The nuts and bolts of the Haloferax CRISPR-Cas system I-B

Lisa Katharina Maier, Aris Edda Stachler, Jutta Brendel, Britta Stoll, Susan Fischer, Karina A. Haas, Thandi S. Schwarz, Omer S. Alkhnbashi, Kundan Sharma, Henning Urlaub, Rolf Backofen, Uri Gophna, Anita Marchfelder*

*Corresponding author for this work

Research output: Contribution to journalReview articlepeer-review


Invading genetic elements pose a constant threat to prokaryotic survival, requiring an effective defence. Eleven years ago, the arsenal of known defence mechanisms was expanded by the discovery of the CRISPR-Cas system. Although CRISPR-Cas is present in the majority of archaea, research often focuses on bacterial models. Here, we provide a perspective based on insights gained studying CRISPR-Cas system I-B of the archaeon Haloferax volcanii. The system relies on more than 50 different crRNAs, whose stability and maintenance critically depend on the proteins Cas5 and Cas7, which bind the crRNA and form the Cascade complex. The interference machinery requires a seed sequence and can interact with multiple PAM sequences. H. volcanii stands out as the first example of an organism that can tolerate autoimmunity via the CRISPR-Cas system while maintaining a constitutively active system. In addition, the H. volcanii system was successfully developed into a tool for gene regulation.

Original languageEnglish
Pages (from-to)469-480
Number of pages12
JournalRNA Biology
Issue number4
StatePublished - 3 Apr 2019


  • Archaea
  • CRISPR-Cas
  • Haloarchaea
  • self-targeting
  • type I-B


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