A Dimeric PINK1-containing Complex on Depolarized Mitochondria Stimulates Parkin Recruitment

Background: PINK1 functions on depolarized mitochondria. However, details regarding its mechanism remain limited. Results: We reveal the formation of a high molecular weight complex composed of two phosphorylated PINK1 molecules that stimulates Parkin recruitment. Conclusion: The dimeric PINK1-containing complex is important for mitochondrial quality control. Significance: The PINK1 molecular process is reminiscent of receptor kinase dimerization in signal transduction. Parkinsonism typified by sporadic Parkinson disease is a prevalent neurodegenerative disease. Mutations in PINK1 (PTEN-induced putative kinase 1), a mitochondrial Ser/Thr protein kinase, or PARKIN, a ubiquitin-protein ligase, cause familial parkinsonism. The accumulation and autophosphorylation of PINK1 on damaged mitochondria results in the recruitment of Parkin, which ultimately triggers quarantine and/or degradation of the damaged mitochondria by the proteasome and autophagy. However, the molecular mechanism of PINK1 in dissipation of the mitochondrial membrane potential (m) has not been fully elucidated. Here we show by fluorescence-based techniques that the PINK1 complex formed following a decrease in m is composed of two PINK1 molecules and is correlated with intermolecular phosphorylation of PINK1. Disruption of complex formation by the PINK1 S402A mutation weakened Parkin recruitment onto depolarized mitochondria. The most disease-relevant mutations of PINK1 inhibit the complex formation. Taken together, these results suggest that formation of the complex containing dyadic PINK1 is an important step for Parkin recruitment onto damaged mitochondria.