Contact-dependent growth inhibition (CDI) systems encode polymorphic toxin/immunity proteins that mediate competition between neighbouring bacterial cells [1]. Despite sharing little sequence identity, the toxin domains are structurally similar and have homology to endonucleases. The EC869 toxin is a Zn(2+)-dependent DNase capable of completely degrading the genomes of target cells [1].

1: Structural basis of toxicity and immunity in contact-dependent growth inhibition (CDI) systems. Morse RP, Nikolakakis KC, Willett JL, Gerrick E, Low DA, Hayes CS, Goulding CW; Proc Natl Acad Sci U S A. 2012;109:21480-21485. PMID:23236156

2: Diversification of beta-Augmentation Interactions between CDI Toxin/Immunity Proteins. Morse RP, Willett JL, Johnson PM, Zheng J, Credali A, Iniguez A, Nowick JS, Hayes CS, Goulding CW; J Mol Biol. 2015;427:3766-3784. PMID:26449640