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Transcription termination and antitermination of bacterial CRISPR arrays

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 d...

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Detalles Bibliográficos
Autores principales: Stringer, Anne M, Baniulyte, Gabriele, Lasek-Nesselquist, Erica, Seed, Kimberley D, Wade, Joseph T
Formato: Online Artículo Texto
Lenguaje:English
Publicado: eLife Sciences Publications, Ltd 2020
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7665894/
https://www.ncbi.nlm.nih.gov/pubmed/33124980
http://dx.doi.org/10.7554/eLife.58182
Descripción
Sumario: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 sequences 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.