The pentatricopeptide repeat protein OTP82 is required for RNA editing of plastid ndhB and ndhG transcripts.
Several hundred nucleus-encoded factors are required for regulating gene expression in plant organelles. Among them, the most numerous are the members of the pentatricopeptide repeat (PPR) protein family. We found that PPR protein OTP82 is essential for RNA editing of the ndhB-9 and ndhG-1 sites within transcripts encoding subunits of chloroplast NAD(P)H dehydrogenase. Despite the defects in RNA editing, otp82 did not show any phenotypes in NDH activity, stability or interaction with photosystem I, suggesting that the RNA editing events mediated by OTP82 are functionally silent even though they induce amino acid alterations. In agreement with this result, both sites are partially edited even in the wild type, implying the possibility that a single gene produces heterogeneous proteins that are functionally equivalent. Although only five nucleotides separate the ndhB-8 and ndhB-9 sites, the ndhB-8 site is normally edited in otp82 mutants, suggesting that both sites are recognized by different PPR proteins. OTP82 falls into the DYW subclass containing conserved C-terminal E and DYW motifs. As in CRR22 and CRR28, the DYW motif present in OTP82 is not essential for RNA editing in vivo.
Department of Botany, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan.
Kenji
K
Okuda
Kamel
K
Hammani
Sandra K
SK
Tanz
Lianwei
L
Peng
Yoichiro
Y
Fukao
Fumiyoshi
F
Myouga
Reiko
R
Motohashi
Kazuo
K
Shinozaki
Ian
I
Small
Toshiharu
T
Shikanai
D000595:Amino Acid Sequence; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D002736:Chloroplasts / Q000235:genetics / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D015151:Immunoblotting; D008969:Molecular Sequence Data; D009154:Mutation; D009245:NADH Dehydrogenase / Q000235:genetics* / Q000378:metabolism; D009693:Nucleic Acid Hybridization; D045331:Photosystem I Protein Complex / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified; D011485:Protein Binding; D017393:RNA Editing; D018747:RNA, Chloroplast / Q000235:genetics*; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid
D029681:Arabidopsis Proteins; C000603134:OTP82 protein, Arabidopsis; D045331:Photosystem I Protein Complex; D018747:RNA, Chloroplast; D016601:RNA-Binding Proteins; C079008:ndhB protein, Arabidopsis; C538752:pentatricopeptide repeat protein, Arabidopsis; D049452:Green Fluorescent Proteins; D009245:NADH Dehydrogenase; C548935:ndhG protein, Arabidopsis