Rational design of minimum CRISPR guide RNA by site-specific Cas9–RNA conjugation

2020 ◽  
Vol 56 (54) ◽  
pp. 7515-7518
Author(s):  
Xinyu Ling ◽  
Xiaoqin Gao ◽  
Liying Chang ◽  
Heqi Chen ◽  
Xiaomeng Shi ◽  
...  
Keyword(s):  
Rational Design ◽  
Site Specific ◽  
Guide Rna

Site-specific Cas9–crRNA conjugation reduces the synthetic burden of customized guide RNA.

Rational Design of Two-Dimensional Bimetallic Wave Structures from Zigzag Chains via Site-Specific Coordination around the 2,6-Naphthalenediphosphonic Acid Motif

2016 ◽  
Vol 2016 (21) ◽  
pp. 3506-3512 ◽  
Author(s):  
Aysun Bulut ◽  
Yunus Zorlu ◽  
Michael Wörle ◽  
Salih Paşa ◽  
Hüseyin Kurt ◽  
...  
Keyword(s):  
Rational Design ◽  
Two Dimensional ◽  
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 REP-X: An Evolution-guided Strategy for the Rational Design of Cysteine-less Protein Variants

2019 ◽  
Author(s):  
Kevin Dalton ◽  
Tom Lopez ◽  
Vijay Pande ◽  
Judith Frydman
Keyword(s):  
Rational Design ◽  
Biochemical Characterization ◽  
Cysteine Residue ◽  
Rational Approach ◽  
Protein Activity ◽  
Methanococcus Maripaludis ◽  
Site Specific ◽  
Protein Variants ◽  
Group Ii Chaperonin ◽  
Reduced Activity

AbstractSite-specific labeling of proteins is often a prerequisite for biophysical and biochemical characterization. Chemical modification of a unique cysteine residue is among the most facile methods for site-specific labeling of proteins. However, many proteins have multiple reactive cysteines, which must be mutated to other residues to enable labeling of unique positions. This trial-and-error process often results in cysteine-free proteins with reduced activity or stability. Herein we describe a general methodology to rationally engineer cysteine-less proteins. Briefly, natural variation across orthologues is exploited to identify suitable cysteine replacements compatible with protein activity and stability. As a proof-of-concept, we recount the successful engineering of a cysteine-less mutant of the group II chaperonin from methanogenic archaeon Methanococcus maripaludis. A webapp, REP-X (Replacement at Endogenous Positions from eXtant sequences), which enables users to design their own cysteine-less protein variants, will make this rational approach widely available.

scholarly journals Decoupling tRNA promoter and processing activities enables specific Pol-II Cas9 guide RNA expression

2018 ◽  
Author(s):  
David JHF Knapp ◽  
Yale S Michaels ◽  
Max Jamilly ◽  
Quentin RV Ferry ◽  
Hector Barbosa ◽  
...  
Keyword(s):  
Rational Design ◽  
Rna Expression ◽  
Temporal Control ◽  
High Background ◽  
Pol Ii ◽  
Trna Processing ◽  
Guide Rna ◽  
Promising Strategy ◽  
Screening Platform

ABSTRACTSpatial/temporal control of Cas9 guide RNA expression could considerably expand the utility of CRISPR-based technologies. Current approaches based on tRNA processing offer a promising strategy but suffer from high background. Here we developed a variant screening platform to identify differential sequence determinants of human tRNA promoter and processing activities. Rational design based on the ensuing principles allowed us to engineer an improved tRNA scaffold that enabled highly specific guide RNA production from a Pol-II promoter.

scholarly journals Genome-wide Cas9 binding specificity in Saccharomyces cerevisiae

PeerJ ◽  
2020 ◽  
Vol 8 ◽  
pp. e9442 ◽  
Author(s):  
Zachary J. Waldrip ◽  
Piroon Jenjaroenpun ◽  
Oktawia DeYoung ◽  
Intawat Nookaew ◽  
Sean D. Taverna ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
High Specificity ◽  
Genomic Locus ◽  
Site Specific ◽  
Guide Rna ◽  
Genome Wide ◽  
A Genome ◽  
Wide Scale ◽  
Chromosome Iii ◽  
Genomic Editing

