Transcription termination and antitermination of bacterial CRISPR arrays
Abstract
A hallmark of CRISPR-Cas immunity systems is the CRISPR array, a genomic locus consisting of short, repeated sequences ('repeats') interspersed with short, variable sequences ('spacers'). CRISPR arrays are transcribed and processed into individual CRISPR RNAs that each include a single spacer, and direct Cas proteins to complementary sequence in invading nucleic acid. Most bacterial CRISPR array transcripts are unusually long for untranslated RNA, suggesting the existence of mechanisms to prevent premature transcription termination by Rho, a conserved bacterial transcription termination factor that rapidly terminates untranslated RNA. We show that Rho can prematurely terminate transcription of bacterial CRISPR arrays, and we identify a widespread antitermination mechanism that antagonizes Rho to facilitate complete transcription of CRISPR arrays. Thus, our data highlight the importance of transcription termination and antitermination in the evolution of bacterial CRISPR-Cas systems.
Data availability
Raw ChIP-seq data are available from EBI ArrayExpress/ENA using accession number E-MTAB-7242. Raw sequencing data for conjugation experiments involving V. cholerae are available from EBI ArrayExpress/ENA using accession number E-MTAB-9631.
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Nus factors prevent premature transcription termination of bacterial CRISPR arraysEMBL-EBI ArrayExpress, E-MTAB-7242.
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Transcription Termination and Antitermination of Bacterial CRISPR ArraysEMBL-EBI ArrayExpress, E-MTAB-9631.
Article and author information
Author details
Funding
National Institute of General Medical Sciences (R01GM122836)
- Joseph T Wade
National Institute of Allergy and Infectious Diseases (R21AI126416)
- Joseph T Wade
National Institute of Allergy and Infectious Diseases (R01AI127652)
- Kimberley D Seed
Burroughs Wellcome Fund (Investigators in the Pathogenesis of Infectious Disease Award)
- Kimberley D Seed
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Copyright
© 2020, Stringer et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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