Structural and docking studies of potent ethionamide boosters.

Area of Science:

• Biochemistry
• Structural Biology
• Medicinal Chemistry

Background:

• Tuberculosis (TB) is a leading infectious disease killer, with multi-drug resistant (MDR) and extensively drug-resistant (XDR) strains posing significant challenges.
• Ethionamide, a second-line anti-TB drug, is a prodrug requiring bioactivation by EthA, an enzyme repressed by EthR.
• Inhibiting EthR has been shown to enhance ethionamide's efficacy.

Purpose of the Study:

• To determine the crystal structures of three EthR inhibitors.
• To investigate the binding modes of these inhibitors within the EthR binding site using docking studies.
• To understand the structural basis for EthR inhibition to guide the development of novel anti-TB agents.

Main Methods:

• X-ray crystallography was used to obtain high-resolution (0.8 Å) crystal structures of three EthR inhibitors: BDM31343, BDM41325, and BDM41907.
• Molecular docking studies were performed to predict and analyze the binding interactions and orientations of the inhibitors within the EthR binding channel.
• Structure-activity relationship analysis was inferred from the binding poses.

Main Results:

• The crystal structures revealed the precise atomic details of three EthR inhibitors.
• Docking studies indicated two distinct binding orientations for the inhibitors within the largely lipophilic EthR binding site.
• The observed binding modes are attributed to the promiscuous nature of the EthR binding pocket.

Conclusions:

• The structural insights into EthR inhibitors provide a foundation for rational drug design targeting EthR.
• Understanding the binding interactions can aid in the development of more potent and selective inhibitors for combating MDR/XDR-TB.
• These findings contribute to the ongoing efforts to find effective treatments for challenging tuberculosis infections.