Discovery of a new Mycobacterium tuberculosis thymidylate synthase X inhibitor with a unique inhibition profile

作者：Abu El Asrar Rania; Margamuljana Lia; Klaassen Hugo; Nijs Marnik; Marchand Arnaud; Chaltin Patrick; Myllykallio Hannu; Becker Hubert F; De Jonghe Steven; Herdewijn Piet; Lescrinier Eveline^*

来源：Biochemical Pharmacology, 2017, 135: 69-78.

DOI：10.1016/j.bcp.2017.03.017

• Mycobacterium tuberculosis
• Thymidylate synthase X
• Inhibitor
• High-throughput screening
• Profiling

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 NADI(+) 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 IC50 of 710 nM. Its mechanism of inhibition is analyzed in relation to the latest findings of ThyX mechanism and substrate and cofactor binding order.

• 出版日期2017-7-1
• 单位KU Leuven; 河北医科大学