Publications

• A cyclic oligonucleotide signaling pathway in type III CRISPR-Cas systems.

  Kazlauskiene M., Kostiuk G., Venclovas C., Tamulaitis G., Siksnys V.

  Type III CRISPR-Cas systems in prokaryotes provide immunity against invading nucleic acids through the coordinated degradation of transcriptionally active DNA and its transcripts by the Csm effector complex. The Cas10 subunit of the complex contains an HD nuclease domain that is responsible for DN ... >> More

  Type III CRISPR-Cas systems in prokaryotes provide immunity against invading nucleic acids through the coordinated degradation of transcriptionally active DNA and its transcripts by the Csm effector complex. The Cas10 subunit of the complex contains an HD nuclease domain that is responsible for DNA degradation and two Palm domains with elusive functions. In addition, Csm6, a ribonuclease that is not part of the complex, is also required to provide full immunity. We show here that target RNA binding by the Csm effector complex of <i>Streptococcus thermophilus</i> triggers Cas10 to synthesize cyclic oligoadenylates (cA <i>_n</i> ; <i>n</i> = 2 to 6) by means of the Palm domains. Acting as signaling molecules, cyclic oligoadenylates bind Csm6 to activate its nonspecific RNA degradation. This cyclic oligoadenylate-based signaling pathway coordinates different components of CRISPR-Cas to prevent phage infection and propagation. << Less

  Science 357:605-609(2017) [PubMed] [EuropePMC]

  This publication is cited by 1 other entry.

• Type III CRISPR-Cas systems produce cyclic oligoadenylate second messengers.

  Niewoehner O., Garcia-Doval C., Rostoel J.T., Berk C., Schwede F., Bigler L., Hall J., Marraffini L.A., Jinek M.

  In many prokaryotes, type III clustered regularly interspaced short palindromic repeat (CRISPR)-CRISPR-associated (Cas) systems detect and degrade invasive genetic elements by an RNA-guided, RNA-targeting multisubunit interference complex. The CRISPR-associated protein Csm6 additionally contribute ... >> More

  In many prokaryotes, type III clustered regularly interspaced short palindromic repeat (CRISPR)-CRISPR-associated (Cas) systems detect and degrade invasive genetic elements by an RNA-guided, RNA-targeting multisubunit interference complex. The CRISPR-associated protein Csm6 additionally contributes to interference by functioning as a standalone RNase that degrades invader RNA transcripts, but the mechanism linking invader sensing to Csm6 activity is not understood. Here we show that Csm6 proteins are activated through a second messenger generated by the type III interference complex. Upon target RNA binding by the interference complex, its Cas10 subunit converts ATP into a cyclic oligoadenylate product, which allosterically activates Csm6 by binding to its CRISPR-associated Rossmann fold (CARF) domain. CARF domain mutations that abolish allosteric activation inhibit Csm6 activity in vivo, and mutations in the Cas10 Palm domain phenocopy loss of Csm6. Together, these results point to an unprecedented mechanism for regulation of CRISPR interference that bears striking conceptual similarity to oligoadenylate signalling in mammalian innate immunity. << Less

  Nature 548:543-548(2017) [PubMed] [EuropePMC]