title: Functional characterization of ObgC in ribosome biogenesis during chloroplast development.
abstract: The Spo0B-associated GTP-binding protein (Obg) GTPase, essential for bacterial viability, is also conserved in eukaryotes, but its primary role in eukaryotes remains unknown. Here, our functional characterization of Arabidopsis and rice obgc mutants strongly underlines the evolutionarily conserved role of eukaryotic Obgs in organellar ribosome biogenesis. The mutants exhibited a chlorotic phenotype, caused by retarded chloroplast development. A plastid DNA macroarray revealed a plastid-encoded RNA polymerase (PEP) deficiency in an obgc mutant, caused by incompleteness of the PEP complex, as its western blot exhibited reduced levels of RpoA protein, a component of PEP. Plastid rRNA profiling indicated that plastid rRNA processing is defective in obgc mutants, probably resulting in impaired ribosome biogenesis and, in turn, in reduced levels of RpoA protein. RNA co-immunoprecipitation revealed that ObgC specifically co-precipitates with 23S rRNA in vivo. These findings indicate that ObgC functions primarily in plastid ribosome biogenesis during chloroplast development. Furthermore, complementation analysis can provide new insights into the functional modes of three ObgC domains, including the Obg fold, G domain and OCT.
authors.affiliation: Swine Science and Technology Center, Gyeongnam National University of Science and Technology-GNTECH, Jinju 660-758, Korea.
authors.forename: Woo Young
authors.initials: WY
authors.lastname: Bang
authors.forename: Ji
authors.initials: J
authors.lastname: Chen
authors.forename: In Sil
authors.initials: IS
authors.lastname: Jeong
authors.forename: Sam Woong
authors.initials: SW
authors.lastname: Kim
authors.forename: Chul Wook
authors.initials: CW
authors.lastname: Kim
authors.forename: Hyun Suk
authors.initials: HS
authors.lastname: Jung
authors.forename: Kyoung Hwan
authors.initials: KH
authors.lastname: Lee
authors.forename: Hee-Seok
authors.initials: HS
authors.lastname: Kweon
authors.forename: Ishizaki
authors.initials: I
authors.lastname: Yoko
authors.forename: Takashi
authors.initials: T
authors.lastname: Shiina
authors.forename: Jeong Dong
authors.initials: JD
authors.lastname: Bahk
mesh_terms: D017360:Arabidopsis / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002736:Chloroplasts / Q000378:metabolism*; D020869:Gene Expression Profiling; D018506:Gene Expression Regulation, Plant; D005816:Genetic Complementation Test; D016254:Mutagenesis, Insertional; D009154:Mutation; D012275:Oryza / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D034622:RNA Interference; D018749:RNA, Plant / Q000235:genetics; D012338:RNA, Ribosomal, 23S / Q000235:genetics; D012270:Ribosomes / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D018749:RNA, Plant; D012338:RNA, Ribosomal, 23S