Presequence recognition by the tom40 channel contributes to precursor translocation into the mitochondrial matrix

Mol Cell Biol. 2014 Sep 15;34(18):3473-85. doi: 10.1128/MCB.00433-14. Epub 2014 Jul 7.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Binding Sites
  • Carrier Proteins / metabolism
  • Mass Spectrometry
  • Mitochondria / physiology*
  • Mitochondrial Membrane Transport Proteins / chemistry*
  • Mitochondrial Membrane Transport Proteins / genetics*
  • Mitochondrial Membrane Transport Proteins / metabolism*
  • Mitochondrial Precursor Protein Import Complex Proteins
  • Mutation
  • Phosphorylation
  • Protein Conformation
  • Protein Precursors / metabolism
  • Protein Structure, Secondary
  • Protein Transport*
  • Saccharomyces cerevisiae / genetics
  • Saccharomyces cerevisiae / metabolism*
  • Saccharomyces cerevisiae Proteins / chemistry*
  • Saccharomyces cerevisiae Proteins / genetics*
  • Saccharomyces cerevisiae Proteins / metabolism*
  • Structural Homology, Protein

Substances

  • Carrier Proteins
  • Mitochondrial Membrane Transport Proteins
  • Mitochondrial Precursor Protein Import Complex Proteins
  • Protein Precursors
  • Saccharomyces cerevisiae Proteins
  • TOM22 protein, S cerevisiae
  • Tom40 protein, S cerevisiae

Associated data

  • PDB/3EMN