title: Mutations in the GW-repeat protein SUO reveal a developmental function for microRNA-mediated translational repression in Arabidopsis.
abstract: Plant microRNAs (miRNAs) typically mediate RNA cleavage, but examples of miRNA-mediated translational repression have also been reported. However, the functional significance of this latter process is unknown. We identified SUO in a screen for Arabidopsis mutations that increase the accumulation of the miR156-regulated gene SPL3. suo has a loss-of-function phenotype characteristic of plants with reduced Argonaute (AGO)1 activity. An analysis of RNA and protein levels in suo mutants demonstrated that this phenotype is a consequence of a defect in miRNA-mediated translational repression; the effect of suo on vegetative phase change is attributable to a reduction in miR156/miR157 activity. SUO encodes a large protein with N-terminal bromo-adjacent homology (BAH) and transcription elongation factor S-II (TFS2N) domains and two C-terminal GW (glycine and tryptophan) repeats. SUO is present in the nucleus, and colocalizes with the processing-body component DCP1 in the cytoplasm. Our results reveal that SOU is a component of the miRNA pathway in Arabidopsis and demonstrate that translational repression is a functionally important aspect of miRNA activity in plants.
authors.affiliation: Department of Biology, University of Pennsylvania, Philadelphia, PA 19104-6018, USA.
authors.forename: Li
authors.initials: L
authors.lastname: Yang
authors.forename: Gang
authors.initials: G
authors.lastname: Wu
authors.forename: R Scott
authors.initials: RS
authors.lastname: Poethig
mesh_terms: D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development*; D029681:Arabidopsis Proteins / Q000737:chemistry / Q000378:metabolism*; D002467:Cell Nucleus / Q000378:metabolism; D018506:Gene Expression Regulation, Plant; D035683:MicroRNAs / Q000378:metabolism*; D009154:Mutation / Q000235:genetics*; D010641:Phenotype; D014176:Protein Biosynthesis; D020449:Repetitive Sequences, Amino Acid; D012097:Repressor Proteins / Q000378:metabolism*
chemical_list: D029681:Arabidopsis Proteins; D035683:MicroRNAs; C559759:Mirn156 microRNA, Arabidopsis; D012097:Repressor Proteins