The CRISPR system has become heavily utilized in biomedical research as a tool for genomic editing as well as for site-specific chromosomal localization of specific proteins. For example, we developed a CRISPR-based methodology for enriching a specific genomic locus of interest for proteomic analysis in Saccharomyces cerevisiae, which utilized a guide RNA-targeted, catalytically dead Cas9 (dCas9) as an affinity reagent. To more comprehensively evaluate the genomic specificity of using dCas9 as a site-specific tool for chromosomal studies, we performed dCas9-mediated locus enrichment followed by next-generation sequencing on a genome-wide scale. As a test locus, we used the ARS305 origin of replication on chromosome III in S. cerevisiae. We found that enrichment of this site is highly specific, with virtually no off-target enrichment of unique genomic sequences. The high specificity of genomic localization and enrichment suggests that dCas9-mediated technologies have promising potential for site-specific chromosomal studies in organisms with relatively small genomes such as yeasts.

scholarly journals Structural basis for Cas9 off-target activity

2021 ◽  
Author(s):  
Martin Pacesa ◽  
Chun-Han Lin ◽  
Antoine Clery ◽  
Katja Bargsten ◽  
Matthew J. Irby ◽  
...  
Keyword(s):  
Rational Design ◽  
Target Prediction ◽  
Structural Basis ◽  
Guide Rna ◽  
Guide Rnas ◽  
Target Dna ◽  
Bona Fide ◽  
Dna Specificity ◽  
Target Binding ◽  
Target Activity

The target DNA specificity of the CRISPR-associated genome editor nuclease Cas9 is determined by complementarity to a 20-nucleotide segment in its guide RNA. However, Cas9 can bind and cleave partially complementary off-target sequences, which raises safety concerns for its use in clinical applications. Here we report crystallographic structures of Cas9 bound to bona fide off-target substrates, revealing that off-target binding is enabled by a range of non- canonical base pairing interactions and preservation of base stacking within the guide-off-target heteroduplex. Off-target sites containing single-nucleotide deletions relative to the guide RNA are accommodated by base skipping rather than RNA bulge formation. Additionally, PAM-distal mismatches result in duplex unpairing and induce a conformational change of the Cas9 REC lobe that perturbs its conformational activation. Together, these insights provide a structural rationale for the off-target activity of Cas9 and contribute to the improved rational design of guide RNAs and off-target prediction algorithms.

scholarly journals Rational design of a split-Cas9 enzyme complex

2015 ◽  
Vol 112 (10) ◽  
pp. 2984-2989 ◽  
Author(s):  
Addison V. Wright ◽  
Samuel H. Sternberg ◽  
David W. Taylor ◽  
Brett T. Staahl ◽  
Jorge A. Bardales ◽  
...  
Keyword(s):  
Conformational Changes ◽  
Dna Cleavage ◽  
Rational Design ◽  
Genome Engineering ◽  
Guide Rna ◽  
Protein Architecture ◽  
Target Dna ◽  
Molecular Determinants ◽  
Versatile Tool ◽  
Bacterial Immune Systems

Cas9, an RNA-guided DNA endonuclease found in clustered regularly interspaced short palindromic repeats (CRISPR) bacterial immune systems, is a versatile tool for genome editing, transcriptional regulation, and cellular imaging applications. Structures of Streptococcus pyogenes Cas9 alone or bound to single-guide RNA (sgRNA) and target DNA revealed a bilobed protein architecture that undergoes major conformational changes upon guide RNA and DNA binding. To investigate the molecular determinants and relevance of the interlobe rearrangement for target recognition and cleavage, we designed a split-Cas9 enzyme in which the nuclease lobe and α-helical lobe are expressed as separate polypeptides. Although the lobes do not interact on their own, the sgRNA recruits them into a ternary complex that recapitulates the activity of full-length Cas9 and catalyzes site-specific DNA cleavage. The use of a modified sgRNA abrogates split-Cas9 activity by preventing dimerization, allowing for the development of an inducible dimerization system. We propose that split-Cas9 can act as a highly regulatable platform for genome-engineering applications.

scholarly journals Guide RNA requirement for editing-site-specific endonucleolytic cleavage of preedited mRNA by mitochondrial ribonucleoprotein particles in Trypanosoma brucei.

