AGO1-miR173 complex initiates phased siRNA formation in plants

• Published in: Proceedings of the National Academy of Sciences - PNAS Vol. 105; no. 51; pp. 20055 - 20062
• Main Authors: Montgomery, Taiowa A, Yoo, Seong Jeon, Fahlgren, Noah, Gilbert, Sunny D, Howell, Miya D, Sullivan, Christopher M, Alexander, Amanda, Nguyen, Goretti, Allen, Edwards, Ahn, Ji Hoon, Carrington, James C
• Format: Journal Article
• Language: English
• Published: United States National Academy of Sciences 23-12-2008; National Acad Sciences
• Series: Inaugural Article
• Subjects: Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Arabidopsis Proteins - physiology; Arabidopsis thaliana; Argonaute Proteins; Biological Sciences; Flowers & plants; Gene expression; gene expression regulation; Genes; loci; Messenger RNA; MicroRNA; MicroRNAs - metabolism; MicroRNAs - physiology; Nicotiana benthamiana; Nucleotides; Peptides; phytoene desaturase; Plant cells; Plants; Protein synthesis; Registered nurses; Ribonucleic acid; RNA; RNA, Messenger; RNA, Plant - biosynthesis; RNA, Small Interfering - biosynthesis; RNA, Small Interfering - genetics; RNA-binding proteins; Signal to noise ratio; Small interfering RNA; T tests; transacting small interfering RNA
• ISSN: 0027-8424; 1091-6490
• DOI: 10.1073/pnas.0810241105

MicroRNA (miRNA)-guided cleavage initiates entry of primary transcripts into the transacting siRNA (tasiRNA) biogenesis pathway involving RNA-DEPENDENT RNA POLYMERASE6, DICER-LIKE4, and SUPPRESSOR OF GENE SILENCING3. Arabidopsis thaliana TAS1 and TAS2 families yield tasiRNA that form through miR173-guided initiation-cleavage of primary transcripts and target several transcripts encoding pentatricopeptide repeat proteins and proteins of unknown function. Here, the TAS1c locus was modified to produce synthetic (syn) tasiRNA to target an endogenous transcript encoding PHYTOENE DESATURASE and used to analyze the role of miR173 in routing of transcripts through the tasiRNA pathway. miR173 was unique from other miRNAs in its ability to initiate TAS1c-based syn-tasiRNA formation. A single miR173 target site was sufficient to route non-TAS transcripts into the pathway to yield phased siRNA. We also show that miR173 functions in association with ARGONAUTE 1 (AGO1) during TAS1 and TAS2 tasiRNA formation, and we provide data indicating that the miR173-AGO1 complex possesses unique functionality that many other miRNA-AGO1 complexes lack.