Browse
Submit Data
Databases
API
Help

Dataset Information

0 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Enhanced genome-wide knockout screens in bacteria with CRISPR base editors

ABSTRACT: Genome-wide knockout or knockdown screens have become powerful tools for the investigation of genotype-to-phenotype relationships. In bacteria, these screens commonly rely on transcriptional repression by dCas9, gene knockouts through Cas9 editing or random transposon mutagenesis, but depending on the technique, suffer from incomplete gene silencing, low editing efficiencies or they require massive library sizes. Here, we take a distinct approach with base editing to introduce premature stop codons or mutate start codons in Escherichia coli using a ScCas9 nickase derived base editor (ScBE3) that exhibits flexible PAM recognition. We then derive guide design rules by applying machine learning to a gene essentiality screen conducted in E. coli. For further improvement, we combined base-editing with Cas9-induced cleavage of the unedited cell fraction. The efficiency of this dual system was validated through a screen of conditionally essential E. coli genes. This improved setup that decouples the gene editing from the screening leads to more efficient guide depletion and confirmed previously published conditionally essential genes. Overall, base editing represents a useful tool for genome-wide knockout screens in bacteria and will eventually enable genome-wide knockout screens in a broader range of bacterial species to study their diverse genetics.

ORGANISM(S): Escherichia coli

PROVIDER: GSE225335 | GEO | 2024/02/05

REPOSITORIES: GEO

ACCESS DATA

Json Xml

Dataset's files

Source:

			Action	DRS
		Other

Items per page:

1 - 1 of 1

Similar Datasets

Project description:Base editing sensor screens and validation

| PRJNA746395 | ENA

CRISPR-CLEAR: Nucleotide-Resolution Mapping of Regulatory Elements via Allelic Readout of Tiled Base Editing

Project description:CRISPR tiling screens have advanced the identification and characterization of regulatory sequences but are limited by low resolution arising from the indirect readout of editing via guide RNA sequencing. This study introduces CRISPR-CLEAR, an end-to-end experimental assay and computational pipeline, which leverages targeted sequencing of CRISPR-introduced alleles at the endogenous target locus following dense base-editing mutagenesis. This approach enables the dissection of regulatory elements at nucleotide resolution, facilitating a direct assessment of genotype-phenotype effects.

2024-10-03 | GSE278581 | GEO

d7d60018-cab1-4b22-a769-69ff998cccf8 - samples

Project description:The mutagenicity of bacteria was assessed by serially exposing human small intestinal organoids to various bacterial species or isolated toxins. We have used the following abbreviations: EWT: Organoids exposed to E. coli described in PMID: 32106218 EKO: Organoids exposed to isogenic E. coli as EWT, with knockout of the deltaClbQ gene, rendering them unable to produce colibactin DYE: Organoids exposed to FastGreen injection control dye NIS: Organoids exposed to E. coli Nissle ETBF: Organoids exposed to the protease toxin BTF produced by ETBF-bacteria.

| EGAD00001008687 | EGA

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

miRNA-seq of HEK293 cell lines on Illumina iSeq100 instrument

Project description:A validation experiment performed on HEK293 cell lines after genome editing. The design contains three duplicate runs consisted of: HEK293 wild type cell line HEK293 with MIR484 gene knockdown using CRISPR-Cas9 HEK293 with MIR185 gene knockout using CRISPR-Cas9

2023-06-16 | E-MTAB-13009 | biostudies-arrayexpress

CLUSTER guide RNAs enable precise and efficient RNA editing with endogenous ADAR enzymes in vivo

Project description:RNA base editing represents a promising alternative for genome editing. Recent approaches harness the endogenous RNA editing enzyme ADAR to circumvent problems related to the ectopic expression of an editing enzyme, but they suffer from sequence restriction, lack of efficiency, and bystander editing. Here, we present in‐silico optimized CLUSTER guide RNAs, which bind their target mRNAs in a multivalent fashion and thereby enable editing with unprecedented precision as shown by next generation sequencing. CLUSTER guide RNAs can be genetically encoded and manufactured into viruses to work in various cell lines. They achieve on‐target editing on endogenous transcripts like GUSB and NUP43 with yields up to 45% without bystander editing and have been shown to recruit endogenous ADAR in vivo. The CLUSTER approach tremendously enlarges the sequence space available for guide RNA design and opens new avenues for drug development in the field of RNA base editing.

2021-09-20 | GSE184244 | GEO

EGAS00001000166-sc-20180517 - samples

Project description:CRISPR-Cas9 genome editing is widely used to study gene function, from basic biology to biomedical research. Structural rearrangements are a ubiquitous feature of cancer cells and their impact on the functional consequences of CRISPR-Cas9 gene-editing has not yet been assessed. Utilizing CRISPR-Cas9 knockout screens for 250 cancer cell lines, we demonstrate that targeting structurally rearranged regions, in particular tandem or interspersed amplifications, is highly detrimental to cellular fitness in a gene independent manner. In contrast, amplifications caused by whole chromosomal duplications have little to no impact on fitness. This effect is cell line specific and dependent on the ploidy status. We devise a copy-number ratio metric that substantially improves the detection of gene-independent cell fitness effects in CRISPR-Cas9 screens. Furthermore, we develop a computational tool, called Crispy, to account for these effects on a single sample basis and provide corrected gene fitness effects. Our analysis demonstrates the importance of structural rearrangements in mediating the effect of CRISPR-Cas9-induced DNA damage, with implications for the use of CRISPR-Cas9 gene-editing in cancer cells.

| EGAD00001004124 | EGA

Transcriptome-wide off-target RNA editing induced by CRISPR-guided DNA base editors [Modifications - screen]

Project description:Base Editing has been touted the most intelligent and precise application of the CRISPR platform so far, merging the simplicity of RNA-guided nucleases with deaminases that allow for the programmable generation of single base substitutions - without introduction of double-strand breaks. Even though the two-component system has been expected to cause off-target substitutions, studies involving cytosine base editors (CBEs) showed that in most cases, relatively few single base off-targets could be detected on DNA. We introduce the concept of multi-dimensional off-targeting, presenting an extensive amount of RNA cytidines being edited by DNA base editors. Epitranscriptomic off-target effects affected different cell lines and were independent of the guide RNAs used, suggesting Cas9-independent activity of the cytidine deaminase rAPOBEC1 on single-stranded RNA. With the help of protein engineering, we developed CBE variants with massively reduced inadvertent mutation of RNA that preserve and enhance DNA base editing capabilities.

2019-03-31 | GSE121666 | GEO

Transcriptome-wide off-target RNA editing induced by CRISPR-guided DNA base editors [BaseEditors - RNA]

2019-03-31 | GSE121665 | GEO

Transcriptome-wide off-target RNA editing induced by CRISPR-guided DNA base editors [P2A-EGFP control]

2019-04-01 | GSE129131 | GEO