Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

High-throughput screens of PAM-flexible Cas9 variants for gene knock-out and transcriptional modulation

ABSTRACT: A key limitation of the commonly-used CRISPR enzyme S. pyogenes Cas9 is the strict requirement of an NGG protospacer-adjacent motif (PAM) at the target site, which reduces the number of accessible genomic loci. This constraint can be limiting for genome editing applications that require precise Cas9 positioning. Recently, two Cas9 variants with a relaxed PAM requirement (NG) have been developed (xCas9 and Cas9-NG) but their activity has been measured at only a small number of endogenous sites. Here we devised a high-throughput Cas9 pooled competition screen to compare the performance of both PAM-flexible Cas9 variants and wild-type Cas9 at thousands of genomic loci and across 3 modalities (gene knock-out, transcriptional activation and suppression). We show that PAM flexibility comes at a substantial cost of decreased DNA targeting and cutting. Of the PAM-flexible variants, we found that Cas9-NG outperforms xCas9 regardless of genome engineering modality or PAM. Finally, we combined xCas9 mutations with those of Cas9-NG, creating a stronger transcriptional modulator than existing PAM-flexible Cas9 variants.

ORGANISM(S): Homo sapiens

PROVIDER: GSE143892 | GEO | 2020/01/26

REPOSITORIES: GEO

ACCESS DATA

Json Xml

Similar Datasets

Expanding the Scope of Bacterial CRISPR Activation with PAM-flexible dCas9 Variants

Project description:CRISPR-Cas transcriptional tools have been widely applied for programmable regulation of complex biological networks. In comparison to eukaryotic systems, bacterial CRISPR activation (CRISPRa) has stringent target site requirements for effective gene activation. While genes may not always have an NGG protospacer adjacent motif (PAM) at the appropriate position, PAM-flexible dCas9 variants can expand the range of targetable sites. Here we systematically evaluate a panel of PAM-flexible dCas9 variants for their ability to activate bacterial genes. We observe that dxCas9-NG provides a high dynamic range of gene activation for sites with NGN PAMs while dSpRY permits modest activity across almost any PAM. Similar trends were observed for heterologous and endogenous promoters. For all variants tested, improved PAM-flexibility comes with the tradeoff that CRISPRi-mediated gene repression becomes less effective. Weaker CRISPR interference (CRISPRi) gene repression can be partially rescued by expressing multiple sgRNAs to target many sites in the gene of interest. Our work provides a framework to choose the most effective dCas9 variant for a given set of gene targets, which will further expand the utility of CRISPRa/i gene regulation in bacterial systems.

2022-11-15 | GSE217559 | GEO

Vibrio Cholerae CRISPR-cas PAM requirements

Project description:Plasmids were constructed harboring protospacers that are perfect targets for spacers #4 and #21 of the array, but contain NNN (all possible PAM combinations) immediately upstream of the protospacer. The plasmids were introduced into V. cholerae with or without a functional CRISPR-cas system and cells were plated on selective media. Cells were collected and the protospacer plasmids were sequenced in a high throughput manner. PAMs were counted using a custom python script

2024-05-06 | E-MTAB-14044 | biostudies-arrayexpress

High-throughput screens of PAM-flexible Cas9 variants for gene knock-out and transcriptional modulation

Project description:High-throughput screens of PAM-flexible Cas9 variants for gene knock-out and transcriptional modulation

| PRJNA601989 | ENA

CRISPR enhancer scan to detect critical elements for the regulation of EVI1 in a translocated enhancer

Project description:To uncover, in an unbiased fashion, which elements of the 18 kb translocated region control EVI1 transcription, we devised a CRISPR/Cas9-based enhancer scanning approach. We considered all possible sgRNA target sites containing a canonical Cas9 PAM site (NGG) on both strands of the minimal 18 kb translocated region. Deep-sequencing libraries were generated by PCR amplification of sgRNA guide strands using primers that tag the product with standard Illumina adapters and a 4 bp sample barcode in a 2 step-PCR protocol.

