Ophiobolin A Covalently Targets Mitochondrial Complex IV Leading to Metabolic Collapse in Cancer Cells

Area of Science:

• Biochemistry
• Molecular Biology
• Cancer Research

Background:

• Ophiobolin A (OPA) is a fungal sesterterpenoid with known anticancer properties.
• Its precise proteome-wide targets and anticancer mechanisms remain incompletely understood.
• OPA's electrophilic nature suggests covalent interactions with proteins.

Purpose of the Study:

• To elucidate the proteome-wide targets and anticancer mechanism of Ophiobolin A (OPA).
• To investigate the role of specific protein targets in OPA's antiproliferative activity.
• To understand the impact of OPA on mitochondrial function and cellular energetics.

Main Methods:

• Utilized covalent chemoproteomic platforms to map OPA's protein reactivity in lung cancer cells.
• Identified and focused on two key protein targets: COX5A (lysine-72) and HIGD2A (cysteine-53).
• Assessed the functional consequences of OPA engagement with these targets on mitochondrial respiration and ATP levels.

Main Results:

• OPA covalently binds to specific sites on cytochrome c oxidase subunit 5A (COX5A) and mitochondrial hypoxia induced gene 1 domain family member 2A (HIGD2A).
• These proteins are components of mitochondrial complex IV, crucial for electron transport.
• OPA's interaction activates mitochondrial respiration, causing an initial ATP surge and oxidative stress, followed by ATP depletion and cell death.

Conclusions:

• OPA exhibits a unique anticancer mechanism by targeting and activating mitochondrial complex IV (cytochrome C oxidase).
• This activation leads to dysregulated mitochondrial energetics, including initial hyper-respiration and subsequent ATP depletion.
• The study reveals a novel pathway for OPA-induced cancer cell death mediated by compromised mitochondrial function.