@Article{Makarova_Wolf_Alkhnbashi-updat_evolu_class-2015,
  author =	 {Makarova, Kira S. and Wolf, Yuri I. and Alkhnbashi, Omer S. 
                  and Costa, Fabrizio and Shah, Shiraz A. and Saunders, Sita 
                  J. and Barrangou, Rodolphe and Brouns, Stan J. J. and 
                  Charpentier, Emmanuelle and Haft, Daniel H. and Horvath, 
                  Philippe and Moineau, Sylvain and Mojica, Francisco J. M. 
                  and Terns, Rebecca M. and Terns, Michael P. and White, 
                  Malcolm F. and Yakunin, Alexander F. and Garrett, Roger A. 
                  and van der Oost, John and Backofen, Rolf and Koonin, Eugene 
                  V.},
  title =	 {An updated evolutionary classification of {CRISPR}-{Cas} 
                  systems},
  journal =	 {Nat Rev Microbiol},
  year =	 {2015},
  volume =	 {13},
  number =	 {11},
  pages =	 {722-736},
  user =	 {alkhanbo},
  pmid =	 {26411297},
  doi = 	 {10.1038/nrmicro3569},
  issn = 	 {1740-1526},
  issn = 	 {1740-1534},
  abstract =	 {The evolution of CRISPR-cas loci, which encode adaptive 
                  immune systems in archaea and bacteria, involves rapid 
                  changes, in particular numerous rearrangements of the locus 
                  architecture and horizontal transfer of complete loci or 
                  individual modules. These dynamics complicate 
                  straightforward phylogenetic classification, but here we 
                  present an approach combining the analysis of signature 
                  protein families and features of the architecture of cas 
                  loci that unambiguously partitions most CRISPR-cas loci into 
                  distinct classes, types and subtypes. The new classification 
                  retains the overall structure of the previous version but is 
                  expanded to now encompass two classes, five types and 16 
                  subtypes. The relative stability of the classification 
                  suggests that the most prevalent variants of CRISPR-Cas 
                  systems are already known. However, the existence of rare, 
                  currently unclassifiable variants implies that additional 
                  types and subtypes remain to be characterized.}
}