Prohibitin 2 links damaged mitochondria to intracellular bacteria to trigger xenophagy independent of mitophagy

Mitophagy and xenophagy, two selective autophagy pathways sharing common E3 ligases, have been proposed to intersect in host defense against invading pathogens. Here, we show that mitochondrial damage, but not mitophagy, is essential for triggering xenophagy via the inner mitochondrial membrane protein prohibitin 2 (PHB2). Upon bacteria-induced disruption of the outer mitochondrial membrane, PHB2 bridges mitochondria to bacteria by binding bacterial surface proteins, while concurrently interacting with either auto-ubiquitinated E3 ligase ARIH1 or Parkin, two well-characterized mitophagy-associated E3 ligases. This interaction positions polyubiquitin chains near PHB2-targeted bacteria to recruit selective autophagy receptors for initiating xenophagy, leading to the co-autophagic degradation of bacteria and mitochondria, a process unaffected by mitophagy inhibition. Our findings establish an uncovered mechanism of mitochondria-dependent antibacterial autophagy, positioning mitochondrial PHB2 as both a bacterial sensor and an E3 ligase scaffold, and unveiling a previously unidentified process governing the recruitment of mitophagy-associated E3 ligases to intracellular bacteria.