Phase separation of SGS3 drives siRNA body formation and promotes endogenous gene silencing
Huijuan Tan,
Wentao Luo,
Wei Yan,
Jie Liu,
Yalikunjiang Aizezi,
Ruixue Cui,
Ruijun Tian,
Jinbiao Ma,
Hongwei Guo
Affiliations
Huijuan Tan
Institute of Plant and Food Science, Department of Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China; Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes, Southern University of Science and Technology, Shenzhen 518055, China; Institute for Advanced Studies, Wuhan University, Wuhan 430072, China
Wentao Luo
Institute of Plant and Food Science, Department of Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China; Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes, Southern University of Science and Technology, Shenzhen 518055, China
Wei Yan
Institute of Plant and Food Science, Department of Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China; Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes, Southern University of Science and Technology, Shenzhen 518055, China
Jie Liu
Department of Chemistry, College of Science, Southern University of Science and Technology, Shenzhen 518055, China
Yalikunjiang Aizezi
Institute of Plant and Food Science, Department of Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China; Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes, Southern University of Science and Technology, Shenzhen 518055, China
Ruixue Cui
Huashan Hospital affiliated to Fudan University, State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, Multiscale Research Institute of Complex Systems, Department of Biochemistry and Biophysics, School of Life Sciences, Fudan University, Shanghai 200438, China
Ruijun Tian
Department of Chemistry, College of Science, Southern University of Science and Technology, Shenzhen 518055, China
Jinbiao Ma
Huashan Hospital affiliated to Fudan University, State Key Laboratory of Genetic Engineering, Collaborative Innovation Center of Genetics and Development, Multiscale Research Institute of Complex Systems, Department of Biochemistry and Biophysics, School of Life Sciences, Fudan University, Shanghai 200438, China
Hongwei Guo
Institute of Plant and Food Science, Department of Biology, School of Life Sciences, Southern University of Science and Technology, Shenzhen, Guangdong 518055, China; Laboratory of Molecular Design for Plant Cell Factory of Guangdong Higher Education Institutes, Southern University of Science and Technology, Shenzhen 518055, China; Corresponding author
Summary: The generation of small interfering RNA (siRNA) involves many RNA processing components, including SUPPRESSOR OF GENE SILENCING 3 (SGS3), RNA-DEPENDENT RNA POLYMERASE 6 (RDR6), and DICER-LIKE proteins (DCLs). Nonetheless, how these components are coordinated to produce siRNAs is unclear. Here, we show that SGS3 forms condensates via phase separation in vivo and in vitro. SGS3 interacts with RDR6 and drives it to form siRNA bodies in cytoplasm, which is promoted by SGS3-targeted RNAs. Disrupting SGS3 phase separation abrogates siRNA body assembly and siRNA biogenesis, whereas coexpression of SGS3 and RDR6 induces siRNA body formation in tobacco and yeast cells. Dysfunction in translation and mRNA decay increases the number of siRNA bodies, whereas DCL2/4 mutations enhance their size. Purification of SGS3 condensates identifies numerous RNA-binding proteins and siRNA processing components. Together, our findings reveal that SGS3 phase separation-mediated formation of siRNA bodies is essential for siRNA production and gene silencing.
