title: Roles of Tom70 in import of presequence-containing mitochondrial proteins.
abstract: Mitochondrial protein traffic requires precise recognition of the mitochondrial targeting signals by the import receptors on the mitochondrial surface including a general import receptor Tom20 and a receptor for presequence-less proteins, Tom70. Here we took a proteome-wide approach of mitochondrial protein import in vitro to find a set of presequence-containing precursor proteins for recognition by Tom70. The presequences of the Tom70-dependent precursor proteins were recognized by Tom20, whereas their mature parts exhibited Tom70-dependent import when attached to the presequence of Tom70-independent precursor proteins. The mature parts of the Tom70-dependent precursor proteins have the propensity to aggregate, and the presence of the receptor domain of Tom70 prevents their aggregate formation. Therefore Tom70 plays the role of a docking site for not only cytosolic chaperones but also aggregate-prone substrates to maintain their solubility for efficient transfer to downstream components of the mitochondrial import machineries.
authors.affiliation: Department of Chemistry, Graduate School of Science, Japan Science and Technology Agency, Research Centre for Material Science, Nagoya University, Chikusa-ku, Nagoya 464-8602, Japan.
authors.forename: Hayashi
authors.initials: H
authors.lastname: Yamamoto
authors.forename: Kenji
authors.initials: K
authors.lastname: Fukui
authors.forename: Hisashi
authors.initials: H
authors.lastname: Takahashi
authors.forename: Shingo
authors.initials: S
authors.lastname: Kitamura
authors.forename: Takuya
authors.initials: T
authors.lastname: Shiota
authors.forename: Kayoko
authors.initials: K
authors.lastname: Terao
authors.forename: Mayumi
authors.initials: M
authors.lastname: Uchida
authors.forename: Masatoshi
authors.initials: M
authors.lastname: Esaki
authors.forename: Shuh-ichi
authors.initials: S
authors.lastname: Nishikawa
authors.forename: Tohru
authors.initials: T
authors.lastname: Yoshihisa
authors.forename: Koji
authors.initials: K
authors.lastname: Yamano
authors.forename: Toshiya
authors.initials: T
authors.lastname: Endo
mesh_terms: D015180:Electrophoresis, Gel, Two-Dimensional; D008928:Mitochondria / Q000378:metabolism*; D033681:Mitochondrial Membrane Transport Proteins / Q000235:genetics / Q000378:metabolism*; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D024101:Mitochondrial Proteins / Q000235:genetics / Q000378:metabolism*; D018832:Molecular Chaperones; D011498:Protein Precursors / Q000235:genetics / Q000378:metabolism*; D020543:Proteome / Q000032:analysis*; D012331:RNA, Fungal / Q000235:genetics / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
chemical_list: D033681:Mitochondrial Membrane Transport Proteins; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D024101:Mitochondrial Proteins; D018832:Molecular Chaperones; D011498:Protein Precursors; D020543:Proteome; D012331:RNA, Fungal; D029701:Saccharomyces cerevisiae Proteins; C489039:TOM70 protein, S cerevisiae