A Novel Genomic Island Encodes a Copper-Responsive Regulatory System and a Single Icm/Dot Effector Protein Transcriptionally Activated by Copper.

The intracellular pathogen utilizes the Icm/Dot type IV secretion system to translocate >300 effector proteins into host cells during infection. The regulation of some of these effector-encoding genes was previously shown to be coordinated by several global regulators, including three two-component systems (TCSs) found in all the species examined. Here, we describe the first genomic island encoding a single Icm/Dot effector and a dedicated TCS, which regulates its expression.