Capturing the catalytic intermediates of parkin ubiquitination

Abstract Dysfunction of the E3 ligase parkin is causative for early-onset Parkinson’s disease. Parkin accepts ubiquitin from an E2 conjugating enzyme, forming a short-lived catalytic intermediate, and then transfers ubiquitin to outer mitochondrial membrane proteins to signal mitophagy. Here, we used intein chemistry methods along with NMR spectroscopy to capture and determine the structure of the parkin transthiolation intermediate. The structure shows an α-helix, unobserved in all previous structures, that acts as the recognition motif for ubiquitin transfer from the