7ele
Cryo-EM structure of Arabidopsis DCL1 in complex with pre-miRNA 166f
Structural highlights
FunctionDCL1_ARATH Ribonuclease (RNase) III involved in RNA-mediated post-transcriptional gene silencing (PTGS). Functions in the microRNAs (miRNAs) biogenesis pathway by cleaving primary miRNAs (pri-miRNAs) and precursor miRNAs (pre-miRNAs). Functions with DRB1/HYL1 and SERRATE proteins for accurate pri-miRNAs to miRNAs processing. Indirectly involved in the production of trans-acting small interfering RNAs (ta-siRNAs) derived from the TAS1, TAS2 or TAS3 endogenous transcripts by participating in the production of their initiating miRNAs. Involved in the processing of natural siRNAs (nat-siRNAs, derived from cis-natural antisense transcripts) by cleaving 24 nucleotide nat-siRNAs into 21 nucleotide nat-siRNAs. Can produce RDR6-dependent endogenous ta-siRNAs derived from TAS1 and TAS2. Required for the production of 30-40 nucleotide bacterial-induced long siRNAs (lsiRNA). Acts redundantly with DICER-LIKE 3 (DCL3) to promote flowering via repression of FLOWERING LOCUS C (FLC). Represses antiviral RNA silencing through negative regulation of the expression of DCL4 and DCL3.[1] [2] [3] [4] [5] [6] [7] Publication Abstract from PubMedMicroRNAs (miRNAs) are short non-coding RNAs that inhibit the expression of target genes by directly binding to their mRNAs. In animals, pri-miRNAs are cleaved by Drosha to generate pre-miRNAs, which are subsequently cleaved by Dicer to generate mature miRNAs. Instead of being cleaved by two different enzymes, both cleavages in plants are performed by Dicer-like 1 (DCL1). With a similar domain architecture as human Dicer, it is mysterious how DCL1 recognizes pri-miRNAs and performs two cleavages sequentially. Here, we report the single-particle cryo-electron microscopy structures of Arabidopsis DCL1 complexed with a pri-miRNA and a pre-miRNA, respectively, in cleavage-competent states. These structures uncover the plasticity of the PAZ domain, which is critical for the recognition of both pri-miRNA and pre-miRNA. These structures suggest that the helicase module serves as an engine that transfers the substrate between two sequential cleavage events. This study lays a foundation for dissecting the regulation mechanism of miRNA biogenesis in plants and provides insights into the dicing state of human Dicer. Structural basis of microRNA processing by Dicer-like 1.,Wei X, Ke H, Wen A, Gao B, Shi J, Feng Y Nat Plants. 2021 Oct;7(10):1389-1396. doi: 10.1038/s41477-021-01000-1. Epub 2021 , Sep 30. PMID:34593993[8] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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