Abstract
FIS1 is an outer mitochondrial membrane protein that functions in mitochondrial fission in yeast and human. In this study, we identified two Arabidopsis FIS1 homologues named AtFIS1a and AtFIS1b. These proteins have a hydrophobic region in the C-terminus predicted to be a transmembrane domain. To determine whether AtFIS1a localizes to mitochondria, we constructed some expression plasmids of GFP and AtFIS1a. The fusion protein was observed at the surface of mitochondria. GFP-AtFIS1a signals were also observed localizing to peroxisomes and chloroplasts. The C-terminal hydrophobic region of AtFIS1a was enough for it to localize to each of these organelles. To investigate the function of AtFIS1a in organelle fission, we introduced an antisense AtFIS1a gene into living Arabidopsis cells. In these cells, enlarged mitochondria and elongated peroxisomes were observed. These results suggest that AtFIS1a is at least related to division of mitochondria and peroxisomes.
