Chloroplast gene expression is mainly regulated at the post-transcriptional level by numerous nuclear-encoded RNA-binding protein factors. In the present study, we focus on two RNA-binding proteins: cpRNP (chloroplast ribonucleoprotein) and PPR (pentatricopeptide repeat) protein. These are suggested to be major contributors to chloroplast RNA metabolism. Tobacco cpRNPs are composed of five different proteins containing two RNA-recognition motifs and an acidic N-terminal domain. The cpRNPs are abundant proteins and form heterogeneous complexes with most ribosome-free mRNAs and the precursors of tRNAs in the stroma. The complexes could function as platforms for various RNA-processing events in chloroplasts. It has been demonstrated that cpRNPs contribute to RNA stabilization, 3′-end formation and editing. The PPR proteins occur as a superfamily only in the higher plant species. They are predicted to be involved in RNA/DNA metabolism in chloroplasts or mitochondria. Nuclear-encoded HCF152 is a chloroplast-localized protein that usually has 12 PPR motifs. The null mutant of Arabidopsis, hcf152, is impaired in the 5′-end processing and splicing of petB transcripts. HCF152 binds the petB exon–intron junctions with high affinity. The number of PPR motifs controls its affinity and specificity for RNA. It has been suggested that each of the highly variable PPR proteins is a gene-specific regulator of plant organellar RNA metabolism.
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Conference Article|
August 01 2004
Chloroplast RNA-binding and pentatricopeptide repeat proteins
T. Nakamura;
T. Nakamura
*Center for Gene Research, Nagoya University, Nagoya 464–8602, Japan
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G. Schuster;
G. Schuster
†Department of Biology, Technion-Israel Institute of Technology, Haifa 32000, Israel
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M. Sugiura;
M. Sugiura
‡Graduate School of Natural Sciences, Nagoya City University, Nagoya 467–8501, Japan
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M. Sugita
M. Sugita
1
*Center for Gene Research, Nagoya University, Nagoya 464–8602, Japan
1To whom correspondence should be addressed (email sugita@gene.nagoya-u.ac.jp).
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Publisher: Portland Press Ltd
Received:
April 27 2004
Online ISSN: 1470-8752
Print ISSN: 0300-5127
© 2004 The Biochemical Society
2004
Biochem Soc Trans (2004) 32 (4): 571–574.
Article history
Received:
April 27 2004
Citation
T. Nakamura, G. Schuster, M. Sugiura, M. Sugita; Chloroplast RNA-binding and pentatricopeptide repeat proteins. Biochem Soc Trans 1 August 2004; 32 (4): 571–574. doi: https://doi.org/10.1042/BST0320571
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