ToxN acts as a toxin, it is part of a type III toxin-antitoxin system. It acts as a ribosome independent endoribonuclease. It interacts with, and is inhibited by, the RNA antitoxin, ToxI [1,2]. Three ToxN monomers bind to three ToxI monomers to create a trimeric ToxN-ToxI complex [2].

1: The phage abortive infection system, ToxIN, functions as a protein-RNA toxin-antitoxin pair. Fineran PC, Blower TR, Foulds IJ, Humphreys DP, Lilley KS, Salmond GP; Proc Natl Acad Sci U S A. 2009;106:894-899. PMID:19124776

2: A processed noncoding RNA regulates an altruistic bacterial antiviral system. Blower TR, Pei XY, Short FL, Fineran PC, Humphreys DP, Luisi BF, Salmond GP; Nat Struct Mol Biol. 2011;18:185-190. PMID:21240270