@Article{Stachler_Wortz_Alkhnbashi-Adapt_induc_self-JBC2020,
  author =	 {Stachler, Aris-Edda and Wortz, Julia and Alkhnbashi, Omer 
                  S. and Turgeman-Grott, Israela and Smith, Rachel and Allers, 
                  Thorsten and Backofen, Rolf and Gophna, Uri and Marchfelder, 
                  Anita},
  title =	 {Adaptation induced by self-targeting in a type {I}-{B} 
                  {CRISPR}-{Cas} system},
  journal =	 JBC,
  year =	 {2020},
  volume =	 {295},
  number =	 {39},
  pages =	 {13502-13515},
  user =	 {alkhanbo},
  pmid =	 {32723866},
  doi = 	 {10.1074/jbc.RA120.014030},
  issn = 	 {1083-351X},
  issn = 	 {0021-9258},
  abstract =	 {Haloferax volcanii is, to our knowledge, the only 
                  prokaryote known to tolerate CRISPR-Cas-mediated damage to 
                  its genome in the WT background; the resulting cleavage of 
                  the genome is repaired by homologous recombination restoring 
                  the WT version. In mutant Haloferax strains with enhanced 
                  self-targeting, cell fitness decreases and 
                  microhomology-mediated end joining becomes active, 
                  generating deletions in the targeted gene. Here we use 
                  self-targeting to investigate adaptation in H. volcanii 
                  CRISPR-Cas type I-B. We show that self-targeting and genome 
                  breakage events that are induced by self-targeting, such as 
                  those catalyzed by active transposases, can generate DNA 
                  fragments that are used by the CRISPR-Cas adaptation 
                  machinery for integration into the CRISPR loci. Low cellular 
                  concentrations of self-targeting crRNAs resulted in 
                  acquisition of large numbers of spacers originating from the 
                  entire genomic DNA. In contrast, high concentrations of 
                  self-targeting crRNAs resulted in lower acquisition that was 
                  mostly centered on the targeting site. Furthermore, we 
                  observed naive spacer acquisition at a low level in WT 
                  Haloferax cells and with higher efficiency upon 
                  overexpression of the Cas proteins Cas1, Cas2, and Cas4. 
                  Taken together, these findings indicate that naive 
                  adaptation is a regulated process in H. volcanii that 
                  operates at low basal levels and is induced by DNA breaks.}
}