A chloroplast protein homologous to the eubacterial topological specificity factor minE plays a role in chloroplast division.
We report the identification of a nucleus-encoded minE gene, designated AtMinE1, of Arabidopsis. The encoded AtMinE1 protein possesses both N- and C-terminal extensions, relative to the eubacterial and algal chloroplast-encoded MinE proteins. The N-terminal extension functioned as a chloroplast-targeting transit peptide, as revealed by a transient expression assay using an N terminus:green fluorescent protein fusion. Histochemical beta-glucuronidase staining of transgenic Arabidopsis lines harboring an AtMinE1 promoter::uidA reporter fusion unveiled specific activation of the promoter in green tissues, especially at the shoot apex, which suggests a requirement for cell division-associated AtMinE1 expression for proplastid division in green tissues. In addition, we generated transgenic plants overexpressing a full-length AtMinE1 cDNA and examined the subcellular structures of those plants. Giant heteromorphic chloroplasts were observed in transgenic plants, with a reduced number per cell, whereas mitochondrial morphology remained similar to that of wild-type plants. Taken together, these observations suggest that MinE is the third conserved component involved in chloroplast division.
Itoh
R
R
Plant Science Center, RIKEN, Wako, Saitama 351-0198, Japan. ryuitoh@postman.riken.go.jp
Fujiwara
M
M
Nagata
N
N
Yoshida
S
S
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000235:genetics* / Q000378:metabolism / Q000648:ultrastructure; D029681:Arabidopsis Proteins / Q000235:genetics / Q000502:physiology*; D001419:Bacteria / Q000378:metabolism; D001426:Bacterial Proteins / Q000235:genetics / Q000502:physiology; D018797:Cell Cycle Proteins; D002467:Cell Nucleus / Q000378:metabolism; D002736:Chloroplasts / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D029968:Escherichia coli Proteins; D018506:Gene Expression Regulation, Plant; D017930:Genes, Reporter / Q000235:genetics; D006651:Histocytochemistry; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D010802:Phylogeny; D018520:Plant Shoots / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity
D029681:Arabidopsis Proteins; D001426:Bacterial Proteins; D018797:Cell Cycle Proteins; D029968:Escherichia coli Proteins; C093548:MinE protein, E coli; D011993:Recombinant Fusion Proteins