Optimized photochemistry and enzymology enable efficient analysis of RNA structures and interactions in cells
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ABSTRACT: RNA has the intrinsic property to base pair, forming complex structures fundamental to its diverse functions. Direct determination of RNA structures and interactions in living cells remain a major challenge in biology. Crosslinking and proximity-ligation-based approaches, such as PARIS (Psoralen Analysis of RNA Interactions and Structures), offer many advantages, such as the ability to directly capture complex RNA duplexes in cells with single molecule accuracy, near base pair resolution in high throughput and without size limit. Based on a systematic optimization of the photochemistry and enzymology, here we present PARIS2, a re-invented method for capturing RNA duplexes with >3000-fold improved efficiency. PARIS2 captures ribosome small subunit binding sites on mRNAs, thus reporting translation process. PARIS2 also captures the snRNP binding sites on various types of RNA targets. We applied PARIS2 to enterovirus D-68, a re-emerging viral pathogen associated with severe neurological symptoms and discovered dynamic/alternative conformations in the 5’UTR. The new photochemical and enzymological improvements and the PARIS2 method should be widely applicable to basic RNA research and RNA-related diseases.
Project description:RNA has the intrinsic property to base pair, forming complex structures fundamental to its diverse functions. Here we develop PARIS, a method based on reversible psoralen-crosslinking for global mapping of RNA duplexes with near base-pair resolution in living cells. PARIS analysis in three human and mouse cell types reveals frequent long-range structures, higher order architectures, and RNA:RNA interactions in trans across the transcriptome. PARIS determines base-pairing interactions on an individual-molecule level, revealing pervasive alternative conformations. We used PARIS-determined helices to guide phylogenetic analysis of RNA structures, and discovered conserved long-range and alternative structures. XIST, a lncRNA essential for X chromosome inactivation, folds into evolutionarily conserved RNA structural domains that span many kilobases. XIST A-repeat forms complex inter-repeat duplexes that nucleate higher order assembly of the key epigenetic silencing protein SPEN. PARIS is a generally applicable and versatile method that provides novel insights into the RNA structurome and interactome.
Project description:RNA has the intrinsic property to base pair, forming complex structures fundamental to its diverse functions. Here we develop PARIS, a method based on reversible psoralen-crosslinking for global mapping of RNA duplexes with near base-pair resolution in living cells. PARIS analysis in three human and mouse cell types reveals frequent long-range structures, higher order architectures, and RNA:RNA interactions in trans across the transcriptome. PARIS determines base-pairing interactions on an individual-molecule level, revealing pervasive alternative conformations. We used PARIS-determined helices to guide phylogenetic analysis of RNA structures, and discovered conserved long-range and alternative structures. XIST, a lncRNA essential for X chromosome inactivation, folds into evolutionarily conserved RNA structural domains that span many kilobases. XIST A-repeat forms complex inter-repeat duplexes that nucleate higher order assembly of the key epigenetic silencing protein SPEN. PARIS is a generally applicable and versatile method that provides novel insights into the RNA structurome and interactome. Cells are crosslinked with AMT and RNA is extracted from cells by RNase digestion. Crosslinked RNA fragments are selected from total RNA by 2D gel electrophoresis. Purified crosslinked RNA duplexes are proximity ligated and crosslinking is reversed. Then the chimeric RNA molecules are converted into cDNA libraries for high-throughput sequencing.
