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Reduced mitochondria provide an essential function for the cytosolic methionine cycle

Justyna Zítek1, Zoltán Füssy1, Sebastian C Treitli1

  • 1Charles University, Faculty of Science, Department of Parasitology, BIOCEV, Vestec 252 50, Czech Republic.

Current Biology : CB
|November 8, 2022
PubMed

Insights

Mitochondrial-related organelles in protists perform new functions. In Paratrimastix pyriformis, these organelles host the glycine cleavage system, supplying one-carbon units for essential cellular processes.

Area of Science:

  • Cell Biology
  • Protistology
  • Biochemistry

Background:

  • Mitochondria are often lost in oxymonad protists, with Fe-S cluster assembly shifting to the cytosol.
  • The functions of mitochondrial-related organelles (MROs) in diverse protists are increasingly recognized.

Purpose of the Study:

  • To investigate the proteome of the MRO in Paratrimastix pyriformis, an oxymonad relative.
  • To identify novel functions of MROs in free-living protists.

Main Methods:

  • High-accuracy proteome analysis of MROs using Localization of Organelle Proteins by Isotope Tagging (LOPIT).

Main Results:

  • Identified enzymes linked to the glycine cleavage system (GCS) within the MRO.
  • These enzymes produce folate derivatives and formate, crucial for one-carbon metabolism.
  • These products likely support the cytosolic methionine cycle and S-adenosyl methionine recycling.

Conclusions:

  • The MRO in P. pyriformis hosts the glycine cleavage system, a previously unrecognized function.
  • This finding supports the presence of GCS in MROs of free-living protists.
  • The absence of GCS in endosymbiotic species correlates with the loss of the methionine cycle and mitochondria.
Keywords:
LOPITParatrimastixglycine cleavage systemmethionine cyclemitochondrion-related organelleone-carbon metabolismproteomespatial proteomics

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