LASER couples damage sensing to ESCRT assembly for lysosome repair

Recruitment and assembly of Endosomal Sorting Complex Required for Transport (ESCRT) I-III rapidly counteracts membrane damage, but how ESCRT-I recognizes defective lysosomal membranes is unclear. Leveraging genome-wide CRISPRi screens in a damage-sensitized genetic background, we discovered LC3/GABARAP Assisted Stimulator for ESCRT Recruitment (LASER), a multicomponent protein assembly that forms rapidly upon calcium release from damaged lysosomes, and which couples sensing of lysosomal membrane damage to ESCRT-dependent repair.

At the core of LASER is Trk-fused gene (TFG), an ER exit sites (ERES) resident protein that translocates to damaged lysosomes by binding to ATG8 family proteins (LC3/GABARAP) conjugated to lysosomal phospholipids. ATG8-bound TFG forms oligomeric assemblies that directly recruit the essential ESCRT-I subunit, Tumor Suppressor Gene 101 (TSG101), via conserved motif recognition enhanced by avidity-driven interactions. TFG binding to TSG101 stimulates sequential ESCRT I-II-III polymerization and promotes membrane repair.