Cytosolic enzymes with a mitochondrial ancestry from the anaerobic chytrid Piromyces sp. E2

Mol Microbiol. 1998 Dec;30(5):1017-27. doi: 10.1046/j.1365-2958.1998.01130.x.


The anaerobic chytrid Piromyces sp. E2 lacks mitochondria, but contains hydrogen-producing organelles, the hydrogenosomes. We are interested in how the adaptation to anaerobiosis influenced enzyme compartmentalization in this organism. Random sequencing of a cDNA library from Piromyces sp. E2 resulted in the isolation of cDNAs encoding malate dehydrogenase, aconitase and acetohydroxyacid reductoisomerase. Phylogenetic analysis of the deduced amino acid sequences revealed that they are closely related to their mitochondrial homologues from aerobic eukaryotes. However, the deduced sequences lack N-terminal extensions, which function as mitochondrial leader sequences in the corresponding mitochondrial enzymes from aerobic eukaryotes. Subcellular fractionation and enzyme assays confirmed that the corresponding enzymes are located in the cytosol. As anaerobic chytrids evolved from aerobic, mitochondria-bearing ancestors, we suggest that, in the course of the adaptation from an aerobic to an anaerobic lifestyle, mitochondrial enzymes were retargeted to the cytosol with the concomitant loss of their N-terminal leader sequences.

MeSH terms

  • 5' Untranslated Regions
  • Aconitate Hydratase / classification*
  • Aconitate Hydratase / genetics
  • Aconitate Hydratase / metabolism
  • Alcohol Oxidoreductases / classification*
  • Alcohol Oxidoreductases / genetics
  • Alcohol Oxidoreductases / metabolism
  • Amino Acid Sequence
  • Anaerobiosis
  • Base Sequence
  • Cytosol / enzymology
  • DNA, Complementary
  • DNA, Fungal
  • Gene Dosage
  • Gene Expression
  • Ketol-Acid Reductoisomerase
  • Malate Dehydrogenase / classification*
  • Malate Dehydrogenase / genetics
  • Malate Dehydrogenase / metabolism
  • Mitochondria / enzymology
  • Molecular Sequence Data
  • Piromyces / enzymology*
  • Piromyces / genetics
  • RNA, Fungal
  • RNA, Messenger


  • 5' Untranslated Regions
  • DNA, Complementary
  • DNA, Fungal
  • RNA, Fungal
  • RNA, Messenger
  • Alcohol Oxidoreductases
  • Malate Dehydrogenase
  • Ketol-Acid Reductoisomerase
  • Aconitate Hydratase

Associated data

  • GENBANK/Y16743
  • GENBANK/Y16747
  • GENBANK/Y16748