CRISPR-Cas protein Cas3 controls virulence in the oral pathogen Porphyromonas gingivalis.

Our results show that compared to wild type, a deletion mutant of the cas3 gene, an essential nuclease part of the class 1 type I CRISPR-Cas system, increases the virulence of P gingivalis. Overall design: we performed targeted deletion of cas3 to understand type I CRISPR-Cas systems and because it was among the most up-regulated CRISPR-Cas genes in our metatranscriptomic study (30). Using dual transcriptomic evaluations, coupled with cell and infection assays, this study demonstrates that Cas3 controls P. gingivalis virulence upon intracellular infection, but seems to have no role in virulence when growing in the planktonic phase