@Article{Brendel_Stoll_Lange-compl_Cas_prote-JBC2014,
  author =	 {Brendel, Jutta and Stoll, Britta and Lange, Sita J. and 
                  Sharma, Kundan and Lenz, Christof and Stachler, Aris-Edda 
                  and Maier, Lisa-Katharina and Richter, Hagen and Nickel, 
                  Lisa and Schmitz, Ruth A. and Randau, Lennart and Allers, 
                  Thorsten and Urlaub, Henning and Backofen, Rolf and 
                  Marchfelder, Anita},
  title =	 {A complex of {Cas} proteins 5, 6, and 7 is required for the 
                  biogenesis and stability of {crRNAs} in {Haloferax} volcanii},
  journal =	 JBC,
  year =	 {2014},
  volume =	 {289},
  number =	 {10},
  pages =	 {7164-77},
  user =	 {sita},
  pmid =	 {24459147},
  doi = 	 {10.1074/jbc.M113.508184},
  issn = 	 {1083-351X},
  issn = 	 {0021-9258},
  abstract =	 {The CRISPR-Cas (clustered regularly interspaced short 
                  palindromic repeats/ CRISPR associated) system is a 
                  prokaryotic defence mechanism against foreign genetic 
                  elements. A plethora of CRISPR-Cas versions exist, with more 
                  than 40 different Cas protein families and several different 
                  molecular approaches to fight the invading DNA. One of the 
                  key players in the system is the crRNA, which directs the 
                  invader - degrading Cas protein complex to the invader. The 
                  CRISPR-Cas types I and III use the Cas6 protein to generate 
                  mature crRNAs. Here, we show that the Cas6 protein is 
                  necessary for crRNA production but that additional Cas 
                  proteins that form a Cascade-like complex are needed for 
                  crRNA stability in the CRISPR-Cas type I-B system in 
                  Haloferax volcanii in vivo. Deletion of the cas6 gene 
                  results in loss of mature crRNAs and interference. However, 
                  cells that have the complete cas gene cluster (cas1-8) 
                  removed and are transformed with the cas6 gene are not able 
                  to produce and stably maintain mature crRNAs. crRNA 
                  production and stability is rescued only if cas5, 6 and 7 
                  are present. Mutational analysis of the cas6 gene reveals 
                  three amino acids (His41, Gly256 and Gly258) that are 
                  essential for pre-crRNA cleavage, while the mutation of two 
                  amino acids (Ser115 and Ser224) leads to an increase of 
                  crRNA amounts. This is the first systematic in vivo analysis 
                  of Cas6 protein variants. In addition, we show that the H. 
                  volcanii I-B system contains a Cascade-like complex with a 
                  Cas7, Cas5 and Cas6 core that protects the crRNA.}
}