Organelle fission in eukaryotes.

The cellular machineries that power chloroplast and mitochondrial division in eukaryotes carry out the topologically challenging job of constricting and severing these double-membraned organelles. Consistent with their endosymbiotic origins, mitochondria in protists and chloroplasts in photosynthetic eukaryotes have evolved organelle-targeted forms of FtsZ, the prokaryotic ancestor of tubulin, as key components of their fission complexes. In fungi, animals and plants, mitochondria no longer utilize FtsZ for division, but several mitochondrial division proteins that localize to the outer membrane and intermembrane space, including two related to the filament-forming dynamins, have been identified in yeast and animals. Although the reactions that mediate organelle division are not yet understood, recent progress in uncovering the constituents of the organelle division machineries promises rapid advancement in our understanding of the biochemical mechanisms underlying the distinct but related processes of chloroplast and mitochondrial division in eukaryotes.