1,3-Diarylpyrazolyl-acylsulfonamides Target HadAB/BC Complex in Mycobacterium tuberculosis

Area of Science:

• Medicinal Chemistry
• Biochemistry
• Microbiology

Background:

• Drug resistance in Mycobacterium tuberculosis (Mtb) necessitates novel therapeutic strategies targeting essential biosynthetic pathways.
• The HadAB/BC complex, a 3-hydroxyl-ACP dehydratase, is vital for mycolic acid elongation in Mtb.
• Existing inhibitors like isoxyl and thioacetazone are susceptible to EthA-mediated resistance.

Purpose of the Study:

• To identify and characterize novel inhibitors of the Mtb HadAB/BC complex.
• To explore an alternative inhibition mechanism that circumvents EthA-mediated resistance.
• To provide structural insights for further drug development.

Main Methods:

• Synthesis and evaluation of 1,3-diarylpyrazolyl-acylsulfonamides as HadAB/BC inhibitors.
• Resistance mapping in Mtb mutants and chemoproteomic analysis to confirm target engagement.
• Enzyme activity assays and mycolic acid biosynthesis inhibition studies.
• Crystallographic analysis of Mtb HadAB in complex with a lead compound.

Main Results:

• 1,3-diarylpyrazolyl-acylsulfonamides potently inhibit HadAB/BC enzyme activities.
• Compounds demonstrated concentration-dependent inhibition of mycolic acid biosynthesis in Mtb.
• Resistance mutations mapped to HadC, confirming target specificity.
• Chemoproteomics validated binding to HadA, HadB, and HadC.
• Crystal structure revealed unique binding interactions within the HadAB active site.
• Unlike existing drugs, these compounds do not require EthA activation, avoiding EthA-mediated resistance.

Conclusions:

• 1,3-diarylpyrazolyl-acylsulfonamides represent a promising new class of Mtb inhibitors targeting the HadAB/BC complex.
• Their EthA-independent mechanism offers a strategy to overcome existing drug resistance.
• Structural data provides a foundation for rational design of next-generation anti-tubercular agents.