title: Presequence recognition by the tom40 channel contributes to precursor translocation into the mitochondrial matrix.
abstract: More than 70% of mitochondrial proteins utilize N-terminal presequences as targeting signals. Presequence interactions with redundant cytosolic receptor domains of the translocase of the outer mitochondrial membrane (TOM) are well established. However, after the presequence enters the protein-conducting Tom40 channel, the recognition events that occur at the trans side leading up to the engagement of the presequence with inner membrane-bound receptors are less well defined. Using a photoaffinity-labeling approach with modified presequence peptides, we identified Tom40 as a presequence interactor of the TOM complex. Utilizing mass spectrometry, we mapped Tom40's presequence-interacting regions to both sides of the β-barrel. Analysis of a phosphorylation site within one of the presequence-interacting regions revealed altered translocation kinetics along the presequence pathway. Our analyses assess the relation between the identified presequence-binding region of Tom40 and the intermembrane space domain of Tom22. The identified presequence-interacting region of Tom40 is capable of functioning independently of the established trans-acting TOM presequence-binding domain during matrix import.
authors.affiliation: Institute of Cellular Biochemistry, University Medical Center Göttingen, Göttingen, Germany.
authors.forename: Jonathan
authors.initials: J
authors.lastname: Melin
authors.affiliation: Institute of Cellular Biochemistry, University Medical Center Göttingen, Göttingen, Germany.
authors.forename: Christian
authors.initials: C
authors.lastname: Schulz
authors.affiliation: International Institute of Molecular and Cell Biology, Warsaw, Poland.
authors.forename: Lidia
authors.initials: L
authors.lastname: Wrobel
authors.affiliation: Institute of Cellular Biochemistry, University Medical Center Göttingen, Göttingen, Germany.
authors.forename: Olaf
authors.initials: O
authors.lastname: Bernhard
authors.affiliation: International Institute of Molecular and Cell Biology, Warsaw, Poland.
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Chacinska
authors.affiliation: Proteomics Group, Max Planck Institute for Experimental Medicine, Göttingen, Germany.
authors.forename: Olaf
authors.initials: O
authors.lastname: Jahn
authors.affiliation: Institute of Cellular Biochemistry, University Medical Center Göttingen, Göttingen, Germany.
authors.forename: Bernhard
authors.initials: B
authors.lastname: Schmidt
authors.affiliation: Institute of Cellular Biochemistry, University Medical Center Göttingen, Göttingen, Germany Max Planck Institute for Biophysical Chemistry, Göttingen, Germany Peter.Rehling@medizin.uni-goettingen.de.
authors.forename: Peter
authors.initials: P
authors.lastname: Rehling
mesh_terms: D000818:Animals; D001665:Binding Sites; D002352:Carrier Proteins / Q000378:metabolism; D013058:Mass Spectrometry; D008928:Mitochondria / Q000502:physiology*; D033681:Mitochondrial Membrane Transport Proteins / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism*; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D009154:Mutation; D010766:Phosphorylation; D011487:Protein Conformation; D011498:Protein Precursors / Q000378:metabolism; D017433:Protein Structure, Secondary; D021381:Protein Transport; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000235:genetics* / Q000378:metabolism*; D040681:Structural Homology, Protein
chemical_list: D002352:Carrier Proteins; D033681:Mitochondrial Membrane Transport Proteins; D000090622:Mitochondrial Precursor Protein Import Complex Proteins; D011498:Protein Precursors; D029701:Saccharomyces cerevisiae Proteins; C090857:TOM22 protein, S cerevisiae; C066555:Tom40 protein, S cerevisiae