Multiple drug binding modes in Mycobacterium tuberculosis CYP51B1.

Area of Science:

• Biochemistry
• Molecular Biology
• Medicinal Chemistry

Background:

• The Mycobacterium tuberculosis (Mtb) genome contains 20 cytochrome P450 enzymes (CYPs) involved in essential biosynthetic pathways.
• CYP51B1, a homolog of eukaryotic sterol demethylase in Mtb, is a potential target for novel therapeutics.

Purpose of the Study:

• To investigate the binding interactions of three nitrogen heterocycle-containing drug fragments with the Mtb CYP51B1 enzyme.
• To elucidate the binding modes of these fragments at the heme active site using advanced spectroscopic techniques.

Main Methods:

• Continuous wave (CW) and pulsed electron paramagnetic resonance (EPR) spectroscopy were employed.
• Hyperfine sublevel correlation spectroscopy (HYSCORE) and electron-nuclear double resonance (ENDOR) were utilized to probe molecular interactions.

Main Results:

• All three drug fragments formed a mixture of complexes with CYP51B1.
• Some complexes retained the axial water ligand, indicating varied binding states.
• Spectroscopic analysis revealed specific drug binding modes through interactions with the axial water and drug fragment protons.

Conclusions:

• CYP51B1 exhibits complex binding behavior with multiple coexisting binding modes in solution.
• Understanding these interactions is crucial for designing effective CYP-inhibitor drugs against Mtb.
• This research provides insights to guide the development of future tuberculosis therapeutics.