Abstract
Selective autophagy of damaged organelles is important to maintain cellular homeostasis. The mechanisms how autophagy selects specific targets is often poorly understood. Rabaptin5 was previously known as a major regulator of early endosome identity and maturation. Here, we identify two novel Rabaptin5 interactors: FIP200, a subunit of the ULK1 autophagy initiator complex, and ATG16L1, a central component of the E3-like enzyme in LC3 lipidation. Autophagy of early endosomes damaged by chloroquine or monensin treatment requires Rabaptin5 and particularly a short sequence motif that binds to the WD domain of ATG16L1. Rabaptin5 and its interaction with ATG16L1 further contributes to the autophagic elimination of Salmonella enterica early after infection, when it resides in phagosomes with early endosomal characteristics. Our results demonstrate a novel function of Rabaptin5 in quality control of early endosomes in the selective targeting of autophagy to damaged early endosomes and phagosomes.