scholarly journals The guide sRNA sequence determines the activity level of box C/D RNPs

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Andrea Graziadei ◽  
Frank Gabel ◽  
John Kirkpatrick ◽  
Teresa Carlomagno
Keyword(s):  
Structural Biology ◽  
Activity Level ◽  
Methylation Site ◽  
Rna Sequences ◽  
Site Specific ◽  
Guide Rna ◽  
Conformational Ensembles ◽  
Catalytic Module ◽  
Rnp Complex ◽  
Rrna Methylation

2’-O-rRNA methylation, which is essential in eukaryotes and archaea, is catalysed by the Box C/D RNP complex in an RNA-guided manner. Despite the conservation of the methylation sites, the abundance of site-specific modifications shows variability across species and tissues, suggesting that rRNA methylation may provide a means of controlling gene expression. As all Box C/D RNPs are thought to adopt a similar structure, it remains unclear how the methylation efficiency is regulated. Here, we provide the first structural evidence that, in the context of the Box C/D RNP, the affinity of the catalytic module fibrillarin for the substrate–guide helix is dependent on the RNA sequence outside the methylation site, thus providing a mechanism by which both the substrate and guide RNA sequences determine the degree of methylation. To reach this result, we develop an iterative structure-calculation protocol that exploits the power of integrative structural biology to characterize conformational ensembles.

scholarly journals Electronic Circular Dichroism of the Cas9 Protein and gRNA:Cas9 Ribonucleoprotein Complex

2021 ◽  
Vol 22 (6) ◽  
pp. 2937
Author(s):  
Monika Halat ◽  
Magdalena Klimek-Chodacka ◽  
Jagoda Orleanska ◽  
Malgorzata Baranska ◽  
Rafal Baranski
Keyword(s):  
Circular Dichroism ◽  
Conformational Changes ◽  
Structural Changes ◽  
Electronic Circular Dichroism ◽  
Guide Rna ◽  
Cas9 Protein ◽  
Rnp Complex ◽  
Characteristic Features ◽  
Circular Dichroïsm

The Streptococcus pyogenes Cas9 protein (SpCas9), a component of CRISPR-based immune system in microbes, has become commonly utilized for genome editing. This nuclease forms a ribonucleoprotein (RNP) complex with guide RNA (gRNA) which induces Cas9 structural changes and triggers its cleavage activity. Here, electronic circular dichroism (ECD) spectroscopy was used to confirm the RNP formation and to determine its individual components. The ECD spectra had characteristic features differentiating Cas9 and gRNA, the former showed a negative/positive profile with maxima located at 221, 209 and 196 nm, while the latter revealed positive/negative/positive/negative pattern with bands observed at 266, 242, 222 and 209 nm, respectively. For the first time, the experimental ECD spectrum of the gRNA:Cas9 RNP complex is presented. It exhibits a bisignate positive/negative ECD couplet with maxima at 273 and 235 nm, and it differs significantly from individual spectrum of each RNP components. Additionally, the Cas9 protein and RNP complex retained biological activity after ECD measurements and they were able to bind and cleave DNA in vitro. Hence, we conclude that ECD spectroscopy can be considered as a quick and non-destructive method of monitoring conformational changes of the Cas9 protein as a result of Cas9 and gRNA interaction, and identification of the gRNA:Cas9 RNP complex.

scholarly journals Efficient site-specific cleavage by RNase MRP requires interaction with two evolutionarily conserved mitochondrial RNA sequences.

1990 ◽  
Vol 10 (5) ◽  
pp. 2191-2201 ◽  
Author(s):  
J L Bennett ◽  
D A Clayton
Keyword(s):  
Sequence Homology ◽  
Mammalian Species ◽  
Saturation Mutagenesis ◽  
Mitochondrial Rna ◽  
Rna Sequences ◽  
Site Specific ◽  
Conserved Sequence ◽  
Sequence Block ◽  
Rnase Mrp

