Structure-based targeting of Atg8 uncovers its essential role in autophagy-mediated detoxification

Autophagy degrades and recycles intracellular material, allowing cells to maintain homeostasis and adapt to environmental stress. In the rice blast fungus Magnaporthe oryzae , the core autophagy protein MoAtg8 is required for autophagosome formation and host infection. Here, we determined the crystal structure of MoAtg8 and used it for structure-guided virtual screening of a focused compound library enriched for natural products and autophagy-related molecules. This screen identified nordihydroguaiaretic acid (NDGA), a naturally occurring lignan, as a MoAtg8-binding compound. NDGA suppressed conidial germination and appressorium formation, disrupted membrane integrity, and reduced pathogenicity in M. oryzae , with no detectable phytotoxicity to rice under the conditions tested. Mechanistically, the 5-lipoxygenase Mo5Lox, a target of NDGA, bound NDGA with lower affinity than MoAtg8. MoAtg8 associated with NDGA through Gln81 and promoted its autophagy-dependent delivery to vacuoles, thereby reducing compound availability to toxicity-associated targets. Disruption of autophagy or mutation of Gln81 in MoAtg8 increased fungal sensitivity to NDGA. These findings identify an autophagy-mediated detoxification route for an exogenous antifungal compound and reveal how MoAtg8-dependent trafficking modulates NDGA efficacy in a plant-pathogenic fungus.