Structure and mechanism of the CMR complex for CRISPR-mediated antiviral immunity

Mol Cell. 2012 Feb 10;45(3):303-13. doi: 10.1016/j.molcel.2011.12.013. Epub 2012 Jan 5.


The prokaryotic clusters of regularly interspaced palindromic repeats (CRISPR) system utilizes genomically encoded CRISPR RNA (crRNA), derived from invading viruses and incorporated into ribonucleoprotein complexes with CRISPR-associated (CAS) proteins, to target and degrade viral DNA or RNA on subsequent infection. RNA is targeted by the CMR complex. In Sulfolobus solfataricus, this complex is composed of seven CAS protein subunits (Cmr1-7) and carries a diverse "payload" of targeting crRNA. The crystal structure of Cmr7 and low-resolution structure of the complex are presented. S. solfataricus CMR cleaves RNA targets in an endonucleolytic reaction at UA dinucleotides. This activity is dependent on the 8 nt repeat-derived 5' sequence in the crRNA, but not on the presence of a protospacer-associated motif (PAM) in the target. Both target and guide RNAs can be cleaved, although a single molecule of guide RNA can support the degradation of multiple targets.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Archaeal Proteins / chemistry*
  • Archaeal Proteins / isolation & purification
  • Archaeal Viruses / immunology
  • Base Sequence
  • Crystallography, X-Ray
  • Inverted Repeat Sequences*
  • Macromolecular Substances / chemistry
  • Macromolecular Substances / isolation & purification
  • Microscopy, Electron
  • Models, Molecular
  • Molecular Sequence Data
  • Nucleic Acid Conformation
  • Protein Structure, Quaternary
  • Protein Structure, Tertiary
  • Protein Subunits / chemistry
  • Protein Subunits / isolation & purification
  • RNA Cleavage
  • RNA, Archaeal / chemistry*
  • RNA, Archaeal / genetics
  • RNA, Archaeal / isolation & purification
  • Sulfolobus solfataricus / genetics
  • Sulfolobus solfataricus / immunology
  • Sulfolobus solfataricus / metabolism*
  • Sulfolobus solfataricus / virology


  • Archaeal Proteins
  • Macromolecular Substances
  • Protein Subunits
  • RNA, Archaeal