This Article Full Text Full Text (PDF) Supplemental Data All Versions of this Article: 19/11/3451    most recent tpc.107.055319v1 Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (4) Citing Articles via Google Scholar Google Scholar Articles by Gy, I. Articles by Mallory, A. C. Search for Related Content PubMed PubMed Citation Articles by Gy, I. Articles by Mallory, A. C. Agricola Articles by Gy, I. Articles by Mallory, A. C.

Arabidopsis FIERY1, XRN2, and XRN3 Are Endogenous RNA Silencing Suppressors^[W]

Laboratoire de Biologie Cellulaire, Institut Jean-Pierre Bourgin, Institut National de la Recherche Agronomique (INRA), 78026 Versailles Cedex, France

⁶ Address correspondence to amallory{at}versailles.inra.fr.

The eukaryotic defense response posttranscriptional gene silencing (PTGS) is directed by short-interfering RNAs and thwarts invading nucleic acids via the RNA slicing activity of conserved ARGONAUTE (AGO) proteins. PTGS can be counteracted by exogenous or endogenous suppressors, including the cytoplasmic exoribonuclease XRN4, which also degrades microRNA (miRNA)-guided mRNA cleavage products but does not play an obvious role in development. Here, we show that the nuclear exoribonucleases XRN2 and XRN3 are endogenous PTGS suppressors. We also identify excised MIRNA loops as templates for XRN2 and XRN3 and show that XRN3 is critical for proper development. Independently, we identified the nucleotidase/phosphatase FIERY1 (FRY1) as an endogenous PTGS suppressor through a suppressor screen in a hypomorphic ago1 genetic background. FRY1 is one of six Arabidopsis thaliana orthologs of yeast Hal2. Yeast hal2 mutants overaccumulate 3'-phosphoadenosine 5'-phosphate, which suppresses the 5'3' exoribonucleases Xrn1 and Rat1. fry1 mutant plants recapitulate developmental and molecular characteristics of xrn mutants and likely restore PTGS in ago1 hypomorphic mutants by corepressing XRN2, XRN3, and XRN4, thus increasing RNA silencing triggers. We anticipate that screens incorporating partially compromised silencing components will uncover additional PTGS suppressors that may not be revealed using robust silencing systems.

This article has been cited by other articles:

				S. L. Zimmer, Z. Fei, and D. B. Stern Genome-Based Analysis of Chlamydomonas reinhardtii Exoribonucleases and Poly(A) Polymerases Predicts Unexpected Organellar and Exosomal Features Genetics, May 1, 2008; 179(1): 125 - 136. [Abstract] [Full Text] [PDF]