Minimal peptide length required to span the mitochondrial protein translocases in Trypanosoma brucei

Mol Biochem Parasitol. 2021 Jul:244:111393. doi: 10.1016/j.molbiopara.2021.111393. Epub 2021 Jun 29.


Mitochondrial protein import depends on heterooligomeric translocases in the outer and inner membranes. Using import substrates consisting of various lengths of the N-terminal part of mitochondrial dihydrolipoamide dehydrogenase (LDH) fused to dihydrofolate reductase we present an in vivo analysis showing that in Trypanosoma brucei at least 96 aa of mature LDH are required to efficiently produce an import intermediate that spans both translocases. This is different to yeast, where around 50 aa are sufficient to achieve the same task and likely reflects the different arrangement and architecture of the trypanosomal mitochondrial translocases. Furthermore, we show that formation of the stuck import intermediate leads to a strong growth inhibition suggesting that, depending on the length of the LDH, the import channels in the translocases are quantitatively blocked.

Keywords: ATOM complex; Mitochondrial protein import; TIM complex; Trypanosoma.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Dihydrolipoamide Dehydrogenase / genetics*
  • Dihydrolipoamide Dehydrogenase / metabolism
  • Gene Expression Regulation
  • Mitochondria / enzymology
  • Mitochondria / genetics*
  • Mitochondrial Proteins / genetics*
  • Mitochondrial Proteins / metabolism
  • Protein Translocation Systems / genetics*
  • Protein Translocation Systems / metabolism
  • Protein Transport
  • Protozoan Proteins / genetics*
  • Protozoan Proteins / metabolism
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • Saccharomyces cerevisiae / enzymology
  • Saccharomyces cerevisiae / genetics
  • Species Specificity
  • Tetrahydrofolate Dehydrogenase / genetics*
  • Tetrahydrofolate Dehydrogenase / metabolism
  • Trypanosoma brucei brucei / enzymology
  • Trypanosoma brucei brucei / genetics*


  • Mitochondrial Proteins
  • Protein Translocation Systems
  • Protozoan Proteins
  • Recombinant Fusion Proteins
  • Tetrahydrofolate Dehydrogenase
  • Dihydrolipoamide Dehydrogenase