The Organelle Zinc Finger Family of Proteins Contributes to RNA Processing in Plant Organelles
Gipson, Andrew Brendan
Our lab previously discovered a small family of organelle-localized proteins in plants characterized by the presence of zinc finger domains, the Organelle Zinc finger (OZ) family. Two members of this family, OZ1 and OZ2, are necessary for successful processing and maturation of RNA produced from the circular genomes of plant chloroplasts and mitochondria. We discovered that OZ2 is a splicing factor, and I performed experiments showing that OZ2 binds to a set of both general and specific splicing factors.In the chloroplast, OZ1 is required for many RNA editing events, a process by which specific cytosines are enzymatically converted to uracils as a correction mechanism for evolutionarily conserved missense mutations in the organelle genomes. RNA editing is carried out by a large multi-protein complex called the “editosome.” As well as OZ1, editosomes contain members of the PPR protein family, the RIP/MORF family, and the ORRM family. OZ1 is an 82-kDa protein with distinct domains, including a family-specific N-terminal region, a pair of zinc finger domains, and a unique C-terminal region. To elucidate the functions of these domains, I generated truncations of OZ1 for use in protein-protein interaction assays that identified the C-terminal region of OZ1 as the primary interactor with PPR proteins, the editosome factors required for site-specificity and enzymatic editing. Expression of these OZ1 constructs in vivo showed that the zinc finger domains were required to restore editing in oz1 knockout plants. Mutation of key structural residues in the zinc finger domains showed that they are necessary for editing and required for interaction with ORRM1, a general editing factor with an RNA-binding domain. This work establishes the OZ protein family as a novel group of factors necessary for RNA metabolism in plant organelles.
chloroplast; editosome; organelle; RNA editing; zinc finger
Hanson, Maureen R.
Wijk, Klaas Van; Ke, Ailong
Biochemistry, Molecular and Cell Biology
Ph. D., Biochemistry, Molecular and Cell Biology
Doctor of Philosophy
Attribution-NonCommercial-NoDerivatives 4.0 International
dissertation or thesis
Except where otherwise noted, this item's license is described as Attribution-NonCommercial-NoDerivatives 4.0 International