1. Academic Validation
  2. The tracrRNA in CRISPR Biology and Technologies

The tracrRNA in CRISPR Biology and Technologies

  • Annu Rev Genet. 2021 Nov 23:55:161-181. doi: 10.1146/annurev-genet-071719-022559.
Chunyu Liao 1 Chase L Beisel 1 2
Affiliations

Affiliations

  • 1 Helmholtz Institute for RNA-based Infection Research (HIRI), Helmholtz Centre for Infection Research (HZI), 97080 Würzburg, Germany; email: Chase.Beisel@helmholtz-hiri.de.
  • 2 Medical Faculty, University of Würzburg, 97080 Würzburg, Germany.
Abstract

CRISPR-Cas adaptive immune systems in bacteria and archaea utilize short CRISPR RNAs (crRNAs) to guide sequence-specific recognition and clearance of foreign genetic material. Multiple crRNAs are stored together in a compact format called a CRISPR array that is transcribed and processed into the individual crRNAs. While the exact processing mechanisms vary widely, some CRISPR-Cas systems, including those encoding the Cas9 nuclease, rely on a trans-activating crRNA (tracrRNA). The tracrRNA was discovered in 2011 and was quickly co-opted to create single-guide RNAs as core components of CRISPR-Cas9 technologies. Since then, further studies have uncovered processes extending beyond the traditional role of tracrRNA in crRNA biogenesis, revealed Cas nucleases besides Cas9 that are dependent on tracrRNAs, and established new applications based on tracrRNA engineering. In this review, we describe the biology of the tracrRNA and how its ongoing characterization has garnered new insights into prokaryotic immune defense and enabled key technological advances.

Keywords

RNA processing; RNase III; crystal structure; immune defense; sgRNA.

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