed by 5-formyltetrahydrofolate cyclo-ligase. Kinetic studies show that 5-FTHF is a weak inhibitor of EfTS, suggesting that the EfTS-5-FTHF complex may function as a source of folates and/or may regulate one-carbon metabolism. The structure represents the first example of endogenous 5-FTHF bound to a protein involved in folate metabolism.
authors.affiliation: Dipartimento di Chimica, University of Siena, Siena, Italy.
authors.forename: Cecilia
authors.initials: C
authors.lastname: Pozzi
authors.forename: Stefania
authors.initials: S
authors.lastname: Ferrari
authors.forename: Debora
authors.initials: D
authors.lastname: Cortesi
authors.forename: Rosaria
authors.initials: R
authors.lastname: Luciani
authors.forename: Robert M
authors.initials: RM
authors.lastname: Stroud
authors.forename: Alessia
authors.initials: A
authors.lastname: Catalano
authors.forename: Maria Paola
authors.initials: MP
authors.lastname: Costi
authors.forename: Stefano
authors.initials: S
authors.lastname: Mangani
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D013293:Enterococcus faecalis / Q000201:enzymology*; D005492:Folic Acid / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D007700:Kinetics; D008024:Ligands; D008958:Models, Molecular; D008969:Molecular Sequence Data; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D017385:Sequence Homology; D013940:Thymidylate Synthase / Q000737:chemistry* / Q000378:metabolism
chemical_list: D008024:Ligands; D005492:Folic Acid; D013940:Thymidylate Synthase