Crystal and cryo-EM studies of the effector duet complexed with CaM and Rac1, together with biochemical and immunological analyses, provide key insight into a concerted invasion strategy in which pathogenic bacteria coordinate the DUF1-RID duet, the components of which act synergistically to suppress ROS generation and promote dissemination of pathogens, ultimately resulting in sepsis. The gene discussed is RAC1; the disease is Sepsis.