Journal Article

Mycobacterium tuberculosis thymidylate synthase (ThyX) is a target for plumbagin, a natural product with antimycobacterial activity

Patra, Madhu Manti, Sarkar, Apurba, Ghosh, Shreya, Shaw, Rahul, Calcuttawala, Fatema, Das Gupta, Sujoy K., Mukherjee, Noyonika

2020

Overview

Plumbagin derived from the plant Plumbago indica, known as Chitrak in India, is an example of a medicinal compound used traditionally to cure a variety of ailments. Previous reports have indicated that it can inhibit the growth of Mycobacterium tuberculosis (Mtb), the causative agent of the deadly disease TB. In this investigation, we provide an insight into its mode of action. We show here that a significant mycobacterial target that is inhibited by plumbagin is the enzyme ThyX, a form of thymidylate synthase, that is responsible for the synthesis of dTMP from dUMP in various bacterial pathogens, including Mtb. Using a purified preparation of the recombinant version of Mtb ThyX, we demonstrate that plumbagin, a 2,4 napthoquinone, but not lawsone, a structurally related medicinal compound, inhibits its activity in vitro. We also show that the intracellular [dTTP]/[dATP] ratio in Mycobacterium smegmatis (Msm) cells decrease upon treatment with plumbagin, and this, in turn, leads to cell death. Such a conclusion is supported by the observation that over-expression of thyx in the plumbagin treated Msm cells leads to the restoration of viability. The results of our investigation indicate that plumbagin kills mycobacterial cells primarily by targeting ThyX, a vital enzyme required for their survival.

• Publisher: Public Library of Science,Public Library of Science (PLoS)
• Subject: Antitubercular Agents / Biological Products / Biology and Life Sciences / Cell death / Cell Survival - drug effects / Deoxyadenine Nucleotides - metabolism / Dihydrofolate reductase / Diseases / Drug resistance / Engineering and Technology / Enzymes / Gene expression / Herbal medicine / Laboratories / Medicine and Health Sciences / Mode of action / Mycobacterium tuberculosis / Mycobacterium tuberculosis - drug effects / Mycobacterium tuberculosis - enzymology / Naphthoquinones - pharmacology / Naphthoquinones - therapeutic use / Natural products / Overexpression / Pathogenic microorganisms / Plumbagin / Research and Analysis Methods / Restoration / Thymidylate synthase / Thymidylate Synthase - antagonists & inhibitors / Thymine Nucleotides - metabolism / Tuberculosis / Viability