title: Unconventional PINK1 localization to the outer membrane of depolarized mitochondria drives Parkin recruitment.
abstract: Dysfunction of PTEN-induced putative kinase 1 (PINK1), a Ser/Thr kinase with an N-terminal mitochondrial-targeting sequence (MTS), causes familial recessive parkinsonism. Reduction of the mitochondrial membrane potential limits MTS-mediated matrix import and promotes PINK1 accumulation on the outer mitochondrial membrane (OMM) of depolarized mitochondria. PINK1 then undergoes autophosphorylation and phosphorylates ubiquitin and Parkin, a cytosolic ubiquitin ligase, for clearance of damaged mitochondria. The molecular basis for PINK1 localization on the OMM of depolarized mitochondria rather than release to the cytosol is poorly understood. Here, we disentangle the PINK1 localization mechanism using deletion mutants and a newly established constitutively active PINK1 mutant. Disruption of the MTS through N-terminal insertion of aspartic acid residues results in OMM localization of PINK1 in energized mitochondria. Unexpectedly, the MTS and putative transmembrane domain (TMD) are dispensable for OMM localization, whereas mitochondrial translocase Tom40 (also known as TOMM40) and an alternative mitochondrial localization signal that resides between the MTS and TMD are required. PINK1 utilizes a mitochondrial localization mechanism that is distinct from that of conventional MTS proteins and that presumably functions in conjunction with the Tom complex in OMM localization when the conventional N-terminal MTS is inhibited.
authors.affiliation: Protein Metabolism Project, Tokyo Metropolitan Institute of Medical Science, Setagaya-ku, Tokyo 156-8506, Japan.
authors.forename: Kei
authors.initials: K
authors.lastname: Okatsu
authors.affiliation: Protein Metabolism Project, Tokyo Metropolitan Institute of Medical Science, Setagaya-ku, Tokyo 156-8506, Japan Laboratory of Protein Metabolism, Tokyo Metropolitan Institute of Medical Science, Setagaya-ku, Tokyo 156-8506, Japan.
authors.forename: Mayumi
authors.initials: M
authors.lastname: Kimura
authors.affiliation: Department of Life Science, College of Science, Rikkyo University, Nishi-Ikebukuro, Tokyo 171-8501, Japan.
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Oka
authors.affiliation: Laboratory of Protein Metabolism, Tokyo Metropolitan Institute of Medical Science, Setagaya-ku, Tokyo 156-8506, Japan tanaka-kj@igakuken.or.jp matsuda-nr@igakuken.or.jp.
authors.forename: Keiji
authors.initials: K
authors.lastname: Tanaka
authors.affiliation: Protein Metabolism Project, Tokyo Metropolitan Institute of Medical Science, Setagaya-ku, Tokyo 156-8506, Japan tanaka-kj@igakuken.or.jp matsuda-nr@igakuken.or.jp.
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Matsuda
mesh_terms: D006367:HeLa Cells; D006801:Humans; D053078:Membrane Potential, Mitochondrial / Q000502:physiology*; D033681:Mitochondrial Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism; D051336:Mitochondrial Membranes / Q000378:metabolism*; D046912:Multiprotein Complexes / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D010766:Phosphorylation / Q000502:physiology; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D044767:Ubiquitin-Protein Ligases / Q000235:genetics / Q000378:metabolism*; D000099202:PTEN-Induced Putative Kinase; D000090622:Mitochondrial Precursor Protein Import Complex Proteins
chemical_list: D033681:Mitochondrial Membrane Transport Proteins; D046912:Multiprotein Complexes; D011494:Protein Kinases; D044767:Ubiquitin-Protein Ligases; D000099202:PTEN-Induced Putative Kinase; C111567:parkin protein; C400783:TOMM40 protein, human; D000090622:Mitochondrial Precursor Protein Import Complex Proteins
keywords: Mitochondria; PINK1; Parkin; Parkinson's disease