Activity loss by H46A mutation in Mycobacterium tuberculosis isocitrate lyase is due to decrease in structural...

Area of Science:

• Biochemistry
• Structural Biology
• Computational Biology

Background:

• Mycobacterium tuberculosis isocitrate lyase (MtbICL) is essential for glyoxylate cycle function and a validated target for anti-tuberculosis drug development.
• A specific mutation, H46A, located away from the active site, has been observed to abolish MtbICL enzyme activity.

Purpose of the Study:

• To investigate the structural and dynamic mechanisms by which the H46A mutation leads to the loss of MtbICL enzyme activity.
• To elucidate the allosteric effects of the H46A mutation on MtbICL structure and dynamics.

Main Methods:

• Molecular docking
• Molecular dynamics (MD) simulations
• Residue Interaction Network (RIN) analysis
• Principal Component Analysis (PCA)
• Cross-correlation analysis

Main Results:

• MD simulations and PCA revealed altered conformational flexibility and collective motion modes in the H46A mutant compared to wild-type MtbICL, particularly around the active site.
• RIN analysis indicated a disturbed active site geometry in the mutant enzyme.
• The H46A mutation induced dynamic perturbations that shifted the enzyme from an active to an inactive conformation.

Conclusions:

• The H46A mutation causes significant allosteric changes, leading to active site disruption and enzyme inactivation.
• Understanding these mutation-induced dynamics and interactions is crucial for designing novel anti-tuberculosis drugs and improving existing therapies.