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A zinc finger motif-containing protein is essential for chloroplast RNA editing.

Sun T, Shi X, Friso G, Van Wijk K, Bentolila S, Hanson MR - PLoS Genet. (2015)

Bottom Line: Members of two additional gene families, the RIP/MORF and ORRM families, have each been found to be required for editing of particular sets of Cs in mitochondria and/or chloroplasts.The organelle zinc finger editing factor family (OZ) contains 4 members in Arabidopsis, three that are predicted to be targeted to chloroplasts and one to mitochondria.With the identification of OZ1, there are now 4 nuclear-encoded protein families known to be essential for plant organelle RNA editing.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York, United States of America.

ABSTRACT
C-to-U editing of transcripts in plant organelles is carried out by small (<400 kD) protein complexes called editosomes. Recognition of the proper C target for editing is mediated by pentatricopeptide repeat (PPR) containing proteins that recognize cis-elements. Members of two additional gene families, the RIP/MORF and ORRM families, have each been found to be required for editing of particular sets of Cs in mitochondria and/or chloroplasts. By co-immunoprecipitation of the chloroplast editing factor ORRM1, followed by mass spectrometry, we have now identified a member of the RanBP2 type zinc fingers (pFAM00641) protein family that is required for editing of 14 sites in chloroplasts and affects editing efficiency of another 16 chloroplast C targets. In yeast two-hybrid assays, OZ1 (Organelle Zinc finger 1) interacts with PPR site recognition factors whose cognate sites are affected when OZ1 is mutated. No interaction of OZ1 with the chloroplast editing factors RIP2 and RIP9 was detected; however, OZ1 interacts with ORRM1, which binds to RIP proteins, allowing us to build a model for the chloroplast RNA editosome. The RNA editosomes that act upon most chloroplast C targets are likely to contain a PPR protein recognition factor, either RIP2 or RIP9, ORRM1, and OZ1. The organelle zinc finger editing factor family (OZ) contains 4 members in Arabidopsis, three that are predicted to be targeted to chloroplasts and one to mitochondria. With the identification of OZ1, there are now 4 nuclear-encoded protein families known to be essential for plant organelle RNA editing.

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Transient expression of OZ1 under a 35S promoter in oz1–1 mutant protoplasts complements the editing defects.Two repeats of each treatment were assayed by PPE. The average for each group is displayed in a third bar. Not transfected: untreated oz1–1 mutant protoplasts. 35S::CP-YFP: oz1–1 protoplasts transfected with 35S::cpYFP. 35S::OZ1: oz1–1 protoplasts transfected with 35S::OZ1. E, edited band; U, unedited band; O, oligonucleotide. Significance * (P<0.05), ** (P<0.01), *** (P<0.001).
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pgen.1005028.g007: Transient expression of OZ1 under a 35S promoter in oz1–1 mutant protoplasts complements the editing defects.Two repeats of each treatment were assayed by PPE. The average for each group is displayed in a third bar. Not transfected: untreated oz1–1 mutant protoplasts. 35S::CP-YFP: oz1–1 protoplasts transfected with 35S::cpYFP. 35S::OZ1: oz1–1 protoplasts transfected with 35S::OZ1. E, edited band; U, unedited band; O, oligonucleotide. Significance * (P<0.05), ** (P<0.01), *** (P<0.001).

Mentions: RNA was extracted from protoplasts two days after the transfection and analyzed by PPE to examine the editing efficiency (Fig. 7). No significant difference in editing was seen between the untransfected control and the 35S::cpYFP-transfected control. Introduction of 35S::OZ1 significantly increases the editing level for all the sites we tested. rpoA C200 increased from 3% to 21%, ndhB C836 from 19% to 31% and rps12-(i1) C58 from 3% to 15%. This confirms that the editing defects in the oz-1–1 mutant can be reduced by introduction of OZ1.


A zinc finger motif-containing protein is essential for chloroplast RNA editing.

