A PNPase dependent CRISPR System in Listeria. - Institut Pasteur Access content directly
Journal Articles PLoS Genetics Year : 2014

A PNPase dependent CRISPR System in Listeria.


The human bacterial pathogen Listeria monocytogenes is emerging as a model organism to study RNA-mediated regulation in pathogenic bacteria. A class of non-coding RNAs called CRISPRs (clustered regularly interspaced short palindromic repeats) has been described to confer bacterial resistance against invading bacteriophages and conjugative plasmids. CRISPR function relies on the activity of CRISPR associated (cas) genes that encode a large family of proteins with nuclease or helicase activities and DNA and RNA binding domains. Here, we characterized a CRISPR element (RliB) that is expressed and processed in the L. monocytogenes strain EGD-e, which is completely devoid of cas genes. Structural probing revealed that RliB has an unexpected secondary structure comprising basepair interactions between the repeats and the adjacent spacers in place of canonical hairpins formed by the palindromic repeats. Moreover, in contrast to other CRISPR-Cas systems identified in Listeria, RliB-CRISPR is ubiquitously present among Listeria genomes at the same genomic locus and is never associated with the cas genes. We showed that RliB-CRISPR is a substrate for the endogenously encoded polynucleotide phosphorylase (PNPase) enzyme. The spacers of the different Listeria RliB-CRISPRs share many sequences with temperate and virulent phages. Furthermore, we show that a cas-less RliB-CRISPR lowers the acquisition frequency of a plasmid carrying the matching protospacer, provided that trans encoded cas genes of a second CRISPR-Cas system are present in the genome. Importantly, we show that PNPase is required for RliB-CRISPR mediated DNA interference. Altogether, our data reveal a yet undescribed CRISPR system whose both processing and activity depend on PNPase, highlighting a new and unexpected function for PNPase in "CRISPRology".
Fichier principal
Vignette du fichier
PLOS Genetics_Sesto.pdf (2.38 Mo) Télécharger le fichier
Origin : Publication funded by an institution

Dates and versions

pasteur-01145428 , version 1 (24-04-2015)


Attribution - NonCommercial - NoDerivatives



Nina Sesto, Marie Touchon, José Marques Andrade, Jiro Kondo, Eduardo P C Rocha, et al.. A PNPase dependent CRISPR System in Listeria.. PLoS Genetics, 2014, 10 (1), pp.e1004065. ⟨10.1371/journal.pgen.1004065⟩. ⟨pasteur-01145428⟩
467 View
262 Download



Gmail Facebook X LinkedIn More