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Functional characterization of ObgC in ribosome biogenesis during chloroplast development
Author(s) -
Bang Woo Young,
Chen Ji,
Jeong In Sil,
Kim Sam Woong,
Kim Chul Wook,
Jung Hyun Suk,
Lee Kyoung Hwan,
Kweon HeeSeok,
Yoko Ishizaki,
Shiina Takashi,
Bahk Jeong Dong
Publication year - 2012
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1111/j.1365-313x.2012.04976.x
Subject(s) - ribosome biogenesis , biology , plastid , biogenesis , ribosome , ribosomal protein , mutant , genetics , ribosomal rna , microbiology and biotechnology , rna , 23s ribosomal rna , chloroplast , gene
Summary 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.