@Article{Maier_Stachler_Saunders-Activ_Immun_Defen-JBC2014,
  author =	 {Maier, Lisa-Katharina and Stachler, Aris-Edda and Saunders, 
                  Sita J. and Backofen, Rolf and Marchfelder, Anita},
  title =	 {An {Active} {Immune} {Defence} with a {Minimal} {CRISPR} 
                  (clustered regularly interspaced short palindromic repeats) 
                  {RNA} and {Without} the {Cas6} {Protein}},
  journal =	 JBC,
  year =	 {2014},
  volume =	 {290},
  number =	 {7},
  pages =	 {4192-4201},
  user =	 {sita},
  pmid =	 {25512373},
  doi = 	 {10.1074/jbc.M114.617506},
  issn = 	 {0021-9258},
  issn = 	 {1083-351X},
  abstract =	 {The prokaryotic immune system CRISPR-Cas1 is a defence 
                  system that protects prokaryotes against foreign DNA. The 
                  short CRISPR RNAs (crRNAs) are central components of this 
                  immune system. In CRISPR-Cas systems type I and III crRNAs 
                  are generated by the endonuclease Cas6. We developed a 
                  Cas6b2-independent crRNA maturation pathway for the 
                  Haloferax type I-B system in vivo, that expresses a 
                  functional crRNA that we termed independently generated 
                  crRNA (icrRNA). The icrRNA is effective in triggering 
                  degradation of an invader plasmid carrying the matching 
                  protospacer sequence. The Cas6b-independent maturation of 
                  the icrRNA allowed mutation of the repeat sequence without 
                  interfering with signals important for Cas6b processing. We 
                  generated 23 variants of the icrRNA and analysed them for 
                  activity in the interference reaction. icrRNAs with 
                  deletions or mutations of the 3' handle are still active in 
                  triggering a interference reaction. The complete 3' handle 
                  could be removed without loss of activity. However 
                  manipulations of the 5' handle mostly led to loss of 
                  interference activity. Furthermore we could show that in the 
                  presence of an icrRNA a strain without Cas6b (cas6b) is 
                  still active in interference.}
}