2021-07-26 | E-MTAB-9948 | biostudies-arrayexpress

seRNA PAM-1 interacts with Ddx5 to regulate skeletal muscle satellite cell activation and aging through trans regulation of Timp2 expression [PAM-1 ChIRP-seq]

Project description:There is an absolute requirement of Pax7 for the normal function of MuSCs during regenerative myogenesis in skeletal muscle at any stage of life. Here using RNA-seq, H3K27ac and Pax7 ChIP-seq, we discover PAM-1 (Pax7 Associated Muscle lncRNA) that is enriched in activated skeletal muscle satellite cells (ASCs) 24 and 48 hours after activation. Knockdown of PAM-1 reduces proliferating Pax7+Myod+ ASCs number, while overexpression of PAM-1 increases ASCs number. Mechanistically, PAM-1 is located on ASCs and myoblast specific super-enhancer (SE), and we categorize it as seRNA. Through a series of multiomics analysis of PAM-1 interactome in myoblast including PAM-1-DNA interaction by ChIRP-seq, PAM-1 SE-DNA interaction by 4C-seq, PAM-1-protein interaction by mass spectrometry and ChIP-seq, we identify a novel class of transcriptional regulation that seRNA PAM-1 interacts with RNA binding protein Ddx5 and tethers PAM-1 SE to regulate inter-chromosomal targets Timp2. Altogether, our findings identify PAM-1 is driven by Pax7 in ASC and myoblast to regulate myogenic activation through binding with Ddx5 and targeting Timp2.

2022-07-12 | GSE180071 | GEO

Detecting non-canonically-targeted SpCas9 generated DSBs in human cells by LAM-HTGTS

Project description:We identified robust cleavage by non-canonically-targeted SpCas9 that target protospacer with a few bases from the canonical NGG PAM in biochemistry assay. To determine whether this spaced SpCas9 cleavage exists in human cells, we employed high-throughput genome-wide translocation sequencing (LAM-HTGTS) using SpCas9 with three independent canonical sgRNAs served as bait (bait-A, bait-L and bait-D) to compared the cleavage activities of canonically-targeted and non-canonically-targeted SpCas9 in eight locus (RAG1B-D, RAG1K-O) in chromosome 11. We found that almost all 1bp-target shifted SpCas9 generated substantial DSBs as the canonical controls. While detected less frequently, 2bp-targeted shifted SpCas9 generated significant amounts of DSBs in RAG1D and RAG1L locus. These findings underscore the spaced PAM-mediated DSBs occurred in living cells.

2022-02-28 | GSE192459 | GEO

seRNA PAM-1 interacts with Ddx5 to regulate skeletal muscle satellite cell activation and aging through trans regulation of Timp2 expression [PAM-1 KO ChIP-seq]

2022-07-12 | GSE180069 | GEO

RNA-guided Location and Function of the Cas9 CRISPR Endonuclease in Mammalian Cells

Project description:The clustered regularly interspaced short palindromic repeat (CRISPR)-associated enzyme Cas9 is an RNA-guided nuclease that has been widely adapted for genome editing in eukaryotic cells. However, the in vivo target specificity of Cas9 is poorly understood and most studies rely on in silico predictions to define the potential off-target editing spectrum. Using chromatin immunoprecipitation followed by sequencing (ChIP-seq), we delineate the genome-wide binding panorama of catalytically inactive Cas9 directed by two different single guide (sg) RNAs targeting the Trp53 locus. Cas9:sgRNA complexes are able to load onto multiple sites with short seed regions adjacent to 5’NGG3’ protospacer adjacent motifs (PAM). Examination of dmCas9 binding sites using two Trp53 targeting sgRNAs in Arf -/- MEF cell line (mouse).

2014-08-29 | E-GEOD-57650 | biostudies-arrayexpress

Replacing the SpCas9 HNH domain by deaminases generates compact base editors with an alternative targeting scope [DNA-seq]

Project description:Base editors are RNA-guided deaminases that enable site-specific nucleotide transitions. The targeting scope of these Cas-deaminase fusion proteins critically depends on the availability of a protospacer adjacent motif (PAM) at the selected genomic locus, and is limited to a window within the CRISPR-Cas R-loop where single stranded (ss)DNA is accessible to the deaminase. Here, we reason that the Cas9-HNH nuclease domain sterically constrains ssDNA accessibility, and demonstrate that omission of this domain expands the editing window. By exchanging the HNH nuclease domain with an adenosine deaminase, we furthermore engineer adenine base editor variants (HNHx-ABE) with PAM-proximally shifted editing windows. HNHx-ABEs are substantially reduced in size, and expand the targeting scope of base editors. Our finding that the HNH domain is replaceable could moreover benefit future protein engineering efforts, where Cas9 operates together with other enzyme domains.

2020-11-12 | GSE161380 | GEO

Replacing the SpCas9 HNH domain by deaminases generates compact base editors with an alternative targeting scope

2020-11-12 | GSE161293 | GEO

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data