The zinc-finger protein SOP1 is required for a subset of the nuclear exosome functions in Arabidopsis
2016
Bellec, Yannick | Podicheti, Ram | Bouteiller, Nathalie | Anne, Pauline | Morineau, Céline | Haslam, Richard P. | Beaudoin, Frederic | Napier, Johnathan A. | Mockaitis, Keithanne | Gagliardi, Dominique | Vaucheret, Hervé | Lange, Heike | Faure, Jean Denis
Correct gene expression requires tight RNA quality control both at transcriptional and post-transcriptional levels. Using a splicing-defective allele of PASTICCINO2 (PAS2), a gene essential for plant development, we isolated suppressor mutations modifying pas2-1 mRNA profiles and restoring wild-type growth. Three suppressor of pas2 (sop) mutations modified the degradation of mis-spliced pas2-1 mRNA species, allowing the synthesis of a functional protein. Cloning of the suppressor mutations identified the core subunit of the exosome SOP2/RRP4, the exosome nucleoplasmic cofactor SOP3/HEN2 and a novel zinc-finger protein SOP1 that colocalizes with HEN2 in nucleoplasmic foci. The three SOP proteins counteract post-transcriptional (trans) gene silencing (PTGS), which suggests that they all act in RNA quality control. In addition, sop1 mutants accumulate some, but not all of the mis-processed mRNAs and other types of RNAs that are observed in exosome mutants. Taken together, our data show that SOP1 is a new component of nuclear RNA surveillance that is required for the degradation of a specific subset of nuclear exosome targets.
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