The RanBP2 zinc finger domains of chloroplast RNA editing factor OZ1 are required for protein–protein interactions and conversion of C to U
SUMMARY In the chloroplast, organelle zinc finger 1 (OZ1) is a RanBP2‐type zinc finger (Znf) protein required for many RNA editing events, a process by which specific cytosines are enzymatically converted to uracils as a correction mechanism for missense mutations in the organelle genomes. RNA editi...
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Veröffentlicht in: | The Plant journal : for cell and molecular biology 2022-01, Vol.109 (1), p.215-226 |
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Zusammenfassung: | SUMMARY
In the chloroplast, organelle zinc finger 1 (OZ1) is a RanBP2‐type zinc finger (Znf) protein required for many RNA editing events, a process by which specific cytosines are enzymatically converted to uracils as a correction mechanism for missense mutations in the organelle genomes. RNA editing is carried out by a large multi‐protein complex called the ‘editosome’ that contains members of the pentatricopeptide repeat (PPR) protein family, the RNA editing factor interacting protein (also known as MORF) family and the organelle RNA‐recognition motif (ORRM) family, in addition to OZ1. OZ1 is an 82‐kDa protein with distinct domains, including a pair of Znf domains and a unique C‐terminal region. To elucidate the functions of these domains, we have generated truncations of OZ1 for use in protein–protein interaction assays that identified the C‐terminal region of OZ1, as well as the Znf domains as the primary interactors with PPR proteins, which are factors required for site‐specificity and enzymatic editing. Expression of these OZ1 truncations in vivo showed that the Znf domains were required to restore chloroplast RNA editing in oz1 knockout plants. Mutation of key structural residues in the Znf domains showed that they are necessary for editing and required for interaction with ORRM1, a general editing factor with an RNA‐binding domain. These functional characterizations of the Znfs and novel C‐terminal domain contribute to our understanding of the model for the chloroplast plant editosome.
Significance Statement
The chloroplast RNA editing factor OZ1 (organelle zinc finger 1) contains a number of unique domains and a pair of zinc finger (Znf) domains that, in spite of the presence of homologs across terrestrial plant lineages, have not been functionally characterized. Both the C‐terminal and Znf domains are necessary for protein–protein interactions, and the Znfs are essential for chloroplast RNA editing. |
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ISSN: | 0960-7412 1365-313X |
DOI: | 10.1111/tpj.15569 |