RNase MRP is a site-specific endonuclease that processes primer mitochondrial RNA from the leading-strand origin of mitochondrial DNA replication. Using deletional analysis and saturation mutagenesis, we have determined the substrate requirements for cleavage by mouse mitochondrial RNase MRP. Two regions of sequence homology among vertebrate mitochondrial RNA primers, conserved sequence blocks II and III, were found to be critical for both efficient and accurate cleavage; a third region of sequence homology, conserved sequence block I, was dispensable. Analysis of insertion and deletion mutations within conserved sequence block II demonstrated that the specificity of RNase MRP accommodates the natural sequence heterogeneity of conserved sequence block II in vivo. Heterologous assays with human RNase MRP and mutated mouse mitochondrial RNA substrates indicated that sequences essential for substrate recognition are conserved between mammalian species.

scholarly journals Identification of RNA sequences and structures involved in site-specific cleavage of IGF-II mRNAs

RNA ◽  
1998 ◽  
Vol 4 (12) ◽  
pp. 1623-1635 ◽  
Author(s):  
ERWIN L. VAN DIJK ◽  
JOHN S. SUSSENBACH ◽  
P. ELLY HOLTHUIZEN
Keyword(s):  
Rna Sequences ◽  
Site Specific

scholarly journals Guide RNA-mRNA chimeras, which are potential RNA editing intermediates, are formed by endonuclease and RNA ligase in a trypanosome mitochondrial extract.

1995 ◽  
Vol 15 (6) ◽  
pp. 2933-2941 ◽  
Author(s):  
L N Rusché ◽  
K J Piller ◽  
B Sollner-Webb
Keyword(s):  
Rna Editing ◽  
Mitochondrial Rna ◽  
Site Specific ◽  
Rna Ligase ◽  
Guide Rna ◽  
Guide Rnas ◽  
Editing Domain ◽  
Mitochondrial Transcripts ◽  
Mitochondrial Extract

RNA editing in kinetoplast mitochondrial transcripts involves the insertion and/or deletion of uridine residues and is directed by guide RNAs (gRNAs). It is thought to occur through a chimeric intermediate in which the 3' oligo(U) tail of the gRNA is covalently joined to the 3' portion of the mRNA at the site being edited. Chimeras have been proposed to be formed by a transesterification reaction but could also be formed by the known mitochondrial site-specific nuclease and RNA ligase. To distinguish between these models, we studied chimera formation in vitro directed by a trypanosome mitochondrial extract. This reaction was found to occur in two steps. First, the mRNA is cleaved in the 3' portion of the editing domain, and then the 3' fragment derived from this cleavage is ligated to the gRNA. The isolated mRNA 3' cleavage product is a more efficient substrate for chimera formation than is the intact mRNA, inconsistent with a transesterification mechanism but supporting a nuclease-ligase mechanism. Also, when normal mRNA cleavage is inhibited by the presence of a phosphorothioate, normal chimera formation no longer occurs. Rather, this phosphorothioate induces both cleavage and chimera formation at a novel site within the editing domain. Finally, levels of chimera-forming activity correlate with levels of mitochondrial RNA ligase activity when reactions are conducted under conditions which inhibit the ligase, including the lack of ATP containing a cleavable alpha-beta bond. These data show that chimera formation in the mitochondrial extract occurs by a nuclease-ligase mechanism rather than by transesterification.

scholarly journals Repressing Integrase attachment site operation with CRISPR-Cas9 in E. coli

2017 ◽  
Author(s):  
Andrey Shur ◽  
Richard M. Murray
Keyword(s):  
Dna Sequences ◽  
Dna Recombination ◽  
Attachment Site ◽  
Memory Systems ◽  
Rna Sequences ◽  
Guide Rna ◽  
Future Goals ◽  
Attachment Sites ◽  
Synthetic Cell ◽  
Specific Pair

AbstractSerine integrases are bacteriophage proteins responsible for integrating the phage genome into that of the host. Synthetic biologists have co-opted these proteins into useful tools for permanent DNA logic, utilizing their specific DNA recombination abilities to build synthetic cell differentiation and genetic memory systems. Each integrase has a specific pair of DNA sequences (attP/attB sites) that it recombines, but multiple identical sites can result in unpredictable recombination. We have developed a way to control integrase activity on identical attP/attB sites by using catalytically dead Cas9 (dCas9) as a programmable binding protein that can compete with integrase for binding to specific attachment sites. Utilizing a plasmid that contains two identical Bxb1 attP sites, integration can be repressed up to 8 fold at either one of the two attP sites when guide RNA and dCas9 are present. Guide RNA sequences that bind specifically to attB, or either of two attP sites, have been developed. Future goals are to utilize this technology to construct larger and more complex integrase logic circuits.

