title: Dual role of the receptor Tom20 in specificity and efficiency of protein import into mitochondria.
abstract: Mitochondria import most of their resident proteins from the cytosol, and the import receptor Tom20 of the outer-membrane translocator TOM40 complex plays an essential role in specificity of mitochondrial protein import. Here we analyzed the effects of Tom20 binding on NMR spectra of a long mitochondrial presequence and found that it contains two distinct Tom20-binding elements. In vitro import and cross-linking experiments revealed that, although the N-terminal Tom20-binding element is essential for targeting to mitochondria, the C-terminal element increases efficiency of protein import in the step prior to translocation across the inner membrane. Therefore Tom20 has a dual role in protein import into mitochondria: recognition of the targeting signal in the presequence and tethering the presequence to the TOM40 complex to increase import efficiency.
authors.affiliation: Department of Chemistry, Graduate School of Science, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan.
authors.forename: Hayashi
authors.initials: H
authors.lastname: Yamamoto
authors.forename: Nobuka
authors.initials: N
authors.lastname: Itoh
authors.forename: Shin
authors.initials: S
authors.lastname: Kawano
authors.forename: Yoh-ichi
authors.initials: Y
authors.lastname: Yatsukawa
authors.forename: Takaki
authors.initials: T
authors.lastname: Momose
authors.forename: Tadashi
authors.initials: T
authors.lastname: Makio
authors.forename: Mayumi
authors.initials: M
authors.lastname: Matsunaga
authors.forename: Mihoko
authors.initials: M
authors.lastname: Yokota
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Esaki
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Shodai
authors.forename: Daisuke
authors.initials: D
authors.lastname: Kohda
authors.forename: Alyson E Aiken
authors.initials: AE
authors.lastname: Hobbs
authors.forename: Robert E
authors.initials: RE
authors.lastname: Jensen
authors.forename: Toshiya
authors.initials: T
authors.lastname: Endo
mesh_terms: D001665:Binding Sites / Q000235:genetics; D047468:Immunoprecipitation; D008928:Mitochondria / Q000378:metabolism*; D033681:Mitochondrial Membrane Transport Proteins / Q000378:metabolism*; D008958:Models, Molecular; D019906:Nuclear Magnetic Resonance, Biomolecular; D011485:Protein Binding / Q000235:genetics / Q000502:physiology; D021381:Protein Transport / Q000502:physiology; D006180:Proton-Translocating ATPases / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*
chemical_list: D033681:Mitochondrial Membrane Transport Proteins; D029701:Saccharomyces cerevisiae Proteins; C489350:TOM20 protein, S cerevisiae; C066555:Tom40 protein, S cerevisiae; D006180:Proton-Translocating ATPases