Mitochondrial fusion in yeast requires the transmembrane GTPase Fzo1p

Greg J. Hermann, John W. Thatcher, John P. Mills, Karen G. Hales, Margaret T. Fuller, Jodi Nunnari, Janet M. Shaw

Research output: Contribution to journalArticlepeer-review

417 Scopus citations


Membrane fusion is required to establish the morphology and cellular distribution of the mitochondrial compartment. In Drosophila, mutations in the fuzzy onions (fzo) GTPase block a developmentally regulated mitochondrial fusion event during spermatogenesis. Here we report that the yeast orthologue of fuzzy onions, Fzo1p, plays a direct and conserved role in mitochondrial fusion. A conditional fzo1 mutation causes the mitochondrial reticulum to fragment and blocks mitochondrial fusion during yeast mating. Fzo1p is a mitochondrial integral membrane protein with its GTPase domain exposed to the cytoplasm. Point mutations that alter conserved residues in the GTPase do- main do not affect Fzo1p localization but disrupt mitochondrial fusion. Suborganellar fractionation suggests that Fzo1p spans the outer and is tightly associated with the inner mitochondrial membrane. This topology may be required to coordinate the behavior of the two mitochondrial membranes during the fusion reaction. We propose that the fuzzy onions family of transmembrane GTPases act as molecular switches to regulate a key step in mitochondrial membrane docking and/or fusion.

Original languageEnglish (US)
Pages (from-to)359-373
Number of pages15
JournalJournal of Cell Biology
Issue number2
StatePublished - Oct 19 1998


  • GTPase
  • Membrane fusion
  • Mitochondria
  • mtDNA
  • Organelle morphology

ASJC Scopus subject areas

  • Cell Biology


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