A novel family of toxin/antitoxin proteins in Bacillus species

► We identify homologies between the toxin domains of CDI systems and PF04740 proteins. ► Several PF04740 C-terminal domains have cytotoxic RNase activities. ► The activity of each PF04740 protein is specifically blocked by cognate antitoxin. ► We conclude that PF04740 proteins constitute a new toxin-antitoxin family.