Purification and characterization of ribonucleoprotein effector complexes of Sulfolobus islandicus CRISPR-Cas systems

Archaea are preferred hosts for CRISPR-Cas systems. This adaptive immune system is not only widespread in archaeal organisms, but different types of CRISPR-Cas also co-exist in the same organism. Sulfolobus islandicus provides a good model for CRISPR research as genetic assays have been developed for revealing CRISPR immunity for the crenarchaeal model, and native ribonucleoprotein effector complexes have been expressed in this crenarchaeon and purified for characterization. Here we report a detailed protocol of purification and characterization of the Sulfolobus islandicus Cmr-beta, the largest CRISPR effector known to date. The method can readily be applied to the purification of effectors encoded by other CRISPR-Cas systems in this organism, with the possibility to extend the application to other Sulfolobales.