RISC-Interacting Clearing 3’- 5’ Exoribonucleases (RICEs) degrade uridylated cleavage fragments to maintain functional RISC in Arabidopsis
- Texas A&M University, United States
- Michigan Technological University, United States
Abstract
RNA-induced Silencing Complex (RISC) is composed of miRNAs and AGO proteins. AGOs use miRNAs as guides to slice target mRNAs to produce truncated 5' and 3' RNA fragments. The 5' cleaved RNA fragments are marked with uridylation for degradation. Here, we identified novel cofactors of Arabidopsis AGOs, named RICE1 and RICE2. RICE proteins specifically degraded single-strand (ss) RNAs in vitro; but neither miRNAs nor miRNA*s in vivo. RICE1 exhibited a DnaQ-like exonuclease fold and formed a homohexamer with the active sites located at the interfaces between RICE1 subunits. Notably, ectopic expression of catalytically-inactive RICE1 not only significantly reduced miRNA levels; but also increased 5' cleavage RISC fragments with extended uridine tails. We conclude that RICEs act to degrade uridylated 5’ products of AGO cleavage to maintain functional RISC. Our study also suggests a possible link between decay of cleaved target mRNAs and miRNA stability in RISC.
Data availability
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small RNAs in RICE mutantsPublicly available at the NCBI Gene Expression Omnibus (accession no: GSE96951).
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protein structure of RICE1Publicly available at the RCSB Protein Data Bank (accession no. 5V5F).
Article and author information
Author details
Funding
National Science Foundation (CAREER MCB-1253369)
- Xiuren Zhang
Cancer Prevention and Research Institute of Texas (RP160822)
- Xiuren Zhang
The authors declare that there was no funding for this work.
Copyright
© 2017, Zhang et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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RISC-Interacting Clearing 3’- 5’ Exoribonucleases (RICEs) degrade uridylated cleavage fragments to maintain functional RISC in Arabidopsis
eLife 6:e24466.
https://doi.org/10.7554/eLife.24466
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