Project description:Small interfering RNAs (siRNAs) are the key components for RNA interference (RNAi), a conserved RNA silencing mechanism in many eukaryotes. In Drosophila, an RNase III enzyme Dicer-2 (Dcr-2), aided by its cofactor Loquacious-PD (Loqs-PD), plays major role in generating 21 base-pair (bp) siRNA duplexes from long double-stranded RNAs (dsRNAs). The ATP hydrolysis by the helicase domain of Dcr-2 is critical to the successful processing of a long dsRNA into consecutive siRNA duplexes. Here we report the cryo-EM structures of Dcr-2/Loqs-PD in the apo state and in multiple processing states of a 50-bp dsRNA substrate. The structures elucidated interactions between Dcr-2 and Loqs-PD, and significant conformational changes of Dcr-2 during a dsRNA processing cycle. The N-terminal helicase and DUF283 domains undergo conformational change upon initial dsRNA binding, forming an ATP binding pocket and a 5’-phosphate binding pocket. The overall conformation of Dcr-2/Loqs-PD is relatively rigid during translocating along the dsRNA in the presence of ATP, while the interaction between DUF283 and RIIIDb domains prevents non-specific cleavage during translocation by blocking the access of dsRNA to the RNase active center. Additional ATP-dependent conformational changes are required to form an active-dicing state and precisely cleave the dsRNA into 21-bp siRNA duplex confirmed by the structure in the post-dicing state. Collectively, this study revealed the molecular mechanism for the full-cycle of ATP-dependent dsRNA processing by Dcr-2/Loqs-PD.
Project description:Reverse-stranded paired-end 75 base-pair RNA sequencing libraries of 93 metastatic FFPE samples were constructed using Illumina Total RNA Stranded Kits. Ribosomal RNAs (rRNAs) were depleted by using the Ribo-Zero rRNA Removal Kit (Illumina). Libraries were sequenced on a HiSEQ2500 machine. Five samples were re-sequenced using paired-end 50 base-pair libraries due to the smaller insert sizes.
Project description:We studied functional and structural features of mouse and human SINE repeat elements-derived RNAs in SINEUP long non-coding RNAs which upregulate the translation of the target protein coding gene. To check the interaction of functional SINE RNAs with ribosomal RNAs, we created PARIS2 (psoralen analysis of RNA interactions and structures) libraries from SINEUP (with embedded mouse SINEB2 or human FRAM repeat) and the target sense GFP plasmids co-transfected human cells.
Project description:We have compared a relatively new method for RNA 3’ prime sequencing, QuantSeq with traditional RNA-Seq which captures reads from the entire RNA-transcript. In addition, we have compared read quantification using traditional base-to-base mapping (Tophat2) with the new pseudoalignment method Salmon. We have performed this experiment on peripheral blood mononuclear cells (PBMC) stimulated with Poly (I:C), a viral mimic that induces innate antiviral responses.
Project description:Structure probing experiments were performed on in vitro transcripts and E. coli and human cell cultures under natively extracted (cell-free) and in-cell conditions to benchmark the performance of the newly introduced PAIR-MaP correlated chemical probing strategy for detecting RNA duplexes. Multiple-hit dimethyl sulfate (DMS) probing was done using new buffer conditions that facilitate DMS modification of all four nucleotides.
Project description:Until now, it has been reasonably assumed that specific base-pair recognition is the only mechanism controlling the specificity of transcription factor (TF)−DNA binding. Contrary to this assumption, here we show that nonspecific DNA sequences possessing certain repeat symmetries, when present outside of specific TF binding sites (TFBSs), statistically control TF−DNA binding preferences. We used high-throughput protein−DNA binding assays to measure the binding levels and free energies of binding for several human TFs to tens of thousands of short DNA sequences with varying re- peat symmetries. Based on statistical mechanics modeling, we iden- tify a new protein−DNA binding mechanism induced by DNA se- quence symmetry in the absence of specific base-pair recognition, and experimentally demonstrate that this mechanism indeed gov- erns protein−DNA binding preferences.
Project description:DNA mate pair and RNA sequencing data of conventional osteosarcomas. Mate pair libraries, with average insert sizes of 2-4 kb, were prepared for sequencing using the Nextera Mate Pair Library Preparation Kit. Paired-end 76 base pair reads were generated using an Illumina NextSeq 500 sequencing instrument. Total RNA was enriched for polyadenylated RNA using magnetic oligo(dT) beads. Enriched RNA was prepared for sequencing using the TruSeq RNA Sample Preparation Kit v2 and paired-end 151 base pair reads were generated from the cDNA libraries using an Illumina NextSeq 500 instrument.