Mechanistic Insight into the Enzymatic Inhibition of β-Amyrin against Mycobacterial Rv1636: In Silico and In Vitro...

Area of Science:

• Biochemistry and Biophysics
• Molecular Biology
• Drug Discovery

Background:

• Mycobacterium tuberculosis utilizes universal stress proteins like Rv1636 for survival under host-induced stress.
• Rv1636 binds independently to both ATP and cAMP, playing a crucial role in mycobacterial resilience.
• β-Amyrin, a plant-derived triterpenoid, possesses diverse pharmacological properties with therapeutic potential.

Purpose of the Study:

• To investigate the binding interaction between Rv1636 and β-Amyrin using integrated biochemical, biophysical, and computational approaches.
• To elucidate the structural and functional consequences of β-Amyrin binding to Rv1636.

Main Methods:

• Molecular docking and molecular dynamics simulations to predict binding modes and complex stability.
• Cloning, expression, and purification of Rv1636 protein.
• In vitro ATPase activity assays, circular dichroism spectroscopy, and isothermal titration calorimetry (ITC).

Main Results:

• Molecular docking identified VAL60 as a critical residue in Rv1636 binding with β-Amyrin and ATP.
• Molecular dynamics simulations confirmed the stability of the Rv1636-β-Amyrin complex.
• β-Amyrin significantly inhibited Rv1636 ATPase activity and induced changes in protein secondary structure, with spontaneous binding confirmed by ITC.

Conclusions:

• β-Amyrin binds with high affinity to Rv1636, forming a stable complex and inhibiting its essential ATPase function.
• This inhibition suggests a potential mechanism for targeting Rv1636, making Mycobacterium tuberculosis more susceptible to host stress.
• β-Amyrin represents a promising natural compound for developing novel anti-tubercular strategies.