1997 ◽  
Vol 17 (9) ◽  
pp. 5377-5385 ◽  
Author(s):  
B K Adler ◽  
S L Hajduk
Keyword(s):  
Cytochrome B ◽  
Editing Site ◽  
Mitochondrial Rna ◽  
Ample Evidence ◽  
Site Specific ◽  
Rna Ligase ◽  
Guide Rna ◽  
Guide Rnas ◽  
Endonucleolytic Cleavage

RNA editing in trypanosome mitochondria entails the posttranscriptional internal addition and occasional deletion of uridines from precursor mRNAs. Ample evidence exists to show that the information specifying the site and number of uridines added or deleted comes from small, mitochondrially encoded guide RNAs (gRNAs). More recent work indicates that the process involves an enzymatic cascade, initiating with an endonucleolytic cleavage of the pre-mRNA at an editing site. The cleaved editing site can undergo uridine (U) addition to or deletion from the 3' end of the 5' fragment via a mitochondrial terminal uridylyl transferase (TUTase) or terminal uridylyl exonuclease, respectively. Mitochondrial RNA ligase subsequently rejoins the mRNA. Activities to carry out these processes have been found in trypanosome mitochondria, including an editing-site-specific endonuclease activity which cleaves preedited but not edited mRNAs. We have found that this enzymatic activity cosediments with the same 19S ribonucleoprotein particle previously shown to contain TUTase, RNA ligase, and gRNAs and remains stable after salt treatment. Depletion of endogenous cytochrome b gRNAs by the addition of complementary oligonucleotides in vitro completely inhibits editing-site cleavage of synthetic preedited cytochrome b mRNA. The addition of synthetic cognate gRNA for cytochrome b but not unrelated small RNA restores editing-site cleavage. These studies show that in addition to specifying the site and number of uridines added or deleted, gRNAs provide the necessary information for cleavage by the editing-site-specific endonuclease.

scholarly journals RNA-CLAMP Enables Photo-activated Control of CRISPR-Cas9 Gene Editing by Site-specific Intramolecular Cross-linking of the sgRNA

2021 ◽  
Author(s):  
Dongyang Zhang ◽  
Shuaijiang Jin ◽  
Luping Liu ◽  
Ember Tota ◽  
Zijie Li ◽  
...  
Keyword(s):  
Dna Cleavage ◽  
Mammalian Cells ◽  
Gene Editing ◽  
Cross Linking ◽  
Stimuli Responsive ◽  
Spatiotemporal Resolution ◽  
Site Specific ◽  
Guide Rna ◽  
Dna Cleavage Activity ◽  
Versatile Tool

AbstractHere we introduce RNA-CLAMP, a technology which enables site-specific and enzymatic cross-linking (clamping) of two selected stem loops within an RNA of interest. Intramolecular clamping of the RNA can disrupt normal RNA function, whereas subsequent photo-cleavage of the crosslinker restores activity. We applied the RNA-CLAMP technique to the single guide RNA of the CRISPR-Cas9 gene editing system. By clamping two stem loops of the single-guide RNA (sgRNA) with a photo-cleavable cross-linker, gene editing was completely silenced. Visible light irradiation cleaved the crosslinker and restored gene editing with high spatiotemporal resolution. Furthermore, by designing two photo-cleavable linkers which are responsive to different wavelength of lights, we achieved multiplexed photo-activation of gene editing in mammalian cells. Notably, although the Cas9-sgRNA RNP is not capable of DNA cleavage activity upon clamping, it maintained the capability to bind to the target DNA. The RNA-CLAMP enabled photo-activated CRISPR-Cas9 gene editing platform offers clean background, free choice of activation wavelength and multiplexing capability. We believe that this technology to precisely and rapidly control gene editing will serve as a versatile tool in the future development of stimuli responsive gene editing technologies. Beyond gene editing, RNA-CLAMP provides a site-specific tool for manipulating the internal structure of functional RNAs.

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