Transposon-encoded nucleases use guide RNAs to selfishly bias their inheritance
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ABSTRACT:
PROVIDER: PRJNA925099 | ENA |
REPOSITORIES: ENA
Similar Datasets
Project description:Insertion sequences (IS) are compact and pervasive transposable elements found in bacteria, which encode only the genes necessary for their mobilization and maintenance. IS200/IS605 elements undergo ‘peel-and-paste’ transposition catalyzed by a TnpA transposase, but intriguingly, they also encode diverse, TnpB-family genes that are evolutionarily related to the CRISPR-associated effectors Cas9 and Cas12. Recent studies demonstrated that TnpB-family enzymes function as RNA-guided DNA endonucleases, but the broader biological role of this activity has remained enigmatic. Here we show that IscB and TnpB are essential to prevent loss of the donor IS element and potential transposon extinction as a consequence of the TnpA transposition mechanism. We first performed phylogenetic analysis of IscB/TnpB proteins and selected a family of related IS elements from Geobacillus stearothermophilus that we predicted would be mobilized by a common TnpA homolog. After reconstituting transposition using a heterologous expression system in E. coli, we found that IS elements were readily lost from the donor site due to the activity of TnpA in rejoining the flanking sequences back together upon excision. However, these IS elements also encode non-coding RNAs that guide TnpB and IscB nucleases to precisely recognize and cleave these excision products, leading either to elimination of the excision product or re-installation of the transposon through recombination. Indeed, under experimental conditions in which TnpA and TnpB-RNA complexes were co-expressed together with a genomically integrated IS element, transposon retention was significantly increased relative to conditions expressing TnpA alone. Remarkably, both TnpA and TnpB recognize the same AT-rich transposon-adjacent motif (TAM) during transposon excision and RNA-guided DNA cleavage, respectively, revealing a striking convergence in the evolution of DNA sequence specificity between transposase and nuclease. Collectively, our study reveals that RNA-guided DNA cleavage is a primal biochemical activity that arose to bias the selfish inheritance of transposable elements, which was later co-opted during the evolution of CRISPR-Cas adaptive immunity for antiviral defense.
2023-06-01 | GSE223127 | GEO
Project description:TnpB nucleases represent the evolutionary precursors to CRISPR-Cas12 and are widespread in all domains of life. IS605-family TnpB homologs function in bacteria as programmable RNA-guided homing endonucleases driving transposon maintenance through DSB-stimulated homologous recombination. Here we uncover molecular mechanisms of transposition lifecycle of IS607-family elements that, remarkably, also encode group I introns. We discover molecular features for a candidate ‘IStron’ from Clostridium botulinum that allow the element to carefully control the relative levels of spliced products versus functional guide RNAs. Our results suggest that IStron transcripts have evolved a sensitive equilibrium to balance competing and mutually exclusive activities that promote transposon maintenance while limiting adverse fitness costs on the host. Collectively, this work highlights molecular innovation in the multi-functional utility of transposon-encoded noncoding RNAs.
2024-05-06 | GSE261343 | GEO
Project description:TnpB nucleases represent the evolutionary precursors to CRISPR-Cas12 and are widespread in all domains of life. IS605-family TnpB homologs function in bacteria as programmable RNA-guided homing endonucleases driving transposon maintenance through DSB-stimulated homologous recombination. Here we uncover molecular mechanisms of transposition lifecycle of IS607-family elements that, remarkably, also encode group I introns. We discover molecular features for a candidate ‘IStron’ from Clostridium botulinum that allow the element to carefully control the relative levels of spliced products versus functional guide RNAs. Our results suggest that IStron transcripts have evolved a sensitive equilibrium to balance competing and mutually exclusive activities that promote transposon maintenance while limiting adverse fitness costs on the host. Collectively, this work highlights molecular innovation in the multi-functional utility of transposon-encoded noncoding RNAs.
2024-05-06 | GSE261342 | GEO
Project description:Antagonistic conflict between transposon-encoded introns and guide RNAs
| PRJNA1086522 | ENA
Project description:Antagonistic conflict between transposon-encoded introns and guide RNAs (RIP-Seq)
| PRJNA1086529 | ENA
Project description:Antagonistic conflict between transposon-encoded introns and guide RNAs (RNA-Seq)
| PRJNA1086528 | ENA
Project description:eHap CRISPR-Cas9 mutagenized cells with no selection serves as a control. RPS6p antibody staining on the mutagenized eHap cells was used in a flow-sorting approach to isolate RPS6p high and low populations respectively. The genomic DNA from these different samples was isolated, subjected to PCR to amplify the genomically-encoded guide RNA sequences, the product(s) of which was then sequenced on a Hi-Seq X Ten instrument by Novogene.
2020-04-23 | E-MTAB-8926 | biostudies-arrayexpress
Project description:CRISPR-Cas systems can be utilized as programmable-spectrum antimicrobials to combat bacterial infections. However, how CRISPR nucleases perform as antimicrobials across target sites and strains remains poorly explored. Here, we address this knowledge gap by systematically interrogating the use of CRISPR antimicrobials against multidrug-resistant and hypervirulent strains of Klebsiella pneumoniae. Comparing different Cas nucleases, we found that AsCas12a exhibited robust targeting across different strains. The elucidated modes of escape from this nuclease varied widely, restraining opportunities to enhance killing. We also encountered individual guide RNAs yielding different extents of clearance across strains. The differences were attributed to improper RNA folding, leading to inefficient DNA cleavage and subsequent repair via homologous recombination. To explore features that could improve targeting across strains, we performed a genome-wide screen in different K. pneumoniae strains that yielded guide design rules and trained an algorithm for predicting guide efficiency. Finally, we showed that Cas12a antimicrobials can be exploited to eliminate K. pneumoniae when encoded in phagemids delivered by T7-like phages. Altogether, our results highlight the importance of evaluating antimicrobial activity of CRISPR antimicrobials across relevant strains and define critical parameters for efficient CRISPR-based targeting.
2023-07-17 | GSE237136 | GEO
Project description:This SuperSeries is composed of the SubSeries listed below.
2024-05-06 | GSE261344 | GEO