title: Discovery of a new Mycobacterium tuberculosis thymidylate synthase X inhibitor with a unique inhibition profile.
abstract: Tuberculosis (TB), mainly caused by Mycobacterium tuberculosis (Mtb), is an infection that is responsible for roughly 1.5 million deaths per year. The situation is further complicated by the wide-spread resistance to the existing first- and second-line drugs. As a result of this, it is urgent to develop new drugs to combat the resistant bacteria as well as have lower side effects, which can promote adherence to the treatment regimens. Targeting the de novo synthesis of thymidylate (dTMP) is an important pathway to develop drugs for TB. Although Mtb carries genes for two families of thymidylate synthases (TS), ThyA and ThyX, only ThyX is essential for its normal growth. Both enzymes catalyze the conversion of uridylate (dUMP) to dTMP but employ a different catalytic approach and have different structures. Also, ThyA is the only TS found in humans. This is the rationale for identifying selective inhibitors against ThyX. We exploited the NADPH oxidation to NADP+step, catalyzed by ThyX, to develop a spectrophotometric biochemical assay. Success of the assay was demonstrated by its effectiveness (average Z'=0.77) and identification of selective ThyX inhibitors. The most potent compound is a tight-binding inhibitor with an IC50of 710nM. Its mechanism of inhibition is analyzed in relation to the latest findings of ThyX mechanism and substrate and cofactor binding order.
authors.affiliation: Laboratory of Medicinal Chemistry, Rega Institute for Medical Research, KU Leuven, Herestraat 49, 3000 Leuven, Belgium.
authors.forename: Rania
authors.initials: R
authors.lastname: Abu El Asrar
authors.affiliation: Laboratory of Medicinal Chemistry, Rega Institute for Medical Research, KU Leuven, Herestraat 49, 3000 Leuven, Belgium.
authors.forename: Lia
authors.initials: L
authors.lastname: Margamuljana
authors.affiliation: CISTIM Leuven vzw, Bio-incubator 2, Gaston Geenslaan 2, 3001 Heverlee, Belgium.
authors.forename: Hugo
authors.initials: H
authors.lastname: Klaassen
authors.affiliation: CISTIM Leuven vzw, Bio-incubator 2, Gaston Geenslaan 2, 3001 Heverlee, Belgium.
authors.forename: Marnik
authors.initials: M
authors.lastname: Nijs
authors.affiliation: CISTIM Leuven vzw, Bio-incubator 2, Gaston Geenslaan 2, 3001 Heverlee, Belgium.
authors.forename: Arnaud
authors.initials: A
authors.lastname: Marchand
authors.affiliation: CISTIM Leuven vzw, Bio-incubator 2, Gaston Geenslaan 2, 3001 Heverlee, Belgium; Center for Drug Design and Discovery (CD3) KU Leuven R&D, Bio-incubator 2, Gaston Geenslaan 2, 3001 Heverlee, Belgium.
authors.forename: Patrick
authors.initials: P
authors.lastname: Chaltin
authors.affiliation: Laboratoire d'Optique et Biosciences, INSERM U1182-CNRS UMR7645, Ecole Polytechnique, 91128 Palaiseau Cedex, France.
authors.forename: Hannu
authors.initials: H
authors.lastname: Myllykallio
authors.affiliation: Laboratoire d'Optique et Biosciences, INSERM U1182-CNRS UMR7645, Ecole Polytechnique, 91128 Palaiseau Cedex, France; Sorbonne Universités, UPMC Univ Paris 06, 4 Place Jussieu, 75005 Paris, France.
authors.forename: Hubert F
authors.initials: HF
authors.lastname: Becker
authors.affiliation: Laboratory of Medicinal Chemistry, Rega Institute for Medical Research, KU Leuven, Herestraat 49, 3000 Leuven, Belgium.
authors.forename: Steven
authors.initials: S
authors.lastname: De Jonghe
authors.affiliation: Laboratory of Medicinal Chemistry, Rega Institute for Medical Research, KU Leuven, Herestraat 49, 3000 Leuven, Belgium.
authors.forename: Piet
authors.initials: P
authors.lastname: Herdewijn
authors.affiliation: Laboratory of Medicinal Chemistry, Rega Institute for Medical Research, KU Leuven, Herestraat 49, 3000 Leuven, Belgium. Electronic address: eveline.lescrinier@kuleuven.be.
authors.forename: Eveline
authors.initials: E
authors.lastname: Lescrinier
mesh_terms: D000995:Antitubercular Agents / Q000378:metabolism* / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D055808:Drug Discovery / Q000379:methods*; D004791:Enzyme Inhibitors / Q000378:metabolism* / Q000494:pharmacology; D006801:Humans; D009169:Mycobacterium tuberculosis / Q000187:drug effects / Q000201:enzymology*; D011485:Protein Binding / Q000187:drug effects / Q000502:physiology; D013940:Thymidylate Synthase / Q000037:antagonists & inhibitors* / Q000378:metabolism*
chemical_list: D000995:Antitubercular Agents; D004791:Enzyme Inhibitors; D013940:Thymidylate Synthase
keywords: Folinic acid (Pub Chem CID: 15150); High-throughput screening; Inhibitor; Mycobacterium tuberculosis; Profiling; Thymidylate synthase X