Septins stabilize mitochondria in Tetrahymena thermophila.
We describe phylogenetic and functional studies of three septins in the free-living ciliate Tetrahymena thermophila. Both deletion and overproduction of septins led to vacuolization of mitochondria, destabilization of the nuclear envelope, and increased autophagy. All three green fluorescent protein-tagged septins localized to mitochondria. Specific septins localized to the outer mitochondrial membrane, to septa formed during mitochondrial scission, or to the mitochondrion-associated endoplasmic reticulum. The only other septins known to localize to mitochondria are human ARTS and murine M-septin, both alternatively spliced forms of Sep4 (S. Larisch, Cell Cycle 3:1021-1023, 2004; S. Takahashi, R. Inatome, H. Yamamura, and S. Yanagi, Genes Cells 8:81-93, 2003). It therefore appears that septins have been recruited to mitochondrial functions independently in at least two eukaryotic lineages and in both cases are involved in apoptotic events.
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Department of Cellular Biology, University of Georgia, Athens, GA 30602-2607, USA.
Strzyzewska-Jówko
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Gaertig
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Jerka-Dziadosz
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D000818:Animals; D017209:Apoptosis / Q000502:physiology; D003598:Cytoskeletal Proteins / Q000235:genetics / Q000378:metabolism*; D004721:Endoplasmic Reticulum / Q000378:metabolism / Q000648:ultrastructure; D019143:Evolution, Molecular; D049452:Green Fluorescent Proteins; D046529:Microscopy, Electron, Transmission; D008928:Mitochondria / Q000378:metabolism* / Q000648:ultrastructure; D051336:Mitochondrial Membranes / Q000378:metabolism* / Q000648:ultrastructure; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism*; D016808:Tetrahymena thermophila / Q000378:metabolism* / Q000648:ultrastructure
D003598:Cytoskeletal Proteins; D015800:Protozoan Proteins; D049452:Green Fluorescent Proteins