Structural basis for allosteric modulation of M. tuberculosis proteasome core particle

Area of Science:

• Biochemistry
• Structural Biology
• Microbiology

Background:

• The Mycobacterium tuberculosis (Mtb) proteasome system is essential for pathogen survival by degrading damaged proteins.
• Targeting the Mtb 20S proteasome core particle (CP) is a promising strategy for tuberculosis treatment.
• Allosteric regulation of Mtb 20S CP is known, but its structural basis remains unclear.

Purpose of the Study:

• To determine the high-resolution structure of the Mtb 20S CP in an auto-inhibited state.
• To elucidate the structural mechanisms of allosteric regulation in Mtb 20S CP.
• To explore the potential of targeting allosteric sites for antituberculosis drug development.

Main Methods:

• Single-particle electron cryomicroscopy (cryo-EM) was used to determine the Mtb 20S CP structure.
• Hydrogen-deuterium exchange mass spectrometry (HDX-MS) provided insights into protein dynamics.
• Biochemical experiments were conducted to assess Mtb 20S CP activity and allosteric modulation.

Main Results:

• The study determined the structure of Mtb 20S CP in an auto-inhibited conformation.
• A rearrangement of switch helices at the α/β interface was observed, leading to the collapse of the S1 pocket and inhibition of substrate binding.
• Biochemical assays confirmed that Mtb 20S CP activity can be modulated via allosteric sites distant from the active site.

Conclusions:

• The findings reveal a novel auto-inhibited conformation of the Mtb 20S CP.
• Understanding the structural basis of allosteric regulation provides a new avenue for therapeutic intervention.
• Targeting allosteric sites represents a promising strategy for developing novel antituberculosis drugs.