Electron microscopy studies of Type III CRISPR machines in Sulfolobus solfataricus

Giuseppe Cannone, Mariam Webber-Birungi, Laura Spagnolo

Research output: Contribution to journalArticlepeer-review


The CRISPR (clustered regularly interspaced short palindromic repeats) system is an adaptive immune system that targets viruses and other mobile genetic elements in bacteria and archaea. Cells store information of past infections in their genome in repeat-spacer arrays. After transcription, these arrays are processed into unit-length crRNA (CRISPR RNA) that is loaded into effector complexes encoded by Cas (CRISPR-associated) genes. CRISPR-Cas complexes target invading nucleic acid for degradation. CRISPR effector complexes have been classified into three main types (I-III). Type III effector complexes share the Cas10 subunit. In the present paper, we discuss the structures of the two Type III effector complexes from Sulfolobus solfataricus, SsoCSM (subtype III-A) and SsoCMR (subtype III-B), obtained by electron microscopy and single particle analysis. We also compare these structures with Cascade (CRISPR-associated complex for antiviral defence) and with the RecA nucleoprotein.
Original languageEnglish
Pages (from-to)1427-1430
Number of pages4
JournalBiochemical Society Transactions
Issue number6
Early online date20 Nov 2013
Publication statusPublished - 1 Dec 2013


  • clustered regulalry interspaced short palindromic repeats (CRISPR) - CRISPR-associated (Cas)
  • RNA (crRNA)
  • RecA
  • RNA polymerase


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