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

Ophiobolin
A (OPA) is a sesterterpenoid fungal natural product
with broad anticancer activity. While OPA possesses multiple electrophilic
moieties that can covalently react with nucleophilic amino acids on
proteins, the proteome-wide targets and mechanism of OPA remain poorly
understood in many contexts. In this study, we used covalent chemoproteomic
platforms to map the proteome-wide reactivity of the OPA in a highly
sensitive lung cancer cell line. Among several proteins that OPA engaged,
we focused on two targets: lysine-72 of cytochrome c oxidase subunit
5A (COX5A) and cysteine-53 of mitochondrial hypoxia induced gene 1
domain family member 2A (HIGD2A). These two subunit proteins are part
of complex IV (cytochrome C oxidase) within the electron transport
chain and contributed significantly to the antiproliferative activity
of OPA. OPA activated mitochondrial respiration in a COX5A- and HIGD2A-dependent
manner, leading to an initial spike in mitochondrial ATP and heightened
mitochondrial oxidative stress. OPA compromised mitochondrial membrane
potential, ultimately leading to ATP depletion. We have used chemoproteomic
strategies to discover a unique anticancer mechanism of OPA through
activation of complex IV leading to compromised mitochondrial energetics
and rapid cell death.

Ophiobolin A（OPA）是一种广谱抗肿瘤活性四萜类真菌天然产物。尽管OPA拥有多个亲电基团，能够与蛋白质上的亲核氨基酸共价反应，但OPA在许多情境下的全蛋白质组靶点及其作用机制仍然知之甚少。在本研究中，我们运用共价化学蛋白质组学平台，对高度敏感的肺癌细胞系中OPA的全蛋白质组反应进行了高灵敏度映射。在OPA所涉及的多种蛋白质中，我们聚焦于两个靶点：细胞色素c氧化酶亚基5A（COX5A）的赖氨酸72位点和线粒体低氧诱导基因1家族成员2A（HIGD2A）的半胱氨酸53位点。这两个亚基蛋白是电子传递链中的复合物IV（细胞色素C氧化酶）的组成部分，对OPA的抗增殖活性贡献显著。OPA以COX5A和HIGD2A依赖的方式激活线粒体呼吸，导致线粒体ATP的初始峰值和线粒体氧化应激的增强。OPA破坏了线粒体膜电位，最终导致ATP耗竭。我们通过化学蛋白质组学策略，揭示了OPA通过激活复合物IV，导致线粒体能量代谢受损和细胞快速死亡的独特抗癌机制。