A ruler protein in a complex for antiviral defense determines the length of small interfering CRISPR RNAs

Abstract

Background: CRISPR immune systems protect prokaryotes from their viruses using small interfering RNAs (crRNAs), which require maturation events during their biogenesis. Results: In Staphylococcus epidermidis, crRNAs undergo maturation in a Cas10-Csm ribonucleoprotein complex; Csm3 modulates the extent of maturation. Conclusion: Csm3 acts as a ruler for crRNAs. Significance: Investigating CRISPR immunity is important to understand prokaryotic ecology and to develop biotechnological applications. © 2013 by The American Society for Biochemistry and Molecular Biology, Inc.