Altered stoichiometry Escherichia coli Cascade complexes with shortened CRISPR RNA spacers are capable of interference and primed adaptation

Konstantin Kuznedelov, Vladimir Mekler, Sofia Lemak, Monika Tokmina-Lukaszewska, Kirill A. Datsenko, Ishita Jain, Ekaterina Savitskaya, John Mallon, Sergey Shmakov, Brian Bothner, Scott Bailey, Alexander F. Yakunin, Konstantin Severinov, Ekaterina Semenova

Research output: Contribution to journalArticle

Abstract

The Escherichia coli type I-E CRISPR-Cas system Cascade effector is a multisubunit complex that binds CRISPR RNA (crRNA). Through its 32-nucleotide spacer sequence, Cascade-bound crRNA recognizes protospacers in foreign DNA, causing its destruction during CRISPR interference or acquisition of additional spacers in CRISPR array during primed CRISPR adaptation. Within Cascade, the cr-RNA spacer interacts with a hexamer of Cas7 subunits. We show that crRNAs with a spacer length reduced to 14 nucleotides cause primed adaptation, while crRNAs with spacer lengths of more than 20 nucleotides cause both primed adaptation and target interference in vivo. Shortened crRNAs assemble into altered-stoichiometry Cascade effector complexes containing less than the normal amount of Cas7 subunits. The results show that Cascade assembly is driven by crRNA and suggest that multisubunit type I CRISPR effectors may have evolved from much simpler ancestral complexes.

Original languageEnglish (US)
Pages (from-to)10849-10861
Number of pages13
JournalNucleic acids research
Volume44
Issue number22
DOIs
StatePublished - Dec 2016

ASJC Scopus subject areas

  • Genetics

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    Kuznedelov, K., Mekler, V., Lemak, S., Tokmina-Lukaszewska, M., Datsenko, K. A., Jain, I., Savitskaya, E., Mallon, J., Shmakov, S., Bothner, B., Bailey, S., Yakunin, A. F., Severinov, K., & Semenova, E. (2016). Altered stoichiometry Escherichia coli Cascade complexes with shortened CRISPR RNA spacers are capable of interference and primed adaptation. Nucleic acids research, 44(22), 10849-10861. https://doi.org/10.1093/nar/gkw914