Function
Toxic component of a type III toxin-antitoxin (TA) system. An endoribonuclease that is probably sequence-specific. It is neutralized by its cognate antitoxin RNA AntiQ, which has 2.8 35 nucleotide-long repeats. Cannot be cloned in L.lactis subsp. cremoris strain NZ9000 in the absence of the antitoxin gene; expression in strain NZ9000 even in the presence of antiQ inhibits growth in a bacteriostatic fashion (PubMed:23279123). Confers resistance to 936 and c2 phages but not P335 phages in L.lactis, causes an abortive infection (Abi phenotype). Viral DNA is replicated but not cleaved from its concatemeric form, while the viral major structural protein is produced normally in the presence of this protein (PubMed:9835558). Operon expression in E.coli confers resistance to 3 phages of the Myoviridae family (T4, RB69 and phage 2) and 1 of the Siphoviridae family (T5), but not other tested phages (T1, T3, lambda vir, HK97, Mu and pilH alpha). The presence of this operon in L.lactis subsp. lactis strain IL1403 during phage P008 infection alters the viral transcription profiles (PubMed:23813728).