Toxic component of an LXG toxin-immunity module. The C-terminus (residues 322-545) has RNase activity in E.coli which is neutralized by cognate immunity protein BC_0921, but not by immunity proteins specific to other toxins with the LXG domain (PubMed:22200572). Degrades 5S rRNA and several tRNAs in vitro; cleavage is endonucleolytic within the anticodon loop for tRNA(GAU-Ile) and tRNA(UUC-Glu) but total for 5S rRNA and at least one other tRNA. RNase activity is suppressed by cognate immunity protein BC_0921 (PubMed:29923643). Probably interacts with cognate immunity protein BC_0921. The interaction inhibits the toxic activity of BC_0921 (Probable). Delivery to target cells requires a type VII secretion system (T7SS). In the N-terminal section; belongs to the LXG family. In the C-terminal section; belongs to the bacterial EndoU family.