Structure and function of Parkin E3 ubiquitin ligasereveals aspects of RING and HECT ligases

摘要

Parkin is a RING-between-RING E3 ligase that functions in the covalent attachment of ubiquitinto specific substrates, and mutations in Parkin are linked to Parkinson’s disease, cancerand mycobacterial infection. The RING-between-RING family of E3 ligases are suggested tofunction with a canonical RING domain and a catalytic cysteine residue usually restricted toHECT E3 ligases, thus termed ‘RING/HECT hybrid’ enzymes. Here we present the 1.58structure of Parkin-R0RBR, revealing the fold architecture for the four RING domains, andseveral unpredicted interfaces. Examination of the Parkin active site suggests a catalyticnetwork consisting of C431 and H433. In cells, mutation of C431 eliminatesParkin-catalysed degradation of mitochondria, and capture of an ubiquitin oxyester confirmsC431 as Parkin’s cellular active site. Our data confirm that Parkin is a RING/HECT hybrid, andprovide the first crystal structure of an RING-between-RING E3 ligase at atomic resolution,providing insight into this disease-related protein.