RnlB_antitoxin, formerly known as yfjO, has been found to be the antidote protein to RNase LS or RnlA in E. coli. Bacterial toxin-antitoxin systems consist of a stable toxin and an unstable antitoxin. In this case, a novel type II system, RnlA is the stable toxin that causes inhibition of cell growth and rapidly degrades T4 late mRNAs to prevent their expression, and this is neutralised by the activity of the unstable antitoxin RnlB [1].

1: Escherichia coli rnlA and rnlB compose a novel toxin-antitoxin system. Koga M, Otsuka Y, Lemire S, Yonesaki T; Genetics. 2011;187:123-130. PMID:20980243