On the role of subunit M in cytochrome cbb₃ oxidase

Area of Science:

• Biochemistry and Molecular Biology
• Microbiology
• Structural Biology

Background:

• Cytochrome cbb3 oxidases are vital heme-copper oxidases (HCOs) involved in cellular respiration and proton translocation.
• These oxidases play a critical role in the metabolism of human pathogens, making them potential therapeutic targets.
• The core cbb3 complex consists of subunits N, O, and P, with subunit N being highly conserved.

Purpose of the Study:

• To characterize the interactions between subunit M and the core cbb3 subunits (N, O, P) using molecular dynamics simulations.
• To investigate the influence of the fourth subunit (M) on the water/proton channels within the cbb3 complex.
• To assess the CcoNOPH complex and discuss the functional redundancy between CcoM and CcoQ.

Main Methods:

• Large-scale all-atom molecular dynamics simulations were employed to study the CcoNOPM complex.
• Analysis focused on inter-subunit interactions, particularly involving subunit M.
• Water and proton channel dynamics within the complex were examined.

Main Results:

• Detailed characterization of interactions between subunit M and the core cbb3 subunits (N, O, P).
• Determination of the impact of subunit M on the previously described water/proton channels.
• Assessment of the CcoNOPH complex structure and functional implications.

Conclusions:

• Subunit M plays a significant role in the stability and assembly of the cbb3 complex.
• The presence of subunit M influences the proton translocation pathway, impacting enzyme function.
• Findings provide a deeper understanding of cbb3 oxidase structure-function relationships and their potential as drug targets.