Sun T, Shi X, Friso G, Van Wijk K, Bentolila S, Hanson MR - PLoS Genet. (2015)

Transient expression of OZ1 under a 35S promoter in oz1–1 mutant protoplasts complements the editing defects.Two repeats of each treatment were assayed by PPE. The average for each group is displayed in a third bar. Not transfected: untreated oz1–1 mutant protoplasts. 35S::CP-YFP: oz1–1 protoplasts transfected with 35S::cpYFP. 35S::OZ1: oz1–1 protoplasts transfected with 35S::OZ1. E, edited band; U, unedited band; O, oligonucleotide. Significance * (P<0.05), ** (P<0.01), *** (P<0.001).
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4359148&req=5

pgen.1005028.g007: Transient expression of OZ1 under a 35S promoter in oz1–1 mutant protoplasts complements the editing defects.Two repeats of each treatment were assayed by PPE. The average for each group is displayed in a third bar. Not transfected: untreated oz1–1 mutant protoplasts. 35S::CP-YFP: oz1–1 protoplasts transfected with 35S::cpYFP. 35S::OZ1: oz1–1 protoplasts transfected with 35S::OZ1. E, edited band; U, unedited band; O, oligonucleotide. Significance * (P<0.05), ** (P<0.01), *** (P<0.001).
Mentions: RNA was extracted from protoplasts two days after the transfection and analyzed by PPE to examine the editing efficiency (Fig. 7). No significant difference in editing was seen between the untransfected control and the 35S::cpYFP-transfected control. Introduction of 35S::OZ1 significantly increases the editing level for all the sites we tested. rpoA C200 increased from 3% to 21%, ndhB C836 from 19% to 31% and rps12-(i1) C58 from 3% to 15%. This confirms that the editing defects in the oz-1–1 mutant can be reduced by introduction of OZ1.

Bottom Line: Members of two additional gene families, the RIP/MORF and ORRM families, have each been found to be required for editing of particular sets of Cs in mitochondria and/or chloroplasts.The organelle zinc finger editing factor family (OZ) contains 4 members in Arabidopsis, three that are predicted to be targeted to chloroplasts and one to mitochondria.With the identification of OZ1, there are now 4 nuclear-encoded protein families known to be essential for plant organelle RNA editing.

View Article: PubMed Central - PubMed

Affiliation: Department of Molecular Biology and Genetics, Cornell University, Ithaca, New York, United States of America.

ABSTRACT
C-to-U editing of transcripts in plant organelles is carried out by small (<400 kD) protein complexes called editosomes. Recognition of the proper C target for editing is mediated by pentatricopeptide repeat (PPR) containing proteins that recognize cis-elements. Members of two additional gene families, the RIP/MORF and ORRM families, have each been found to be required for editing of particular sets of Cs in mitochondria and/or chloroplasts. By co-immunoprecipitation of the chloroplast editing factor ORRM1, followed by mass spectrometry, we have now identified a member of the RanBP2 type zinc fingers (pFAM00641) protein family that is required for editing of 14 sites in chloroplasts and affects editing efficiency of another 16 chloroplast C targets. In yeast two-hybrid assays, OZ1 (Organelle Zinc finger 1) interacts with PPR site recognition factors whose cognate sites are affected when OZ1 is mutated. No interaction of OZ1 with the chloroplast editing factors RIP2 and RIP9 was detected; however, OZ1 interacts with ORRM1, which binds to RIP proteins, allowing us to build a model for the chloroplast RNA editosome. The RNA editosomes that act upon most chloroplast C targets are likely to contain a PPR protein recognition factor, either RIP2 or RIP9, ORRM1, and OZ1. The organelle zinc finger editing factor family (OZ) contains 4 members in Arabidopsis, three that are predicted to be targeted to chloroplasts and one to mitochondria. With the identification of OZ1, there are now 4 nuclear-encoded protein families known to be essential for plant organelle RNA editing.

Show MeSH