title: ARC3, a chloroplast division factor, is a chimera of prokaryotic FtsZ and part of eukaryotic phosphatidylinositol-4-phosphate 5-kinase.
abstract: The arc3 (accumulation and replication of chloroplast) mutant of Arabidopsis thaliana has a small number of abnormally large chloroplasts in the cell, suggesting that chloroplast division is arrested in the mutant and ARC3 has an important role in the initiation of chloroplast division. To elucidate the role of ARC3, first we identified the ARC3 gene, and determined the location of ARC3 protein during chloroplast division because the localization and spatial orientation of such division factors are vital for correct chloroplast division. Sequencing analysis showed that ARC3 was a fusion of the prokaryotic FtsZ and part of the eukaryotic phosphatidylinositol-4-phosphate 5-kinase (PIP5K) genes. The PIP5K-homologous region of ARC3 had no catalytic domain but a membrane-occupation-and-recognition-nexus (MORN) repeat motif. Immunofluorescence microscopy, Western blotting analysis and in vitro chloroplast import and protease protection assays revealed that ARC3 protein was soluble, and located on the outer surface of the chloroplast in a ring-like structure at the early stage of chloroplast division. Prokaryotes have one FtsZ as a gene for division but have no ARC3 counterparts, the chimera of FtsZ and PIP5K, suggesting that the ARC3 gene might have been generated from FtsZ as another division factor during the evolution of chloroplast by endosymbiosis.
authors.affiliation: Department of Biological Sciences, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, 4259, Nagatsuta-cho, Midori-ku, Yokohama, Japan. hshimada@bio.titech.ac.jp
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Shimada
authors.forename: Masato
authors.initials: M
authors.lastname: Koizumi
authors.forename: Kouta
authors.initials: K
authors.lastname: Kuroki
authors.forename: Mariko
authors.initials: M
authors.lastname: Mochizuki
authors.forename: Hitoshi
authors.initials: H
authors.lastname: Fujimoto
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Ohta
authors.forename: Tatsuru
authors.initials: T
authors.lastname: Masuda
authors.forename: Ken-ichiro
authors.initials: K
authors.lastname: Takamiya
mesh_terms: D020816:Amino Acid Motifs / Q000235:genetics; D000595:Amino Acid Sequence / Q000235:genetics; D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics / Q000648:ultrastructure; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism*; D001483:Base Sequence / Q000235:genetics; D002736:Chloroplasts / Q000201:enzymology* / Q000235:genetics / Q000648:ultrastructure; D018076:DNA, Complementary / Q000032:analysis / Q000235:genetics; D005057:Eukaryotic Cells / Q000201:enzymology; D019143:Evolution, Molecular; D046529:Microscopy, Electron, Transmission; D008969:Molecular Sequence Data; D009154:Mutation / Q000235:genetics; D012275:Oryza; D010641:Phenotype; D017853:Phosphotransferases (Alcohol Group Acceptor) / Q000235:genetics* / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics*; D011387:Prokaryotic Cells / Q000201:enzymology; D011993:Recombinant Fusion Proteins / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D012995:Solubility; D013559:Symbiosis / Q000235:genetics
chemical_list: C493630:ARC3 protein, Arabidopsis; D029681:Arabidopsis Proteins; D018076:DNA, Complementary; C095113:FTSZ protein, Arabidopsis; D010940:Plant Proteins; D011993:Recombinant Fusion Proteins; D017853:Phosphotransferases (Alcohol Group Acceptor); C020077:1-phosphatidylinositol-4-phosphate 5-kinase