scholarly journals Site-specific covalent labeling of large RNAs with nanoparticles empowered by expanded genetic alphabet transcription

2020 ◽  
Author(s):  
Yan Wang ◽  
Yaoyi Chen ◽  
Yanping Hu ◽  
Xianyang Fang
Keyword(s):  
Structural Biology ◽  
Base Pair ◽  
Solid Phase ◽  
Site Specific ◽  
X Ray ◽  
X Ray Scattering ◽  
Rna Labeling ◽  
Virus Serotype ◽  
Genetic Alphabet ◽  
Ray Scattering

AbstractConjugation of RNAs with nanoparticles is of significant importance for its numerous applications in biology and medicine, which however remains challenging, especially for large ones. So far, the majority of RNA labeling rely on solid-phase chemical synthesis, which is generally limited to RNAs smaller than 100 nts. We here present an efficient and generally applicable labeling strategy for site-specific covalent conjugation of large RNAs with gold nanoparticle (AuNP) empowered by expanded genetic alphabet transcription. We synthesize an amine-derivatized TPT3 (TPT3A), which are site-specifically incorporated into a 97-nt 3’SL RNA and a 719-nt mini genomic RNA (DENV-mini) from Dengue virus serotype 2 (DENV2) by standard in vitro transcription with expanded genetic alphabet containing the A-T, G-C natural base pairs and the TPT3-NaM unnatural base pair. TPT3 modification cause minimal structural perturbations to the RNAs by small angle X-ray scattering. The purified TPT3A-modified RNAs are covalently conjugated with mono-Sulfo-NHS-Nanogold nanoparticles via the highly selective amine-NHS ester reaction and purified under non-denaturing conditions. We demonstrate the application of the AuNP-RNA conjugates in large RNA structural biology by an emerging molecular ruler, X-ray scattering interferometry (XSI). The inter-nanoparticle distance distributions in the 3’SL and DENV-mini RNAs derived from XSI measurements support the hypothetical model of flavivirus genome circularization, thus validate the applicability of this novel labeling strategy. The presented strategy overcomes the size constraints in conventional RNA labeling strategies, and is expected to have wide applications in large RNA structural biology and RNA nanotechnology.Significance StatementWe present a site-specific labeling strategy for large RNAs by T7 transcription with expanded genetic alphabet containing TPT3-NaM unnatural base pair. The applicability of this labeling strategy is validated by X-ray scattering interferometry measurements on a 97-nt and a 719-nt RNAs. This strategy can be applicable to natural RNAs or artificial RNA nanostructures with sizes from tens up to thousands of nucleotides, or covalent conjugation of RNAs with other metal nanoparticles. The usage of a far upstream forward primer during PCR enables easy purification of RNA from DNA templates, the non-denaturing conditions for conjugation reactions and purification avoids potential large RNA misfolding. This labeling strategy expands our capability to site-specifically conjugate RNA with nanoparticles for many applications.

scholarly journals The Need for Transfer Learning in CRISPR-Cas Off-Target Scoring

2021 ◽  
Author(s):  
Pavan K Kota ◽  
Yidan Pan ◽  
Hoang-Anh Vu ◽  
Mingming Cao ◽  
Richard G Baraniuk ◽  
...  
Keyword(s):  
Transfer Learning ◽  
Benchmark Dataset ◽  
Model Complexity ◽  
Improve Performance ◽  
Rna Sequences ◽  
Guide Rna ◽  
Learning Techniques ◽  
Scalable Design ◽  
Biological Differences

