TIM23 facilitates PINK1 activation by safeguarding against OMA1-mediated degradation in damaged mitochondria

PINK1 is activated by autophosphorylation and forms a high-molecular-weight complex, thereby initiating the selective removal of damaged mitochondria by autophagy. Other than translocase of the outer mitochondrial membrane complexes, members of PINK1-containing protein complexes remain obscure. By mass spectrometric analysis of PINK1 co-immunoprecipitates, we identify the inner membrane protein TIM23 as a component of the PINK1 complex. TIM23 downregulation decreases PINK1 levels and significantly delays autophosphorylation, indicating that TIM23 promotes PINK1 accumulation in response to depolarization. Moreover, inactivation of the mitochondrial protease OMA1 not only enhances PINK1 accumulation but also represses the reduction in PINK1 levels induced by TIM23 downregulation, suggesting that TIM23 facilitates PINK1 activation by safeguarding against degradation by OMA1. Indeed, deficiencies of pathogenic PINK1 mutants that fail to interact with TIM23 are partially restored by OMA1 inactivation. These findings indicate that TIM23 plays a distinct role in activating mitochondrial autophagy by protecting PINK1. [Display omitted] •The mitochondrial translocase TIM23 is identified as a member of the PINK1 complex•Inactivation of TIM23 leads to a reduction in PINK1 and mislocalization of Parkin•TIM23 prevents OMA1 from degrading PINK1 in damaged mitochondria•Some pathogenic PINK1 mutations impair interactions with PINK1 and TIM23 Akabane et al. show that TIM23 is a component of the PINK1-containing protein complex and safeguards PINK1 against OMA1-dependent degradation in damaged mitochondria, indicating that TIM23 plays a distinct role in facilitating PINK1 activation and subsequent mitochondrial clearance.