Probable toxic component of a putative type VII toxin-antitoxin (TA) system, probably an RNase. Probably neutralized by antitoxin MJ1215 or MJ1217. Neutralization may be due to AMPylation by antitoxin. Homodimer, probably forms a complex with antitoxin MJ1215 or MJ1217. Modified by antitoxin MJ1215 or MJ1217; probably at least 2 successive AMPylation events occur on Tyr-83. Belongs to the HepT RNase toxin family.