CRISPR-Cas: biology, mechanisms and relevance

Philos Trans R Soc Lond B Biol Sci. 2016 Nov 5;371(1707):20150496. doi: 10.1098/rstb.2015.0496.


Prokaryotes have evolved several defence mechanisms to protect themselves from viral predators. Clustered regularly interspaced short palindromic repeats (CRISPR) and their associated proteins (Cas) display a prokaryotic adaptive immune system that memorizes previous infections by integrating short sequences of invading genomes-termed spacers-into the CRISPR locus. The spacers interspaced with repeats are expressed as small guide CRISPR RNAs (crRNAs) that are employed by Cas proteins to target invaders sequence-specifically upon a reoccurring infection. The ability of the minimal CRISPR-Cas9 system to target DNA sequences using programmable RNAs has opened new avenues in genome editing in a broad range of cells and organisms with high potential in therapeutical applications. While numerous scientific studies have shed light on the biochemical processes behind CRISPR-Cas systems, several aspects of the immunity steps, however, still lack sufficient understanding. This review summarizes major discoveries in the CRISPR-Cas field, discusses the role of CRISPR-Cas in prokaryotic immunity and other physiological properties, and describes applications of the system as a DNA editing technology and antimicrobial agent.This article is part of the themed issue 'The new bacteriology'.

Keywords: CRISPR; Cas9; bacteriophage; genome editing.

Publication types

  • Review
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Archaea / genetics
  • Archaea / immunology
  • Archaea / physiology*
  • Bacterial Physiological Phenomena* / genetics
  • Bacterial Physiological Phenomena* / immunology
  • CRISPR-Cas Systems / genetics*