The scalable design of safe guide RNA sequences for CRISPR gene editing depends on the computational "scoring" of DNA locations that may be edited. As there is no widely accepted benchmark dataset to compare scoring models, we present a curated "TrueOT" dataset that contains thoroughly validated datapoints to best reflect the properties of in vivo editing. Many existing models are trained on data from high throughput assays. We hypothesize that such models may suboptimally transfer to the low throughput data in TrueOT due to fundamental biological differences between proxy assays and in vivo behavior. We developed new Siamese convolutional neural networks, trained them on a proxy dataset, and compared their performance against existing models on TrueOT. Our simplest model with a single convolutional and pooling layer surprisingly exhibits state-ofthe-art performance on TrueOT. Adding subsequent layers improves performance on the proxy dataset while compromising performance on TrueOT. We demonstrate that model complexity can only improve performance on TrueOT if transfer learning techniques are employed. These results suggest an urgent need for the CRISPR community to agree upon a benchmark dataset such as TrueOT and highlight that various sources of CRISPR data cannot be assumed to be equivalent. Our codebase and datasets are available on GitHub at github.com/baolab-rice/CRISPR_OT_scoring.

scholarly journals dbGuide: A database of functionally validated guide RNAs for genome editing in human and mouse cells

2020 ◽  
Author(s):  
Alexander A. Gooden ◽  
Christine N. Evans ◽  
Timothy P. Sheets ◽  
Michelle E. Clapp ◽  
Raj Chari
Keyword(s):  
Epigenetic Modification ◽  
Gene Activation ◽  
Amplicon Sequencing ◽  
Ease Of Use ◽  
Rna Sequences ◽  
Additional Species ◽  
Base Editing ◽  
Guide Rna ◽  
Guide Rnas ◽  
Human And Mouse

ABSTRACTWith the technology’s accessibility and ease of use, CRISPR has been employed widely in many different organisms and experimental settings. As a result, thousands of publications have used CRISPR to make specific genetic perturbations, establishing in itself a resource of validated guide RNA sequences. While numerous computational tools to assist in the design and identification of candidate guide RNAs exist, these are still just at best predictions and generally, researchers inevitably will test multiple sequences for functional activity. Here, we present dbGuide (https://sgrnascorer.cancer.gov/dbguide), a database of functionally validated guide RNA sequences for CRISPR/Cas9-based knockout in human and mouse. Our database not only contains computationally determined candidate guide RNA sequences, but of even greater value, over 4000 sequences which have been functionally validated either through direct amplicon sequencing or manual curation of literature from over 1000 publications. Finally, our established framework will allow for continual addition of newly published and experimentally validated guide RNA sequences for CRISPR/Cas9-based knockout as well as incorporation of sequences from different gene editing systems, additional species, and other types of site-specific functionalities such as base editing, gene activation, repression, and epigenetic modification.

scholarly journals CRISpy-pop: a web tool for designing CRISPR/Cas9-driven genetic modifications in diverse populations

2020 ◽  
Author(s):  
Hayley R. Stoneman ◽  
Russell L. Wrobel ◽  
Michael Place ◽  
Michael Graham ◽  
David J. Krause ◽  
...  
Keyword(s):  
Web Application ◽  
Genomic Data ◽  
Model Organisms ◽  
Bacterial Strains ◽  
Rna Sequences ◽  
Guide Rna ◽  
Guide Rnas ◽  
Population Genomic ◽  
Current Implementation ◽  
Multiple Strains

AbstractCRISPR/Cas9 is a powerful tool for editing genomes, but design decisions are generally made with respect to a single reference genome. With population genomic data becoming available for an increasing number of model organisms, researchers are interested in manipulating multiple strains and lines. CRISpy-pop is a web application that generates and filters guide RNA sequences for CRISPR/Cas9 genome editing for diverse yeast and bacterial strains. The current implementation designs and predicts the activity of guide RNAs against more than 1000 Saccharomyces cerevisiae genomes, including 167 strains frequently used in bioenergy research. Zymomonas mobilis, an increasingly popular bacterial bioenergy research model, is also supported. CRISpy-pop is available as a web application (https://CRISpy-pop.glbrc.org/) with an intuitive graphical user interface. CRISpy-pop also cross-references the human genome to allow users to avoid the selection of sgRNAs with potential biosafety concerns. Additionally, CRISpy-pop predicts the strain coverage of each guide RNA within the supported strain sets, which aids in functional population genetic studies. Finally, we validate how CRISpy-pop can accurately predict the activity of guide RNAs across strains using population genomic data.

Sign in / Sign up

Export Citation Format

Share Document