The V-ATPase/ATG16L1 axis is controlled by the V1H subunit

Abstract

Defects in organellar acidification indicate compromised or infected compartments. Recruitment of the autophagy-related ATG16L1 complex to pathologically neutralized organelles targets ubiquitin-like ATG8 molecules to perturbed membranes. How this process is coupled to proton gradient disruption is unclear. Here, we reveal that the V₁H subunit of the vacuolar ATPase (V-ATPase) proton pump binds directly to ATG16L1. The V₁H/ATG16L1 interaction only occurs within fully assembled V-ATPases, allowing ATG16L1 recruitment to be coupled to increased V-ATPase assembly following organelle neutralization. Cells lacking V₁H fail to target ATG8s during influenza infection or after activation of the immune receptor stimulator of interferon genes (STING). We identify a loop within V₁H that mediates ATG16L1 binding. A neuronal V₁H isoform lacks this loop and is associated with attenuated ATG8 targeting in response to ionophores in primary murine and human iPSC-derived neurons. Thus, V₁H controls ATG16L1 recruitment following proton gradient dissipation, suggesting that the V-ATPase acts as a cell-intrinsic damage sensor.

Keywords: ATG16L1; ATP6V1H; CASM; STING; V-ATPase; VAIL; autophagy; influenza; non-canonical autophagy; vacuolar ATPase.