Transcriptional and post-transcriptional regulation of type I and III CRISPR-Cas activity

Although CRISPR-Cas systems benefit their hosts by providing phage resistance, other costs, such as autoimmunity, may occur. One way that bacteria might maximize the benefits of their CRISPR-Cas systems is via regulation – e.g. by upregulating the systems when there is a high risk of infection or a phage epidemic. By developing a new method and using existing approaches, we have identified a suite of regulators that influence Class 1 (type I and III) expression and activity. In addition to cell-density dependent regulation (quorum sensing), we have identified both transcriptional and post-transcriptional regulators of CRISPR-Cas activity.